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Sample records for active-controlled parallel-group study

  1. Efficacy and Safety of FospropofolFD Compared to Propofol When Given During the Induction of General Anaesthesia: A Phase II, Multi-centre, Randomized, Parallel-Group, Active-Controlled, Double-Blind, Double-Dummy Study.

    PubMed

    Liu, Rong; Luo, Chaozhi; Liu, Jin; Zhang, Wensheng; Li, Yan; Xu, Jing

    2016-07-01

    The present phase II study aimed to compare the efficacy and safety of fospropofol disodium for injection (FospropofolFD ) and propofol when given during the induction of general anaesthesia in patients scheduled for elective surgery. FospropofolFD is a water-soluble prodrug of propofol. Approved by the Ethical Committee, 240 participants aged 18-65 years were equally randomly allocated to receive an intravenous bolus of FospropofolFD 20 mg/kg or propofol 2 mg/kg without any anaesthetic pre-treatment. The primary efficacy end-point was the sedation success rate within 5 min. after administering investigational drugs (the sedation success is defined as obtaining Modified Observer's Assessment of Alertness/Sedation scale score of 1). All the participants completed the induction and intubation within 25 min. after administration. The sedation success rates within 5 min. after administration of FospropofolFD 20 mg/kg and propofol 2 mg/kg were 94.50% versus 100% in the intention-to-treat population and 95.10% versus 100% in the per-protocol population, respectively. The non-inferiority test obtained a p-value less than 0.025, and the lower limits of the one-sided 97.5% confidence interval were more than -0.09. This meant that FospropofolFD 20 mg/kg was considered non-inferior to propofol 2 mg/kg for the primary efficacy end-point. Compared with propofol 2 mg/kg, FospropofolFD 20 mg/kg had a slower sedation efficacy. No serious adverse events were observed in the two groups. The sedation success rate within 5 min. after administration of FospropofolFD 20 mg/kg was non-inferior to propofol 2 mg/kg, and FospropofolFD 20 mg/kg can be used for the induction of general anaesthesia safely. PMID:26781338

  2. A Randomized Parallel-Group Dietary Study for Stage II–IV Ovarian Cancer Survivors

    PubMed Central

    Paxton, Raheem J.; Garcia-Prieto, Celia; Berglund, Maria; Hernandez, Mike; Hejek, Richard A.; Handy, Beverly; Brown, Jubilee; Jones, Lovell A.

    2011-01-01

    Background Few studies have examined the dietary habits of ovarian cancer survivors. Therefore, we conducted a study to assess the feasibility and impact of two dietary interventions for ovarian cancer survivors. Methods In this randomized, parallel-group study, 51 women (mean age, 53 years) diagnosed with stage II–IV ovarian cancer were recruited and randomly assigned to a low fat, high fiber (LFHF) diet or a modified National Cancer Institute diet supplemented with a soy-based beverage and encapsulated fruit and vegetable juice concentrates (FVJCs). Changes in clinical measures, serum carotenoid and tocopherol levels, dietary intake, anthropometry, and health-related quality of life (HRQOL) were assessed with paired t-tests. Results The recruitment rate was 25%, and the retention rate was 75% at 6 months. At baseline, 28% and 45% of women met guidelines for intake of fiber and of fruits and vegetables, respectively. After 6 months, total serum carotenoid levels and α- and β-carotene concentrations were significantly increased in both groups (P < 0.01); however, β-carotene concentrations were increased more in the FVJC group. Serum β-cryptoxanthin levels, fiber intake (+5.2 g/day), and daily servings of juice (+0.9 servings/day) and vegetables (+1.3 servings/day) were all significantly increased in the LFHF group (all P < 0.05). Serum levels of albumin, lutein and zeaxanthin, retinol, and retinyl palmitate were significantly increased in the FVJC group (all P < 0.05). No changes in cancer antigen-125, anthropometry, or HRQOL were observed. Conclusion Overall, this study supports the feasibility of designing dietary interventions for stage II–IV ovarian cancer survivors and provides preliminary evidence that a low fat high fiber diet and a diet supplemented with encapsulated FVJC may increase phytonutrients in ovarian cancer survivors. PMID:22119991

  3. Tretinoin Nanogel 0.025% Versus Conventional Gel 0.025% in Patients with Acne Vulgaris: A Randomized, Active Controlled, Multicentre, Parallel Group, Phase IV Clinical Trial

    PubMed Central

    Chandrashekhar, B S; Anitha, M.; Ruparelia, Mukesh; Vaidya, Pradyumna; Aamir, Riyaz; Shah, Sunil; Thilak, S; Aurangabadkar, Sanjeev; Pal, Sandeep; Saraswat, Abir

    2015-01-01

    Background: Conventional topical tretinoin formulation is often associated with local adverse events. Nanogel formulation of tretinoin has good physical stability and enables good penetration of tretinoin into the pilo-sebaceous glands. Aim: The present study was conducted to assess the efficacy and safety of a nanogel formulation of tretinoin as compared to its conventional gel formulation in the treatment of acne vulgaris of the face. Materials and Methods: This randomized, active controlled, multicentric, phase IV clinical trial evaluated the treatment of patients with acne vulgaris of the face by the two gel formulations locally applied once daily at night for 12 wk. Acne lesion counts (inflammatory, non-inflammatory & total) and severity grading were carried out on the monthly scheduled visits along with the tolerability assessments. Results: A total of 207 patients were randomized in the study. Reductions in the total (72.9% vs. 65.0%; p = 0.03) and inflammatory (78.1% vs. 66.9%; p = 0.02) acne lesions were reported to be significantly greater with the nanogel formulation as compared to the conventional gel formulation. Local adverse events were significantly less (p = 0.04) in the nanogel group (13.3%) as compared to the conventional gel group (24.7%). Dryness was the most common adverse event reported in both the treatment groups while peeling of skin, burning sensation and photosensitivity were reported in patients using the conventional gel only. Conclusion: In the treatment of acne vulgaris of the face, tretinoin nanogel formulation appears to be more effective and better tolerated than the conventional gel formulation. PMID:25738069

  4. Supervised Home Training of Dialogue Skills in Chronic Aphasia: A Randomized Parallel Group Study

    ERIC Educational Resources Information Center

    Nobis-Bosch, Ruth; Springer, Luise; Radermacher, Irmgard; Huber, Walter

    2011-01-01

    Purpose: The aim of this study was to prove the efficacy of supervised self-training for individuals with aphasia. Linguistic and communicative performance in structured dialogues represented the main study parameters. Method: In a cross-over design for randomized matched pairs, 18 individuals with chronic aphasia were examined during 12 weeks of…

  5. The Japan Statin Treatment Against Recurrent Stroke (J-STARS): A Multicenter, Randomized, Open-label, Parallel-group Study

    PubMed Central

    Hosomi, Naohisa; Nagai, Yoji; Kohriyama, Tatsuo; Ohtsuki, Toshiho; Aoki, Shiro; Nezu, Tomohisa; Maruyama, Hirofumi; Sunami, Norio; Yokota, Chiaki; Kitagawa, Kazuo; Terayama, Yasuo; Takagi, Makoto; Ibayashi, Setsuro; Nakamura, Masakazu; Origasa, Hideki; Fukushima, Masanori; Mori, Etsuro; Minematsu, Kazuo; Uchiyama, Shinichiro; Shinohara, Yukito; Yamaguchi, Takenori; Matsumoto, Masayasu

    2015-01-01

    Background Although statin therapy is beneficial for the prevention of initial stroke, the benefit for recurrent stroke and its subtypes remains to be determined in Asian, in whom stroke profiles are different from Caucasian. This study examined whether treatment with low-dose pravastatin prevents stroke recurrence in ischemic stroke patients. Methods This is a multicenter, randomized, open-label, blinded-endpoint, parallel-group study of patients who experienced non-cardioembolic ischemic stroke. All patients had a total cholesterol level between 4.65 and 6.21 mmol/L at enrollment, without the use of statins. The pravastatin group patients received 10 mg of pravastatin/day; the control group patients received no statins. The primary endpoint was the occurrence of stroke and transient ischemic attack (TIA), with the onset of each stroke subtype set to be one of the secondary endpoints. Finding Although 3000 patients were targeted, 1578 patients (491 female, age 66.2 years) were recruited and randomly assigned to pravastatin group or control group. During the follow-up of 4.9 ± 1.4 years, although total stroke and TIA similarly occurred in both groups (2.56 vs. 2.65%/year), onset of atherothrombotic infarction was less frequent in pravastatin group (0.21 vs. 0.64%/year, p = 0.0047, adjusted hazard ratio 0.33 [95%CI 0.15 to 0.74]). No significant intergroup difference was found for the onset of other stroke subtypes, and for the occurrence of adverse events. Interpretation Although whether low-dose pravastatin prevents recurrence of total stroke or TIA still needs to be examined in Asian, this study has generated a hypothesis that it may reduce occurrence of stroke due to larger artery atherosclerosis. Funding This study was initially supported by a grant from the Ministry of Health, Labour and Welfare, Japan. After the governmental support expired, it was conducted in collaboration between Hiroshima University and the Foundation for Biomedical Research and

  6. A comparative study of the clinical efficacy and safety of agomelatine with escitalopram in major depressive disorder patients: A randomized, parallel-group, phase IV study

    PubMed Central

    Urade, Chetan S.; Mahakalkar, Sunil M.; Tiple, Prashant G.

    2015-01-01

    Objective: To compare the efficacy of agomelatine with escitalopram in the treatment of major depressive disorder (MDD), improve sleep in MDD patients and study the adverse effects of agomelatine. Materials and Methods: Randomized, parallel-group, open-label study. The primary efficacy outcome was change from baseline to last post-baseline value in Hamilton depression rating scale and Leeds sleep evaluation questionnaire scale. Both parametric and nonparametric tests were applied for analysis. Results: Within-group and between-groups comparison of the mean HAMD17 scores showed statistically significant changes (P < 0.0001). Escitalopram showed early onset of response and remission compared to agomelatine at 10th week (P < 0.0001) and 14th week (P < 0.0001), respectively. In agomelatine, within-group and between-groups change of the mean LSEQ score was statistically significant at subsequent follow-up visits (P < 0.0001). Conclusion: Escitalopram is superior to agomelatine in efficacy, considering the early response, early remission, and better relief from symptoms of MDD in adults. Agomelatine may be preferred in MDD patients having insomnia as a predominant symptom. Liver function monitoring should be done in patients on long-term agomelatine therapy. PMID:26813706

  7. A Randomized, Prospective, Parallel Group Study of Laparoscopic vs. Laparoendoscopic Single Site Donor Nephrectomy for Kidney Donation

    PubMed Central

    Aull, Meredith J.; Afaneh, Cheguevara; Charlton, Marian; Serur, David; Douglas, Melissa; Christos, Paul J.; Kapur, Sandip; Del Pizzo, Joseph J.

    2014-01-01

    Few prospective, randomized studies have assessed benefits of laparoendoscopic single site donor nephrectomy (LESS-DN) over laparoscopic donor nephrectomy (LDN). Our center initiated such a trial in January 2011, following subjects randomized to LESS-DN vs. LDN from surgery through 5 years post-donation. Subjects complete recovery/satisfaction questionnaires at 2, 6, and 12 months post-donation; transplant recipient outcomes are also recorded. 100 subjects (49 LESS-DN, 51 LDN) underwent surgery; donor demographics were similar between groups, and included a predominance of female, living unrelated donors, mean age of 47 years who underwent left donor nephrectomy. Operative parameters (overall time, time to extraction, warm ischemia time, blood loss) were similar between groups. Conversion to hand-assist laparoscopy was required in 3 LESS-DN (6.1%) vs. 2 LDN (3.9%; P=0.67). Questionnaires revealed 97.2% of LESS-DN vs. 79.5% of LDN (P=0.03) were 100% recovered by two months after donation. No significant difference was seen in satisfaction scores between the groups. Recipient outcomes were similar between groups. Our randomized trial comparing LESS donor nephrectomy to LDN confirms that LESS-DN offers a safe alternative to conventional LDN in terms of intra- and post-operative complications. LDN and LESS-DN offer similar recovery and satisfaction after donation. PMID:24934732

  8. Pharmacokinetics of serelaxin in patients with severe renal impairment or end-stage renal disease requiring hemodialysis: A single-dose, open-label, parallel-group study.

    PubMed

    Dahlke, Marion; Halabi, Atef; Canadi, Jasna; Tsubouchi, Chiaki; Machineni, Surendra; Pang, Yinuo

    2016-04-01

    Serelaxin, a recombinant human relaxin-2 hormone, is in clinical development for treating acute heart failure. This open-label, parallel-group study investigated serelaxin pharmacokinetics (PK) after a single 4-hour intravenous infusion (10 µg/kg) in patients with severe renal impairment (n = 6) or end-stage renal disease (ESRD) requiring hemodialysis (PK on the day of dialysis [n = 6] or during dialysis-free interval [n = 6]), compared with matched healthy subjects (n = 18). In all participants, serum serelaxin concentration peaked at the end of infusion and subsequently declined with mean terminal elimination half-life of 6.5-8.8 hours. Compared with healthy subjects, a moderate decrease in serelaxin systemic clearance (37%-52%) and increase in its exposure (30%-115%) were observed in all patients. During the 4-hour hemodialysis in ESRD patients, 30% serelaxin was removed, with hemodialysis clearance constituting approximately 52% of total systemic clearance. Serelaxin was well tolerated with no deaths, serious adverse events (AE), or AE-related discontinuations. Antiserelaxin antibodies were not detected in any participant. Given the shallow dose-response relationship observed with serelaxin in clinical studies and its wide therapeutic window, the observed PK differences in patients with severe renal impairment compared with healthy subjects are unlikely to pose a safety risk and do not warrant a predefined dosage adjustment in such patients. PMID:26239266

  9. A Double-Blind, Placebo-Controlled, Parallel-Group Pilot Study of Milnacipran for Chronic Radicular Pain (Sciatica) Associated With Lumbosacral Disc Disease

    PubMed Central

    Pae, Chi-Un; Patkar, Ashwin A.

    2014-01-01

    Objective: The current study investigates whether milnacipran, an equipotent serotonin-norepinephrine reuptake inhibitor, is effective in reducing chronic radicular pain in patients (N = 11) with lumbosacral disc disease. Method: This study is a 10-week randomized, parallel-group, double-blind, placebo-controlled trial of milnacipran (100–200 mg/d, dosed twice a day). Subjects (enrolled from October 2010 to September 2011 through the Duke University Pain and Palliative Care Clinic, Durham, North Carolina) included patients with radiologically confirmed disc disease with nerve root compression. The primary outcome measure was radicular pain measured by visual analog scale score (VAS-Rad); patients were asked to specifically rate radicular pain (“shooting or electrical or prickly pain in 1 or both legs”). Secondary outcome measures included nociceptive low back pain by visual analog scale (VAS-Noc), Oswestry Low Back Pain Disability Questionnaire, Neuropathic Pain Questionnaire, Medical Outcomes Study (MOS) 36-Item Short-Form Health Survey, Beck Depression Inventory, and State-Trait Anxiety Inventory. Between-group changes in outcome measures between baseline and endpoint were analyzed using Mann-Whitney U nonparametric measure of central tendency. Results: Milnacipran treatment yielded statistically significant reduction in radicular pain (VAS-Rad, P = .01) and nociceptive low back pain (VAS-Noc, P = .04) compared to placebo. No statistically significant between-group differences were observed in the other secondary outcome measures. Conclusions: In this small pilot study, milnacipran treatment was associated with reduction in radicular and nociceptive low back pain in patients with lumbosacral disc disease. Larger studies of milnacipran in this population are warranted. Trial Registration: ClinicalTrials.gov identifier: NCT01777581. PMID:25664215

  10. Iodixanol Has a Favourable Fibrinolytic Profile Compared to Iohexol in Cardiac Patients Undergoing Elective Angiography: A Double-Blind, Randomized, Parallel Group Study

    PubMed Central

    Treweeke, Andrew T.; Maskrey, Benjamin H.; Hickson, Kirsty; Miller, John H.; Leslie, Stephen J.; Megson, Ian L.

    2016-01-01

    Background There is no consensus and a limited evidence base for choice of contrast agents (CA) in angiography. This study evaluated the impact of iohexol and iodixanol CA on fibrinolytic factors (tissue plasminogen activator [t-PA] and plasminogen activator inhibitor-1 [PAI-1]), as well as platelet-monocyte conjugates in cardiac patients undergoing elective angiography in a double-blind, randomised parallel group study. Methods Patients (men, 50–70 years old; n = 12) were randomised to receive either iohexol (Omnipaque; n = 6) or iodixanol (Visipaque; n = 6) during elective angiography at Raigmore Hospital, Inverness, UK. Arterial and venous blood samples were drawn prior to CA delivery and following angiography. Assessment of platelet-monocyte conjugation, t-PA and PAI-1 antigen and activity was conducted in samples pre- and post-angiography. Outcome Plasma t-PA antigen was depressed equally in the study groups after angiography, but there was a greater reduction in PAI-1 antigen in the group receiving iodixanol. These findings corresponded to a substantial reduction in t-PA activity in patients receiving iohexol, with no change in those receiving iodixanol (P = 0.023 between the CA groups). Both CAs caused a reduction in platelet-monocyte conjugation, with no difference between the groups. No adverse events were reported during the trial. Conclusion Avoiding reduced plasma t-PA activity might be an important consideration in choosing iodixanol over iohexol in patients at risk of thrombosis following angiography. The trial is registered on the ISRCTN register (ISRCTN51509735) and funded by the Coronary Thrombosis Trust and National Health Service (Highland) R&D Endowments. The funders had no influence over study design or reporting. Trial Registration Controlled-Trials.com ISRCTN51509735 PMID:26784323

  11. Intake of black-vinegar-mash-garlic enhances salivary release of secretory IgA: A randomized, double-blind, placebo-controlled, parallel-group study

    PubMed Central

    NAKASONE, YASUSHI; SATO, NORIMASA; AZUMA, TAKAYUKI; HASUMI, KEIJI

    2016-01-01

    Several previous studies have provided evidence that suggests the beneficial effects of garlic and black vinegar on human health, including benefits to immune function. The preliminary study indicated that the intake of black-vinegar-mash-garlic-containing food, created from aged garlic pickled in the mash of black vinegar, enhanced the release of secretory immunoglobulin A (sIgA) in the saliva. The aim of the present study was to evaluate the effect of the food in a randomized, double-blind, placebo-controlled, parallel-group trial. The trial was conducted in subjects aged between 30 and 60 years whose rate of salivary sIgA release was moderately low. Subjects consumed 2.49 g of placebo or black-vinegar-mash-garlic-containing food (active food) daily for 8 weeks. The data obtained with 54 eligible subjects (n=28 and 26 for placebo and active, respectively) were analyzed for efficacy. The rates of salivary sIgA release in the active food group (35.9±84.6 and 47.9±123.4 µg/min at weeks 4 and 8 of intake; changes from pretrial value) were higher compared to the respective rates in the placebo food group (−12.3±72.1 and −3.2±85.9 µg/min, P=0.028 and 0.082, respectively). These findings indicate that intake of black-vinegar-mash-garlic-containing food enhanced the intraoral immune response. There was no adverse event associated with the intake of active food. PMID:27347407

  12. Protocol for Cilostazol Stroke Prevention Study for Antiplatelet Combination (CSPS.com): a randomized, open-label, parallel-group trial

    PubMed Central

    Toyoda, Kazunori; Uchiyama, Shinichiro; Hoshino, Haruhiko; Kimura, Kazumi; Origasa, Hideki; Naritomi, Hiroaki; Minematsu, Kazuo; Yamaguchi, Takenori

    2015-01-01

    Rationale and aims Monotherapy with antiplatelet agents is only modestly effective in secondary prevention of ischemic stroke (IS), particularly in patients with multiple risk factors such as cervicocephalic arterial stenosis, diabetes, and hypertension. While dual antiplatelet therapy (DAPT) with aspirin and clopidogrel reduced IS recurrence, particularly in the early stages after IS, it increased the risk of bleeding. Compared with aspirin, cilostazol prevented IS recurrence without increasing the incidence of serious bleeds. In patients with intracranial arterial stenosis, no significant increase in bleeding events was observed for DAPT with cilostazol and aspirin, compared to that for aspirin monotherapy. DAPT involving cilostazol may therefore be safer than conventional DAPT. These findings prompted us to conduct the Cilostazol Stroke Prevention Study for Antiplatelet Combination (CSPS.com; ClinicalTrials.gov identifier: NCT01995370) to evaluate the safety and efficacy of DAPT involving cilostazol for secondary IS prevention, in comparison with that of antiplatelet monotherapy. Design The CSPS.com is a multicenter, randomized, open-label, parallel-group trial. A total of 4000 high-risk patients with noncardioembolic IS will be randomized 8–180 days after onset to receive aspirin or clopidogrel monotherapy, or DAPT with cilostazol and aspirin or clopidogrel for at least one-year. Study outcomes The primary outcome is IS recurrence. Secondary outcomes are composite occurrences of any stroke, death from any cause, myocardial infarction, vascular death, and other vascular events. Discussion The CSPS.com is expected to provide evidence indicating whether secondary IS prevention in high-risk patients can be improved by using DAPT involving cilostazol. PMID:25487817

  13. Twice weekly fluticasone propionate added to emollient maintenance treatment to reduce risk of relapse in atopic dermatitis: randomised, double blind, parallel group study

    PubMed Central

    Berth-Jones, John; Damstra, Robert J; Golsch, Stefan; Livden, John K; Van Hooteghem, Oliver; Allegra, Fulvio; Parker, Christine A

    2003-01-01

    Objective To explore the efficacy and safety of fluticasone propionate, cream and ointment, applied twice weekly in addition to maintenance treatment with emollients, in reducing the risk of relapse of chronic recurrent atopic dermatitis. Design Randomised, double blind, parallel group study of 20 weeks' duration. Setting Dermatology outpatient clinics (6 countries, 39 centres). Participants Adult (aged 12-65) patients with moderate to severe atopic dermatitis who were experiencing a flare. Methods Participants applied fluticasone propionate (0.05% cream or 0.005% ointment; once or twice daily) regularly for four weeks to stabilise their condition. The patients whose disease was brought under control then continued into a 16 week maintenance phase, applying emollient on a daily basis with a bath oil as needed and either the same formulation of fluticasone propionate or its placebo base (emollient alone) twice weekly to the areas that were usually affected. Main outcome measure Time to relapse of atopic dermatitis during maintenance phase. Results 376 patients entered the stabilisation phase, and 295 continued into the maintenance phase. After 16 weeks in the maintenance phase, the disease remained under control in 133 patients (87 using fluticasone propionate twice weekly, 46 using emollient alone), 135 (40 fluticasone propionate, 95 emollient) had experienced a relapse, and 27 had discontinued. Median time to relapse was six weeks for emollient alone compared with more than 16 weeks for additional fluticasone propionate. Patients who applied fluticasone propionate cream twice weekly were 5.8 times less likely (95% confidence interval 3.1 to 10.8, P < 0.001) and patients using fluticasone propionate ointment 1.9 times less likely (1.2 to 3.2, P=0.010) to have a relapse than patients applying emollient alone. The groups showed no differences in adverse events. Conclusion After atopic dermatitis had been stabilised the addition of fluticasone propionate twice weekly

  14. A comparison of mebeverine with high-fibre dietary advice and mebeverine plus ispaghula in the treatment of irritable bowel syndrome: an open, prospectively randomised, parallel group study.

    PubMed

    Chapman, N D; Grillage, M G; Mazumder, R; Atkinson, S N

    1990-11-01

    OBJECTIVE To compare the efficacy and acceptability of mebeverine and high-fibre dietary advice versus mebeverine and ispaghula in fixed combination in the treatment of irritable bowel syndrome in adults. DESIGN Open, prospectively randomised, parallel group comparison of mebeverine/dietary advice and mebeverine/ispaghula during an eight-week study period. SETTING General practices in the UK. PATIENTS One hundred and eleven patients with irritable bowel syndrome diagnosed by symptom profile or negative investigations between the ages of 18 and 75 years were entered. All patients had a history of abdominal pain occurring at least once a week for a period of three months or more. INTERVENTION Dosage was 135 mg of mebeverine hydrochloride, three times daily before meals, together with advice on high-fibre dietary intake, or 135 mg of mebeverine hydrochloride plus 3.5 g of ispaghula husk twice or three times daily before meals. MEASUREMENTS AND RESULTS Details of abdominal pain severity and frequency, bowel frequency and stool consistency were recorded by means of clinicians' assessments and patient diaries. Pre-treatment assessments revealed no significant differences between the two groups with respect to any of the parameters. Both treatment groups demonstrated highly significant improvements in the numbers of pain attacks and their severity; no statistically significant differences between the two groups were demonstrated. Five patients in the mebeverine/dietary advice group reported five concurrent effects and nine patients in the mebeverine/ispaghula group reported 13 concurrent effects. All of the mebeverine/dietary advice group found their treatment acceptable but up to 28% of the mebeverine/ispaghula group found their treatment unpalatable. CONCLUSION Both treatments are effective in the treatment of irritable bowel syndrome in adults. The fixed combination of mebeverine/ispaghula, however, was found to be unpalatable by up to 28% of the patients in that group

  15. Rationale and design of Short-Term EXenatide therapy in Acute ischaemic Stroke (STEXAS): a randomised, open-label, parallel-group study

    PubMed Central

    McGrath, Rachel T; Hocking, Samantha L; Priglinger, Miriam; Day, Susan; Herkes, Geoffrey K; Krause, Martin; Fulcher, Gregory R

    2016-01-01

    Introduction Both hyperglycaemia and hypoglycaemia in acute ischaemic stroke (AIS) are associated with increased infarct size and worse functional outcomes. Thus, therapies that can maintain normoglycaemia during stroke are clinically important. Glucagon-like peptide 1 (GLP-1) analogues, including exenatide, are routinely used in the treatment of hyperglycaemia in type 2 diabetes, but data on the usefulness of this class of agents in the management of elevated glucose levels in AIS are limited. Owing to their glucose-dependent mechanism of action, GLP-1 analogues are associated with a low risk of hypoglycaemia, which may give them an advantage over intensive insulin therapy in the acute management of hyperglycaemia in this setting. Methods and analysis The Short-Term EXenatide therapy in Acute ischaemic Stroke study is a randomised, open-label, parallel-group pilot study designed to investigate the efficacy of exenatide at lowering blood glucose levels in patients with hyperglycaemia with AIS. A total of 30 patients presenting with AIS and blood glucose levels >10 mmol/L will be randomised to receive the standard therapy (intravenous insulin) or intravenous exenatide for up to 72 h. Outcomes including blood glucose levels within the target range (5–10 mmol/L), the incidence of hypoglycaemia and the feasibility of administering intravenous exenatide in this patient population will be assessed. A follow-up visit at 3 months will facilitate evaluation of neurological outcomes post-stroke. Ethics and dissemination This study has been approved by the local Institutional Review Board (Northern Sydney Local Health District Human Research Ethics Committee). The study results will be communicated via presentations at scientific conferences and through publication in peer-reviewed journals. Conclusions As GLP-1 analogues require elevated glucose levels to exert their insulin potentiating activity, the use of exenatide in the management of hyperglycaemia in AIS may

  16. Efficacy and safety of leuprorelin acetate 6-month depot in prostate cancer patients: a Phase III, randomized, open-label, parallel-group, comparative study in Japan

    PubMed Central

    Suzuki, Kazuhiro; Namiki, Mikio; Fujimoto, Tsukasa; Takabayashi, Nobuyoshi; Kudou, Kentarou; Akaza, Hideyuki

    2015-01-01

    Objective Leuprorelin acetate (TAP-144-SR) is commonly used worldwide in prostate cancer patients. This study was conducted to assess the non-inferiority of a 6-month depot formulation of TAP-144-SR (TAP-144-SR [6M]) 22.5 mg to a 3-month depot formulation of TAP-144-SR (TAP-144-SR [3M]) 11.25 mg in prostate cancer patients in Japan. Methods This was a 48-week Phase III, open-label, parallel-group comparative study. TAP-144-SR (6M) 22.5 mg (6M group) and TAP-144-SR (3M) 11.25 mg (3M group) were administered to 81 and 79 subjects, respectively. The primary endpoint was the rate of serum testosterone suppression to the castrate level (≤100 ng/dl). Results Serum testosterone of all subjects excluding one subject in the 3M group was suppressed to the castrate level throughout 48 weeks. The estimated between-group difference (6M group − 3M group) in suppression rate was 1.3% (95% confidence interval: −3.4, 6.8), and its lower confidence interval was more than −10% of the pre-determined allowable limit value to judge the non-inferiority. The prostate-specific antigen concentrations were stable throughout the study in both groups. Progressive disease in the best overall response based on the Response Evaluation Criteria In Solid Tumors was 0.0% for the 6M group and 2.6% for the 3M group. Adverse events occurred in 92.6% in the 6M group and 89.9% in the 3M group. Adverse events leading to discontinuation were reported in 2.5% in the 6M group and 3.8% in the 3M group. Conclusions TAP-144-SR (6M) was not inferior to TAP-144-SR (3M) for the suppressive effect on serum testosterone level. TAP-144-SR (6M) was also as well tolerated as TAP-144-SR (3M). PMID:26486824

  17. The effect of umeclidinium added to inhaled corticosteroid/long-acting β2-agonist in patients with symptomatic COPD: a randomised, double-blind, parallel-group study.

    PubMed

    Sousa, Ana R; Riley, John H; Church, Alison; Zhu, Chang-Qing; Punekar, Yogesh S; Fahy, William A

    2016-01-01

    Benefits of triple therapy with a long-acting muscarinic antagonist (LAMA), added to inhaled corticosteroid (ICS)/long-acting β2-agonist (LABA), have been demonstrated. Limited data assessing the efficacy of the LAMA umeclidinium (UMEC) added to ICS/LABA are available. The aim of this study is to evaluate the efficacy and safety of UMEC added to ICS/LABAs in patients with moderate-to-very-severe COPD. This is a multicentre, randomised, double-blind, parallel-group study. Patients were symptomatic (modified Medical Research Council Dyspnoea Scale score ⩾2), despite receiving ICS/LABA (fluticasone propionate/salmeterol (FP/SAL, branded) 500/50 mcg, budesonide/formoterol (BD/FOR, branded) 200/6 mcg or 400/12 mcg, or other ICS/LABAs) ⩾30 days before the run-in (7±2 days). Patients were randomised 1:1 to once-daily UMEC 62.5 mcg or placebo (PBO), added to twice-daily open-label ICS/LABA for 12 weeks. Primary end point was trough forced expiratory volume in 1 s (FEV1) at Day 85; secondary end point was weighted mean (WM) 0-6 h FEV1 at Day 84; other end points included COPD Assessment Test (CAT) score and Transition Dyspnoea Index (TDI) score. Adverse events (AEs) were investigated. In the UMEC+ICS/LABA and PBO+ICS/LABA groups, 119 and 117 patients were randomised, respectively. Patients received FP/SAL (40%), BD/FOR (43%) and other ICS/LABAs (17%). UMEC+ICS/LABA resulted in significant improvements in trough FEV1 (Day 85) and in WM 0-6 h FEV1 (Day 84) versus PBO+ICS/LABA (difference: 123 and 148 ml, respectively, both P<0.001). Change from baseline for UMEC+ICS/LABA versus PBO+ICS/LABA was significantly different for CAT score at Day 84 (-1.31, P<0.05), but not for TDI score (0.40, P=0.152). AE incidence was similar with UMEC+ICS/LABA (38%) and PBO+ICS/LABA (42%). UMEC+ICS/LABA improved lung function and CAT score in patients with symptomatic COPD versus PBO+ICS/LABA (ClinicalTrials.gov NCT02257372). PMID:27334739

  18. The effect of umeclidinium added to inhaled corticosteroid/long-acting β2-agonist in patients with symptomatic COPD: a randomised, double-blind, parallel-group study

    PubMed Central

    Sousa, Ana R; Riley, John H; Church, Alison; Zhu, Chang-Qing; Punekar, Yogesh S; Fahy, William A

    2016-01-01

    Benefits of triple therapy with a long-acting muscarinic antagonist (LAMA), added to inhaled corticosteroid (ICS)/long-acting β2-agonist (LABA), have been demonstrated. Limited data assessing the efficacy of the LAMA umeclidinium (UMEC) added to ICS/LABA are available. The aim of this study is to evaluate the efficacy and safety of UMEC added to ICS/LABAs in patients with moderate-to-very-severe COPD. This is a multicentre, randomised, double-blind, parallel-group study. Patients were symptomatic (modified Medical Research Council Dyspnoea Scale score ⩾2), despite receiving ICS/LABA (fluticasone propionate/salmeterol (FP/SAL, branded) 500/50 mcg, budesonide/formoterol (BD/FOR, branded) 200/6 mcg or 400/12 mcg, or other ICS/LABAs) ⩾30 days before the run-in (7±2 days). Patients were randomised 1:1 to once-daily UMEC 62.5 mcg or placebo (PBO), added to twice-daily open-label ICS/LABA for 12 weeks. Primary end point was trough forced expiratory volume in 1 s (FEV1) at Day 85; secondary end point was weighted mean (WM) 0–6 h FEV1 at Day 84; other end points included COPD Assessment Test (CAT) score and Transition Dyspnoea Index (TDI) score. Adverse events (AEs) were investigated. In the UMEC+ICS/LABA and PBO+ICS/LABA groups, 119 and 117 patients were randomised, respectively. Patients received FP/SAL (40%), BD/FOR (43%) and other ICS/LABAs (17%). UMEC+ICS/LABA resulted in significant improvements in trough FEV1 (Day 85) and in WM 0–6 h FEV1 (Day 84) versus PBO+ICS/LABA (difference: 123 and 148 ml, respectively, both P<0.001). Change from baseline for UMEC+ICS/LABA versus PBO+ICS/LABA was significantly different for CAT score at Day 84 (−1.31, P<0.05), but not for TDI score (0.40, P=0.152). AE incidence was similar with UMEC+ICS/LABA (38%) and PBO+ICS/LABA (42%). UMEC+ICS/LABA improved lung function and CAT score in patients with symptomatic COPD versus PBO+ICS/LABA (ClinicalTrials.gov NCT02257372). PMID:27334739

  19. Budesonide/formoterol as effective as prednisolone plus formoterol in acute exacerbations of COPD A double-blind, randomised, non-inferiority, parallel-group, multicentre study

    PubMed Central

    Ställberg, Björn; Selroos, Olof; Vogelmeier, Claus; Andersson, Eva; Ekström, Tommy; Larsson, Kjell

    2009-01-01

    Background Oral corticosteroids and inhaled bronchodilators with or without antibiotics represent standard treatment of COPD exacerbations of moderate severity. Frequent courses of oral steroids may be a safety issue. We wanted to evaluate in an out-patient setting whether a 2-week course of inhaled budesonide/formoterol would be equally effective for treatment of acute COPD exacerbations as standard therapy in patients judged by the investigator not to require hospitalisation. Methods This was a double-blind, randomised, non-inferiority, parallel-group, multicentre study comparing two treatment strategies; two weeks' treatment with inhaled budesonide/formoterol (320/9 μg, qid) was compared with prednisolone (30 mg once daily) plus inhaled formoterol (9 μg bid) in patients with acute exacerbations of COPD attending a primary health care centre. Inclusion criteria were progressive dyspnoea for less than one week, FEV1 30–60% of predicted normal after acute treatment with a single dose of oral corticosteroid plus nebulised salbutamol/ipratropium bromide and no requirement for subsequent immediate hospitalisation, i.e the clinical status after the acute treatment allowed for sending the patient home. A total of 109 patients (mean age 67 years, 33 pack-years, mean FEV1 45% of predicted) were randomized to two weeks' double-blind treatment with budesonide/formoterol or prednisolone plus formoterol and subsequent open-label budesonide/formoterol (320/9 μg bid) for another 12 weeks. Change in FEV1 was the primary efficacy variable. Non-inferiority was predefined. Results Non-inferiority of budesonide/formoterol was proven because the lower limit of FEV1-change (97.5% CI) was above 90% of the efficacy of the alternative treatment. Symptoms, quality of life, treatment failures, need for reliever medication (and exacerbations during follow-up) did not differ between the groups. No safety concerns were identified. Conclusion High dose budesonide/formoterol was as

  20. Comparison of usual podiatric care and early physical therapy intervention for plantar heel pain: study protocol for a parallel-group randomized clinical trial

    PubMed Central

    2013-01-01

    Background A significant number of individuals suffer from plantar heel pain (PHP) and many go on to have chronic symptoms and continued disability. Persistence of symptoms adds to the economic burden of PHP and cost-effective solutions are needed. Currently, there is a wide variation in treatment, cost, and outcomes of care for PHP with limited information on the cost-effectiveness and comparisons of common treatment approaches. Two practice guidelines and recent evidence of effective physical therapy intervention are available to direct treatment but the timing and influence of physical therapy intervention in the multidisciplinary management of PHP is unclear. The purpose of this investigation is to compare the outcomes and costs associated with early physical therapy intervention (ePT) following initial presentation to podiatry versus usual podiatric care (uPOD) in individuals with PHP. Methods A parallel-group, block-randomized clinical trial will compare ePT and uPOD. Both groups will be seen initially by a podiatrist before allocation to a group that will receive physical therapy intervention consisting primarily of manual therapy, exercise, and modalities, or podiatric care consisting primarily of a stretching handout, medication, injections, and orthotics. Treatment in each group will be directed by practice guidelines and a procedural manual, yet the specific intervention for each participant will be selected by the treating provider. Between-group differences in the Foot and Ankle Ability Measure 6 months following the initial visit will be the primary outcome collected by an independent investigator. In addition, differences in the European Quality of Life – Five Dimensions, Numeric Pain Rating Scale, Global Rating of Change (GROC), health-related costs, and cost-effectiveness at 6 weeks, 6 months, and 1 year will be compared between groups. The association between successful outcomes based on GROC score and participant expectations of recovery

  1. Comparison of methimazole/hydrocortisone ointment with oral methimazole in patients with graves disease: A prospective, randomized, open-label, parallel-group, 18-month study

    PubMed Central

    Chen, Ling; Wang, Hong-qing; Gao, Yan-yan; Liang, Jun; Wang, Men; Bai, Jie; Qi, Wen-bo; Zhang, Jun-sheng; Zhang, Jian; Ren, Juan-qing; Li, Hui-qing

    2008-01-01

    Background: Thionamide antithyroid drugs (ATDs) have certain disadvantages and are associated with some adverse events (AEs). To overcome the problems associated with ATDs, a compound antithyroid ointment (CATO) containing methimazole (MMI) and hydrocortisone has been developed for use as a local thyroid treatment (LTT). Objective: The aim of this study was to assess the clinical effectiveness and tolerability of CATO LTT in patients with Graves disease (GD). Methods: This was a prospective, randomized, open-label, parallel-group clinical trial conducted at the Provincial Hospital Affiliated to Shandong University (Jinan, China). Patients with GD aged 19 to 65 years were randomized to receive either CATO LTT 0.3 g/d or oral MMI 37.5 mg/d (control group) treatment for 18 months, with a 4-year follow-up period. Hyperthyroid symptoms, thyroid function, granulocyte count, liver function, and AEs were assessed at baseline and every 2 weeks until serum thyroid hormone (TH) concentration normalized, at which point patients were assessed monthly. The primary efficacy end points were the duration of treatment required for serum TH concentration to normalize and the remission rate after completing the 18-month treatment regimen. Results: A total of 154 patients (133 women, 21 men; mean [SD] age, 39.6 [11.8] years; all Han Chinese) participated in the study; all patients completed the 18-month treatment period. Compared with the MMI group (n 76), the CATO- treated group (n 78) had a significantly shorter median (range) time to restoration of normal serum thyroid hormone concentration (43 [12–150] vs 22 [7–60] days; P < 0.001), a significantly lower rate of recurrence of hyperthyroidism (309/1520 [20.3%] vs 193/1368 [14.1%] person-time; P < 0.001), a significantly lower drug hypothyroidism rate (185/1520 [12.2%] vs 54/1368 [3.9%] person-time; P < 0.001), and a higher remission rate (year 1:46/69 [66.7%] vs 65/72 [90.3%] patients, P 0.001; year 2:40/69 [58.0%] vs 60/72 [83

  2. Study to eliminate ground resonance using active controls

    NASA Technical Reports Server (NTRS)

    Straub, F. K.

    1984-01-01

    The effectiveness of active control blade feathering in increasing rotor body damping and the possibility to eliminate ground resonance instabilities were investigated. An analytical model representing rotor flapping and lead-lag degrees of freedom and body pitch, roll, longitudinal and lateral motion is developed. Active control blade feathering is implemented as state variable feedback through a conventional swashplate. The influence of various feedback states, feedback gain, and weighting between the cyclic controls is studied through stability and response analyses. It is shown that blade cyclic inplane motion, roll rate and roll acceleration feedback can add considerable damping to the system and eliminate ground resonance instabilities, which the feedback phase is also a powerful parameter, if chosen properly, it maximizes augmentation of the inherent regressing lag mode damping. It is shown that rotor configuration parameters, like blade root hinge offset, flapping stiffness, and precone considerably influence the control effectiveness. It is found that active control is particularly powerful for hingeless and bearingless rotor systems.

  3. An Open Label Parallel Group Study to Assess the Effects of Amlodipine and Cilnidipine on Pulse Wave Velocity and Augmentation Pressures in Mild to Moderate Essential Hypertensive Patients

    PubMed Central

    Rajashekar, Sujith Tumkur; Buchineni, Madhavulu; Meriga, Rajesh Kumar; Reddy, Chirra Bhakthavasthala; Kumar, Kolla Praveen

    2015-01-01

    Introduction Hypertension is a major cardiovascular risk factor, which affects both large and small arteries. Because of the associated morbidity and mortality and the cost to society, it is an important public health challenge. Population based studies have reported that large artery stiffness is an important determinant of cardiovascular events and mortality in general population and in patients with hypertension. This study was designed to compare the effects of 8 weeks blood pressure control using Amlodepine and cilnidipine on haemodynamic parameters and vascular indices in mild to moderate hypertensive patients. Materials and Methods A total of 60 patients were enrolled in the study. Thirty patients were randomly allocated to either Amlodipine 5 mg OD or Cilnidipine 10 mg OD for duration of eight weeks. Blood Pressure (BP), Heart Rate (HR), carotid-femoral Pulse Wave Velocity (cf PWV), Augmentation Index (AIx) and Aortic augmentation pressure (AoAP) were measured at baseline and at the end of eight weeks. Results The mean change in the central artery stiffness from baseline to week-8 in the Amlodipine group as compared to Cilnidipine group cf PWV -139.3±27.7 vs. -234.1±74.8 cm/s p=<0.0001, AoAP -3.8±1.5 vs. -5.6±3.3 mm of Hg p=0.008 and AIx -6.8±2.4 vs. -10.8±4.4 %, p=<0.0001 respectively. Conclusion This study showed that the L/N-type calcium channel antagonist Cilnidipine has a similar antihypertensive action to Amlodipine, but is superior in improving the arterial stiffness. PMID:26676157

  4. Fixed combination of cinnarizine and dimenhydrinate versus betahistine dimesylate in the treatment of Ménière's disease: a randomized, double-blind, parallel group clinical study.

    PubMed

    Novotný, Miroslav; Kostrica, Rom

    2002-01-01

    In a randomized, double-blind clinical study, we evaluated the efficacy and tolerability of the fixed combination of cinnarizine, 20 mg, and dimenhydrinate, 40 mg (Arlevert [ARL]) in comparison to betahistine dimesylate (12 mg) in 82 patients suffering from Ménière's disease for at least 3 months and showing the characteristic triad of symptoms (paroxysmal vertigo attacks, cochlear hearing loss, and tinnitus). The treatment (one tablet three times daily) extended to 12 weeks, with control visits at 1, 3, 6, and 12 weeks after drug intake. The study demonstrated for both the fixed-combination ARL and for betahistine a highly efficient reduction of vertigo symptoms in the course of the 12 weeks of treatment; however, no statistically significant difference between the two treatment groups could be established. Similar results were found for tinnitus (approximately 60% reduction) and for the associated vegetative symptoms (almost complete disappearance). Vestibulospinal reactions, recorded by means of craniocorpography, also improved distinctly, with a statistically significant superiority of ARL versus betahistine (p < .042) for the parameter of lateral sway (Unterberger's test). The caloric tests (electronystagmography) showed only minor changes for both treatment groups in the course of the study. A statistically significant improvement of hearing function of the affected ear (p = .042) was found for the combination preparation after 12 weeks of treatment. The tolerability was judged by the vast majority of patients (97.5%) in both groups to be very good. Only one patient (betahistine group) reported a nonserious adverse event, and two betahistine patients did not complete the study. In conclusion, the combination preparation proved to be a highly efficient and safe treatment option for Ménière's disease and may be used both in the management of acute episodes and in long-term treatment. Efficacy and safety were found to be similar to the widely used standard

  5. Itolizumab in combination with methotrexate modulates active rheumatoid arthritis: safety and efficacy from a phase 2, randomized, open-label, parallel-group, dose-ranging study.

    PubMed

    Chopra, Arvind; Chandrashekara, S; Iyer, Rajgopalan; Rajasekhar, Liza; Shetty, Naresh; Veeravalli, Sarathchandra Mouli; Ghosh, Alakendu; Merchant, Mrugank; Oak, Jyotsna; Londhey, Vikram; Barve, Abhijit; Ramakrishnan, M S; Montero, Enrique

    2016-04-01

    The objective of this study was to assess the safety and efficacy of itolizumab with methotrexate in active rheumatoid arthritis (RA) patients who had inadequate response to methotrexate. In this open-label, phase 2 study, 70 patients fulfilling American College of Rheumatology (ACR) criteria and negative for latent tuberculosis were randomized to four arms: 0.2, 0.4, or 0.8 mg/kg itolizumab weekly combined with oral methotrexate, and methotrexate alone (2:2:2:1). Patients were treated for 12 weeks, followed by 12 weeks of methotrexate alone during follow-up. Twelve weeks of itolizumab therapy was well tolerated. Forty-four patients reported adverse events (AEs); except for six severe AEs, all others were mild or moderate. Infusion-related reactions mainly occurred after the first infusion, and none were reported after the 11th infusion. No serum anti-itolizumab antibodies were detected. In the full analysis set, all itolizumab doses showed evidence of efficacy. At 12 weeks, 50 % of the patients achieved ACR20, and 58.3 % moderate or good 28-joint count Disease Activity Score (DAS-28) response; at week 24, these responses were seen in 22 and 31 patients. Significant improvements were seen in Short Form-36 Health Survey and Health Assessment Questionnaire Disability Index scores. Overall, itolizumab in combination with methotrexate was well tolerated and efficacious in RA for 12 weeks, with efficacy persisting for the entire 24-week evaluation period. (Clinical Trial Registry of India, http://ctri.nic.in/Clinicaltrials/login.php , CTRI/2008/091/000295). PMID:26050104

  6. Efficacy and safety of two pH-dependent-release mesalamine doses in moderately active ulcerative colitis: a multicenter, randomized, double-blind, parallel-group study

    PubMed Central

    Suzuki, Yasuo; Iida, Mitsuo; Ito, Hiroaki; Saida, Isamu

    2016-01-01

    Background/Aims The therapeutic effect of mesalamine is considered to be dose-dependent; however, no consensus has been reached regarding the optimal doses for individual patients. This study aimed to provide new insight for dose optimization using two doses of pH-dependent release mesalamine for induction of remission of moderately active ulcerative colitis (UC). Methods In a multicenter, double-blind, randomized study, 110 patients with moderately active UC were assigned to two groups after treatment with a constant dose of mesalamine. Fifty-five patients were treated with a pH-dependent release formulation of 3.6 or 4.8 g/day for 8 weeks. The primary endpoint was a decrease in the UC disease activity index (UCDAI) adjusted by covariates. Results In the full analysis set (n=110), the mean decrease in UCDAI was 3.1 in the 3.6 g/day group and 3.4 in the 4.8 g/day group (P>0.05). In a subgroup analysis, the effectiveness of the 4.8 g/day dose was greater in particular populations, such as those who had been previously treated with a lower dose of mesalamine and those with more severe disease. The safety was comparable between the two groups. Conclusions The results suggest that treatment with pH-dependent release mesalamine at either 3.6 or 4.8 g/day was effective and safe for the induction of remission in patients with moderately active UC. However, the patients receiving mesalamine at 2.4 g/day but in whom the therapeutic effect is not sufficient and having more severe symptoms (UCDAI 9-10), benefit from higher doses of mesalamine compared to others. PMID:26884735

  7. The effect of Helicobacter pylori infection and eradication in patients with gastro-oesophageal reflux disease: A parallel-group, double-blind, placebo-controlled multicentre study

    PubMed Central

    Menne, Dieter; Schütze, Kurt; Vieth, Michael; Goergens, Reiner; Malfertheiner, Peter; Leodolter, Andreas; Fried, Michael; Fox, Mark R

    2013-01-01

    Objectives This study aimed to resolve controversy regarding the effects of Helicobacter pylori eradication therapy and H. pylori infection in gastro-oesophageal reflux disease. Design A randomized, double-blind, multicentre trial was performed in patients presenting with reflux symptoms. H. pylori-positive patients were randomized to receive either antibiotics or placebo for 7 days. H. pylori-negative patient controls received placebo. All received esomeprazole 20 mg b.d. for 7 days, followed by 40 mg o.d. to complete an 8-week course, and were followed up for 32 weeks by telephone. Results In this study, 198/589 (34%) patients were H. pylori-positive and 113 H. pylori-negative patients served as controls. Baseline endoscopy revealed 63% Los Angeles grade 0A and 37% Los Angeles grade BCD oesophagitis with no difference between patient groups. Symptom improvement on esomeprazole was seen in 89%. H. pylori eradication was successful in 82%. H. pylori eradication had no effect on symptomatic relapse (hazard ratio 1.15, 95% CI 0.74–1.8; p = 0.5). Overall, H. pylori-positive patients had a lower probability of relapse compared to H. pylori-negative controls (hazard ratio 0.6, 95% CI 0.43–0.85; p = 0.004). Relapse hazard was modulated also by oesophagitis grade (BCD vs. 0A, hazard ratio 2.1, 95% CI 1.5–3.0). Conclusion Relapse of gastro-oesophageal reflux disease symptoms after a course of high dose acid suppression took longer for H. pylori-positive patients than H. pylori-negative controls; however eradication therapy had no effect on the risk of relapse; ClincialTrials.gov number, NCT00574925. PMID:24917966

  8. Sitagliptin versus mitiglinide switched from mealtime dosing of a rapid-acting insulin analog in patients with type 2 diabetes: a randomized, parallel-group study

    PubMed Central

    Takeshita, Yumie; Takamura, Toshinari; Kita, Yuki; Takazakura, Akiko; Kato, Ken-ichiro; Isobe, Yuki; Kaneko, Shuichi

    2015-01-01

    Purpose We determined the feasibility of substituting sitagliptin or mitiglinide for bolus insulin injection therapy in patients with type 2 diabetes. Methods 60 patients with type 2 diabetes were enrolled and randomized to switch from mealtime dosing of a rapid-acting insulin analog to either sitagliptin or mitiglinide for 16 weeks. Results Body weight, body mass index, and waist circumference decreased significantly in both groups at the end of the study. Mitiglinide significantly increased fasting plasma glucose (FPG) levels at the end of the study from 146.5±36.3 to 168.0±38.8 mg/dL, whereas sitagliptin did not affect FPG. Glycated hemoglobin (HbA1c) and 1,5-anhydroglucitol increased significantly in both groups. The C peptide immunoreactivity (CPR) responses after arginine were diminished in both groups. γ-GTP and triglycerides increased, and high-density lipoprotein cholesterol and adiponectin decreased, in the sitagliptin group, but not in the mitiglinide group. Mean Diabetes Treatment Satisfaction Questionnaire scores improved significantly in both groups. Patients whose mean total daily doses of rapid-acting insulin analog were 16.6 and 17.8 units were switched to sitagliptin and mitiglinide, respectively, without a change in the HbA1c level. Total insulin doses/body weight predicted changes in HbA1c only in the sitagliptin group, but not in the mitiglinide group. Use of >0.27 IU/kg of a rapid-acting insulin analog predicted an increase in HbA1c after switching to sitagliptin. The CPR index (CPI) was also a predictor for a change in HbA1c in the sitagliptin group, but not in the mitiglinide group; patients with a CPI<1.4 developed a worse HbA1c after switching to sitagliptin. Conclusions Sitagliptin may predominantly act on FPG, whereas mitiglinide may act on postprandial plasma glucose to achieve glycemic control after switching from a bolus insulin regimen. Additional therapy to sitagliptin or mitiglinide is clearly required to obtain

  9. Efficacy of Diosmectite (Smecta)® in the Treatment of Acute Watery Diarrhoea in Adults: A Multicentre, Randomized, Double-Blind, Placebo-Controlled, Parallel Group Study

    PubMed Central

    Khediri, Faouzi; Mrad, Abdennebi Ilhem; Azzouz, Moussadek; Doughi, Hedi; Najjar, Taoufik; Mathiex-Fortunet, Hélène; Garnier, Philippe; Cortot, Antoine

    2011-01-01

    Background. Although diosmectite has demonstrated efficacy in the treatment of acute watery diarrhoea in children, its efficacy in adults still needs to be assessed. The objective of this study was therefore to assess the efficacy of diosmectite on the time to recovery in adults with acute diarrhoea. Methods. A total of 346 adults with at least three watery stools per day over a period of less than 48 hours were prospectively randomized to diosmectite (6 g tid) or placebo during four days. The primary endpoint was time to diarrhoea recovery. Results. In the intention-to-treat population, median time to recovery was 53.8 hours (range [3.7–167.3]) with diosmectite (n = 166) versus 69.0 hours [2.2–165.2] with placebo, (n = 163; P = .029), which corresponds to a difference of 15.2 hours. Diosmectite was well tolerated. Conclusion. Diosmectite at 6 g tid was well tolerated and reduced the time to recovery of acute watery diarrhoea episode in a clinically relevant manner. PMID:21760777

  10. Confirmatory double-blind, parallel-group, placebo-controlled study of efficacy and safety of edaravone (MCI-186) in amyotrophic lateral sclerosis patients

    PubMed Central

    Itoyama, Yasuto; Sobue, Gen; Tsuji, Shoji; Aoki, Masashi; Doyu, Manabu; Hamada, Chikuma; Kondo, Kazuoki; Yoneoka, Takatomo; Akimoto, Makoto; Yoshino, Hiide

    2014-01-01

    n Our objective was to confirm the efficacy and safety of edaravone in amyotrophic lateral sclerosis (ALS) patients. We conducted a 36-week confirmatory study, consisting of 12-week pre-observation period followed by 24-week treatment period. Patients received placebo or edaravone i.v. infusion over 60 min for the first 14 days in cycle 1, and for 10 of the first 14 days during cycles 2 to 6. The efficacy primary endpoint was changed in the revised ALS functional rating scale (ALSFRS-R) scores during the 24-week treatment. Patients were treated with placebo (n = 104) and edaravone (n = 102). Changes in ALSFRS-R during the 24-week treatment were −6.35 ± 0.84 in the placebo group (n = 99) and −5.70 ± 0.85 in the edaravone group (n = 100), with a difference of 0.65 ± 0.78 (p = 0.411). Adverse events amounted to 88.5% (92/104) in the placebo group and 89.2% (91/102) in the edaravone group. In conclusion, the reduction of ALSFRS-R was smaller in the edaravone group than in the placebo group, but efficacy of edaravone for treatment of ALS was not demonstrated. Levels and frequencies of reported adverse events were similar in the two groups. PMID:25286015

  11. Achieving lipid goals with rosuvastatin compared with simvastatin in high risk patients in real clinical practice: a randomized, open-label, parallel-group, multi-center study: the DISCOVERY-Beta study.

    PubMed

    Laks, Toivo; Keba, Ester; Leiner, Mariann; Merilind, Eero; Petersen, Mall; Reinmets, Sirje; Väli, Sille; Sööt, Terje; Otter, Karin

    2008-01-01

    The aim of this multi-center, open-label, randomized, parallel-group trial was to compare the efficacy of rosuvastatin with that of simvastatin in achieving the 1998 European Atherosclerosis Society (EAS) lipid treatment goals. 504 patients (> or =18 years) with primary hypercholesterolemia and a 10-year cardiovascular (CV) risk >20% or history of coronary heart disease (CHD) or other established atherosclerotic disease were randomized in a 2:1 ratio to receive rosuvastatin 10 mg or simvastatin 20 mg once daily for 12 weeks. A significantly higher proportion of patients achieved 1998 EAS low-density lipoprotein cholesterol (LDL-C) goal after 12 weeks of treatment with rosuvastatin 10 mg compared to simvastatin 20 mg (64 vs 51.5%, p < 0.01). Similarly, significantly more patients achieved the 1998 EAS total cholesterol (TC) goal and the 2003 EAS LDL-C and TC goals (p < 0.001) with rosuvastatin 10 mg compared with simvastatin 20 mg. The incidence of adverse events and the proportion of patients who discontinued study treatment were similar between treatment groups. In conclusion, in the DISCOVERY-Beta Study in patients with primary hypercholesterolemia greater proportion of patients in the rosuvastatin 10 mg group achieved the EAS LDL-C treatment goal compared with the simvastatin 20 mg group. Drug tolerability was similar across both treatment groups. PMID:19337553

  12. Achieving lipid goals with rosuvastatin compared with simvastatin in high risk patients in real clinical practice: a randomized, open-label, parallel-group, multi-center study: the DISCOVERY-Beta study

    PubMed Central

    Laks, Toivo; Keba, Ester; Leiner, Mariann; Merilind, Eero; Petersen, Mall; Reinmets, Sirje; Väli, Sille; Sööt, Terje; Otter, Karin

    2008-01-01

    The aim of this multi-center, open-label, randomized, parallel-group trial was to compare the efficacy of rosuvastatin with that of simvastatin in achieving the 1998 European Atherosclerosis Society (EAS) lipid treatment goals. 504 patients (≥18 years) with primary hypercholesterolemia and a 10-year cardiovascular (CV) risk >20% or history of coronary heart disease (CHD) or other established atherosclerotic disease were randomized in a 2:1 ratio to receive rosuvastatin 10 mg or simvastatin 20 mg once daily for 12 weeks. A significantly higher proportion of patients achieved 1998 EAS low-density lipoprotein cholesterol (LDL-C) goal after 12 weeks of treatment with rosuvastatin 10 mg compared to simvastatin 20 mg (64 vs 51.5%, p < 0.01). Similarly, significantly more patients achieved the 1998 EAS total cholesterol (TC) goal and the 2003 EAS LDL-C and TC goals (p < 0.001) with rosuvastatin 10 mg compared with simvastatin 20 mg. The incidence of adverse events and the proportion of patients who discontinued study treatment were similar between treatment groups. In conclusion, in the DISCOVERY-Beta Study in patients with primary hypercholesterolemia greater proportion of patients in the rosuvastatin 10 mg group achieved the EAS LDL-C treatment goal compared with the simvastatin 20 mg group. Drug tolerability was similar across both treatment groups. PMID:19337553

  13. Safety and pharmacokinetics of single and multiple intravenous bolus doses of diclofenac sodium compared with oral diclofenac potassium 50 mg: A randomized, parallel-group, single-center study in healthy subjects.

    PubMed

    Munjal, Sagar; Gautam, Anirudh; Okumu, Franklin; McDowell, James; Allenby, Kent

    2016-01-01

    In a randomized, parallel-group, single-center study in 42 healthy adults, the safety and pharmacokinetic parameters of an intravenous formulation of 18.75 and 37.5 mg diclofenac sodium (DFP-08) following single- and multiple-dose bolus administration were compared with diclofenac potassium 50 mg oral tablets. Mean AUC0-inf values for a 50-mg oral tablet and an 18.75-mg intravenous formulation were similar (1308.9 [393.0]) vs 1232.4 [147.6]). As measured by the AUC, DFP-08 18.75 mg and 37.5 mg demonstrated dose proportionality for extent of exposure. One subject in each of the placebo and DFP-08 18.75-mg groups and 2 subjects in the DFP-08 37.5-mg group reported adverse events that were considered by the investigator to be related to the study drug. All were mild in intensity and did not require treatment. Two subjects in the placebo group and 1 subject in the DFP-08 18.75-mg group reported grade 1 thrombophlebitis; no subjects reported higher than grade 1 thrombophlebitis after receiving a single intravenous dose. The 18.75- and 37.5-mg doses of intravenous diclofenac (single and multiple) were well tolerated for 7 days. Additional efficacy and safety studies are required to fully characterize the product. PMID:26096889

  14. A randomised, double-blind, parallel-group study to demonstrate equivalence in efficacy and safety of CT-P13 compared with innovator infliximab when coadministered with methotrexate in patients with active rheumatoid arthritis: the PLANETRA study

    PubMed Central

    Yoo, Dae Hyun; Hrycaj, Pawel; Miranda, Pedro; Ramiterre, Edgar; Piotrowski, Mariusz; Shevchuk, Sergii; Kovalenko, Volodymyr; Prodanovic, Nenad; Abello-Banfi, Mauricio; Gutierrez-Ureña, Sergio; Morales-Olazabal, Luis; Tee, Michael; Jimenez, Renato; Zamani, Omid; Lee, Sang Joon; Kim, HoUng; Park, Won; Müller-Ladner, Ulf

    2013-01-01

    Objectives To compare the efficacy and safety of innovator infliximab (INX) and CT-P13, an INX biosimilar, in active rheumatoid arthritis patients with inadequate response to methotrexate (MTX) treatment. Methods Phase III randomised, double-blind, multicentre, multinational, parallel-group study. Patients with active disease despite MTX (12.5–25 mg/week) were randomised to receive 3 mg/kg of CT-P13 (n=302) or INX (n=304) with MTX and folic acid. The primary endpoint was the American College of Rheumatology 20% (ACR20) response at week 30. Therapeutic equivalence of clinical response according to ACR20 criteria was concluded if the 95% CI for the treatment difference was within ±15%. Secondary endpoints included ACR response criteria, European League Against Rheumatism (EULAR) response criteria, change in Disease Activity Score 28 (DAS28), Medical Outcomes Study Short-Form Health Survey (SF-36), Simplified Disease Activity Index, Clinical Disease Activity Index, as well as pharmacokinetic (PK) and pharmacodynamic (PD) parameters, safety and immunogenicity. Results At week 30, ACR20 responses were 60.9% for CT-P13 and 58.6% for INX (95% CI −6% to 10%) in the intention-to-treat population. The proportions in CT-P13 and INX groups achieving good or moderate EULAR responses (C reactive protein (CRP)) at week 30 were 85.8% and 87.1%, respectively. Low disease activity or remission according to DAS28–CRP, ACR–EULAR remission rates, ACR50/ACR70 responses and all other PK and PD endpoints were highly similar at week 30. Incidence of drug-related adverse events (35.2% vs 35.9%) and detection of antidrug antibodies (48.4% vs 48.2%) were highly similar for CT-P13 and INX, respectively. Conclusions CT-P13 demonstrated equivalent efficacy to INX at week 30, with a comparable PK profile and immunogenicity. CT-P13 was well tolerated, with a safety profile comparable with that of INX. ClinicalTrials.gov Identifier NCT01217086 PMID:23687260

  15. A randomised, double-blind, multicentre, parallel-group, prospective study comparing the pharmacokinetics, safety, and efficacy of CT-P13 and innovator infliximab in patients with ankylosing spondylitis: the PLANETAS study

    PubMed Central

    Park, Won; Hrycaj, Pawel; Jeka, Slawomir; Kovalenko, Volodymyr; Lysenko, Grygorii; Miranda, Pedro; Mikazane, Helena; Gutierrez-Ureña, Sergio; Lim, MieJin; Lee, Yeon-Ah; Lee, Sang Joon; Kim, HoUng; Yoo, Dae Hyun; Braun, Jürgen

    2013-01-01

    Objectives To compare the pharmacokinetics (PK), safety and efficacy of innovator infliximab (INX) and CT-P13, a biosimilar to INX, in patients with active ankylosing spondylitis (AS). Methods Phase 1 randomised, double-blind, multicentre, multinational, parallel-group study. Patients were randomised to receive 5 mg/kg of CT-P13 (n=125) or INX (n=125). Primary endpoints were area under the concentration-time curve (AUC) at steady state and observed maximum steady state serum concentration (Cmax,ss) between weeks 22 and 30. Additional PK, efficacy endpoints, including 20% and 40% improvement response according to Assessment in Ankylosing Spondylitis International Working Group criteria (ASAS20 and ASAS40), and safety outcomes were also assessed. Results Geometric mean AUC was 32 765.8 μgh/ml for CT-P13 and 31 359.3 μgh/ml for INX. Geometric mean Cmax,ss was 147.0  μg/ml for CT-P13 and 144.8 μg/ml for INX. The ratio of geometric means was 104.5% (90% CI 94% to 116%) for AUC and 101.5% (90% CI 95% to 109%) for Cmax,ss. ASAS20 and ASAS40 responses at week 30 were 70.5% and 51.8% for CT-P13 and 72.4% and 47.4% for INX, respectively. In the CT-P13 and INX groups more than one adverse event occurred in 64.8% and 63.9% of patients, infusion reactions occurred in 3.9% and 4.9%, active tuberculosis occurred in 1.6% and 0.8%, and 27.4% and 22.5% of patients tested positive for anti-drug antibodies, respectively. Conclusions The PK profiles of CT-P13 and INX were equivalent in patients with active AS. CT-P13 was well tolerated, with an efficacy and safety profile comparable to that of INX up to week 30. PMID:23687259

  16. Ketoprofen versus paracetamol (acetaminophen) or ibuprofen in the management of fever: results of two randomized, double-blind, double-dummy, parallel-group, repeated-dose, multicentre, phase III studies in children.

    PubMed

    Kokki, Hannu; Kokki, Merja

    2010-01-01

    Fever is a common symptom in children and one of the major concerns of parents of younger and preschool-age children. To compare the efficacy and safety of ketoprofen with that of paracetamol (acetaminophen) and ibuprofen in the treatment of febrile conditions in children. Two prospective, randomized, double-blind, double-dummy, repeated-dose, multicentre, phase III studies with two parallel groups in each study were conducted in primary-care outpatient clinics. Children aged 6 months to 6 years presenting with a febrile condition and an oral body temperature of > or =38.8 degrees C or rectal temperature of > or =39 degrees C were eligible for inclusion. Patients were randomized to receive either ketoprofen syrup 0.5 mg/kg, ibuprofen suspension 5 mg/kg or paracetamol suspension 15 mg/kg every 6 hours by the oral route. The primary outcome measure was the change in temperature at 3 hours (H3), compared with baseline (H0). All three treatments provided similar mean maximum decreases of 1.4-1.5 degrees C in body temperature at H3 compared with H0. Use of ketoprofen was not associated with any increased risk of adverse events compared with the two reference compounds. Ketoprofen 0.5 mg/kg appeared to be equivalent to the standard antipyretic doses of the reference products ibuprofen 5 mg/kg and paracetamol 15 mg/kg. Ketoprofen at the 0.5 mg/kg dose should be an effective and safe option for symptomatic management of fever in children. PMID:20380479

  17. Rosuvastatin versus atorvastatin in achieving lipid goals in patients at high risk for cardiovascular disease in clinical practice: A randomized, open-label, parallel-group, multicenter study (DISCOVERY Alpha study)

    PubMed Central

    Binbrek, Azan S.; Elis, Avishay; Al-Zaibag, Muayed; Eha, Jaan; Keber, Irena; Cuevas, Ada M.; Mukherjee, Swati; Miller, Thomas R.

    2006-01-01

    Background: The majority of clinical trials investigating the clinical benefits of lipid-lowering therapies (LLTs) have focused on North American or western and nothern European populations. Therefore, it is timely to confirm the efficacy of these agents in other patient populations in routine clinical practice. Objective: The aim of the Direct Statin COmparison of low-density lipoprotein cholesterol (LDL-C) Values: an Evaluation of Rosuvastatin therapY (DISCOVERY) Alpha study was to compare the effects of rosuvastatin 10 mg with those of atorvastatin 10 mg in achieving LDL-C goals in the Third Joint Task Force of European and Other Societies on Cardiovascular Disease Prevention in Clinical Practice guidelines. Methods: This randomized, open-label, parallel-group study was conducted at 93 centers in eastern Europe (Estonia, Latvia, Romania, Russia, Slovenia), Central and South America (Chile, Dominican Republic, El Salvador, Guatemala, Honduras, Nicaragua, Panama), and the Middle East (Israel, Kuwait, Saudi Arabia, United Arab Emirates). Male and female patients aged ≥18 years with primary hypercholesterolemia (LDL-C level, >135 mg/dL if LLT-naive or ≥120 mg/dL if switching statins; triglyceride [TG] level, <400 mg/dL) and a 10-year coronary heart disease (CHD) risk >20% or a history of CHD or other established atherosclerotic disease were eligible for inclusion in the study. Patients were randomly assigned to receive rosuvastatin 10-mg or atorvastatin 10-mg tablets QD for 12 weeks. No formal statistical analyses or comparisons were performed on lipid changes between switched and LLT-naive patients because of the different lipid inclusion criteria for these patients. The primary end point was the proportion of patients achieving 1998 European LDL-C goals after 12 weeks of treatment. A subanalysis was performed to assess the effects of statins in patients who had received previous statin treatment versus those who were LLT-naive. Tolerability was assessed using

  18. A randomized, parallel-group study to evaluate the efficacy of umeclidinium/vilanterol 62.5/25 μg on health-related quality of life in patients with COPD

    PubMed Central

    Siler, Thomas M; Donald, Alison C; O’Dell, Dianne; Church, Alison; Fahy, William A

    2016-01-01

    Background The combination of the inhaled muscarinic antagonist umeclidinium (UMEC) with the long-acting β2-agonist vilanterol (VI) has been shown to provide significant improvements in lung function compared with UMEC, VI, or placebo (PBO) in patients with chronic obstructive pulmonary disease (COPD). This study was specifically designed to support these findings by assessing health-related quality of life and symptomatic outcomes in a similar population. Methods This was a 12-week multicenter, randomized, double-blind, parallel-group, placebo-controlled study. Eligible patients were randomized 1:1 to receive once-daily UMEC/VI 62.5/25 μg (via ELLIPTA® dry powder inhaler) or PBO for 12 weeks. The primary endpoint was St George’s Respiratory Questionnaire (SGRQ) total score at day 84. Secondary efficacy endpoints included rescue albuterol use (puffs/day) over weeks 1–12 and trough forced expiratory volume in 1 second on day 84. Adverse events were also assessed. Results A total of 496 patients were included in the intent-to-treat population in the UMEC/VI (n=248) and PBO (n=248) treatment groups. UMEC/VI 62.5/25 μg provided a significant and clinically meaningful improvement in SGRQ total score at day 84 versus PBO (difference between treatments in SGRQ total score change from baseline: −4.03 [95% confidence interval {CI}: −6.28, −1.79]; P<0.001). UMEC/VI 62.5/25 μg resulted in a statistically significant reduction in rescue albuterol use versus PBO (−0.7 puffs/day [95% CI: −1.1, −0.4]; P<0.001). UMEC/VI 62.5/25 μg provided a significant and clinically meaningful improvement in trough forced expiratory volume in 1 second on day 84 versus PBO (122 mL [95% CI: 71, 172]; P<0.001). The incidence of adverse events was similar between treatments (32% and 30% of patients in the UMEC/VI 62.5/25 μg and PBO groups, respectively). Conclusion The results of this study demonstrate that treatment with UMEC/VI 62.5/25 μg provides clinically important

  19. Prophylactic use of anti-emetic medications reduced nausea and vomiting associated with exenatide treatment: a retrospective analysis of an open-label, parallel-group, single-dose study in healthy subjects

    PubMed Central

    Ellero, C; Han, J; Bhavsar, S; Cirincione, B B; DeYoung, M B; Gray, A L; Yushmanova, I; Anderson, P W

    2010-01-01

    Aims Transient nausea and, to a lesser extent, vomiting are common adverse effects of exenatide that can be mitigated by dose titration and usually do not result in treatment discontinuation. This retrospective analysis of data from a phase 1, open-label, parallel-group, single-dose study in healthy subjects evaluated the effect of oral anti-emetics on exenatide-associated nausea and vomiting and on the pharmacokinetics of exenatide. Methods A single subcutaneous dose (10 μg) of exenatide was administered to 120 healthy subjects (19–65 years, BMI 23–35 kg/m2). Incidences of nausea and vomiting were compared between 60 subjects premedicated with two oral anti-emetics 30 min before the exenatide dose and 60 non-premedicated subjects. Similarly, the area under the concentration-time curve (AUC) and the maximum observed concentration (Cmax) of plasma exenatide concentrations over 8 h post-dose were compared. Results Among all subjects [61% male, 32 ± 12 years, body mass index (BMI) 29.1 ± 3.4 kg/m2 (mean ± sd)], mild to moderate nausea was the most frequent adverse event after exenatide dosing. Vomiting was also observed. Subjects premedicated with anti-emetics experienced significantly less nausea and vomiting (16.7 and 6.7%, respectively) vs. non-premedicated subjects (61.7 and 38.3%, respectively; P-value < 0.0001 for both nausea and vomiting). The mean area under the concentration-time curve and the maximum observed concentration AUC and Cmax of plasma exenatide concentrations during 8 h post-dose were not significantly different between groups. Conclusion Administration of oral anti-emetics before a single 10-μg exenatide dose was associated with significant reductions in treatment-emergent nausea and vomiting, with no discernible effect on the pharmacokinetics of exenatide. Use of anti-emetic therapy may provide a short-term strategy to minimize the nausea and vomiting associated with exenatide treatment. PMID:20854385

  20. Long-term efficacy and safety of incobotulinumtoxinA and conventional treatment of poststroke arm spasticity: a prospective, non-interventional, open-label, parallel-group study

    PubMed Central

    Dressler, Dirk; Rychlik, Reinhard; Kreimendahl, Fabian; Schnur, Nicole; Lambert-Baumann, Judith

    2015-01-01

    Objective To compare the efficacy and safety of incobotulinumtoxinA with conventional antispastic therapy for poststroke arm spasticity in routine clinical practice over a 1-year period. Design Prospective, non-interventional, open-label, parallel-group study. Setting 47 centres in Germany. Participants Patients with poststroke arm spasticity; 108 receiving incobotulinumtoxinA, 110 conventional therapy. Intervention Conventional antispastic treatment including oral antispastic medications, physiotherapy and occupational therapy or 3-monthly incobotulinumtoxinA injections plus conventional therapy if required. Main outcome measures The main outcome measure was changes in muscle tone (Ashworth Scale) over the 1-year treatment period. Changes in functional disability (Disability Assessment Scale) and quality of life (Short-Form-12 Health Survey) were additionally assessed. Ratings for therapy outcome (Goal Attainment Scale), and efficacy and tolerability of treatment (Global Clinical Impression Scale) were also obtained. Results Muscle tone improved for all spasticity patterns with the Ashworth Scale responder rates between 63% and 86% (incobotulinumtoxinA) and 16–27% (conventional therapy). Median improvement in functional disability was –1.0 (incobotulinumtoxinA) and 0.0 (conventional measures) for all domains. Treatment goals were attained by 93% of incobotulinumtoxinA patients and 30% of patients under conventional therapy. Most physicians (93%) and patients (90%) rated efficacy as good or very good under incobotulinumtoxinA; the proportions were much lower under conventional therapy (36% and 37%). Tolerability under incobotulinumtoxinA was considered good or very good by 99% of physicians and patients (76% and 66%, respectively, under conventional therapy). Quality of life under incobotulinumtoxinA improved by 8.0 (physical score) and 10.8 (mental score) and by 0.8 and 5.7, respectively, under conventional therapy. Conclusions IncobotulinumtoxinA combined

  1. A double-blind, randomized, placebo-controlled, parallel-group study of THC/CBD oromucosal spray in combination with the existing treatment regimen, in the relief of central neuropathic pain in patients with multiple sclerosis.

    PubMed

    Langford, R M; Mares, J; Novotna, A; Vachova, M; Novakova, I; Notcutt, W; Ratcliffe, S

    2013-04-01

    Central neuropathic pain (CNP) occurs in many multiple sclerosis (MS) patients. The provision of adequate pain relief to these patients can very difficult. Here we report the first phase III placebo-controlled study of the efficacy of the endocannabinoid system modulator delta-9-tetrahydrocannabinol (THC)/cannabidiol (CBD) oromucosal spray (USAN name, nabiximols; Sativex, GW Pharmaceuticals, Salisbury, Wiltshire, UK), to alleviate CNP. Patients who had failed to gain adequate analgesia from existing medication were treated with THC/CBD spray or placebo as an add-on treatment, in a double-blind manner, for 14 weeks to investigate the efficacy of the medication in MS-induced neuropathic pain. This parallel-group phase of the study was then followed by an 18-week randomized-withdrawal study (14-week open-label treatment period plus a double-blind 4-week randomized-withdrawal phase) to investigate time to treatment failure and show maintenance of efficacy. A total of 339 patients were randomized to phase A (167 received THC/CBD spray and 172 received placebo). Of those who completed phase A, 58 entered the randomized-withdrawal phase. The primary endpoint of responder analysis at the 30 % level at week 14 of phase A of the study was not met, with 50 % of patients on THC/CBD spray classed as responders at the 30 % level compared to 45 % of patients on placebo (p = 0.234). However, an interim analysis at week 10 showed a statistically significant treatment difference in favor of THC/CBD spray at this time point (p = 0.046). During the randomized-withdrawal phase, the primary endpoint of time to treatment failure was statistically significant in favor of THC/CBD spray, with 57 % of patients receiving placebo failing treatment versus 24 % of patients from the THC/CBD spray group (p = 0.04). The mean change from baseline in Pain Numerical Rating Scale (NRS) (p = 0.028) and sleep quality NRS (p = 0.015) scores, both secondary endpoints in phase B, were also statistically

  2. Study of an Active Control System for a Spinning Body

    NASA Technical Reports Server (NTRS)

    Adams, J. J.

    1961-01-01

    The mission requirements for some satellites require that they spin continuously and at the same time maintain a precise direction of the spin axis. An analog-computer study has been made of an attitude control system which is suitable for such a satellite. The control system provides the necessary attitude control through the use of a spinning wheel, which will provide precession torques, commanded by an automatic closed-loop servomechanism system. The sensors used in the control loop are rate gyroscopes for damping of any wobble motion and a sun seeker for attitude control. The results of the study show that the controller can eliminate the wobble motion of the satellite resulting from a rectangular pulse moment disturbance and then return the spin axis to the reference space axis. The motion is damped to half amplitude in less than one cycle of the wobble motion. The controller can also reduce the motion resulting from a step change in product of inertia both by causing the new principal axis to be steadily alined with the spin vector and by reducing the cone angle generated by the reference body axis. These methods will reduce the motion whether the satellite is a disk, sphere, or rod configuration.

  3. [Features of active control used in pharmacological studies].

    PubMed

    Nikol'skaia, K A; Kondashevskaia, M V

    2003-09-01

    The effects of 5 injections of salt solution and unfractionary heparin in dose 0.36 microgram/kg (Serva, Germany 10 kDa, activity 180 U/mg) have been studied in Wistar rats. It was found that two injections of salt solution were enough to form a stable defensive state in all rats which was manifested as an expectation of pain in tail-flick testing. The defensive motivation provoked by the injections negatively influenced the learning process as saline-induced rats refused to solve a food-getting task in a problem situation. Explorative and locomotor activities were depressed in these rats and were accompanied by numerous stressful and neurotic-like manifestations. Unlike saline-rats, practically all heparinized-rats instead of 45% of intact rats were able to solve a cognitive task despite the injections. Anxiety was decreased, but sensitivity to different external factors was increased in the heparin-induced rats. Formed habit in these rats was characterized by a high organization and stability. However, the majority heparin effects in tail-flick test were discovered when comparing the heparin-induced rats with intact ones and were not observed in comparison with the saline-rats. It is suggested that the saline-control should be considered as specific control having defensive features which are necessary to take into account in interpretation of effects of other pharmacological preparations. PMID:14758633

  4. A Phase III Randomized, Double-blind, Parallel-group Study to Evaluate the Efficacy and Safety of Acarmet (Metformin HCl 500 mg Plus Acarbose 50 mg Tablets) Versus Acarbose Alone in Subjects With Type 2 Diabetes Mellitus

    ClinicalTrials.gov

    2010-11-19

    The Objectives of the Study is to Evaluate the Efficacy and Safety of Acarmet (Metformin HCl 500 mg; Plus Acarbose 50 mg Tablets) Thrice Daily Versus Acarbose 50 mg Thrice Daily Over 16 Weeks in; Subjects With Type 2 Diabetes Mellitus.

  5. Repeat spinal anesthesia in cesarean section: A comparison between 10 mg and 12 mg doses of intrathecal hyperbaric (0.05%) bupivacaine repeated after failed spinal anesthesia: A prospective, parallel group study

    PubMed Central

    Bhar, Debasish; RoyBasunia, Sandip; Das, Anjan; Chhaule, Subinay; Mondal, Sudipta Kumar; Bisai, Subrata; Chattopadhyay, Surajit; Mandal, Subrata Kumar

    2016-01-01

    Background: Spinal anesthesia for cesarean section is not a 100% successful technique. At times, despite straightforward insertion and drug administration, intrathecal anesthesia for cesarean section fails to obtain any sensory or motor block. Very few studies and literature are available regarding repeat administration of spinal anesthesia and its drug dosage, especially after first spinal failure in cesarean section lower segment cesarean section (LSCS) due to fear of the excessive spread of drug. The aim of our study is to compare the outcome between two different doses of 0.5% hyperbaric bupivacaine repeated intrathecally after failed spinal. Materials and Methods: After taking informed consent and Ethical Committee approval this prospective, randomized single-blinded study was conducted in 100 parturients of American Society of Anesthesiologists I-II who were posted for elective LSCS and had Bromage score 0 and no sensory block even at L4 dermatome after 10 min of first spinal anesthesia; were included in the study. Group A (n = 50) patients received 2.4 ml and Group B (n = 50) patients received 2 ml of 0.5% hyperbaric bupivacaine respectively for administering repeat spinal anesthesia. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), oxygen saturation, respiratory rate and electrocardiogram were monitored both intra- and post-operatively and complications were recorded. Results: Incidence of high spinal, bradycardia, hypotension, respiratory complications, and nausea vomiting are significantly higher in Group A compared to Group B (P < 0.05). SBP, DBP, and HR were significantly low in Group A patients compared to Group B in the first 10 min (P < 0.05). Conclusion: Spinal anesthesia can be safely repeated in the cesarean section with 10 mg of 0.5% hyperbaric bupivacaine provided after first spinal anesthesia, the level of sensory block is below L4 and motor power in Bromage scale is 0. PMID:27212775

  6. Design of and rationale for the Japan Diabetes Optimal Integrated Treatment study for 3 major risk factors of cardiovascular diseases (J-DOIT3): a multicenter, open-label, randomized, parallel-group trial

    PubMed Central

    Ueki, Kohjiro; Sasako, Takayoshi; Kato, Masayuki; Okazaki, Yukiko; Okahata, Sumie; Katsuyama, Hisayuki; Haraguchi, Mikiko; Morita, Ai; Ohashi, Ken; Hara, Kazuo; Morise, Atsushi; Izumi, Kazuo; Ohashi, Yasuo; Noda, Mitsuhiko; Kadowaki, Takashi

    2016-01-01

    Objective Multifactorial intervention including the management of levels of blood glucose (BG), blood pressure (BP), and lipids has been suggested to decrease cardiovascular disease (CVD) risk. However, the target ideal and feasible levels for these individual parameters have not been fully evaluated. In this study, we examine the hypothesis that stricter control compared with the current targets in the Japanese guideline for BG, BP, and lipids could efficiently and safely reduce CVD risk. Research Design and Methods We screened patients with type 2 diabetes and hypertension and/or dyslipidemia among 81 hospitals in Japan and allocated them into 2 groups: the intensive therapy group (ITG) and the conventional therapy group (CTG). For the 2 respective groups, the target for glycated hemoglobin (HbA1c) is <6.2% (44 mmol/mol) and <6.9% (52 mmol/mol), for BP it is <120/75 mm Hg and <130/80 mm Hg, and for low-density lipoprotein cholesterol it is <80 mg/dL (<70 mg/dL in the presence of CVD history) and <120 mg/dL (<100 mg/dL in the presence of CVD history). The primary end point is the occurrence of CVD events or death by any cause. These patients are scheduled for stepwise intensifications of medication for BG, BP, and lipid control in the ITG, until the number of primary end point events reaches 250. Results We recruited 2542 patients and randomly allocated 1271 into the ITG and 1271 into the CTG between June 2006 and March 2009. The mean HbA1c was 8.0% (64 mmol/mol) and the mean duration of diabetes was 8.3 years. Conclusions This randomized controlled study will test the hypothesis that strict multifactorial intervention therapy is effective for the prevention of CVDs in patients with type 2 diabetes who are at high CVD risk. Trial registration number NCT00300976. PMID:26843962

  7. Comparative study of the efficacy and safety between blonanserin and risperidone for the treatment of schizophrenia in Chinese patients: A double-blind, parallel-group multicenter randomized trial.

    PubMed

    Li, Huafang; Yao, Chen; Shi, Jianguo; Yang, Fude; Qi, Shuguang; Wang, Lili; Zhang, Honggeng; Li, Jie; Wang, Chuanyue; Wang, Chuansheng; Liu, Cui; Li, Lehua; Wang, Qiang; Li, Keqing; Luo, Xiaoyan; Gu, Niufan

    2015-10-01

    This randomized, double-blind study compared the efficacy and safety of blonanserin and risperidone to treat Chinese schizophrenia patients aged ≥18 and < 65 years. Patients with Positive and Negative Syndrome Scale (PANSS) total scores ≥70 and ≤ 120 were randomized to receive blonanserin or risperidone using a gradual dose-titration method (blonanserin tablets: 8-24 mg/day; risperidone tablets: 2-6 mg/day), twice daily. Treatment populations consisted of 128 blonanserin-treated patients and 133 risperidone-treated patients. Intention-to-treat analysis was performed using the last observation carried forward method. Reductions of PANSS total scores by blonanserin and risperidone treatment were -30.59 and -33.56, respectively. Risperidone treatment was associated with elevated levels of serum prolactin (67.16% risperidone versus 52.31% blonanserin) and cardiac-related abnormalities (22.39% risperidone versus 12.31% blonanserin), and blonanserin patients were more prone to extrapyramidal side effects (48.46% blonanserin versus 29.10% risperidone). In conclusion, blonanserin was as effective as risperidone for the treatment of Chinese patients with schizophrenia. The overall safety profiles of these drugs are comparable, although blonanserin was associated with a higher incidence of EPS and risperidone was associated with a higher incidence of prolactin elevation and weight gain. Thus, blonanserin is useful for the treatment of Chinese schizophrenia patients. PMID:26343601

  8. The first double-blind, randomised, parallel-group certolizumab pegol study in methotrexate-naive early rheumatoid arthritis patients with poor prognostic factors, C-OPERA, shows inhibition of radiographic progression

    PubMed Central

    Atsumi, Tatsuya; Yamamoto, Kazuhiko; Takeuchi, Tsutomu; Yamanaka, Hisashi; Ishiguro, Naoki; Tanaka, Yoshiya; Eguchi, Katsumi; Watanabe, Akira; Origasa, Hideki; Yasuda, Shinsuke; Yamanishi, Yuji; Kita, Yasuhiko; Matsubara, Tsukasa; Iwamoto, Masahiro; Shoji, Toshiharu; Okada, Toshiyuki; Miyasaka, Nobuyuki; Koike, Takao

    2016-01-01

    Objectives To evaluate efficacy and safety of combination therapy using certolizumab pegol (CZP) and methotrexate (MTX) as first-line treatment for MTX-naive, early rheumatoid arthritis (RA) with poor prognostic factors, compared with MTX alone. Methods MTX-naive, early RA patients with ≤12 months persistent disease, high anti-cyclic citrullinated peptide, and either rheumatoid factor positive and/or presence of bone erosions were enrolled in this multicentre, double-blind, randomised placebo (PBO)-controlled study. Patients were randomised 1:1 to CZP+MTX or PBO+MTX for 52 weeks. Primary endpoint was inhibition of radiographic progression (change from baseline in modified Total Sharp Score (mTSS CFB)) at week 52. Secondary endpoints were mTSS CFB at week 24, and clinical remission rates at weeks 24 and 52. Results 316 patients randomised to CZP+MTX (n=159) or PBO+MTX (n=157) had comparable baseline characteristics reflecting features of early RA (mean disease duration: 4.0 vs 4.3 months; Disease Activity Score 28-joint assessment (DAS28)) (erythrocyte sedimentation rate (ESR)): 5.4 vs 5.5; mTSS: 5.2 vs 6.0). CZP+MTX group showed significantly greater inhibition of radiographic progression relative to PBO+MTX at week 52 (mTSS CFB=0.36 vs 1.58; p<0.001) and week 24 (mTSS CFB=0.26 vs 0.86; p=0.003). Clinical remission rates (Simple Disease Activity Index, Boolean and DAS28 (ESR)) of the CZP+MTX group were significantly higher compared with those of the PBO+MTX group, at weeks 24 and 52. Safety results in both groups were similar, with no new safety signals observed with addition of CZP to MTX. Conclusions In MTX-naive early RA patients with poor prognostic factors, CZP+MTX significantly inhibited structural damage and reduced RA signs and symptoms, demonstrating the efficacy of CZP in these patients. Trial registration number (NCT01451203). PMID:26139005

  9. The effect of addition of low dose fentanyl to epidural bupivacaine (0.5%) in patients undergoing elective caesarean section: A randomized, parallel group, double blind, placebo controlled study

    PubMed Central

    Parate, LH; Manjrekar, SP; Anandaswamy, TC; Manjunath, B

    2015-01-01

    Background: Opioids have synergistic action with local anesthetics which may alter characteristics of epidural block. Giving opioids to mother before delivery of baby is still fully not accepted with some fearing risk of neonatal depression. Aims: Our primary aim was to evaluate the analgesic effect of addition of 50 μg fentanyl to epidural 0.5% bupivacaine in patients undergoing elective caesarean section using visual analog scale. The secondary aim was to assess onset of analgesia, volume of drug required to achieve T6 level, grade and duration of motor block and Apgar score. Materials and Methods: In this prospective, randomized, double blind, placebo controlled study 64 patients scheduled for elective caesarean section under epidural anesthesia were randomly divided into two groups of 32 each. The fentanyl group received 1ml of 50 μg fentanyl and the saline group received 1ml of normal saline mixed with 10ml of 0.5% bupivacaine for epidural anesthesia. VAS score, time to achieve T6 level, dose of bupivacaine, intraoperative analgesic consumption and duration of analgesia, grade and duration of motor block and any adverse maternal and neonatal effects were noted. Statistical Analysis: Data was analyzed using Students t test, chi-square test and Mann-Whitney U-test. The values of P < 0.05 were considered statistically significant. Results: Fentanyl improved the VAS score significantly (1.6 ± 1.32) compared to the saline group (3.77 ± 1.0, P < 0.0001). It also reduced the intraoperaitve analgesic supplementation compared to the saline group. (P = 0.031). The postoperative duration of analgesia was prolonged in the fentanyl group (275.80 ± 13.61 min) compared to the saline group (191.47 ± 12.16 min, P < 0.0001). The other characteristics of epidural block were unaltered. Conclusion: Addition of 50 μg fentanyl to epidural 0.5% bupivacaine significantly reduces the VAS score. It also reduces intra-operative analgesia supplementation and prolongs the duration

  10. Some experiences using wind-tunnel models in active control studies. [minimization of aeroelastic response

    NASA Technical Reports Server (NTRS)

    Doggett, R. V., Jr.; Abel, I.; Ruhlin, C. L.

    1976-01-01

    A status report and review of wind tunnel model experimental techniques that have been developed to study and validate the use of active control technology for the minimization of aeroelastic response are presented. Modeling techniques, test procedures, and data analysis methods used in three model studies are described. The studies include flutter mode suppression on a delta-wing model, flutter mode suppression and ride quality control on a 1/30-size model of the B-52 CCV airplane, and an active lift distribution control system on a 1/22 size C-5A model.

  11. Rationale and design of the HepZero study: a prospective, multicenter, international, open, randomized, controlled clinical study with parallel groups comparing heparin-free dialysis with heparin-coated dialysis membrane (Evodial) versus standard care: study protocol for a randomized controlled trial

    PubMed Central

    2013-01-01

    Background Anticoagulation for chronic dialysis patients with contraindications to heparin administration is challenging. Current guidelines state that in patients with increased bleeding risks, strategies that can induce systemic anticoagulation should be avoided. Heparin-free dialysis using intermittent saline flushes is widely adopted as the method of choice for patients at risk of bleeding, although on-line blood predilution may also be used. A new dialyzer, Evodial (Gambro, Lund, Sweden), is grafted with unfractionated heparin during the manufacturing process and may allow safe and efficient heparin-free hemodialysis sessions. In the present trial, Evodial was compared to standard care with either saline flushes or blood predilution. Methods The HepZero study is the first international (seven countries), multicenter (10 centers), randomized, controlled, open-label, non-inferiority (and if applicable subsequently, superiority) trial with two parallel groups, comprising 252 end-stage renal disease patients treated by maintenance hemodialysis for at least 3 months and requiring heparin-free dialysis treatments. Patients will be treated during a maximum of three heparin-free dialysis treatments with either saline flushes or blood predilution (control group), or Evodial. The first heparin-free dialysis treatment will be considered successful when there is: no complete occlusion of air traps or dialyzer rendering dialysis impossible; no additional saline flushes to prevent clotting; no change of dialyzer or blood lines because of clotting; and no premature termination (early rinse-back) because of clotting. The primary objectives of the study are to determine the effectiveness of the Evodial dialyzer, compared with standard care in terms of successful treatments during the first heparin-free dialysis. If the non-inferiority of Evodial is demonstrated then the superiority of Evodial over standard care will be tested. The HepZero study results may have major clinical

  12. Early (≤ 1-h) vs. late (>1-h) administration of frovatriptan plus dexketoprofen combination vs. frovatriptan monotherapy in the acute treatment of migraine attacks with or without aura: a post hoc analysis of a double-blind, randomized, parallel group study.

    PubMed

    Allais, Gianni; Bussone, Gennaro; Tullo, Vincenzo; Cortelli, Pietro; Valguarnera, Fabio; Barbanti, Piero; Sette, Giuliano; Frediani, Fabio; D'Arrigo, Giacomo; d'Onofrio, Florindo; Comi, Giancarlo; Curone, Marcella; Colombo, Bruno; Omboni, Stefano; Benedetto, Chiara

    2015-05-01

    The early use of triptan in combination with a nonsteroidal anti-inflammatory drug after headache onset may improve the efficacy of acute migraine treatment. In this retrospective analysis of a randomized, double-blind, parallel group study, we assessed the efficacy of early or late intake of frovatriptan 2.5 mg + dexketoprofen 25 or 37.5 mg (FroDex 25 and FroDex 37.5) vs. frovatriptan 2.5 mg alone (Frova) in the acute treatment of migraine attacks. In this double-blind, randomized parallel group study 314 subjects with acute migraine with or without aura were randomly assigned to Frova, FroDex 25, or FroDex 37.5. Pain free (PF) at 2-h (primary endpoint), PF at 4-h and pain relief (PR) at 2 and 4-h, speed of onset at 60, 90, 120 and 240-min, and sustained pain free (SPF) at 24-h were compared across study groups according to early (≤1-h; n = 220) or late (>1-h; n = 59) intake. PF rates at 2 and 4-h were significantly larger with FroDex 37.5 vs. Frova (early intake, n = 71 FroDex 37.5 and n = 75 Frova: 49 vs. 32 % and 68 vs. 52 %, p < 0.05; late intake, n = 20 Frodex 37.5, and n = 18 Frova: 55 vs. 17 %, p < 0.05 and 85 vs. 28 %, p < 0.01). Also with FroDex 25, in the early intake group (n = 74) PF episodes were significantly higher than Frova. PR at 2 and 4-h was significantly better under FroDex 37.5 than Frova (95 % vs. 50 %, p < 0.001, 100 % vs. 72 %, p < 0.05) in the late intake group (n = 21). SPF episodes at 24-h after early dosing were 25 % (Frova), 45 % (FroDex 25) and 41 % (FroDex 37.5, p < 0.05 combinations vs. monotherapy), whereas they were not significantly different with late intake. All treatments were equally well tolerated. FroDex was similarly effective regardless of intake timing from headache onset. PMID:26017535

  13. Experimental study of active control of wave transmission through hollow cylindrical struts

    NASA Astrophysics Data System (ADS)

    Pelinescu, Ion; Balachandran, Balakumar

    2001-08-01

    Experimental investigations conducted into active control of longitudinal waves transmitted through a hollow cylindrical strut are presented in this article. Following along the lines of our previous work, an active strut of finite extent length, instrumented with sensors, piezoelectric, and magnetostrictive actuators, is studied in the frequency range of 10 Hz to 2 kHz. Single and multiple actuator arrangements are employed in open loop control investigations, and the effectiveness of the control effort in minimizing longitudinal harmonic disturbances transmitted through the strut is experimentally investigated. Initial efforts towards development of feedforward and feedback boundary control algorithms for reducing longitudinal vibratory loads in finite length cylinders is also presented. For the feedback controller development, the strut-actuator ensemble is modeled by using the one dimensional wave equation and the direct method of Liapunov is used. The feedforward control algorithm is based on the previous model of the active strut and relies on measurements of axial strains and accelerations at the strut ends. The influence of the boundary conditions and static forces applied to the strut are also investigated. The relevance of the current work to control of structure-borne helicopter cabin interior noise is also discussed.

  14. Efficacy and safety of monotherapy with the novel sodium/glucose cotransporter-2 inhibitor tofogliflozin in Japanese patients with type 2 diabetes mellitus: a combined Phase 2 and 3 randomized, placebo-controlled, double-blind, parallel-group comparative study

    PubMed Central

    2014-01-01

    Background In recent years, several oral antidiabetic drugs with new mechanisms of action have become available, expanding the number of treatment options. Sodium/glucose cotransporter-2 (SGLT2) inhibitors are a new class of oral antidiabetic drugs with an insulin-independent mechanism promoting urinary glucose excretion. We report the results of a combined Phase 2 and 3 clinical study (Japic CTI-101349) of the SGLT2 inhibitor tofogliflozin (CSG452, RG7201) in Japanese patients with type 2 diabetes mellitus. Methods The efficacy and safety of tofogliflozin were assessed in this multicenter, placebo-controlled, randomized, double-blind parallel-group study involving 230 patients with type 2 diabetes mellitus with inadequate glycemic control on diet/exercise therapy. Between 30 October 2010 and 28 February 2012, patients at 33 centers were randomized to either placebo (n = 56) or tofogliflozin (10, 20, or 40 mg; n = 58 each) orally, once daily for 24 weeks. The primary efficacy endpoint was the change from baseline in HbA1c at week 24. Results Overall, 229 patients were included in the full analysis set (placebo: n = 56; tofogliflozin 10 mg: n = 57; tofogliflozin 20 and 40 mg: n = 58 each). The least squares (LS) mean change (95% confidence interval) from baseline in HbA1c at week 24 was −0.028% (−0.192 to 0.137) in the placebo group, compared with −0.797% (−0.960 to −0.634) in the tofogliflozin 10 mg group, −1.017% (−1.178 to −0.856) in the tofogliflozin 20 mg group, and −0.870% (−1.031 to −0.709) in the tofogliflozin 40 mg group (p < 0.0001 for the LS mean differences in all tofogliflozin groups vs placebo). There were also prominent decreases in fasting blood glucose, 2-h postprandial glucose, and body weight in all tofogliflozin groups compared with the placebo group. The main adverse events were hyperketonemia, ketonuria, and pollakiuria. The incidence of hypoglycemia was low. Furthermore, most adverse events were

  15. Active Control of Fan Noise-Feasibility Study. Volume 1; Flyover System Noise Studies

    NASA Technical Reports Server (NTRS)

    Kraft, Robert E.; Janardan, B. A.; Kontos, G. C.; Gliebe, P. R.

    1994-01-01

    A study has been completed to examine the potential reduction of aircraft flyover noise by the method of active noise control (ANC). It is assumed that the ANC system will be designed such that it cancels discrete tones radiating from the engine fan inlet or fan exhaust duct. Thus, without considering the engineering details of the ANC system design, tone levels are arbitrarily removed from the engine component noise spectrum and the flyover noise EPNL levels are compared with and without the presence of tones. The study was conducted for a range of engine cycles, corresponding to fan pressure ratios from 1.3 to 1.75. The major conclusions that can be drawn are that, for a fan pressure ratio of 1.75, ANC of tones gives about the same suppression as acoustic treatment without ANC, and for a fan pressure ratio of 1.45, ANC appears to offer less effectiveness than passive treatment. Additionally, ANC appears to be more effective at sideline and cutback conditions than at approach. Overall EPNL suppressions due to tone removal range from about 1 to 3 dB at takeoff engine speeds and from 1 to 5 db at approach speeds. Studies of economic impact of the installation of an ANC system for the four engine cases indicate increases of DOC ranging from 1 to 2 percent, favoring the lower fan pressure ratio engines. Further study is needed to confirm the results by examining additional engine data, particularly at low fan pressure ratios, and studying the details of the current results to obtain a more complete understanding. Further studies should also include determining the effects of combining passive and active treatment.

  16. Active Control of Fan Noise: Feasibility Study. Volume 4; Flyover System Noise Studies

    NASA Technical Reports Server (NTRS)

    Kraft, R. E.; Janardan, B. A.; Gliebe, P. R.; Kontos, G. C.

    1996-01-01

    An extension of a prior study has been completed to examine the potential reduction of aircraft flyover noise by the method of active noise control (ANC). It is assumed that the ANC system will be designed such that it cancels discrete tones radiating from the engine fan inlet or fan exhaust duct, at least to the extent that they no longer protrude above the surrounding broadband noise levels. Thus, without considering the engineering details of the ANC system design, tone levels am arbitrarily removed from the engine component noise spectrum and the flyover noise EPNL levels are compared with and without the presence of tones. The study was conducted for a range of engine cycles, corresponding to fan pressure ratios of 1.3, 1.45, 1.6, and 1.75. This report is an extension of an effort reported previously. The major conclusions drawn from the prior study, which was restricted to fan pressure ratios of 1.45 and 1.75, are that, for a fan pressure ratio of 1.75, ANC of tones gives about the same suppression as acoustic treatment without ANC. For a fan pressure ratio of 1.45, ANC appears to offer less effectiveness from passive treatment. In the present study, the other two fan pressure ratios are included in a more detailed examination of the benefits of the ANC suppression levels. The key results of this extended study are the following observations: (1) The maximum overall benefit obtained from suppression of BPF alone was 2.5 EPNdB at high fan speeds. The suppression benefit increases with increase in fan pressure ratio (FPR), (2) The maximum overall benefit obtained from suppression of the first three harmonics was 3 EPNdB at high speeds. Suppression benefit increases with increase in FPR, (3) At low FPR, only about 1.0 EPNdB maximum reduction was obtained. Suppression is primarily from reduction of BPF at high FPR values and from the combination of tones at low FPR, (4) The benefit from ANC is about the same as the benefit from passive treatment at fan pressure

  17. Experimental Study of the Temporal Nature of an Actively Controlled Three Dimensional Turret Wake

    NASA Astrophysics Data System (ADS)

    Shea, Patrick; Glauser, Mark

    2011-11-01

    Experimental measurements have been performed to characterize the actively controlled wake of a three-dimensional, non- conformal turret which is a bluff body commonly used for housing optical systems on airborne platforms. As a bluff body, turrets can generate strong turbulent flow fields that degrade the performance of the optical systems and the aircraft. Experiments were performed in a low-speed wind tunnel at Syracuse University using particle image velocimetry and dynamic pressure measurements with the objective of developing a better understanding of the spatial and temporal nature of the wake flow field. Active control was achieved using dynamic suction in the vicinity of the turret aperture and was found to have a significant impact on the structure of the wake as well as the temporal characteristics of the flow field. With a better understanding of the wake characteristics, closed-loop, active flow control systems will be developed to help reduce fluctuating loading and aero- optical distortions associated with the turbulent flow field.

  18. Experimental study on semi-active control of frame-shear wall eccentric structure using MR dampers

    NASA Astrophysics Data System (ADS)

    Li, Xiu Ling, Sr.; Li, Hong Nan, Sr.

    2006-03-01

    Magnetorheological (MR) damper is a kind of intelligent actuator, which shows immense potential in the field of structural vibration control. The construction and mechanical behavior of MR damper are introduced firstly, and then a new mechanical model--double sigmoid model is proposed based on the experimental study of MR damper. The simulation system of the 3-floor frame-shear wall eccentric structure with MR dampers was built according to the coupled translation and torsion response control using MR damper, based on Matlab/Simulink software environment and hardware/software resources of dSPACE. The shaking table experiment of the structural model was implemented by using rapid control prototyping (RCP) technology. The validity of two passive control strategies and one semi-active control strategy is verified under three input earthquake excitation with different peak value. The experimental results show that the coupled translation and torsion response is significantly mitigated, and the semi-active control strategies can achieve higher performance levels as compared to those of the two passive control cases. Moreover, the location of the MR damper has an important effect on the control results.

  19. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Wing planform study and final configuration selection

    NASA Technical Reports Server (NTRS)

    1981-01-01

    This report summarizes the Wing Planform Study Task and Final Configuration Selection of the Integrated Application of Active Controls (IAAC) Technology Project within the Energy Efficient Transport Program. Application of Active Controls Technology (ACT) in combination with increased wing span resulted in significant improvements over the Conventional Baseline Configuration (Baseline) and the Initial ACT Configuration previously established. The configurations use the same levels of technology (except for ACT), takeoff gross weight, and payload as the Baseline. The Final ACT Configuration (Model 768-107) incorporates pitch-augmented stability (which enabled an approximately 10% aft shift in cruise center of gravity and a 45% reduction in horizontal tail sizes), lateral/directional-augmented stability, an angle-of-attack limiter, and wing-load alleviation. Flutter-mode control was not beneficial for this configuration. This resulted in an 890 kg (1960 lb) reduction in airplane takeoff gross weight and a 9.8% improvement in cruise lift/drag. At the Baseline mission range (3590 km) (1938 nmi), this amounts to 10% block fuel reduction. Good takeoff performance at high-altitude airports on a hot day was also achieved. Results of this task strongly indicate that the IAAC Project should proceed with the Final ACT evaluation and begin the required control system development and testing.

  20. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Wing planform study and final configuration selection

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The Wing Planform Study and Final Configuration Selection Task of the Integrated Application of Active Controls (IAAC) Technology Project within the Energy Efficient Transport Program is documented. Application of Active Controls Technology (ACT) in combination with increased wing span resulted in significant improvements over the Conventional Baseline Configuration (Baseline) and the Initial ACT Configuration previously established. The configurations use the same levels of technology, takeoff gross weight, and payload as the Baseline. The Final ACT Configuration (Model 768-107) incorporates pitch-augmented stability (which enabled an approximately 10% aft shift in cruise center of gravity and a 44% reduction in horizontal tail size), lateral/directional-augmented stability, an angle-of-attack limiter, and wing-load alleviation. Flutter-mode control was not beneficial for this configuration. This resulted in an 890 kg (1960 lb) reduction in airplane takeoff gross weight and a 9.8% improvement in cruise lift/drag. At the Baseline mission range (3589 km 1938 nmi), this amounts to 10% block-fuel reduction. Results of this task strongly indicate that the IAAC Project should proceed with the Final ACT evaluation, and begin the required control system development and test.

  1. Actuator Feasibility Study for Active Control of Ducted Axial Fan Noise

    NASA Technical Reports Server (NTRS)

    Simonich, John C.

    1994-01-01

    A feasibility study was performed to investigate actuator technology which is relevant for a particular application of active noise control for gas turbine stator vanes. This study investigated many different classes of actuators and ranked them on the order of applicability. The most difficult requirements the actuators had to meet were high frequency response, large amplitude deflections, and a thin profile. Based on this assessment, piezoelectric type actuators were selected as the most appropriate actuator class. Specifically, Rainbows (a new class of high performance piezoelectric actuators), and unimorphs (a ceramic/metal composite) appeared best suited to the requirements. A benchtop experimental study was conducted. The performance of a variety of different actuators was examined, including high polymer films, flextensional actuators, miniature speakers, unimorphs, and Rainbows. The displacement/frequency response and phase characteristics of the actuators were measured. Physical limitations of actuator operation were also examined. This report includes the first known, high displacement, dynamic data obtained for Rainbow actuators. A new "hard" ceramic Rainbow actuator which does not appear to be limited in operation by self heating as "soft" ceramic Rainbows was designed, constructed and tested. The study concludes that a suitable actuator for active noise control in gas turbine engines can be achieved with state of the art materials and processing.

  2. Active control and experiment study of a flexible hub-beam system

    NASA Astrophysics Data System (ADS)

    Cai, Guoping; Teng, Youyou; Lim, C. W.

    2010-05-01

    The first-order approximation coupling (FOAC) model was proposed recently for dynamics and control of flexible hub-beam systems. This model may deal with system dynamics for both low and high rotation speed, while the classical zeroth-order approximation coupling (ZOAC) model is only available for low rotation speed. This paper assumes the FOAC model to present experimental study of active positioning control of a flexible hub-beam system. Linearization and nonlinear control strategies are both considered. An experiment system based on a DSP TMS320F2812 board is introduced. The difference between linearization and nonlinear control strategies are studied both numerically and experimentally. Simulation and experimental results indicate that, linearized controller can make the system reach an expected position with suppressed vibration of flexible beam, but the time taken to position is longer than expected, whereas nonlinear controller works well with precise positioning, suppression of vibration and time control.

  3. Observation of EHO in NSTX and theoretical study of its active control using HHFW antenna

    NASA Astrophysics Data System (ADS)

    Park, J.-K.; Goldston, R. J.; Crocker, N. A.; Fredrickson, E. D.; Bell, M. G.; Maingi, R.; Tritz, K.; Jaworski, M. A.; Kubota, S.; Kelly, F.; Gerhardt, S. P.; Kaye, S. M.; Menard, J. E.; Ono, M.

    2014-04-01

    Two important topics for tokamak edge-localized modes (ELM) control, based on non-axisymmetric (3D) magnetic perturbations, are studied in NSTX and combined envisioning ELM control in the future NSTX-U operation: experimental observations of the edge harmonic oscillation (EHO) in NSTX (with lower frequency than EHOs in DIII-D and elsewhere), and theoretical study of its external drive using the high-harmonic fast wave (HHFW) antenna as a 3D field coil. EHOs were observed particularly clearly in NSTX ELM-free operation with very low n core modes. A number of diagnostics have confirmed n = 4-6 edge-localized and coherent oscillations in the 2-8 kHz frequency range. These oscillations seem to have a favoured operational window in rotational shear, similar to EHOs in DIII-D quiescent H modes. However, in NSTX, they are not observed to provide significant particle or impurity transport, possibly due to their weak amplitudes, of a few mm displacements, as measured by reflectometry. The external drive of these modes has been proposed in NSTX, by utilizing audio-frequency currents in the HHFW antenna straps. Analysis shows that the HHFW straps can be optimized to maximize n = 4-6 while minimizing n = 1-3. Also, ideal perturbed equilibrium code calculations show that the optimized configuration with only 1 kAt current can produce comparable or larger displacements than the observed internal modes. Thus it may be possible to use externally driven EHOs to relax the edge pressure gradient and control ELMs in NSTX-U and future devices. Fine and external control over the edge pressure gradient would be a very valuable tool for tokamak control.

  4. Observation of EHO in NSTX and Theoretical Study of its Active Control Using HHFW Antenna

    SciTech Connect

    J.-K. Park, et. al.

    2013-01-14

    Two important topics in the tokamak ELM control, using the non-axisymmetric (3D) magnetic perturbations, are studied in NSTX and combined envisioning ELM control in the future NSTX-U operation: Experimental observations of the edge harmonic oscillation in NSTX (not necessarily the same as EHOs in DIII-D), and theoretical study of its external drive using the high harmonic fast wave (HHFW) antenna as a 3D field coil. Edge harmonic oscillations were observed particularly well in NSTX ELM-free operation with low n core modes, with various diagnostics confirming n = 4 ~ 6 edge-localized and coherent oscillations in 2 ~ 8kHz frequency range. These oscillations seem to have a favored operational window in rotational shear, similarly to EHOs in DIII-D QH modes . However, in NSTX, they are not observed to provide particle or impurity control, possibly due to their weak amplitudes, of a few mm displacements, as measured by reflectometry. The external drive of these modes has been proposed in NSTX, by utilizing audio-frequency currents in the HHFW antenna straps. Analysis shows that the HHFW straps can be optimized to maximize n = 4 ~ 6 while minimizing n = 1 ~ 3. Also, IPEC calculations show that the optimized configuration with only 1kAt current can produce comparable or larger displacements than the observed internal modes. If this optimized external drive can be constructively combined, or further resonated with the internal modes, the edge harmonic oscillations in NSTX may be able to produce sufficient particle control to modify ELMs.

  5. Experimental studies on active control of a dynamic system via a time-delayed absorber

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Sun, Yixia

    2015-04-01

    The traditional passive absorber is fully effective within a narrow and certain frequency band. To solve this problem, a time-delayed acceleration feedback is introduced to convert a passive absorber into an active one. Both the inherent and the intentional time delays are included. The former mainly comes from signal acquiring and processing, computing, and applying the actuation force, and its value is fixed. The latter is introduced in the controller, and its value is actively adjustable. Firstly, the mechanical model is established and the frequency response equations are obtained. The regions of stability are delineated in the plane of control parameters. Secondly, the design scheme of control para- meters is performed to help select the values of the feedback gain and time delay. Thirdly, the experimental studies are conducted. Effects of both negative and positive feedback control are investigated. Experimental results show that the proper choices of control parameters may broaden the effective frequency band of vibration absorption. Moreover, the time-delayed absorber greatly suppresses the resonant response of the primary system when the passive absorber totally fails. The experimental results are in good agreement with the theoretical predictions and numerical simulations.

  6. Prevention and Treatment of Lower Limb Deep Vein Thrombosis after Radiofrequency Catheter Ablation: Results of a Prospective active controlled Study

    PubMed Central

    Li, Lan; Zhang, Bao-jian; Zhang, Bao-ku; Ma, Jun; Liu, Xu-zheng; Jiang, Shu-bin

    2016-01-01

    We conducted a prospective, single-center, active controlled study from July 2013 to January 2015, in Chinese patients with rapid ventricular arrhythmia who had received radiofrequency catheter ablation (RFCA) treatment to determine formation of lower extremity deep vein thrombosis (LDVT) post RFCA procedure, and evaluated the effect of rivaroxaban on LDVT. Patients with asymptomatic pulmonary thromboembolism who had not received any other anticoagulant and had received no more than 36 hours of treatment with unfractionated heparin were included. Post RFCA procedure, patients received either rivaroxaban (10 mg/d for 14 days beginning 2–3 hours post-operation; n = 86) or aspirin (100 mg/d for 3 months beginning 2–3 hours post-operation; n = 90). The primary outcome was a composite of LDVT occurrence, change in diameter of femoral veins, and safety outcomes that were analyzed based on major or minor bleeding events. In addition, blood flow velocity was determined. No complete occlusive thrombus or bleeding events were reported with either of the group. The lower incidence rate of non-occluded thrombus in rivaroxaban (5.8%) compared to the aspirin group (16.7%) indicates rivaroxaban may be administered post-RFCA to prevent and treat femoral venous thrombosis in a secure and effective way with a faster inset of action than standard aspirin therapy. PMID:27329582

  7. Numerical study of active control of mixing in electro-osmotic flows by temperature difference using lattice Boltzmann methods.

    PubMed

    Alizadeh, A; Wang, J K; Pooyan, S; Mirbozorgi, S A; Wang, M

    2013-10-01

    In this paper, the effect of temperature difference between inlet flow and walls on the electro-osmotic flow through a two-dimensional microchannel is investigated. The main objective is to study the effect of temperature variations on the distribution of ions and consequently internal electric potential field, electric body force, and velocity fields in an electro-osmotic flow. We assume constant temperature and zeta potential on walls and use the mean temperature of each cross section to characterize the Boltzmann ion distribution across the channel. Based on these assumptions, the multiphysical transports are still able to be described by the classical Poisson-Boltzmann model. In this work, the Navier-Stokes equation for fluid flow, the Poisson-Boltzmann equation for ion distribution, and the energy equation for heat transfer are solved by a couple lattice Boltzmann method. The modeling results indicate that the temperature difference between walls and the inlet solution may lead to two symmetrical vortices at the entrance region of the microchannel which is appropriate for mixing enhancements. The advantage of this phenomenon for active control of mixing in electro-osmotic flow is the manageability of the vortex scale without extra efforts. For instance, the effective domain of this pattern could broaden by the following modulations: decreasing the external electric potential field, decreasing the electric double layer thickness, or increasing the temperature difference between inlet flow and walls. This work may provide a novel strategy for design or optimization of microsystems. PMID:23859813

  8. Integrative application of active controls (IAAC) technology to an advanced subsonic transport project. Initial act configuration design study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The performance and economic benefits of a constrained application of Active Controls Technology (ACT) are identified, and the approach to airplane design is established for subsequent steps leading to the development of a less constrained final ACT configuration. The active controls configurations are measured against a conventional baseline configuration, a state-of-the-art transport, to determine whether the performance and economic changes resulting from ACT merit proceeding with the project. The technology established by the conventional baseline configuration was held constant except for the addition of ACT. The wing, with the same planform, was moved forward on the initial ACT configuration to move the loading range aft relative to the wing mean aerodynamic chord. Wing trailing-edge surfaces and surface controls also were reconfigured for load alleviation and structural stabilization.

  9. Integrated application of active controls (IAAC) technology to an advanced subsonic transport project. Initial ACT configuration design study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The initial ACT configuration design task of the integrated application of active controls (IAAC) technology project within the Energy Efficient Transport Program is summarized. A constrained application of active controls technology (ACT) resulted in significant improvements over a conventional baseline configuration previously established. The configuration uses the same levels of technology, takeoff gross weight, payload, and design requirements/objectives as the baseline, except for flying qualities, flutter, and ACT. The baseline wing is moved forward 1.68 m. The configuration incorporates pitch-augmented stability (which enabled an approximately 10% aft shift in cruise center of gravity and a 45% reduction in horizontal tail size), lateral/directional-augmented stability, an angle of attack limiter, wing load alleviation, and flutter mode control. This resulted in a 930 kg reduction in airplane operating empty weight and a 3.6% improvement in cruise efficiency, yielding a 13% range increase. Adjusted to the 3590 km baseline mission range, this amounts to 6% block fuel reduction and a 15.7% higher incremental return on investment, using 1978 dollars and fuel cost.

  10. A randomized, double-masked, parallel-group, comparative study to evaluate the clinical efficacy and safety of 1% azithromycin–0.1% dexamethasone combination compared to 1% azithromycin alone, 0.1% dexamethasone alone, and vehicle in the treatment of subjects with blepharitis

    PubMed Central

    Hosseini, Kamran; Lindstrom, Richard L; Foulks, Gary; Nichols, Kelly K

    2016-01-01

    Purpose To evaluate the clinical efficacy and safety of a 1% azithromycin–0.1% dexamethasone combination in DuraSite (“combination”) compared to 0.1% dexamethasone in DuraSite, 1% azithromycin in DuraSite, and vehicle in the treatment of subjects with blepharitis. Materials and methods This was a Phase III, double-masked, vehicle-controlled, four-arm study in which 907 subjects with blepharitis were randomized to combination (n=305), 0.1% dexamethasone (n=298), 1% azithromycin (n=155), or vehicle (n=149). Ten study visits were scheduled: screening visit, days 1 and 4 (dosing phase) and 15, and months 1–6 (follow-up phase). On day 1, subjects applied one drop of the study drug to the eyelid of the inflamed eye(s) twice daily, and continued with twice-daily dosing for 14 days. After completing 14 days of dosing, subjects were followed for 6 months for efficacy and safety. Results A total of 57 subjects (6.3%) had complete clinical resolution at day 15: 25 (8.2%), 17 (5.7%), 8 (5.2%), and 7 (4.7%) subjects in the combination-, 0.1% dexamethasone-, 1% azithromycin-, and vehicle-treatment groups, respectively. The combination was superior to 1% azithromycin and vehicle alone, but not to 0.1% dexamethasone alone. Mean composite (total) clinical sign and symptom scores improved in all four treatment groups during the post-treatment evaluation phase for the intent-to-treat population, but outcomes were superior when a drop containing 0.1% dexamethasone was utilized. Clinical response was noted as early as day 4, and persisted as long as 6 months. Most adverse events were considered mild in severity and not related to the study drug. Conclusion A higher percentage of subjects in the combination group achieved complete clinical resolution of the signs and symptoms of blepharitis at day 15 than with 1% azithromycin and vehicle, but outcomes were similar to treatment with 0.1% dexamethasone alone. The combination was well tolerated. PMID:27570444

  11. Study protocol of Prednisone in episodic Cluster Headache (PredCH): a randomized, double-blind, placebo-controlled parallel group trial to evaluate the efficacy and safety of oral prednisone as an add-on therapy in the prophylactic treatment of episodic cluster headache with verapamil

    PubMed Central

    2013-01-01

    Background Episodic cluster headache (ECH) is a primary headache disorder that severely impairs patient’s quality of life. First-line therapy in the initiation of a prophylactic treatment is verapamil. Due to its delayed onset of efficacy and the necessary slow titration of dosage for tolerability reasons prednisone is frequently added by clinicians to the initial prophylactic treatment of a cluster episode. This treatment strategy is thought to effectively reduce the number and intensity of cluster attacks in the beginning of a cluster episode (before verapamil is effective). This study will assess the efficacy and safety of oral prednisone as an add-on therapy to verapamil and compare it to a monotherapy with verapamil in the initial prophylactic treatment of a cluster episode. Methods and design PredCH is a prospective, randomized, double-blind, placebo-controlled trial with parallel study arms. Eligible patients with episodic cluster headache will be randomized to a treatment intervention with prednisone or a placebo arm. The multi-center trial will be conducted in eight German headache clinics that specialize in the treatment of ECH. Discussion PredCH is designed to assess whether oral prednisone added to first-line agent verapamil helps reduce the number and intensity of cluster attacks in the beginning of a cluster episode as compared to monotherapy with verapamil. Trial registration German Clinical Trials Register DRKS00004716 PMID:23889923

  12. A Comparison of Cefditoren Pivoxil 8-12 mg/kg/day and Cefditoren Pivoxil 16-20 mg/kg/day in Treatment of Children With Acute Presumed Bacterial Rhinosinusitis: A Prospective, Randomized, Investigator-Blinded, Parallel-Group Study

    PubMed Central

    Tangsathapornpong, Auchara; Tanuchit, Sermkiat

    2015-01-01

    Objectives Cefditoren pivoxil (CDT) has been used in the treatment of rhinosinusitis. However, little is known about the efficacy of this drug at low and high doses. This study was to compare the efficacy and safety of low dose (8-12 mg/kg/day) and high dose (16-20 mg/kg/day) CDT in the treatment of children with uncomplicated acute rhinosinusitis (ARS). Methods This investigation was a randomized, investigator-blinded, and parallel study, conducted in patients (aged 1-15 years) with a clinical diagnosis of uncomplicated ARS. Two groups of patients randomly received low dose or high dose CDT for 14 days. Patients' symptoms were assessed quantitatively using a quantitative symptom score (the S5 score). The changes in sinus symptoms and adverse events were provided by patients and their parents/caregivers. The response rate and adverse effects were evaluated at days 7 and 14. The relapse rate was recorded at days 21 and 28. The recurrences of sinus symptoms at day 60 were also assessed. Results One hundred forty patients were recruited and randomized; 72 received low dose CDT (group I) and 68 received high dose CDT (group II). There were no significant differences in demographic data including sex, age, presenting symptoms, medical history, and X-ray findings between two groups. The responses rate at day 14 in groups I and II were 95.5% and 95.4%, respectively (P>0.99). There were no significant differences between groups in relapse rate at day 28 and no recurrence at day 60 in either group. The most common treatment-related adverse events were diarrhea (4.2% in group I vs. 2.9% in group II) and vomiting (2.8% in group I vs. 10.3% in group II). There was no statistically significant difference in adverse events between groups. Conclusion Both low and high doses regimens of CDT appeared a similar clinical outcome for treatment in uncomplicated ARS in pediatric patients. PMID:26045911

  13. Bath additives for the treatment of childhood eczema (BATHE): protocol for multicentre parallel group randomised trial

    PubMed Central

    Santer, Miriam; Rumsby, Kate; Ridd, Matthew J; Francis, Nick A; Stuart, Beth; Chorozoglou, Maria; Wood, Wendy; Roberts, Amanda; Thomas, Kim S; Williams, Hywel C; Little, Paul

    2015-01-01

    Introduction Bath emollients are widely prescribed for childhood eczema, yet evidence of their benefits over direct application of emollients is lacking. Objectives To determine the clinical and cost-effectiveness of adding bath emollient to the standard management of eczema in children Methods and analysis Design: Pragmatic open 2-armed parallel group randomised controlled trial. Setting: General practitioner (GP) practices in England and Wales. Participants: Children aged over 12 months and less than 12 years with eczema, excluding inactive or very mild eczema (5 or less on Nottingham Eczema Severity Scale). Interventions: Children will be randomised to either bath emollients plus standard eczema care or standard eczema care only. Outcome measures: Primary outcome is long-term eczema severity, measured by the Patient-Oriented Eczema Measure (POEM) repeated weekly for 16 weeks. Secondary outcomes include: number of eczema exacerbations resulting in healthcare consultations over 1 year; eczema severity over 1 year; disease-specific and generic quality of life; medication use and healthcare resource use; cost-effectiveness. Aiming to detect a mean difference between groups of 2.0 (SD 7.0) in weekly POEM scores over 16 weeks (significance 0.05, power 0.9), allowing for 20% loss to follow-up, gives a total sample size of 423 children. We will use repeated measures analysis of covariance, or a mixed model, to analyse weekly POEM scores. We will control for possible confounders, including baseline eczema severity and child's age. Cost-effectiveness analysis will be carried out from a National Health Service (NHS) perspective. Ethics and dissemination This protocol was approved by Newcastle and North Tyneside 1 NRES committee 14/NE/0098. Follow-up will be completed in 2017. Findings will be disseminated to participants and carers, the public, dermatology and primary care journals, guideline developers and decision-makers. Trial registration number ISRCTN

  14. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Current and advanced act control system definition study. Volume 2: Appendices

    NASA Technical Reports Server (NTRS)

    Hanks, G. W.; Shomber, H. A.; Dethman, H. A.; Gratzer, L. B.; Maeshiro, A.; Gangsaas, D.; Blight, J. D.; Buchan, S. M.; Crumb, C. B.; Dorwart, R. J.

    1981-01-01

    The current status of the Active Controls Technology (ACT) for the advanced subsonic transport project is investigated through analysis of the systems technical data. Control systems technologies under examination include computerized reliability analysis, pitch axis fly by wire actuator, flaperon actuation system design trade study, control law synthesis and analysis, flutter mode control and gust load alleviation analysis, and implementation of alternative ACT systems. Extensive analysis of the computer techniques involved in each system is included.

  15. Treatment of asthma exacerbations with the human-powered nebuliser: a randomised parallel-group clinical trial

    PubMed Central

    Hallberg, Christopher J; Lysaught, M Therese; Najarro, René Antonio; Cea Gil, Fausto; Villatoro, Clara; Diaz de Uriarte, Ana Celia; Olson, Lars E

    2014-01-01

    Background: Nebulisers aid the treatment of respiratory diseases, including asthma, but they require electricity and are often cost-prohibitive for low- and middle-income countries. Aims: The aim of this study was to compare a low-cost, human-powered nebuliser compressor with an electric nebuliser compressor for the treatment of mild to moderate asthma exacerbations in adults and children. Methods: This was a non-blinded, parallel-group, equivalence study, with 110 subjects between 6 and 65 years of age, conducted in the emergency department of a district hospital in Ilopango, El Salvador. Participants were assigned by random allocation to receive a 2.5-mg dose of salbutamol from the experimental human-powered nebuliser or the electric nebuliser control. All assigned participants completed treatment and were included in analysis. The study was not blinded as this was clinically unfeasible; however, data analysis was blinded. Results: The mean improvement in peak flow of the experimental and control groups was 37.5 (95% confidence interval (CI) 26.7–48.2) l/min and 38.7 (95% CI, 26.1–51.3) l/min, respectively, with a mean difference of 1.3 (95% CI, −15.1 to 17.7) l/min. The mean improvement in percent-expected peak flow for the experimental and control groups was 12.3% (95% CI, 9.1–15.5%) and 13.8% (95% CI, 9.8–17.9%), respectively, with a mean difference of 1.5% (95% CI, −3.6 to 6.6%). Conclusions: The human-powered nebuliser compressor is equivalent to a standard nebuliser compressor for the treatment of mild-to-moderate asthma. (Funded by the Opus Dean’s Fund, Marquette University College of Engineering; ClinicalTrials.gov NCT01795742.) PMID:24965834

  16. Status and trends in active control technology

    NASA Technical Reports Server (NTRS)

    Rediess, H. A.; Szalai, K. J.

    1975-01-01

    The emergence of highly reliable fly-by-wire flight control systems makes it possible to consider a strong reliance on automatic control systems in the design optimization of future aircraft. This design philosophy has been referred to as the control configured vehicle approach or the application of active control technology. Several studies and flight tests sponsored by the Air Force and NASA have demonstrated the potential benefits of control configured vehicles and active control technology. The present status and trends of active control technology are reviewed and the impact it will have on aircraft designs, design techniques, and the designer is predicted.

  17. Actively controlled shaft seals for aerospace applications

    NASA Technical Reports Server (NTRS)

    Salant, Richard F.

    1991-01-01

    Actively controlled mechanical seals have recently been developed for industrial use. This study investigates the feasibility of using such seals for aerospace applications. In a noncontacting mechanical seal, the film thickness depends on the geometry of the seal interface. The amount of coning, which is a measure of the radial convergence or divergence of the seal interface, has a primary effect on the film thickness. Active control of the film thickness is established by controlling the coning with a piezoelectric material. A mathematical model has been formulated to predict the performance of an actively controlled mechanical seal.

  18. “Everybody Brush!”: Protocol for a Parallel-Group Randomized Controlled Trial of a Family-Focused Primary Prevention Program With Distribution of Oral Hygiene Products and Education to Increase Frequency of Toothbrushing

    PubMed Central

    2015-01-01

    Background Twice daily toothbrushing with fluoridated toothpaste is the most widely advocated preventive strategy for dental caries (tooth decay) and is recommended by professional dental associations. Not all parents, children, or adolescents follow this recommendation. This protocol describes the methods for the implementation and evaluation of a quality improvement health promotion program. Objective The objective of the study is to show a theory-informed, evidence-based program to improve twice daily toothbrushing and oral health-related quality of life that may reduce dental caries, dental treatment need, and costs. Methods The design is a parallel-group, pragmatic randomized controlled trial. Families of Medicaid-insured children and adolescents within a large dental care organization in central Oregon will participate in the trial (n=21,743). Families will be assigned to one of three groups: a test intervention, an active control, or a passive control condition. The intervention aims to address barriers and support for twice-daily toothbrushing. Families in the test condition will receive toothpaste and toothbrushes by mail for all family members every three months. In addition, they will receive education and social support to encourage toothbrushing via postcards, recorded telephone messages, and an optional participant-initiated telephone helpline. Families in the active control condition will receive the kit of supplies by mail, but no additional instructional information or telephone support. Families assigned to the passive control will be on a waiting list. The primary outcomes are restorative dental care received and, only for children younger than 36 months old at baseline, the frequency of twice-daily toothbrushing. Data will be collected through dental claims records and, for children younger than 36 months old at baseline, parent interviews and clinical exams. Results Enrollment of participants and baseline interviews have been completed. Final

  19. Experimental study of the semi-active control of a nonlinear two-span bridge using stochastic optimal polynomial control

    NASA Astrophysics Data System (ADS)

    El-Khoury, O.; Kim, C.; Shafieezadeh, A.; Hur, J. E.; Heo, G. H.

    2015-06-01

    This study performs a series of numerical simulations and shake-table experiments to design and assess the performance of a nonlinear clipped feedback control algorithm based on optimal polynomial control (OPC) to mitigate the response of a two-span bridge equipped with a magnetorheological (MR) damper. As an extended conventional linear quadratic regulator, OPC provides more flexibility in the control design and further enhances system performance. The challenges encountered in this case are (1) the linearization of the nonlinear behavior of various components and (2) the selection of the weighting matrices in the objective function of OPC. The first challenge is addressed by using stochastic linearization which replaces the nonlinear portion of the system behavior with an equivalent linear time-invariant model considering the stochasticity in the excitation. Furthermore, a genetic algorithm is employed to find optimal weighting matrices for the control design. The input current to the MR damper installed between adjacent spans is determined using a clipped stochastic optimal polynomial control algorithm. The performance of the controlled system is assessed through a set of shake-table experiments for far-field and near-field ground motions. The proposed method showed considerable improvements over passive cases especially for the far-field ground motion.

  20. Active Control of Fan Noise-Feasibility Study. Volume 2: Canceling Noise Source-Design of an Acoustic Plate Radiator Using Piezoceramic Actuators

    NASA Technical Reports Server (NTRS)

    Pla, F. G.; Rajiyah, H.

    1995-01-01

    The feasibility of using acoustic plate radiators powered by piezoceramic thin sheets as canceling sources for active control of aircraft engine fan noise is demonstrated. Analytical and numerical models of actuated beams and plates are developed and validated. An optimization study is performed to identify the optimum combination of design parameters that maximizes the plate volume velocity for a given resonance frequency. Fifteen plates with various plate and actuator sizes, thicknesses, and bonding layers were fabricated and tested using results from the optimization study. A maximum equivalent piston displacement of 0.39 mm was achieved with the optimized plate samples tested with only one actuator powered, corresponding to a plate deflection at the center of over 1 millimeter. This is very close to the deflection required for a full size engine application and represents a 160-fold improvement over previous work. Experimental results further show that performance is limited by the critical stress of the piezoceramic actuator and bonding layer rather than by the maximum moment available from the actuator. Design enhancements are described in detail that will lead to a flight-worthy acoustic plate radiator by minimizing actuator tensile stresses and reducing nonlinear effects. Finally, several adaptive tuning methods designed to increase the bandwidth of acoustic plate radiators are analyzed including passive, active, and semi-active approaches. The back chamber pressurization and volume variation methods are investigated experimentally and shown to be simple and effective ways to obtain substantial control over the resonance frequency of a plate radiator. This study shows that piezoceramic-based plate radiators can be a viable acoustic source for active control of aircraft engine fan noise.

  1. Incorrect statistical method in parallel-groups RCT led to unsubstantiated conclusions.

    PubMed

    Allison, David B; Antoine, Lisa H; George, Brandon J

    2016-01-01

    The article by Aiso et al. titled "Compared with the intake of commercial vegetable juice, the intake of fresh fruit and komatsuna (Brassica rapa L. var perviridis) juice mixture reduces serum cholesterol in middle-aged men: a randomized controlled pilot study" does not meet the expected standards of Lipids in Health and Disease. Although the article concludes that there are some significant benefits to their komatsuna juice mixture, these claims are not supported by the statistical analyses used. An incorrect procedure was used to compare the differences in two treatment groups over time, and a large number of outcomes were tested without correction; both issues are known to produce high rates of false positives, making the conclusions of the study unjustified. The study also fails to follow published journal standards regarding clinical trial registration and reporting. PMID:27083538

  2. Active Control of Engine Dynamics

    NASA Astrophysics Data System (ADS)

    2002-11-01

    Active control can alleviate design constraints and improve the response to operational requirements in gas turbines. The Course presented the state-of-the-art including experimental, theoretical knowledge and practical information. Topics treated: stability characteristics; active control approaches; robustness and fundamental limits; combustion systems processes; combustor dynamics; compression system dynamics models; diagnostics and control of compression instabilities; sensor and actuator architectures; R&D needs of future prospects. The course has shown that for combustion systems, as well as in actuator and sensor technologies the active control approach is a viable option even at full scale with potential for aero engines and air breathing missiles.

  3. Active control of buildings during earthquakes

    NASA Technical Reports Server (NTRS)

    Vance, Vicki L.

    1993-01-01

    The objective of this report is to provide an overview of the different types of control systems used in buildings, to discuss the problems associated with current active control mechanisms, and to show the cost-effectiveness of applying active control to buildings. In addition, a small case study investigates the feasibility and benefits of using embedded actuators in buildings. Use of embedded actuators could solve many of the current problems associated with active control by providing a wider bandwidth of control, quicker speed of response, increased reliability and reduced power requirement. Though embedded actuators have not been developed for buildings, they have previously been used in space structures. Many similarities exist between large civil and aerospace structures indicating that direct transfer of concepts between the two disciplines may be possible. In particular, much of the Controls-Structures Interaction (CSI) technology currently being developed could be beneficially applied to civil structures. While several buildings with active control systems have been constructed in Japan, additional research and experimental verification are necessary before active control systems become widely accepted and implemented.

  4. A randomized double-blind, placebo-, and active-controlled study of T-type calcium channel blocker ABT-639 in patients with diabetic peripheral neuropathic pain

    PubMed Central

    Ziegler, Dan; Duan, W. Rachel; An, Guohua; Thomas, James W.; Nothaft, Wolfram

    2015-01-01

    Abstract T-type Cav3.2 calcium channels represent a novel target for neuropathic pain modulation. Preclinical studies with ABT-639, a peripherally acting highly selective T-type Cav3.2 calcium channel blocker, showed dose-dependent reduction of pain in multiple pain models. ABT-639 also demonstrated an acceptable safety profile at single- and multiple-dose levels evaluated in a clinical phase 1 study in healthy volunteers. The primary objective of this phase 2, multicenter, randomized, double-blind, placebo-controlled, and active-controlled study was to compare the analgesic efficacy and safety of ABT-639 with placebo in the treatment of diabetic neuropathic pain. Pregabalin, an approved treatment for painful diabetic neuropathy, was included as a positive control. A total of 194 patients were randomized and treated for 6 weeks; 62 patients received ABT-639 (100 mg twice daily), 70 patients received pregabalin (150 mg twice daily), and 62 patients received placebo. When assessing the mean changes from baseline in patient-recorded pain scores at the end of week 6, there was no significant difference observed for ABT-639 compared with placebo (−2.28 vs −2.36; P = 0.582). Pregabalin treatment resulted in a transient improvement in pain compared with placebo, which did not persist throughout the study. There were no significant safety issues identified with ABT-639. A majority of adverse events were considered mild to moderate in intensity. In conclusion, treatment with the highly selective T-type Cav3.2 calcium channel blocker ABT-639 100 mg twice daily for 6 weeks showed no safety signals that would preclude further investigation but did not reduce neuropathic pain in patients with diabetes (ClinicalTrials.gov identifier: NCT01345045). PMID:26067585

  5. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project. ACT/Control/Guidance System study, volume 1

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The active control technology (ACT) control/guidance system task of the integrated application of active controls (IAAC) technology project within the NASA energy efficient transport program was documented. The air traffic environment of navigation and air traffic control systems and procedures were extrapolated. An approach to listing flight functions which will be performed by systems and crew of an ACT configured airplane of the 1990s, and a determination of function criticalities to safety of flight, are the basis of candidate integrated ACT/Control/Guidance System architecture. The system mechanizes five active control functions: pitch augmented stability, angle of attack limiting, lateral/directional augmented stability, gust load alleviation, and maneuver load control. The scope and requirements of a program for simulating the integrated ACT avionics and flight deck system, with pilot in the loop, are defined, system and crew interface elements are simulated, and mechanization is recommended. Relationships between system design and crew roles and procedures are evaluated.

  6. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: current and advanced act control system definition study

    SciTech Connect

    Not Available

    1982-04-01

    The Current and Advanced Technology ACT control system definition tasks of the Integrated Application of Active Controls (IAAC) Technology project within the Energy Efficient Transport Program are summarized. The systems mechanize six active control functions: (1) pitch augmented stability (2) angle of attack limiting (3) lateral/directional augmented stability (4) gust load alleviation (5) maneuver load control and (6) flutter mode control. The redundant digital control systems meet all function requirements with required reliability and declining weight and cost as advanced technology is introduced.

  7. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Current and advanced act control system definition study

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The Current and Advanced Technology ACT control system definition tasks of the Integrated Application of Active Controls (IAAC) Technology project within the Energy Efficient Transport Program are summarized. The systems mechanize six active control functions: (1) pitch augmented stability; (2) angle of attack limiting; (3) lateral/directional augmented stability; (4) gust load alleviation; (5) maneuver load control; and (6) flutter mode control. The redundant digital control systems meet all function requirements with required reliability and declining weight and cost as advanced technology is introduced.

  8. A Phase 3, Double-Blind, Randomized, Active Controlled Study to Evaluate the Safety of MenAfriVac in Healthy Malians

    PubMed Central

    Tapia, Milagritos D.; Sow, Samba O.; Haidara, Fadima Cheick; Diallo, Fatoumata; Doumbia, Moussa; Enwere, Godwin C.; Paranjape, Gandhali; Hervé, Jacques; Bouma, Enricke; Parulekar, Varsha; Martellet, Lionel; Chaumont, Julie; Plikaytis, Brian D.; Tang, Yuxiao; Kulkarni, Prasad S.; Hartmann, Katharina; Preziosi, Marie-Pierre

    2015-01-01

    Background. A safe, affordable, and highly immunogenic meningococcal A conjugate vaccine (PsA-TT, MenAfriVac) was developed to control epidemic group A meningitis in Africa. Documentation of the safety specifications of the PsA-TT vaccine was warranted, with sufficient exposure to detect potential rare vaccine-related adverse reactions. Methods. This phase 3, double-blind, randomized, active controlled clinical study was designed to evaluate the safety—primarily vaccine-related serious adverse events (SAEs)—up to 3 months after administration of a single dose of the PsA-TT vaccine to subjects aged 1–29 years in Mali. Safety outcomes were also compared to those following a single dose of a licensed meningococcal ACWY polysaccharide vaccine (PsACWY). Results. No vaccine-related SAEs occurred during the 3 months of follow-up of 4004 subjects vaccinated with a single dose of PsA-TT. When compared to PsACWY (1996 subjects), tenderness at the injection site appeared to be more frequent in the PsA-TT group. However, rates of local induration, systemic reactions, adverse events (AEs), and SAEs were similar in both groups, and unsolicited AEs and SAEs were all unrelated to the study vaccines. Conclusions. The study confirmed on a large scale the excellent safety profile of a single dose of PsA-TT when administered to its entire target population of 1–29 years of age. Clinical Trials Registration. PACTR ATMR201003000191317. PMID:26553682

  9. A double-blind, randomized, and active-controlled phase III study of Herbiron drink in the treatment of iron-deficiency anemia in premenopausal females in Taiwan

    PubMed Central

    Lee, Ching-Tzu; Jeng, Cherng-Jye; Yeh, Lian-Shung; Yen, Ming-Shyen; Chen, Shih-Ming; Lee, Chyi-Long; Lin, Willie; Hsu, Chun-Sen

    2016-01-01

    Background About 468 million non-pregnant women are estimated to suffer from iron-deficiency anemia (IDA) worldwide. The highest prevalence of IDA occurs in the Taiwanese population. Objective To evaluate the effectiveness of Herbiron to increase iron absorption in women with IDA. Design Phase III double-blind, randomized, active-controlled, and parallel comparative study enrolled 124 patients with IDA and consisted of a 2-week run-in period, randomization, 12 weeks of supplementation, and 4 weeks of follow-up. The treatment group received Herbiron drink 50 mL p.o., b.i.d., before meals (daily iron intake: 21 mg/day) plus placebo tablets. The control group received a ferrous sulfate tablet, t.i.d., plus placebo 50-mL drink before meals (daily iron intake: 195 mg/day). Results Both treatments significantly improved hemoglobin and all secondary efficacy endpoints. Most IDA patients treated with Herbiron or ferrous sulfate finished the study in the normal range. Ferrous sulfate treatment induced a rapid rate of hemoglobin synthesis, which plateaued by week 8, whereas Herbiron treatment increased the rate of hemoglobin synthesis more slowly, likely due to its nine-fold lower iron content. Gastrointestinal adverse events (diarrhea, abdominal pain, dyspepsia, and nausea) but not infectious adverse events were significantly more common in the ferrous sulfate group (n=11, 18.3%) than those in the Herbiron group (n=1, 1.6%) (p=0.004). Conclusion Twelve weeks of Herbiron treatment delivering 21mg of iron or ferrous sulfate treatment delivering 195 mg of iron induced normal hemoglobin levels in 62 or 91% of non-pregnant women with IDA in Taiwan, respectively, suggesting dose-dependent and bioavailability effects. PMID:27343206

  10. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project. ACT/Control/Guidance System study. Volume 2: Appendices

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The integrated application of active controls (IAAC) technology to an advanced subsonic transport is reported. Supplementary technical data on the following topics are included: (1) 1990's avionics technology assessment; (2) function criticality assessment; (3) flight deck system for total control and functional features list; (4) criticality and reliability assessment of units; (5) crew procedural function task analysis; and (6) recommendations for simulation mechanization.

  11. Efficacy and tolerability of borage oil in adults and children with atopic eczema: randomised, double blind, placebo controlled, parallel group trial

    PubMed Central

    Takwale, A; Tan, E; Agarwal, S; Barclay, G; Ahmed, I; Hotchkiss, K; Thompson, J R; Chapman, T; Berth-Jones, J

    2003-01-01

    Objective To study the efficacy and tolerability of borage oil, which contains a high concentration of γ linolenic acid, in children and adults with atopic eczema. Design Single centre, randomised, double blind, placebo controlled, parallel group trial. Setting Acute district general hospital in Nuneaton, England. Participants 151 patients, of whom 11 failed to return for assessment, leaving an evaluable population of 140 (including 69 children). Intervention Adults received four capsules of borage oil twice daily (920 mg γ linolenic acid), and children received two capsules twice daily, for 12 weeks. Main outcome measures Change in total sign score at 12 weeks measured with the six area, six sign, atopic dermatitis (SASSAD) score (primary endpoint); symptom scores, assessed on visual analogue scales; topical corticosteroid requirement, assessed on a five point scale; global assessment of response by participants; adverse events and tolerability. Results The mean SASSAD score fell from 30 to 27 in the borage oil group and from 28 to 23 in the placebo group. The difference between the mean improvements in the two groups was 1.4 (95% confidence interval -2.2 to 5.0) points in favour of placebo (P = 0.45). No significant differences occurred between treatment groups in the other assessments. Subset analysis of adults and children did not indicate any difference in response. The treatments were well tolerated. Conclusion γ linolenic acid is not beneficial in atopic dermatitis. PMID:14670885

  12. Comparison of Efficacy, Safety and Cost-effectiveness of Rupatadine and Olopatadine in Patients of Chronic Spontaneous Urticaria: A Randomized, Double-blind, Comparative, Parallel Group Trial

    PubMed Central

    Dakhale, Ganesh N; Wankhede, Sumit S; Mahatme, Mohini S; Hiware, Sachin K; Mishra, Dharmendra B; Dudhgaonkar, Sujata S

    2016-01-01

    Objective: To compare efficacy, safety and cost-effectiveness of rupatadine and olopatadine in patients of chronic spontaneous urticaria. Materials and Methods: A 6-week, single-centered, randomized, double blind, parallel group comparative clinical study was conducted on patients with chronic spontaneous urticaria. Following inclusion and exclusion criteria, 60 patients were recruited and were randomized to two treatment groups and received the respective drugs for 6 weeks. At follow-up, parameters assessed were mean total symptom score (MTSS) calculated by adding the mean number of wheals (MNW) and the mean pruritus score (MPS), number of wheals, size of wheal, scale for interference of wheals with sleep (SIWS). Results: Both the drugs significantly reduced the MTSS, number of wheals, size of wheal, scale for interference of wheals with sleep, but olopatadine was found to be superior. In olopatadine group, there was significantly higher reduction in MTSS (p = 0.01), Number of wheals (P < 0.05), Size of wheals (p < 0.05), Scale for intensity of erythema (p < 0.05) and change in eosinopils count (p = 0.015) than that of rupatadine. Incidence of adverse effects was found to be less in olopatadine group when compared with rupatadine group. Cost effectiveness ratio was less in olopatadine group as compared to rupatadine group throughout the treatment. Conclusions: Olopatadine is a better choice in chronic spontaneous urticaria in comparison to rupatadine due to its better efficacy, safety and cost effectiveness profile. PMID:26955097

  13. P3MC: A double blind parallel group randomised placebo controlled trial of Propranolol and Pizotifen in preventing migraine in children

    PubMed Central

    2010-01-01

    Background A recent Cochrane Review demonstrated the remarkable lack of reliable clinical trials of migraine treatments for children, especially for the two most prescribed preventative treatments in the UK, Propranolol and Pizotifen. Migraine trials in both children and adults have high placebo responder rates, e.g. of 23%, but for a trial's results to be generalisable "placebo responders" should not be excluded and for a drug to be worthwhile it should be clearly superior, both clinically and statistically, to placebo. Methods/Design Two multicentre, two arm double blind parallel group randomised controlled trials, with allocation ratio of 2:1 for each comparison, Propranolol versus placebo and Pizotifen versus placebo. The trial is designed to test whether Propranolol is superior to placebo and whether Pizotifen is superior to placebo for the prevention of migraine attacks in children aged 5 - 16 years referred to secondary care out-patient settings with frequent migraine (2-6/4 weeks). The primary outcome measure is the number of migraine attacks during trial weeks 11 to 14. Discussion A strength of this trial is the participation of clinically well defined migraine patients who will also be approached to help with future longer-term follow-up studies. Trial Registration ISRCTN97360154 PMID:20553601

  14. Active control of vibration transmission through struts

    NASA Astrophysics Data System (ADS)

    Pelinescu, Ion; Balachandran, Balakumar

    1998-07-01

    In this work, analytical investigations into active control of longitudinal and flexural vibrations transmitted through a cylindrical strut are conducted. A mechanics based model for a strut fitted with a piezoelectric actuator is developed. For harmonic disturbances, a linear dynamic formulation describing the motion of the actuator is integrated with the formulation describing wave transmission through the strut, and the resulting system is studied in the frequency domain. Open-loop studies are conducted with the aid of numerical simulations, and the potential of active control schemes to attenuate the transmitted vibrations over the frequency range of 10 Hz to 6000 Hz is examined. The relevance of the current work to control of helicopter cabin interior noise is also discussed.

  15. Sandstone compaction under actively controlled uniaxial strain conditions - an experimental study on the causes of subsidence in the Dutch Wadden Area

    NASA Astrophysics Data System (ADS)

    Hol, Sander; Mossop, Antony; van der Linden, Arjan; Zuiderwijk, Pedro; Makurat, Axel; van Eijs, Rob

    2016-04-01

    In the Wadden Sea, a tidal-flat area located between the North Sea and the Dutch mainland shore, and UNESCO World Heritage site, subsidence could potentially impact the ecological system. To guide the licensing process governing gas extraction for the area by a solid understanding of the system's response to production, Nederlandse Aardolie Maatschappij (NAM) has carried out a study on the magnitudes, timing, and mechanisms of subsidence related to gas production. As part of this study program, we address the effect of production-induced reservoir compaction, using core samples from the Moddergat field located at the Wadden Sea coastline, from a depth of ~3800 m TVDSS, to assess the nature of the compaction mechanisms that operate. In this contribution, we focus on the uniaxial strain response of Permian, Aeolian sandstone to pore pressure depletion. As the majority of experiments reported in the literature are conducted under triaxial stress conditions, this data set is somewhat unique, and can help confirm the validity of micromechanical processes found for triaxial stress conditions. We report over 30 data sets of experiments carried out using 1.0 and 1.5 inch diameter plugs, sub-sampled from the extracted sandstone core material. The experiments start at in-situ conditions of pore pressure (Pf=~57 MPa), stress (Sv=~80 MPa, Sh=~67 MPa) and temperature (T up to 100 °C), and deplete to a pore pressure of 3 MPa, under actively controlled lateral constraint boundary conditions (i.e. uniaxial strain). Care was taken to systematically vary porosity and sample morphology to ensure representation of the intra-reservoir variability. Our laboratory data show that pressure-depletion results in a strain in the range of 5·10-3-1·10-2 over the total duration of the experiments of 5-12 weeks, with approximately 80% of the total strain response being close to instantaneous, and 20% developing over time. The total strain response develops during depletion as a result of

  16. mHealth Intervention to Improve Diabetes Risk Behaviors in India: A Prospective, Parallel Group Cohort Study

    PubMed Central

    Spring, Bonnie; Saligram, Nalini; Davé, Raj; Gowda, Arun; Blais, Linelle; Arora, Monika; Ranjani, Harish; Ganda, Om; Hedeker, Donald; Reddy, Sethu; Ramalingam, Sandhya

    2016-01-01

    Background In low/middle income countries like India, diabetes is prevalent and health care access limited. Most adults have a mobile phone, creating potential for mHealth interventions to improve public health. To examine the feasibility and initial evidence of effectiveness of mDiabetes, a text messaging program to improve diabetes risk behaviors, a global nonprofit organization (Arogya World) implemented mDiabetes among one million Indian adults. Objective A prospective, parallel cohort design was applied to examine whether mDiabetes improved fruit, vegetable, and fat intakes and exercise. Methods Intervention participants were randomly selected from the one million Nokia subscribers who elected to opt in to mDiabetes. Control group participants were randomly selected from non-Nokia mobile phone subscribers. mDiabetes participants received 56 text messages in their choice of 12 languages over 6 months; control participants received no contact. Messages were designed to motivate improvement in diabetes risk behaviors and increase awareness about the causes and complications of diabetes. Participant health behaviors (exercise and fruit, vegetable, and fat intake) were assessed between 2012 and 2013 via telephone surveys by blinded assessors at baseline and 6 months later. Data were cleaned and analyzed in 2014 and 2015. Results 982 participants in the intervention group and 943 in the control group consented to take the phone survey at baselne. At the end of the 6-month period, 611 (62.22%) in the intervention and 632 (67.02%) in the control group completed the follow-up telephone survey. Participants receiving texts demonstrated greater improvement in a health behavior composite score over 6 months, compared with those who received no messages F(1, 1238) = 30.181, P<.001, 95% CI, 0.251-0.531. Fewer intervention participants demonstrated health behavior decline compared with controls. Improved fruit, vegetable, and fat consumption (P<.01) but not exercise were observed in those receiving messages, as compared with controls. Conclusions A text messaging intervention was feasible and showed initial evidence of effectiveness in improving diabetes-related health behaviors, demonstrating the potential to facilitate population-level behavior change in a low/middle income country. Trial Registration Australian New Zealand Clinical Trials Registry (ACTRN): 12615000423516; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367946&isReview=true (Archived by WebCite at http://www.webcitation.org/6j5ptaJgF) PMID:27496271

  17. Mechanisms Regulating Insulin Response to Intragastric Glucose in Lean and Non-Diabetic Obese Subjects: A Randomized, Double-Blind, Parallel-Group Trial

    PubMed Central

    Meyer-Gerspach, Anne Christin; Cajacob, Lucian; Riva, Daniele; Herzog, Raphael; Drewe, Juergen; Beglinger, Christoph; Wölnerhanssen, Bettina K.

    2016-01-01

    Background/Objectives The changes in blood glucose concentrations that result from an oral glucose challenge are dependent on the rate of gastric emptying, the rate of glucose absorption and the rate of insulin-driven metabolism that include the incretins, glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1). The rate of insulin-driven metabolism is clearly altered in obese subjects, but it is controversial which of these factors is predominant. We aimed to quantify gastric emptying, plasma insulin, C-peptide, glucagon and glucose responses, as well as incretin hormone secretions in obese subjects and healthy controls during increasing glucose loads. Subjects/Methods The study was conducted as a randomized, double-blind, parallel-group trial in a hospital research unit. A total of 12 normal weight (6 men and 6 women) and 12 non-diabetic obese (BMI > 30, 6 men and 6 women) participants took part in the study. Subjects received intragastric loads of 10 g, 25 g and 75 g glucose dissolved in 300 ml tap water. Results Main outcome measures were plasma GLP-1 and GIP, plasma glucagon, glucose, insulin, C-peptide and gastric emptying. The primary findings are: i) insulin resistance (P < 0.001) and hyperinsulinemia (P < 0.001); ii) decreased insulin disposal (P < 0.001); iii) trend for reduced GLP-1 responses at 75 g glucose; and iv) increased fasting glucagon levels (P < 0.001) in obese subjects. Conclusions It seems that, rather than changes in incretin secretion, fasting hyperglucagonemia and consequent hyperglycemia play a role in reduced disposal of insulin, contributing to hyperinsulinemia and insulin resistance. Trial Registration ClinicalTrials.gov NCT01875575 PMID:26942445

  18. Actively controlled shaft seals for aerospace applications

    NASA Technical Reports Server (NTRS)

    Salant, Richard F.

    1994-01-01

    This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100 C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changed suddenly.

  19. Actively Controlled Shaft Seals for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Salant, Richard F.; Wolff, Paul

    1995-01-01

    This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with a piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changes suddenly. the experimental results were compared to the predictions from the mathematical model. The model was successful in predicting the trends in leakage rate that occurred as the balance ratio and sealed pressure changed

  20. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Current and advanced act control system definition study, volume 1

    NASA Technical Reports Server (NTRS)

    Hanks, G. W.; Shomber, H. A.; Dethman, H. A.; Gratzer, L. B.; Maeshiro, A.; Gangsaas, D.; Blight, J. D.; Buchan, S. M.; Crumb, C. B.; Dorwart, R. J.

    1981-01-01

    An active controls technology (ACT) system architecture was selected based on current technology system elements and optimal control theory was evaluated for use in analyzing and synthesizing ACT multiple control laws. The system selected employs three redundant computers to implement all of the ACT functions, four redundant smaller computers to implement the crucial pitch-augmented stability function, and a separate maintenance and display computer. The reliability objective of probability of crucial function failure of less than 1 x 10 to the -9th power per flight of 1 hr can be met with current technology system components, if the software is assumed fault free and coverage approaching 1.0 can be provided. The optimal control theory approach to ACT control law synthesis yielded comparable control law performance much more systematically and directly than the classical s-domain approach. The ACT control law performance, although somewhat degraded by the inclusion of representative nonlinearities, remained quite effective. Certain high-frequency gust-load alleviation functions may require increased surface rate capability.

  1. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project-longitudinal handling qualities study of a relaxed-stability airplane

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The results of a piloted simulation of longitudinal handling qualities of an airplane with relaxed static stability are described. This task was performed under the Integrated Application of Active Controls (IAAC) Technology Project within the NASA Energy Efficient Transport Program. A representative medium range transport airplane, the Boeing Model 757, was simulated. Evaluations were made of the unaugmented airplane and of the airplane with an Essential Pitch Augmented Stability (PAS) System and with a Primary PAS System at various center of gravity (cg) conditions. Level 2 pilot ratings were attained with cg locations aft to about 57% mean aerodynamic chord (MAC) or 6% aft of the neutral point for unaugmented landing approach. For Mach = 0.80, unaugmented cruise Level 2 ratings were attained to 47% MAC or 5% forward of the maneuver point. The augmented airplane model provided handling qualities close to or within the Level 1 boundary at all cg locations for both Essential and Primary PAS. Analyses of the test conditions when compared with existing handling qualities criteria based on classical unaugmented airplane characteristics agreed well with the pilot ratings. The unaugmented results are comparable to those reported by both the Douglas Aircraft Company and Lockheed California Company from simulation investigations of transport configurations with roughly similar dimensional and mass characteristics.

  2. A comparison of two treatments for childhood apraxia of speech: methods and treatment protocol for a parallel group randomised control trial

    PubMed Central

    2012-01-01

    Background Childhood Apraxia of Speech is an impairment of speech motor planning that manifests as difficulty producing the sounds (articulation) and melody (prosody) of speech. These difficulties may persist through life and are detrimental to academic, social, and vocational development. A number of published single subject and case series studies of speech treatments are available. There are currently no randomised control trials or other well designed group trials available to guide clinical practice. Methods/Design A parallel group, fixed size randomised control trial will be conducted in Sydney, Australia to determine the efficacy of two treatments for Childhood Apraxia of Speech: 1) Rapid Syllable Transition Treatment and the 2) Nuffield Dyspraxia Programme – Third edition. Eligible children will be English speaking, aged 4–12 years with a diagnosis of suspected CAS, normal or adjusted hearing and vision, and no comprehension difficulties or other developmental diagnoses. At least 20 children will be randomised to receive one of the two treatments in parallel. Treatments will be delivered by trained and supervised speech pathology clinicians using operationalised manuals. Treatment will be administered in 1-hour sessions, 4 times per week for 3 weeks. The primary outcomes are speech sound and prosodic accuracy on a customised 292 item probe and the Diagnostic Evaluation of Articulation and Phonology inconsistency subtest administered prior to treatment and 1 week, 1 month and 4 months post-treatment. All post assessments will be completed by blinded assessors. Our hypotheses are: 1) treatment effects at 1 week post will be similar for both treatments, 2) maintenance of treatment effects at 1 and 4 months post will be greater for Rapid Syllable Transition Treatment than Nuffield Dyspraxia Programme treatment, and 3) generalisation of treatment effects to untrained related speech behaviours will be greater for Rapid Syllable Transition

  3. Active control of compressible flows on a curved surface

    NASA Technical Reports Server (NTRS)

    Maestrello, L.; Parikh, P.; Bayliss, A.; Turkel, E.

    1985-01-01

    The effect of localized, time periodic surface heating and cooling over a curved surface is studied. This is a mechanism for the active control of unstable disturbances by phase cancellation and reinforcement. It is shown that the pressure gradient induced by the curvature significantly enhances the effectiveness of this form of active control. In particular, by appropriate choice of phase, active surface heating can completely stabilize and unstable wave.

  4. Application of smart materials to helicopter rotor active control

    NASA Astrophysics Data System (ADS)

    Straub, Friedrich K.; Ealey, Mark A.; Schetky, Lawrence M.

    1997-05-01

    Helicopter design is limited by the compromise inherent in meeting hover and forward flight requirements, and the unsteady environment encountered in forward flight. Active control of helicopter rotors using smart material, in-blade actuation can overcome these barriers and provide substantial reductions in noise and vibrations and improved performance. The present study covers the blade/actuator integration and actuator development for a full scale system to demonstrate active control of noise and vibrations as well as inflight blade tracking on the MD Explorer helicopter. A piezoelectric multilayer stack actuator, driving a trailing edge flap, is used for active control. A shape memory alloy torsion actuator, driving a trailing edge trim tab, is used for inflight tracking. Overall, this DARPA sponsored program entails the design, development, and fabrication of the full scale active control rotor system. If successful, an entry in the NASA Ames 40 X 80 foot wind tunnel and flight tests are planned for a follow on program.

  5. Blood Pressure Response to Zofenopril or Irbesartan Each Combined with Hydrochlorothiazide in High-Risk Hypertensives Uncontrolled by Monotherapy: A Randomized, Double-Blind, Controlled, Parallel Group, Noninferiority Trial

    PubMed Central

    Malacco, Ettore; Omboni, Stefano; Parati, Gianfranco

    2015-01-01

    In this randomized, double-blind, controlled, parallel group study (ZENITH), 434 essential hypertensives with additional cardiovascular risk factors, uncontrolled by a previous monotherapy, were treated for 18 weeks with zofenopril 30 or 60 mg plus hydrochlorothiazide (HCTZ) 12.5 mg or irbesartan 150 or 300 mg plus HCTZ. Rate of office blood pressure (BP) response (zofenopril: 68% versus irbesartan: 70%; p = 0.778) and 24-hour BP response (zofenopril: 85% versus irbesartan: 84%; p = 0.781) was similar between the two treatment groups. Cardiac and renal damage was equally reduced by both treatments, whereas the rate of carotid plaque regression was significantly larger with zofenopril. In conclusion, uncontrolled monotherapy treated hypertensives effectively respond to a combination of zofenopril or irbesartan plus a thiazide diuretic, in terms of either BP response or target organ damage progression. PMID:26347187

  6. A 6-week, multicentre, randomised, double-blind, double-dummy, active-controlled, clinical safety study of lumiracoxib and rofecoxib in osteoarthritis patients

    PubMed Central

    Stricker, Kirstin; Yu, Sue; Krammer, Gerhard

    2008-01-01

    Background Lumiracoxib is a selective cyclooxygenase-2 inhibitor effective in the treatment of osteoarthritis (OA) with a superior gastrointestinal (GI) safety profile as compared to traditional non-steroidal anti-inflammatory drugs (NSAIDs, ibuprofen and naproxen). This safety study compared the GI tolerability, the blood pressure (BP) profile and the incidence of oedema with lumiracoxib and rofecoxib in the treatment of OA. Rofecoxib was withdrawn worldwide due to an associated increased risk of CV events and lumiracoxib has been withdrawn from Australia, Canada, Europe and a few other countries following reports of suspected adverse liver reactions. Methods This randomised, double-blind study enrolled 309 patients (aged greater than or equal to 50 years) with primary OA across 51 centres in Europe. Patients were randomly allocated to receive either lumiracoxib 400 mg od (four times the recommended dose in OA) (n = 154) or rofecoxib 25 mg od (n = 155). The study was conducted for 6 weeks and assessments were performed at Weeks 3 and 6. The primary safety measures were the incidence of predefined GI adverse events (AEs) and peripheral oedema. The secondary safety measures included effect of treatment on the mean sitting systolic and diastolic blood pressure (msSBP and msDBP). Tolerability of lumiracoxib 400 mg was assessed by the incidence of AEs. Results Lumiracoxib and rofecoxib displayed similar GI safety profiles with no statistically significant difference in predefined GI AEs between the two groups (43.5% vs. 37.4%, respectively). The incidence and severity of individual predefined GI AEs was comparable between the two groups. The incidence of peripheral oedema was low and identical in both the groups (n = 9, 5.8%). Only one patient in the lumiracoxib group and three patients in the rofecoxib group had a moderate or severe event. At Week 6 there was a significantly lower msSBP and msDBP in the lumiracoxib group compared to the rofecoxib group (p < 0.05). A

  7. Active Control of Fan Noise: Feasibility Study. Volume 5; Numerical Computation of Acoustic Mode Reflection Coefficients for an Unflanged Cylindrical Duct

    NASA Technical Reports Server (NTRS)

    Kraft, R. E.

    1996-01-01

    A computational method to predict modal reflection coefficients in cylindrical ducts has been developed based on the work of Homicz, Lordi, and Rehm, which uses the Wiener-Hopf method to account for the boundary conditions at the termination of a thin cylindrical pipe. The purpose of this study is to develop a computational routine to predict the reflection coefficients of higher order acoustic modes impinging on the unflanged termination of a cylindrical duct. This effort was conducted wider Task Order 5 of the NASA Lewis LET Program, Active Noise Control of aircraft Engines: Feasibility Study, and will be used as part of the development of an integrated source noise, acoustic propagation, ANC actuator coupling, and control system algorithm simulation. The reflection coefficient prediction will be incorporated into an existing cylindrical duct modal analysis to account for the reflection of modes from the duct termination. This will provide a more accurate, rapid computation design tool for evaluating the effect of reflected waves on active noise control systems mounted in the duct, as well as providing a tool for the design of acoustic treatment in inlet ducts. As an active noise control system design tool, the method can be used preliminary to more accurate but more numerically intensive acoustic propagation models such as finite element methods. The resulting computer program has been shown to give reasonable results, some examples of which are presented. Reliable data to use for comparison is scarce, so complete checkout is difficult, and further checkout is needed over a wider range of system parameters. In future efforts the method will be adapted as a subroutine to the GEAE segmented cylindrical duct modal analysis program.

  8. Active Control of Fan Noise: Feasibility Study. Volume 3; Active Fan Noise Cancellation in the NASA Lewis Active Noise Control Fan Facility

    NASA Technical Reports Server (NTRS)

    Pla, Frederic G.; Hu, Ziqiang; Sutliff, Daniel L.

    1996-01-01

    This report describes the Active Noise Cancellation (ANC) System designed by General Electric and tested in the NASA Lewis Research Center's (LERC) 48 inch Active Noise Control Fan (ANCF). The goal of this study is to assess the feasibility of using wall mounted secondary acoustic sources and sensors within the duct of a high bypass turbofan aircraft engine for global active noise cancellation of fan tones. The GE ANC system is based on a modal control approach. A known acoustic mode propagating in the fan duct is canceled using an array of flush-mounted compact sound sources. The canceling modal signal is generated by a modal controller. Inputs to the controller are signals from a shaft encoder and from a microphone array which senses the residual acoustic mode in the duct. The key results are that the (6,0) was completely eliminated at the 920 Hz design frequency and substantially reduced elsewhere. The total tone power was reduced 6.8 dB (out of a possible 9.8 dB). Farfield reductions of 15 dB (SPL) were obtained. The (4,0) and (4,1) modes were reduced simultaneously yielding a 15 dB PWL decrease. The results indicate that global attenuation of PWL at the target frequency was obtained in the aft quadrant using an ANC actuator and sensor system totally contained within the duct. The quality of the results depended on precise mode generation. High spillover into spurious modes generated by the ANC actuator array caused less than optimum levels of PWL reduction. The variation in spillover is believed to be due to calibration procedure, but must be confirmed in subsequent tests.

  9. ACTIVELY CONTROLLED AFTERBURNER FOR COMPACT WASTE INCINERATION

    EPA Science Inventory

    In a continuing research program directed at developing technology for compact shipboard incinerators, active control of fluid dynamics has been used to enhance mixing in incinerator afterburner (AB) experiments and increase the DRE for a waste surrogate. Experiments were conduc...

  10. The Middeck Active Control Experiment (MACE)

    NASA Technical Reports Server (NTRS)

    Miller, David W.

    1992-01-01

    Viewgraphs on the Middeck Active Control Experiment (MACE) are presented. Topics covered include: program objectives; program features; flight experiment features; current activities; MACE development model lab testing; MACE test article deployed on STS middeck; and development model testing.

  11. The Middeck Active Control Experiment (MACE)

    NASA Astrophysics Data System (ADS)

    Miller, David W.

    Viewgraphs on the Middeck Active Control Experiment (MACE) are presented. Topics covered include: program objectives; program features; flight experiment features; current activities; MACE development model lab testing; MACE test article deployed on STS middeck; and development model testing.

  12. The Middeck Active Control Experiment (MACE)

    NASA Astrophysics Data System (ADS)

    Miller, David W.

    1991-07-01

    Viewgraphs on the Middeck Active Control Experiment (MACE) are presented. Topics covered include: science program objectives and rationale; science requirements; capturing the essential physics; science development approach; development model hardware; development model test plan; and flight hardware and operations.

  13. The Middeck Active Control Experiment (MACE)

    NASA Technical Reports Server (NTRS)

    Miller, David W.

    1991-01-01

    Viewgraphs on the Middeck Active Control Experiment (MACE) are presented. Topics covered include: science program objectives and rationale; science requirements; capturing the essential physics; science development approach; development model hardware; development model test plan; and flight hardware and operations.

  14. Effects of a Topical Saffron (Crocus sativus L) Gel on Erectile Dysfunction in Diabetics: A Randomized, Parallel-Group, Double-Blind, Placebo-Controlled Trial.

    PubMed

    Mohammadzadeh-Moghadam, Hossein; Nazari, Seyed Mohammad; Shamsa, Ali; Kamalinejad, Mohammad; Esmaeeli, Habibollah; Asadpour, Amir Abbas; Khajavi, Abdoljavad

    2015-10-01

    Erectile dysfunction is a man's persistent or recurrent inability to achieve and maintain erection for a satisfactory sexual relationship. As diabetes is a major risk factor for erectile dysfunction, the prevalence of erectile dysfunction among diabetic men has been reported as 35% to 90%. This randomized, parallel-group, double-blind, placebo-controlled trial investigated the effects of a topical saffron (Crocus sativus L) gel on erectile dysfunction in diabetic men. Patients were randomly allocated to 2 equal groups (with 25 patients each). The intervention group was treated with topical saffron, and the control received a similar treatment with placebo. The 2 groups were assessed using the International Index of Erectile Function Questionnaire before the intervention and 1 month after the intervention. Compared to placebo, the prepared saffron gel could significantly improve erectile dysfunction in diabetic patients (P < .001). This preliminary evidence suggests that saffron can be considered as a treatment option for diabetic men with erectile dysfunction. PMID:25948674

  15. Safety evaluation of the consumption of high dose milk fat globule membrane in healthy adults: a double-blind, randomized controlled trial with parallel group design.

    PubMed

    Hari, Sayaka; Ochiai, Ryuji; Shioya, Yasushi; Katsuragi, Yoshihisa

    2015-01-01

    Consumption of milk fat globule membrane (MFGM) in combination with habitual exercise suppresses age-associated muscle loss. The effects of high dose MFGM, however, are not known. A double-blind, randomized controlled trial with parallel group design was conducted to evaluate the safety of consuming high dose MFGM tablets. The subjects were 32 healthy adult men and women. Subjects were given 5 times the recommended daily intake of the tablets containing 6.5 g of MFGM or whole milk powder for 4 weeks. Stomach discomfort and diarrhea were observed; however, these symptoms were transitory and slight and were not related to consumption of the test tablets. In addition, there were no clinically significant changes in anthropometric measurements or blood tests. Total degree of safety assessed by the physicians of all subjects was "safe." These findings suggest that consumption of the tablets containing 6.5 g MFGM for 4 weeks is safe for healthy adults. PMID:25704503

  16. The aircraft energy efficiency active controls technology program

    NASA Technical Reports Server (NTRS)

    Hood, R. V., Jr.

    1977-01-01

    Broad outlines of the NASA Aircraft Energy Efficiency Program for expediting the application of active controls technology to civil transport aircraft are presented. Advances in propulsion and airframe technology to cut down on fuel consumption and fuel costs, a program for an energy-efficient transport, and integrated analysis and design technology in aerodynamics, structures, and active controls are envisaged. Fault-tolerant computer systems and fault-tolerant flight control system architectures are under study. Contracts with leading manufacturers for research and development work on wing-tip extensions and winglets for the B-747, a wing load alleviation system, elastic mode suppression, maneuver-load control, and gust alleviation are mentioned.

  17. Fuel conservation through active control of rotor clearances

    NASA Technical Reports Server (NTRS)

    Beitler, R. S.; Saunders, A. A.; Wanger, R. P.

    1980-01-01

    Under the NASA-sponsored Energy Efficient Engine (EEE) Project, technology is being developed which will significantly reduce the fuel consumption of turbofan engines for subsonic transport aircraft. One technology concept being pursued is active control of rotor tip clearances. Attention is given to rotor tip clearance considerations and an overview of preliminary study results as well as the General Electric EEE clearance control approach is presented. Finally, potential fuel savings with active control of rotor clearances for a typical EEE mission are predicted.

  18. Middeck Active Control Experiment (MACE), phase A

    NASA Technical Reports Server (NTRS)

    Crawley, Edward F.; Deluis, Javier; Miller, David W.

    1989-01-01

    A rationale to determine which structural experiments are sufficient to verify the design of structures employing Controlled Structures Technology was derived. A survey of proposed NASA missions was undertaken to identify candidate test articles for use in the Middeck Active Control Experiment (MACE). The survey revealed that potential test articles could be classified into one of three roles: development, demonstration, and qualification, depending on the maturity of the technology and the mission the structure must fulfill. A set of criteria was derived that allowed determination of which role a potential test article must fulfill. A review of the capabilities and limitations of the STS middeck was conducted. A reference design for the MACE test article was presented. Computing requirements for running typical closed-loop controllers was determined, and various computer configurations were studied. The various components required to manufacture the structure were identified. A management plan was established for the remainder of the program experiment development, flight and ground systems development, and integration to the carrier. Procedures for configuration control, fiscal control, and safety, reliabilty, and quality assurance were developed.

  19. Seismic active control by neural networks.

    SciTech Connect

    Tang, Y.

    1998-01-01

    A study on the application of artificial neural networks (ANNs) to activate structural control under seismic loads is carried out. The structure considered is a single-degree-of-freedom (SDF) system with an active bracing device. The control force is computed by a trained neural network. The feed-forward neural network architecture and an adaptive back-propagation training algorithm is used in the study. The neural net is trained to reproduce the function that represents the response-excitation relationship of the SDF system under seismic loads. The input-output training patterns are generated randomly. In the back-propagation training algorithm, the learning rate is determined by ensuring the decrease of the error function at each epoch. The computer program implemented is validated by solving the classification of the XOR problem. Then, the trained ANN is used to compute the control force according to the control strategy. If the control force exceeds the actuator's capacity limit, it is set equal to that limit. The concept of the control strategy employed herein is to apply the control force at every time step to cancel the system velocity induced at the preceding time step so that the gradual rhythmic buildup of the response is destroyed. The ground motions considered in the numerical example are the 1940 El Centro earthquake and the 1979 Imperial Valley earthquake in California. The system responses with and without the control are calculated and compared. The feasibility and potential of applying ANNs to seismic active control is asserted by the promising results obtained from the numerical examples studied.

  20. Seismic active control by neutral networks

    SciTech Connect

    Tang, Yu

    1995-12-31

    A study on the application of artificial neural networks (ANNs) to active structural control under seismic loads is carried out. The structure considered is a single-degree-of-freedom (SDF) system with an active bracing device. The control force is computed by a trained neural network. The feedforward neural network architecture and an adaptive backpropagation training algorithm is used in the study. The neural net is trained to reproduce the function that represents the response-excitation relationship of the SDF system under seismic loads. The input-output training patterns are generated randomly. In the backpropagation training algorithm, the learning rate is determined by ensuring the decrease of the error function at each epoch. The computer program implemented is validated by solving the classification of the XOR problem. Then, the trained ANN is used to compute the control force according to the control strategy. If the control force exceeds the actuator`s capacity limit, it is set equal to that limit. The concept of the control strategy employed herein is to apply the control force at every time step to cancel the system velocity induced at the preceding time step so that the gradual rhythmic buildup of the response is destroyed. The ground motions considered in the numerical example are the 1940 El Centro earthquake and the 1979 Imperial Valley earthquake in California. The system responses with and without the control are calculated and compared. The feasibility and potential of applying ANNs to seismic active control is asserted by the promising results obtained from the numerical examples studied.

  1. A randomized, blinded, parallel-group, pilot trial of mycophenolate mofetil (CellCept) compared with interferon beta-1a (Avonex) in patients with relapsing–remitting multiple sclerosis

    PubMed Central

    Frohman, Elliot M.; Cutter, Gary; Remington, Gina; Gao, Hongjiang; Rossman, Howard; Weinstock-Guttman, Bianca; Durfee, Jacqueline E.; Conger, Amy; Carl, Ellen; Treadaway, Katherine; Lindzen, Eric; Salter, Amber; Frohman, Teresa C.; Shah, Anjali; Bates, Angela; Cox, Jennifer L.; Dwyer, Michael G.; Stüve, Olaf; Greenberg, Benjamin M.; Racke, Michael K.; Zivadinov, Robert

    2010-01-01

    Background: Mycophenolate mofetil (MMF, CellCept®) has been utilized as an antirejection agent in transplant recipients and in patients with myriad autoimmune disorders including multiple sclerosis (MS). Objective: To investigate radiographic and clinical safety involving monotherapy use of daily oral MMF (1 g b.i.d.) versus weekly intramuscular interferon beta 1a (Avonex® at 30 mcg) in relapsing–remitting MS (RRMS). Methods: We organized a randomized, serial, 6-monthly, MRI-blinded, parallel-group multicenter pilot study to determine the safety of MMF versus interferon beta monotherapy in 35 untreated patients with RRMS, all of whom exhibited evidence of gadolinium (Gd) enhancement on a screening MRI of the brain. The primary outcome was the reduction in the cumulative mean number of combined active lesions (CAL), new Gd-enhancing lesions, and new T2 lesions on MRI analyses. Results: Both interferon beta and MMF appeared safe and well tolerated in the majority of patients. There was no difference between MMF therapy and the standard regimen of interferon beta therapy on the primary safety MRI endpoints of the study. However, the MMF group showed a trend toward a lower accumulation of combined active lesions, CAL, Gd and T2 lesions when compared with interferon beta treated patients. Conclusions: The results from this pilot study suggest that the application of MMF monotherapy in MS deserves further exploration. PMID:21180633

  2. Active controls technology to maximize structural efficiency

    NASA Technical Reports Server (NTRS)

    Hoy, J. M.; Arnold, J. M.

    1978-01-01

    The implication of the dependence on active controls technology during the design phase of transport structures is considered. Critical loading conditions are discussed along with probable ways of alleviating these loads. Why fatigue requirements may be critical and can only be partially alleviated is explained. The significance of certain flutter suppression system criteria is examined.

  3. The Middeck Active Control Experiment (MACE)

    NASA Technical Reports Server (NTRS)

    Miller, David W.; Sepe, Raymond B.; Rey, Daniel; Saarmaa, Erik; Crawley, Edward F.

    1993-01-01

    The Middeck Active Control Experiment (MACE) is a NASA In-Step and Control Structure Interaction (CSI) Office funded Shuttle middeck experiment. The objective is to investigate the extent to which closed-loop behavior of flexible spacecraft in zero-gravity (0-g) can be predicted. This prediction becomes particularly difficult when dynamic behavior during ground testing exhibits extensive suspension and direct gravity coupling. On-orbit system identification and control reconfiguration is investigated to improve performance which would otherwise be limited due to errors in prediction. The program is presently in its preliminary design phase with launch expected in the summer of 1994. The MACE test article consists of three attitude control torque wheels, a two axis gimballing payload, inertial sensors and a flexible support structure. With the acquisition of a second payload, this will represent a multiple payload platform with significant structural flexibility. This paper presents on-going work in the areas of modelling and control of the MACE test article in the zero and one-gravity environments. Finite element models, which include suspension and gravity effects, and measurement models, derived from experimental data, are used as the basis for Linear Quadratic Gaussian controller designs. Finite element based controllers are analytically used to study the differences in closed-loop performance as the test article transitions between the 0-g and 1-g environments. Measurement based controllers are experimentally applied to the MACE test article in the 1-g environment and achieve over an order of magnitude improvement in payload pointing accuracy when disturbed by a broadband torque disturbance. The various aspects of the flight portion of the experiment are also discussed.

  4. Active Control of Wind Tunnel Noise

    NASA Technical Reports Server (NTRS)

    Hollis, Patrick (Principal Investigator)

    1991-01-01

    The need for an adaptive active control system was realized, since a wind tunnel is subjected to variations in air velocity, temperature, air turbulence, and some other factors such as nonlinearity. Among many adaptive algorithms, the Least Mean Squares (LMS) algorithm, which is the simplest one, has been used in an Active Noise Control (ANC) system by some researchers. However, Eriksson's results, Eriksson (1985), showed instability in the ANC system with an ER filter for random noise input. The Restricted Least Squares (RLS) algorithm, although computationally more complex than the LMS algorithm, has better convergence and stability properties. The ANC system in the present work was simulated by using an FIR filter with an RLS algorithm for different inputs and for a number of plant models. Simulation results for the ANC system with acoustic feedback showed better robustness when used with the RLS algorithm than with the LMS algorithm for all types of inputs. Overall attenuation in the frequency domain was better in the case of the RLS adaptive algorithm. Simulation results with a more realistic plant model and an RLS adaptive algorithm showed a slower convergence rate than the case with an acoustic plant as a delay plant. However, the attenuation properties were satisfactory for the simulated system with the modified plant. The effect of filter length on the rate of convergence and attenuation was studied. It was found that the rate of convergence decreases with increase in filter length, whereas the attenuation increases with increase in filter length. The final design of the ANC system was simulated and found to have a reasonable convergence rate and good attenuation properties for an input containing discrete frequencies and random noise.

  5. The Middeck Active Control Experiment (MACE)

    NASA Astrophysics Data System (ADS)

    Miller, David W.; Sepe, Raymond B.; Rey, Daniel; Saarmaa, Erik; Crawley, Edward F.

    1993-02-01

    The Middeck Active Control Experiment (MACE) is a NASA In-Step and Control Structure Interaction (CSI) Office funded Shuttle middeck experiment. The objective is to investigate the extent to which closed-loop behavior of flexible spacecraft in zero-gravity (0-g) can be predicted. This prediction becomes particularly difficult when dynamic behavior during ground testing exhibits extensive suspension and direct gravity coupling. On-orbit system identification and control reconfiguration is investigated to improve performance which would otherwise be limited due to errors in prediction. The program is presently in its preliminary design phase with launch expected in the summer of 1994. The MACE test article consists of three attitude control torque wheels, a two axis gimballing payload, inertial sensors and a flexible support structure. With the acquisition of a second payload, this will represent a multiple payload platform with significant structural flexibility. This paper presents on-going work in the areas of modelling and control of the MACE test article in the zero and one-gravity environments. Finite element models, which include suspension and gravity effects, and measurement models, derived from experimental data, are used as the basis for Linear Quadratic Gaussian controller designs. Finite element based controllers are analytically used to study the differences in closed-loop performance as the test article transitions between the 0-g and 1-g environments. Measurement based controllers are experimentally applied to the MACE test article in the 1-g environment and achieve over an order of magnitude improvement in payload pointing accuracy when disturbed by a broadband torque disturbance. The various aspects of the flight portion of the experiment are also discussed.

  6. Treatment of depressive symptoms in patients with schizophrenia: a randomized, open-label, parallel-group, flexible-dose subgroup analysis of patients treated with extended-release quetiapine fumarate or risperidone.

    PubMed

    Kasper, Siegfried; Montagnani, Gino; Trespi, Graziella; Di Fiorino, Mario

    2015-01-01

    The present analysis assessed the efficacy of extended-release quetiapine fumarate (quetiapine XR) versus risperidone in patients with schizophrenia and depressive symptoms [Hamilton Depression Rating Scale (HAM-D) score≥20 and a HAM-D item 1 score≥2]. This was a subanalysis of patients with schizophrenia from a randomized, open-label, parallel-group, flexible-dose study (NCT00640562) that also enrolled patients with schizoaffective disorder. The primary endpoint of this noninferiority study was change from baseline to week 12 in Calgary Depression Scale for Schizophrenia score (per protocol population). Overall, 114 patients received quetiapine XR (n=60; 400-800 mg/day) or risperidone (n=54; 4-6 mg/day). Change in Calgary Depression Scale for Schizophrenia score was greater for quetiapine XR than for risperidone [least squares means: -7.2 vs. -4.8; treatment difference 2.4 (95% confidence interval 0.3-4.6; P<0.05)]. Adverse events (≥3%) among patients receiving quetiapine XR were sedation, somnolence, and dry mouth, and among those receiving risperidone were anxiety, insomnia, asthenia, hyperprolactinemia, and somnolence. Abnormally high prolactin levels were reported for 57.6 and 8.1% of patients receiving risperidone and quetiapine XR, respectively. Quetiapine XR was superior to risperidone at reducing depressive symptoms in patients with schizophrenia. PMID:25356632

  7. Active control of turbomachine discrete tones

    NASA Astrophysics Data System (ADS)

    Fleeter, Sanford

    This paper was directed at active control of discrete frequency noise generated by subsonic blade rows through cancellation of the blade row interaction generated propagating acoustic waves. First discrete frequency noise generated by a rotor and stator in a duct was analyzed to determine the propagating acoustic pressure waves. Then a mathematical model was developed to analyze and predict the active control of discrete frequency noise generated by subsonic blade rows through cancellation of the propagating acoustic waves, accomplished by utilizing oscillating airfoil surfaces to generate additional control propagating pressure waves. These control waves interact with the propagating acoustic waves, thereby, in principle, canceling the acoustic waves and thus, the far field discrete frequency tones. This model was then applied to a fan exit guide vane to investigate active airfoil surface techniques for control of the propagating acoustic waves, and thus the far field discrete frequency tones, generated by blade row interactions.

  8. Active Control by Conservation of Energy Concept

    NASA Technical Reports Server (NTRS)

    Maestrello, Lucio

    2000-01-01

    Three unrelated experiments are discussed; each was extremely sensitive to initial conditions. The initial conditions are the beginnings of the origins of the information that nonlinearity displays. Initial conditions make the phenomenon unstable and unpredictable. With the knowledge of the initial conditions, active control requires far less power than that present in the system response. The first experiment is on the control of shocks from an axisymmetric supersonic jet; the second, control of a nonlinear panel response forced by turbulent boundary layer and sound; the third, control of subharmonic and harmonics of a panel forced by sound. In all three experiments, control is achieved by redistribution of periodic energy response such that the energy is nearly preserved from a previous uncontrolled state. This type of active control improves the performance of the system being controlled.

  9. Active control of helicopter transmission noise

    NASA Astrophysics Data System (ADS)

    Spencer, R. H.; Burke, M. J.; Tye, G. W.

    An account is given of an effort to reduce helicopter transmission noise by 10 dB, using active methods, as part of the NASA-Lewis/U.S. Army Propulsion Directorate Advanced Rotorcraft Transmission technology integration and demonstration program. The transmission used as a test stand is that of the CH-47C forward rotor. Attention is presently given to the active control system's actuators, sensors, and control algorithms.

  10. Active control of helicopter transmission noise

    NASA Technical Reports Server (NTRS)

    Spencer, R. H.; Burke, M. J.; Tye, G. W.

    1991-01-01

    An account is given of an effort to reduce helicopter transmission noise by 10 dB, using active methods, as part of the NASA-Lewis/U.S. Army Propulsion Directorate Advanced Rotorcraft Transmission technology integration and demonstration program. The transmission used as a test stand is that of the CH-47C forward rotor. Attention is presently given to the active control system's actuators, sensors, and control algorithms.

  11. Active Control of Cryogenic Propellants in Space

    NASA Technical Reports Server (NTRS)

    Notardonato, William

    2011-01-01

    A new era of space exploration is being planned. Exploration architectures under consideration require the long term storage of cryogenic propellants in space. This requires development of active control systems to mitigate the effect of heat leak. This work summarizes current state of the art, proposes operational design strategies and presents options for future architectures. Scaling and integration of active systems will be estimated. Ideal long range spacecraft systems will be proposed with Exploration architecture benefits considered.

  12. Active Control Of Structure-Borne Noise

    NASA Astrophysics Data System (ADS)

    Elliott, S. J.

    1994-11-01

    The successful practical application of active noise control requires an understanding of both its acoustic limitations and the limitations of the electrical control strategy used. This paper is concerned with the active control of sound in enclosures. First, a review is presented of the fundamental physical limitations of using loudspeakers to achieve either global or local control. Both approaches are seen to have a high frequency limit, due to either the acoustic modal overlap, or the spatial correlation function of the pressure field. These physical performance limits could, in principle, be achieved with either a feedback or a feedforward control strategy. These strategies are reviewed and the use of adaptive digital filters is discussed for both approaches. The application of adaptive feedforward control in the control of engine and road noise in cars is described. Finally, an indirect approach to the active control of sound is discussed, in which the vibration is suppressed in the structural paths connecting the source of vibration to the enclosure. Two specific examples of this strategy are described, using an active automotive engine mount and the incorporation of actuators into helicopter struts to control gear-meshing tones. In both cases good passive design can minimize the complexity of the active controller.

  13. Rotor Flapping Response to Active Control

    NASA Technical Reports Server (NTRS)

    Nguyen, Khanh; Johnson, Wayne

    2004-01-01

    Rotor active control using higher harmonic blade pitch has been proposed as a means to reduce both rotor radiated noise and airframe vibration and to enhance rotor performance. The higher harmonic input, however, can affect rotor thrust and cyclic flapping - the basic trim characteristics of the rotor. Some of the trim changes can negate the active control benefits. For example, wind tunnel test results of a full scale BO-105 rotor with individual-blade control indicate some rotor performance improvements, accompanied with changes in rotor trim, using two-per-rev blade pitch input. The observed performance benefits could therefore be a simple manifestation of the trim change rather than an efficient redistribution of the rotor airloads. More recently, the flight test of the BO-105 helicopter equip,ped with individual-blade-control actuators also reported trim changes whenever the two-per-rev blade pitch for noise reduction was activated. The pilot had to adjust the trim control to maintain the aircraft under a constant flight path. These two cases highlight the, importance of trim considerations in the application of active control to rotorcraft.

  14. Comparative trial of a novel botulinum neurotoxin type A versus onabotulinumtoxinA in the treatment of glabellar lines: a multicenter, randomized, double-blind, active-controlled study.

    PubMed

    Won, Chong Hyun; Kim, Hyun Kyu; Kim, Beom Joon; Kang, Hoon; Hong, Joon Pio; Lee, Su-Young; Kim, Chung-Sei

    2015-02-01

    A novel botulinum neurotoxin type A (DWP450; Daewoong Pharmaceutical, Seoul, Korea) has recently been introduced for the treatment of facial wrinkles. The efficacy of this agent has previously been demonstrated in an in vivo study using an electrophysiological protocol in a rat model. To compare the efficacy and safety of DWP450 with onabotulinumtoxinA (OBoNT) for use in the treatment of glabellar lines, we performed a multicenter, double-blind, randomized, active-controlled trial comparing DWP450 and OBoNT (Allergan Inc., Irvine, CA, USA). A total of 268 subjects with moderate to severe glabellar lines were randomized at a 1:1 ratio. Each patient received treatment with 20 U of study medication. Maximum frown responder rates at week 4 were measured to analyze the primary efficacy endpoint. To evaluate secondary efficacy endpoints, response rates were measured at weeks 8, 12, and 16, at maximum frown and rest. Specifically, responder rates at both maximum frown and at rest were assessed based on clinical photography. Subject degree of satisfaction and self-assessed rate of response were also measured. Adverse events (AEs) were documented to evaluate safety. Responder rate by physician-rating severity at maximal contraction at week 4 was 93.89% in the DWP450 group and 88.64% in OBoNT group. As the lower limit of the 97.5% one-sided confidence interval (-1.53%) surpassed the -15% threshold, we determined that DWP450 was not inferior to OBoNT. For the secondary efficacy endpoint analyses, no significant differences were observed between the two groups for any variable at any point in time. The incidences of AEs were similar for the two groups. Most of AEs were considered mild. DWP450 and OBoNT were comparable in efficacy and safety in the treatment of glabellar lines. PMID:25311357

  15. Application of active controls to civil transport aircraft

    NASA Technical Reports Server (NTRS)

    Taylor, L. W., Jr.

    1975-01-01

    The impact of active controls on civil transport aircraft and some of the complex problems involved are described. The approach taken by NASA as part of the Active Control Technology Program is discussed to integrate active controls in the conceptual design phase. It is shown that when handled correctly, active controls improve aircraft performance.

  16. The Efficacy and Safety of Wenxin Keli in Patients with Frequent Premature Ventricular Contractions: A Randomized, Double-blind, Placebo-controlled, Parallel-group, Multicenter Trial

    PubMed Central

    Hua, Wei; Gao, Run-Lin; Zhao, Bu-Chang; Wang, Jing; Chen, Xu-Hua; Cai, Chi; Zhang, Shu

    2015-01-01

    Background: Premature ventricular contractions (PVCs) are common in the general population, and frequent PVCs may result in the poor quality of life or even the damage of cardiac function. We examined the efficacy and safety of a traditional Chinese medicine Wenxin Keli for the treatment of frequent PVCs among a relatively large Chinese cohort. Methods: We performed a randomized, double-blind, placebo-controlled, parallel-group, multicenter trial. A total of 1200 eligible participants were randomly assigned in a ratio of 1:1 to receive Wenxin Keli or the placebo for 4 weeks. The primary and secondary endpoint was the change of PVC numbers and PVC-related symptoms after a 4-week treatment compared with baseline, respectively. In addition, vital signs, laboratory values, and electrocardiographic parameters were assessed in a safety analysis. Results: At the initial evaluation, no significant differences in the baseline characteristics were observed between the Wenxin Keli group and the placebo group. A smaller number of PVCs was observed after the 4-week treatment than at baseline, in both the Wenxin Keli group (5686 ± 5940 vs. 15,138 ± 7597 beats/d, P < 0.001) and the placebo group (10,592 ± 8009 vs. 14,529 ± 5929 beats/d, P < 0.001); moreover, the Wenxin Keli group demonstrated a significantli greater reduction in the frequency of PVCs than the placebo group (P < 0.001). In a full analysis set, patients in the Wenxin Keli group exhibited significantly higher total effective responses in the reduction of PVCs compared to those in the placebo group (83.8% vs. 43.5%, P < 0.001). The per-protocol analysis yielded similar results (83.0% vs. 39.3%, P < 0.001). Treatment with Wenxin Keli also demonstrated superior performance compared to the placebo with respect to PVC-related symptoms. No severe adverse effects attributable to Wenxin Keli were reported. Conclusions: Wenxin Keli treatment effectively reduced the overall number of PVCs and alleviated PVC

  17. Abacavir, zidovudine, or stavudine as paediatric tablets for African HIV-infected children (CHAPAS-3): an open-label, parallel-group, randomised controlled trial

    PubMed Central

    Mulenga, Veronica; Musiime, Victor; Kekitiinwa, Adeodata; Cook, Adrian D; Abongomera, George; Kenny, Julia; Chabala, Chisala; Mirembe, Grace; Asiimwe, Alice; Owen-Powell, Ellen; Burger, David; McIlleron, Helen; Klein, Nigel; Chintu, Chifumbe; Thomason, Margaret J; Kityo, Cissy; Walker, A Sarah; Gibb, Diana M

    2016-01-01

    Summary Background WHO 2013 guidelines recommend universal treatment for HIV-infected children younger than 5 years. No paediatric trials have compared nucleoside reverse-transcriptase inhibitors (NRTIs) in first-line antiretroviral therapy (ART) in Africa, where most HIV-infected children live. We aimed to compare stavudine, zidovudine, or abacavir as dual or triple fixed-dose-combination paediatric tablets with lamivudine and nevirapine or efavirenz. Methods In this open-label, parallel-group, randomised trial (CHAPAS-3), we enrolled children from one centre in Zambia and three in Uganda who were previously untreated (ART naive) or on stavudine for more than 2 years with viral load less than 50 copies per mL (ART experienced). Computer-generated randomisation tables were incorporated securely within the database. The primary endpoint was grade 2–4 clinical or grade 3/4 laboratory adverse events. Analysis was intention to treat. This trial is registered with the ISRCTN Registry number, 69078957. Findings Between Nov 8, 2010, and Dec 28, 2011, 480 children were randomised: 156 to stavudine, 159 to zidovudine, and 165 to abacavir. After two were excluded due to randomisation error, 156 children were analysed in the stavudine group, 158 in the zidovudine group, and 164 in the abacavir group, and followed for median 2·3 years (5% lost to follow-up). 365 (76%) were ART naive (median age 2·6 years vs 6·2 years in ART experienced). 917 grade 2–4 clinical or grade 3/4 laboratory adverse events (835 clinical [634 grade 2]; 40 laboratory) occurred in 104 (67%) children on stavudine, 103 (65%) on zidovudine, and 105 (64%), on abacavir (p=0·63; zidovudine vs stavudine: hazard ratio [HR] 0·99 [95% CI 0·75–1·29]; abacavir vs stavudine: HR 0·88 [0·67–1·15]). At 48 weeks, 98 (85%), 81 (80%) and 95 (81%) ART-naive children in the stavudine, zidovudine, and abacavir groups, respectively, had viral load less than 400 copies per mL (p=0·58); most ART

  18. Active control of robot manipulator compliance

    NASA Technical Reports Server (NTRS)

    Nguyen, C. C.; Pooran, F. J.

    1986-01-01

    Work performed at Catholic University on the research grant entitled Active Control of Robot Manipulator Compliance, supported by NASA/Goddard space Flight Center during the period of May 15th, 1986 to November 15th, 1986 is described. The modelling of the two-degree-of-freedom robot is first presented. Then the complete system including the robot and the hybrid controller is simulated on an IBM-XT Personal Computer. Simulation results showed that proper adjustments of controller gains enable the robot to perform successful operations. Further research should focus on developing a guideline for the controller gain design to achieve system stability.

  19. Randomized, double-blind, placebo-controlled and active-controlled study to assess the relative abuse potential of oxycodone HCl-niacin tablets compared with oxycodone alone in nondependent, recreational opioid users

    PubMed Central

    Webster, Lynn R; Rolleri, Robert L; Pixton, Glenn C; Sommerville, Kenneth W

    2012-01-01

    Background Abuse-deterrent formulations attempt to address public health and societal concerns regarding opioid abuse. Oxycodone HCl-niacin tablets combine oxycodone HCl with niacin and functional inactive excipients to create potential barriers to oral, intranasal, and intravenous abuse. This study compared the relative abuse potential of oral immediate-release oxycodone HCl-niacin with that of oral immediate-release oxycodone HCl and placebo in nondependent, recreational opioid users. Methods Forty-nine participants received oxycodone HCl-niacin 40/240 mg and 80/480 mg, oxycodone 40 mg and 80 mg, and placebo in a randomized, double-blind, placebo-controlled and active-controlled, five-way crossover study. Primary endpoints based on a bipolar 100 mm visual analog scale for drug liking were area under effect curve (AUE0–1h, AUE0–2h, AUE0–3h), peak disliking, and effect at 0.5 hours post-dose (E0.5h). Other endpoints included take drug again assessment, overall drug liking, and pupillometry. Results There were statistically significant differences between oxycodone HCl-niacin and oxycodone HCl doses for all primary endpoints (P < 0.0001, all comparisons), suggesting reduced abuse potential with oxycodone HCl-niacin. Take drug again and overall drug liking showed greater liking of oxycodone alone. Oxycodone HCl-niacin 80/480 mg had consistently lower liking assessments than oxycodone HCl-niacin 40/240 mg, suggesting a dose-response to the aversive effects of niacin. Opioid-related adverse events were similar for equivalent oxycodone doses. The treatment-emergent adverse events most specifically associated with oxycodone HCl-niacin (ie, skin-burning sensation, warmth, and flushing) were consistent with the expected vasocutaneous effects of niacin. No serious adverse events were reported. Conclusion Oxycodone HCl-niacin tablets may, in a dose-dependent manner, decrease the potential for oral abuse of oxycodone without unexpected adverse events or clinically

  20. The combination of oligo- and polysaccharides and reticulated protein for the control of symptoms in patients with irritable bowel syndrome: Results of a randomised, placebo-controlled, double-blind, parallel group, multicentre clinical trial

    PubMed Central

    Alexea, Octavian; Bacarea, Vlad

    2015-01-01

    Background A medical device containing the film-forming agent reticulated protein and a prebiotic mixture of vegetable oligo- and polysaccharides has been developed, recently receiving European approval as MED class III for the treatment of chronic/functional or recidivant diarrhoea due to different causes including irritable bowel syndrome (IBS). In the present paper, we evaluate a protein preparation containing these components in comparison with placebo in adult patients with diarrhoea-predominant IBS. Methods In a randomised, placebo-controlled, double-blind, parallel group, multicentre clinical trial, patients were randomly assigned to receive the combination of oligo- and polysaccharides and reticulated protein and placebo (four oral tablets/day for 56 days). Demographic, clinical and quality of life characteristics and presence and intensity of abdominal pain and flatulence (seven-point Likert scale) were assessed at three study visits (baseline and at 28 and 56 days). Stool emissions were recorded on the diary card using the seven-point Bristol Stool Scale. Results A total of 128 patients were randomised to receive either tablets containing the combination (n = 63) or placebo (n = 65). Treatment with oligo- and polysaccharides and reticulated protein was safe and well tolerated. A significant improvement in symptoms across the study was observed in patients treated with oligo- and polysaccharides and reticulated protein between visit 2 and visit 3 in abdominal pain (p = 0.0167) and flatulence (p = 0.0373). We also detected a statistically significant increase in the quality of life of patients receiving the active treatment from baseline to visit 3 (p < 0.0001). Conclusions Treatment with oligo- and polysaccharides and reticulated protein is safe, improving IBS symptoms and quality of life of patients with diarrhoea-predominant IBS. PMID:27403313

  1. Active control of buckling of flexible beams

    NASA Technical Reports Server (NTRS)

    Baz, A.; Tampe, L.

    1989-01-01

    The feasibility of using the rapidly growing technology of the shape memory alloys actuators in actively controlling the buckling of large flexible structures is investigated. The need for such buckling control systems is becoming inevitable as the design trends of large space structures have resulted in the use of structural members that are long, slender, and very flexible. In addition, as these truss members are subjected mainly to longitudinal loading they become susceptible to structural instabilities due to buckling. Proper control of such instabilities is essential to the effective performance of the structures as stable platforms for communication and observation. Mathematical models are presented that simulate the dynamic characteristics of the shape memory actuator, the compressive structural members, and the associated active control system. A closed-loop computer-controlled system is designed, based on the developed mathematical models, and implemented to control the buckling of simple beams. The performance of the computer-controlled system is evaluated experimentally and compared with the theoretical predictions to validate the developed models. The obtained results emphasize the importance of buckling control and suggest the potential of the shape memory actuators as attractive means for controlling structural deformation in a simple and reliable way.

  2. Active control of the Chinese Giant Solar Telescope

    NASA Astrophysics Data System (ADS)

    Dai, Yichun; Yang, Dehua; Jin, Zhenyu; Liu, Zhong; Qin, Wei

    2014-07-01

    The Chinese Giant Solar Telescope (CGST) is the next generation solar telescope of China with diameter of 8 meter. The unique feature of CGST is that its primary is a ring, which facilitates the polarization detection and thermal control. In its present design and development phase, two primary mirror patterns are considered. For one thing, the primary mirror is expected to construct with mosaic mirror with 24 trapezoidal (or petal) segments, for another thing, a monolithic mirror is also a candidate for its primary mirror. Both of them depend on active control technique to maintain the optical quality of the ring mirror. As a solar telescope, the working conditions of the CGST are quite different from those of the stellar telescopes. To avoid the image deterioration due to the mirror seeing and dome seeing, especially in the case of the concentration of flux in a solar telescope, large aperture solar projects prefer to adopt open telescopes and open domes. In this circumstance, higher wind loads act on the primary mirror directly, which will cause position errors and figure errors of the primary with matters worse than those of the current 10-meter stellar telescopes with dome protect. Therefore, it gives new challenges to the active control capability, telescope structure design, and wind shielding design. In this paper, the study progress of active control of CGST for its mosaic and monolithic mirror are presented, and the wind effects on such two primary mirrors are also investigated.

  3. Effect of amiloride, or amiloride plus hydrochlorothiazide, versus hydrochlorothiazide on glucose tolerance and blood pressure (PATHWAY-3): a parallel-group, double-blind randomised phase 4 trial

    PubMed Central

    Brown, Morris J; Williams, Bryan; Morant, Steve V; Webb, David J; Caulfield, Mark J; Cruickshank, J Kennedy; Ford, Ian; McInnes, Gordon; Sever, Peter; Salsbury, Jackie; Mackenzie, Isla S; Padmanabhan, Sandosh; MacDonald, Thomas M

    2016-01-01

    Summary Background Potassium depletion by thiazide diuretics is associated with a rise in blood glucose. We assessed whether addition or substitution of a potassium-sparing diuretic, amiloride, to treatment with a thiazide can prevent glucose intolerance and improve blood pressure control. Methods We did a parallel-group, randomised, double-blind trial in 11 secondary and two primary care sites in the UK. Eligible patients were aged 18–80 years; had clinic systolic blood pressure of 140 mm Hg or higher and home systolic blood pressure of 130 mmHg or higher on permitted background drugs of angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, β blockers, calcium-channel blockers, or direct renin inhibitors (previously untreated patients were also eligible in specific circumstances); and had at least one component of the metabolic syndrome in addition to hypertension. Patients with known diabetes were excluded. Patients were randomly assigned (1:1:1) to 24 weeks of daily oral treatment with starting doses of 10 mg amiloride, 25 mg hydrochlorothiazide, or 5 mg amiloride plus 12·5 mg hydrochlorothiazide; all doses were doubled after 12 weeks. Random assignment was done via a central computer system. Both participants and investigators were masked to assignment. Our hierarchical primary endpoints, assessed on a modified intention-to-treat basis at 12 and 24 weeks, were the differences from baseline in blood glucose measured 2 h after a 75 g oral glucose tolerance test (OGTT), compared first between the hydrochlorothiazide and amiloride groups, and then between the hydrochlorothiazide and combination groups. A key secondary endpoint was change in home systolic blood pressure at 12 and 24 weeks. This trial is registered with ClinicalTrials.gov, number NCT00797862, and the MHRA, Eudract number 2009-010068-41, and is now complete. Findings Between Nov 18, 2009, and Dec 15, 2014, 145 patients were randomly assigned to amiloride, 146 to

  4. Active control of combustion for optimal performance

    SciTech Connect

    Jackson, M.D.; Agrawal, A.K.

    1999-07-01

    Combustion-zone stoichiometry and fuel-air premixing were actively controlled to optimize the combustor performance over a range of operating conditions. The objective was to maximize the combustion temperature, while maintaining NO{sub x} within a specified limit. The combustion system consisted of a premixer located coaxially near the inlet of a water-cooled shroud. The equivalence ratio was controlled by a variable-speed suction fan located downstream. The split between the premixing air and diffusion air was governed by the distance between the premixer and shroud. The combustor performance was characterized by a cost function evaluated from time-averaged measurements of NO{sub x} and oxygen concentrations in products. The cost function was minimized by downhill simplex algorithm employing closed-loop feedback. Experiments were conducted at different fuel flow rates to demonstrate that the controller optimized the performance without prior knowledge of the combustor behavior.

  5. A randomized, double-blind, placebo-controlled, multiple-dose, parallel-group clinical trial to assess the effects of teduglutide on gastric emptying of liquids in healthy subjects

    PubMed Central

    2014-01-01

    Background Teduglutide, a recombinant analog of human glucagon-like peptide (GLP)-2, is a novel therapy recently approved for the treatment of adult patients with short bowel syndrome who are dependent on parenteral support. Previous studies assessing the effect of GLP-2 on gastric emptying in humans have yielded inconsistent results, with some studies showing no effect and others documenting a GLP-2–dependent delay in gastric emptying. The primary objective of this study was to assess the effect of teduglutide on gastric emptying of liquids in healthy subjects, as measured by the pharmacokinetics of acetaminophen. Methods This double-blind, parallel-group, single-center study enrolled and randomized 36 healthy subjects (22 men, 14 women) to receive subcutaneous doses of teduglutide 4 mg or placebo (2:1 ratio; 23:13) once daily on Days 1 through 10 in the morning. Gastric emptying of a mixed nutrient liquid meal was assessed by measuring acetaminophen levels predose and at 0.25, 0.5, 0.75, 1, 1.25, 1.5, 2, 3, 3.5, 4, 5, 6, 8, 10, 12, and 14 hours after administration of 1000 mg acetaminophen on Days 0 and 10. The primary study endpoint was a pharmacokinetic analysis of acetaminophen absorption in subjects receiving teduglutide or placebo. Results No significant differences in gastric emptying of liquids (acetaminophen area under the concentration [AUC] vs time curve from time 0 to the last measurable concentration, AUC extrapolated to infinity, maximum concentration [Cmax], and time to Cmax) were observed on Day 10 in subjects receiving teduglutide 4 mg versus subjects receiving placebo. There were no serious adverse events (AEs), deaths, or discontinuations due to an AE reported during the study. Conclusions Teduglutide 4 mg/day for 10 days does not affect gastric emptying of liquids in healthy subjects as measured by acetaminophen pharmacokinetics. No unexpected safety signals were observed. Trial registration This study was registered at Clinical

  6. Why caution is recommended with post-hoc individual patient matching for estimation of treatment effect in parallel-group randomized controlled trials: the case of acute stroke trials.

    PubMed

    Jafari, Nahid; Hearne, John; Churilov, Leonid

    2013-11-10

    A post-hoc individual patient matching procedure was recently proposed within the context of parallel group randomized clinical trials (RCTs) as a method for estimating treatment effect. In this paper, we consider a post-hoc individual patient matching problem within a parallel group RCT as a multi-objective decision-making problem focussing on the trade-off between the quality of individual matches and the overall percentage of matching. Using acute stroke trials as a context, we utilize exact optimization and simulation techniques to investigate a complex relationship between the overall percentage of individual post-hoc matching, the size of the respective RCT, and the quality of matching on variables highly prognostic for a good functional outcome after stroke, as well as the dispersion in these variables. It is empirically confirmed that a high percentage of individual post-hoc matching can only be achieved when the differences in prognostic baseline variables between individually matched subjects within the same pair are sufficiently large and that the unmatched subjects are qualitatively different to the matched ones. It is concluded that the post-hoc individual matching as a technique for treatment effect estimation in parallel-group RCTs should be exercised with caution because of its propensity to introduce significant bias and reduce validity. If used with appropriate caution and thorough evaluation, this approach can complement other viable alternative approaches for estimating the treatment effect. PMID:23761106

  7. Semi-active control of seat suspension with MR damper

    NASA Astrophysics Data System (ADS)

    Yao, H. J.; Fu, J.; Yu, M.; Peng, Y. X.

    2013-02-01

    The vibration control of a seat suspension system with magnetorheological (MR) damper is investigated in this study. Firstly, a dynamical model of the seat suspension system with parameter uncertainties (such as mass, stiffness, damping) and actuator saturation is established. Secondly, based on Lyapunov functional theory and considering constraint conditions for damping force, the semi-active controller is designed, and the controller parameters are derived in terms of linear matrix inequalities (LMIs), which guarantees performance index. Finally, compared control strategy and the passive, skyhook control strategy, the simulation results in time and frequency domains demonstrate the proposed approach can achieve better vertical acceleration attenuation for the seat suspension system and improve ride comfort.

  8. Rolling maneuver load alleviation using active controls

    NASA Technical Reports Server (NTRS)

    Woods-Vedeler, Jessica A.; Pototzky, Anthony S.

    1992-01-01

    Rolling Maneuver Load Alleviation (RMLA) was demonstrated on the Active Flexible Wing (AFW) wind tunnel model in the LaRC Transonic Dynamics Tunnel. The design objective was to develop a systematic approach for developing active control laws to alleviate wing incremental loads during roll maneuvers. Using linear load models for the AFW wind-tunnel model which were based on experimental measurements, two RMLA control laws were developed based on a single-degree-of-freedom roll model. The RMLA control laws utilized actuation of outboard control surface pairs to counteract incremental loads generated during rolling maneuvers and roll performance. To evaluate the RMLA control laws, roll maneuvers were performed in the wind tunnel at dynamic pressures of 150, 200, and 250 psf and Mach numbers of .33, .38, and .44, respectively. Loads obtained during these maneuvers were compared to baseline maneuver loads. For both RMLA controllers, the incremental torsion moments were reduced by up to 60 percent at all dynamic pressures and performance times. Results for bending moment load reductions during roll maneuvers varied. In addition, in a multiple function test, RMLA and flutter suppression system control laws were operated simultaneously during roll maneuvers at dynamic pressures 11 percent above the open-loop flutter dynamic pressure.

  9. Rolling Maneuver Load Alleviation using active controls

    NASA Technical Reports Server (NTRS)

    Woods-Vedeler, Jessica A.; Pototzky, Anthony S.

    1992-01-01

    Rolling Maneuver Load Alleviation (RMLA) has been demonstrated on the Active Flexible Wing (AFW) wind tunnel model in the NASA Langley Transonic Dynamics Tunnel. The design objective was to develop a systematic approach for developing active control laws to alleviate wing incremental loads during roll maneuvers. Using linear load models for the AFW wind-tunnel model which were based on experimental measurements, two RMLA control laws were developed based on a single-degree-of-freedom roll model. The RMLA control laws utilized actuation of outboard control surface pairs to counteract incremental loads generated during rolling maneuvers and actuation of the trailing edge inboard control surface pairs to maintain roll performance. To evaluate the RMLA control laws, roll maneuvers were performed in the wind tunnel at dynamic pressures of 150, 200, and 250 psf and Mach numbers of 0.33, .38 and .44, respectively. Loads obtained during these maneuvers were compared to baseline maneuver loads. For both RMLA controllers, the incremental torsion moments were reduced by up to 60 percent at all dynamic pressures and performance times. Results for bending moment load reductions during roll maneuvers varied. In addition, in a multiple function test, RMLA and flutter suppression system control laws were operated simultaneously during roll maneuvers at dynamic pressures 11 percent above the open-loop flutter dynamic pressure.

  10. Head-to-head comparison of intensive lifestyle intervention (U-TURN) versus conventional multifactorial care in patients with type 2 diabetes: protocol and rationale for an assessor-blinded, parallel group and randomised trial

    PubMed Central

    Ried-Larsen, Mathias; Hansen, Katrine B; Johansen, Mette Y; Pedersen, Maria; Zacho, Morten; Hansen, Louise S; Kofoed, Katja; Thomsen, Katja; Jensen, Mette S; Nielsen, Rasmus O; MacDonald, Chris; Langberg, Henning; Vaag, Allan A; Pedersen, Bente K; Karstoft, Kristian

    2015-01-01

    Introduction Current pharmacological therapies in patients with type 2 diabetes (T2D) are challenged by lack of sustainability and borderline firm evidence of real long-term health benefits. Accordingly, lifestyle intervention remains the corner stone in the management of T2D. However, there is a lack of knowledge regarding the optimal intervention programmes in T2D ensuring both compliance as well as long-term health outcomes. Our objective is to assess the effects of an intensive lifestyle intervention (the U-TURN intervention) on glycaemic control in patients with T2D. Our hypothesis is that intensive lifestyle changes are equally effective as standard diabetes care, including pharmacological treatment in maintaining glycaemic control (ie, glycated haemoglobin (HbA1c)) in patients with T2D. Furthermore, we expect that intensive lifestyle changes will decrease the need for antidiabetic medications. Methods and analysis The study is an assessor-blinded, parallel group and a 1-year randomised trial. The primary outcome is change in glycaemic control (HbA1c), with the key secondary outcome being reductions in antidiabetic medication. Participants will be patients with T2D (T2D duration <10 years) without complications who are randomised into an intensive lifestyle intervention (U-TURN) or a standard care intervention in a 2:1 fashion. Both groups will be exposed to the same standardised, blinded, target-driven pharmacological treatment and can thus maintain, increase, reduce or discontinue the pharmacological treatment. The decision is based on the standardised algorithm. The U-TURN intervention consists of increased training and basal physical activity level, and an antidiabetic diet including an intended weight loss. The standard care group as well as the U-TURN group is offered individual diabetes management counselling on top of the pharmacological treatment. Ethics and dissemination This study has been approved by the Scientific Ethical Committee at the

  11. Active control of transmitted sound in buildings

    NASA Astrophysics Data System (ADS)

    Thompsett, Russell Harvey George

    The problem of noise from neighbours has increased dramatically over the last few years. Many of the noise complaints are due to the high level, low frequency noise from modern stereo equipment, and are often described in terms of the low frequency characteristics of the music; the repetitive, booming, bass beat. The objective of this research was to establish the feasibility of applying active noise control to alleviate this problem. The initial approach was to evaluate the possibility of exploiting the dominance of individual modes in the response of rooms at low frequency to effect global control. However, initial investigations using a modal model of the sound field revealed that this would be difficult due to the contribution of many acoustic modes excited off resonance. This conclusion was supported by measurements of acoustic room responses in typical buildings, illustrating a non-resonant characteristic. Consequently, attention was turned to the feasibility of using local active control systems to create zones of quiet by concentrating control at a specific location near the observers ears, for example in a seat headrest, or near the pillows of a bed. The lack of a reference signal in either approach requires the use of a feedback control strategy. With a typically non-resonant system, the predictability in the disturbance necessary for successful feedback control must be contained in the primary excitation, namely the music. Examples of different music styles were investigated and of those with the potential to be a nuisance surprisingly few were significantly more predictable than a random disturbance. As expected the most encouraging control performance simulations were found for modern dance music, with a strong repetitive beat. A real-time, local controller was demonstrated in the laboratory with such a disturbance signal and the properties of the quiet zone were measured. The subjective response when hearing the controller in operation was found to be

  12. A multicentre, pragmatic, parallel group, randomised controlled trial to compare the clinical and cost-effectiveness of three physiotherapy-led exercise interventions for knee osteoarthritis in older adults: the BEEP trial protocol (ISRCTN: 93634563)

    PubMed Central

    2014-01-01

    Background Exercise is consistently recommended for older adults with knee pain related to osteoarthritis. However, the effects from exercise are typically small and short-term, likely linked to insufficient individualisation of the exercise programme and limited attention to supporting exercise adherence over time. The BEEP randomised trial aims to improve patients’ short and long-term outcomes from exercise. It will test the overall effectiveness and cost-effectiveness of two physiotherapy-led exercise interventions (Individually Tailored Exercise and Targeted Exercise Adherence) to improve the individual tailoring of, and adherence to exercise, compared with usual physiotherapy care. Methods/design Based on the learning from a pilot study (ISRCTN 23294263), the BEEP trial is a multi-centre, pragmatic, parallel group, individually randomised controlled trial, with embedded longitudinal qualitative interviews. 500 adults in primary care, aged 45 years and over with knee pain will be randomised to 1 of 3 treatment groups delivered by fully trained physiotherapists in up to 6 NHS services. These are: Usual Physiotherapy Care (control group consisting of up to 4 treatment sessions of advice and exercise), Individually Tailored Exercise (an individualised, supervised and progressed lower-limb exercise programme) or Targeted Exercise Adherence (supporting patients to adhere to exercise and to engage in general physical activity over the longer-term). The primary outcomes are pain and function as measured by the Western Ontario and McMaster Osteoarthritis index. A comprehensive range of secondary outcomes are also included. Outcomes are measured at 3, 6 (primary outcome time-point), 9, 18 and 36 months. Data on adverse events will also be collected. Semi-structured, qualitative interviews with a subsample of 30 participants (10 from each treatment group) will be undertaken at two time-points (end of treatment and 12 to 18 months later) and analysed thematically

  13. The Benchmark Active Controls Technology Model Aerodynamic Data

    NASA Technical Reports Server (NTRS)

    Scott, Robert C.; Hoadley, Sherwood T.; Wieseman, Carol D.; Durham, Michael H.

    1997-01-01

    The Benchmark Active Controls Technology (BACT) model is a part of the Benchmark Models Program (BMP). The BMP is a NASA Langley Research Center program that includes a series of models which were used to study different aeroelastic phenomena and to validate computational fluid dynamics codes. The primary objective of BACT testing was to obtain steady and unsteady loads, accelerations, and aerodynamic pressures due to control surface activity in order to calibrate unsteady CFD codes and active control design tools. Three wind-tunnel tests in the Transonic Dynamics Tunnel (TDT) have been completed. The first and parts of the second and third tests focused on collecting open-loop data to define the model's aeroservoelastic characteristics, including the flutter boundary across the Mach range. It is this data that is being presented in this paper. An extensive database of over 3000 data sets was obtained. This database includes steady and unsteady control surface effectiveness data, including pressure distributions, control surface hinge moments, and overall model loads due to deflections of a trailing edge control surface and upper and lower surface

  14. Quadratic Optimization in the Problems of Active Control of Sound

    NASA Technical Reports Server (NTRS)

    Loncaric, J.; Tsynkov, S. V.; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    We analyze the problem of suppressing the unwanted component of a time-harmonic acoustic field (noise) on a predetermined region of interest. The suppression is rendered by active means, i.e., by introducing the additional acoustic sources called controls that generate the appropriate anti-sound. Previously, we have obtained general solutions for active controls in both continuous and discrete formulations of the problem. We have also obtained optimal solutions that minimize the overall absolute acoustic source strength of active control sources. These optimal solutions happen to be particular layers of monopoles on the perimeter of the protected region. Mathematically, minimization of acoustic source strength is equivalent to minimization in the sense of L(sub 1). By contrast. in the current paper we formulate and study optimization problems that involve quadratic functions of merit. Specifically, we minimize the L(sub 2) norm of the control sources, and we consider both the unconstrained and constrained minimization. The unconstrained L(sub 2) minimization is certainly the easiest problem to address numerically. On the other hand, the constrained approach allows one to analyze sophisticated geometries. In a special case, we call compare our finite-difference optimal solutions to the continuous optimal solutions obtained previously using a semi-analytic technique. We also show that the optima obtained in the sense of L(sub 2) differ drastically from those obtained in the sense of L(sub 1).

  15. Quasi-modal vibration control by means of active control bearings

    NASA Technical Reports Server (NTRS)

    Nonami, K.; Fleming, D. P.

    1986-01-01

    This paper investigates a design method of an active control bearing system with only velocity feedback. The study provides a new quasi-modal control method for a control system design of an active control bearing system in which feedback coefficients are determined on the basis of a modal analysis. Although the number of sensors and actuators is small, this quasi-modal control method produces a control effect close to an ideal modal control.

  16. Modeling the Benchmark Active Control Technology Wind-Tunnel Model for Active Control Design Applications

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R.

    1998-01-01

    This report describes the formulation of a model of the dynamic behavior of the Benchmark Active Controls Technology (BACT) wind tunnel model for active control design and analysis applications. The model is formed by combining the equations of motion for the BACT wind tunnel model with actuator models and a model of wind tunnel turbulence. The primary focus of this report is the development of the equations of motion from first principles by using Lagrange's equations and the principle of virtual work. A numerical form of the model is generated by making use of parameters obtained from both experiment and analysis. Comparisons between experimental and analytical data obtained from the numerical model show excellent agreement and suggest that simple coefficient-based aerodynamics are sufficient to accurately characterize the aeroelastic response of the BACT wind tunnel model. The equations of motion developed herein have been used to aid in the design and analysis of a number of flutter suppression controllers that have been successfully implemented.

  17. Application of active controls technology to the NASA Jet Star airplane

    NASA Technical Reports Server (NTRS)

    Lange, R. H.; Cahill, J. F.; Campion, M. C.; Bradley, E. S.; Macwilkinson, D. G.; Phillips, J. W.

    1975-01-01

    The feasibility was studied of modifying a Jet Star airplane into a demonstrator of benefits to be achieved from incorporating active control concepts in the preliminary design of transport type aircraft. Substantial benefits are shown in terms of fuel economy and community noise by virtue of reduction in induced drag through use of a high aspect ratio wing which is made possible by a gust alleviation system. An intermediate configuration was defined which helps to isolate the benefits produced by active controls technology from those due to other configuration variables. Also, an alternate configuration which incorporated composite structures, but not active controls technology, was defined in order to compare the benefits of composite structures with those of active controls technology.

  18. Active control of aerothermoelastic effects for a conceptual hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Heeg, Jennifer; Gilbert, Michael G.; Pototzky, Anthony S.

    1990-01-01

    Procedures for and results of aeroservothermoelastic studies are described. The objectives of these studies were to develop the necessary procedures for performing an aeroelastic analysis of an aerodynamically heated vehicle and to analyze a configuration in the classical cold state and in a hot state. Major tasks include the development of the structural and aerodynamic models, open loop analyses, design of active control laws for improving dynamic responses and analyses of the closed loop vehicles. The analyses performed focused on flutter speed calculations, short period eigenvalue trends and statistical analyses of the vehicle response to controls and turbulence. Improving the ride quality of the vehicle and raising the flutter boundary of the aerodynamically-heated vehicle up to that of the cold vehicle were the objectives of the control law design investigations.

  19. Actively Controlled Landing Gear for Aircraft Vibration Reduction

    NASA Technical Reports Server (NTRS)

    Horta, Lucas G.; Daugherty, Robert H.; Martinson, Veloria J.

    1999-01-01

    Concepts for long-range air travel are characterized by airframe designs with long, slender, relatively flexible fuselages. One aspect often overlooked is ground induced vibration of these aircraft. This paper presents an analytical and experimental study of reducing ground-induced aircraft vibration loads using actively controlled landing gears. A facility has been developed to test various active landing gear control concepts and their performance. The facility uses a NAVY A6-intruder landing gear fitted with an auxiliary hydraulic supply electronically controlled by servo valves. An analytical model of the gear is presented including modifications to actuate the gear externally and test data is used to validate the model. The control design is described and closed-loop test and analysis comparisons are presented.

  20. Diagnostics and Active Control of Aircraft Interior Noise

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1998-01-01

    This project deals with developing advanced methods for investigating and controlling interior noise in aircraft. The work concentrates on developing and applying the techniques of Near Field Acoustic Holography (NAH) and Principal Component Analysis (PCA) to the aircraft interior noise dynamic problem. This involves investigating the current state of the art, developing new techniques and then applying them to the particular problem being studied. The knowledge gained under the first part of the project was then used to develop and apply new, advanced noise control techniques for reducing interior noise. A new fully active control approach based on the PCA was developed and implemented on a test cylinder. Finally an active-passive approach based on tunable vibration absorbers was to be developed and analytically applied to a range of test structures from simple plates to aircraft fuselages.

  1. Coupled Torsional and Bending Vibrations of Actively Controlled Drillstrings

    NASA Astrophysics Data System (ADS)

    YIGIT, A. S.; CHRISTOFOROU, A. P.

    2000-06-01

    The dynamics of actively controlled drillstrings is studied. The equations of motion are derived using a lumped parameter model in which the coupling between torsional and bending vibrations is considered. The model also includes the dynamics of the rotary drive system which contains the rotary table, the gearbox and an armature controlled DC motor. The interactions between the drillstring and the borehole which are considered, include the impacts of collars with the borehole wall as well as bit rotation-dependent weight and torque on bit (WOB and TOB). Simulation results obtained by numerically solving the equations of motion are in close qualitative agreement with field and laboratory observations regarding stick-slip oscillations. A linear quadratic regulator (LQR) controller is designed based on a linearized model and is shown to be effective in eliminating this type of oscillations. It is also shown that for some operational parameters the control action may excite large bending vibrations due to coupling with the torsional motion.

  2. Active control: an investigation method for combustion instabilities

    NASA Astrophysics Data System (ADS)

    Poinsot, T.; Yip, B.; Veynante, D.; Trouvé, A.; Samaniego, J. M.; Candel, S.

    1992-07-01

    Closed-loop active control methods and their application to combustion instabilities are discussed. In these methods the instability development is impeded with a feedback control loop: the signal provided by a sensor monitoring the flame or pressure oscillations is processed and sent back to actuators mounted on the combustor or on the feeding system. Different active control systems tested on a non-premixed multiple-flame turbulent combustor are described. These systems can suppress all unstable plane modes of oscillation (i.e. low frequency modes). The active instability control (AIC) also constitutes an original and powerful technique for studies of mechanisms leading to instability or resulting from the instability. Two basic applications of this kind are described. In the first case the flame is initially controlled with AIC, the feedback loop is then switched off and the growth of the instability is analysed through high speed Schlieren cinematography and simultaneous sound pressure and reaction rate measurements. Three phases are identified during th growth of the oscillations: (1) a linear phase where acoustic waves induce a flapping motion of the flame sheets without interaction between sheets, (2) a modulation phase, where flame sheets interact randomly and (3) a nonlinear phase where the flame sheets are broken and a limit cycle is reached. In the second case we investigate different types of flame extinctions associated with combustion instability. It is shown that pressure oscillations may lead to partial or total extinctions. Extinctions occur in various forms but usually follow a rapid growth of pressure oscillations. The flame is extinguished during the modulation phase observed in the initiation experiments. In these studies devoted to transient instability phenomena, the control system constitutes a unique investigation tool because it is difficult to obtain the same information by other means. Implications for modelling and prediction of

  3. Fluoxetine versus sertraline in the treatment of patients with undifferentiated somatoform disorder: a randomized, open-label, 12-week, parallel-group trial.

    PubMed

    Han, Changsu; Pae, Chi-Un; Lee, Bun Hee; Ko, Young-Hoon; Masand, Prakash S; Patkar, Ashwin A; Jung, In-Kwa

    2008-02-15

    The present study was conducted to compare the effectiveness and tolerability of fluoxetine and sertraline in the treatment of undifferentiated somatoform disorder (USD), using the Patient Health Questionnaire (PHQ-15), which was specifically designed for assessing the severity of somatic symptoms. A randomized, 12-week, open-label trial of fluoxetine (10-60 mg/d) and sertraline (25-350 mg/d) in patients with USD was conducted. Six visits, at baseline and weeks 1, 2, 4, 8, and 12, were scheduled. Assessments for effectiveness and tolerability were conducted at each visit. The primary effectiveness measure was the mean change in PHQ-15 total score, from baseline to the end of treatment. Secondary effectiveness measures were the mean changes in total scores on the Beck Depression Inventory (BDI) and the 12-item General Health Questionnaire (GHQ-12), from baseline to the end of treatment. A total of 45 subjects were enrolled; of them, 28 were randomly assigned to receive fluoxetine and 17 to receive sertraline. The total score on the PHQ-15 from baseline to the end of treatment significantly decreased in the fluoxetine (-10.7, p<0.0001) and sertraline (-10.3, p<0.0001) treatment groups, with no between-group difference (F=0.0701, p=0.7924). Overall, both treatments were well tolerated and no serious adverse event was reported. This study suggests that both agents may have a potential role in the treatment of USD. A double-blind, placebo-controlled trial and/or head-to-head comparison study with larger samples are required to draw more definite conclusions. PMID:17950970

  4. Application of Semi Active Control Techniques to the Damping Suppression Problem of Solar Sail Booms

    NASA Technical Reports Server (NTRS)

    Adetona, O.; Keel, L. H.; Whorton, M. S.

    2007-01-01

    Solar sails provide a propellant free form for space propulsion. These are large flat surfaces that generate thrust when they are impacted by light. When attached to a space vehicle, the thrust generated can propel the space vehicle to great distances at significant speeds. For optimal performance the sail must be kept from excessive vibration. Active control techniques can provide the best performance. However, they require an external power-source that may create significant parasitic mass to the solar sail. However, solar sails require low mass for optimal performance. Secondly, active control techniques typically require a good system model to ensure stability and performance. However, the accuracy of solar sail models validated on earth for a space environment is questionable. An alternative approach is passive vibration techniques. These do not require an external power supply, and do not destabilize the system. A third alternative is referred to as semi-active control. This approach tries to get the best of both active and passive control, while avoiding their pitfalls. In semi-active control, an active control law is designed for the system, and passive control techniques are used to implement it. As a result, no external power supply is needed so the system is not destabilize-able. Though it typically underperforms active control techniques, it has been shown to out-perform passive control approaches and can be unobtrusively installed on a solar sail boom. Motivated by this, the objective of this research is to study the suitability of a Piezoelectric (PZT) patch actuator/sensor based semi-active control system for the vibration suppression problem of solar sail booms. Accordingly, we develop a suitable mathematical and computer model for such studies and demonstrate the capabilities of the proposed approach with computer simulations.

  5. A Multicenter, Randomized, Parallel-Group Trial Assessing Compliance, Tolerability, Safety, and Efficacy to Treatment with Grass Allergy Tablets in 261 Patients with Grass Pollen Rhinoconjunctivitis

    PubMed Central

    Alesina, Roberta; Milani, Massimo; Pecora, Silvia

    2012-01-01

    Background. Allergen-specific sublingual immunotherapy (SLIT) is considered a causal treatment of respiratory allergies. Compliance to the SLIT is an important aspect for a positive clinical outcome. Study Aim. To evaluate if compliance with grass Allergy Immunotherapy Tablet (AIT) can be increased by providing an electronic compliance device (CED) (Memozax; a tablet-container with a programmable daily acoustic alarm). Patients and Methods. 261 patients with grass allergy were enrolled and randomized (1 : 1) to 1-year treatment with AIT (Grazax) using a CED (group A; n = 122) or without (Group B, n = 139). Compliance was measured through tablet count at each visit. Results. The 12-month compliance, mean (SD), in group A was 83% (21) and 83% (24) in group B. A total of 81% of patients reported a significant clinical improvement of symptoms after treatment in comparison with the previous year. No severe adverse reactions were observed in the study. Conclusion. Compliance to the treatment with AIT administered for 12 consecutive months is in general good. The use of CED is not associated with a greater compliance. AIT treatment was associated with a significant clinical improvement in >80% of patients with a good tolerability and safety profile. PMID:22131999

  6. Auricular Acupuncture Versus Progressive Muscle Relaxation in Patients with Anxiety Disorders or Major Depressive Disorder: A Prospective Parallel Group Clinical Trial.

    PubMed

    de Lorent, Lukas; Agorastos, Agorastos; Yassouridis, Alexander; Kellner, Michael; Muhtz, Christoph

    2016-08-01

    Although acupuncture treatment is increasingly in demand among psychiatric patients, to date no studies have investigated the effectiveness of auricular acupuncture (AA) in treating anxiety disorders or major depressive disorder. Thus, this study aimed to compare the effectiveness of AA versus progressive muscle relaxation (PMR), a standardized and accepted relaxation method. We examined 162 patients with a primary diagnosis of anxiety disorder or major depressive disorder, and each patient chose between treatment with AA, executed according to the National Acupuncture Detoxification Association protocol, and treatment with PMR. Each group had treatments twice a week for 4 weeks. Before and after treatment, each participant rated four items on a visual analog scale: anxiety, tension, anger/aggression, and mood. Statistical analyses were performed with the original visual analog scale scores and the Change-Intensity Index, an appropriate indicator of the difference between two values of a variable. Our results show that treatment with AA significantly decreased tension, anxiety, and anger/aggression throughout the 4 weeks, but did not elevate mood. Between AA and PMR, no statistically significant differences were found at any time. Thus, we suggest that both AA and PMR may be useful, equally-effective additional interventions in the treatment of the above-mentioned disorders. PMID:27555224

  7. Efficacy and Safety of Crocus sativus L. in Patients with Mild Cognitive Impairment: One Year Single-Blind Randomized, with Parallel Groups, Clinical Trial.

    PubMed

    Tsolaki, Magda; Karathanasi, Elina; Lazarou, Ioulietta; Dovas, Kostas; Verykouki, Eleni; Karacostas, Anastasios; Georgiadis, Kostas; Tsolaki, Anthoula; Adam, Katerina; Kompatsiaris, Ioannis; Sinakos, Zacharias

    2016-07-27

    There is evidence to suggest the efficacy of Crocus (saffron) in the management of cognitive decline. This study examined the efficacy of Crocus in patients with amnesic and multi domain MCI (aMCImd). The participants included 17 patients on Crocus and 18 on a waiting list, who were examined with a short neuropsychological battery, MRI 3T, while some patients were examined via 256-channel electroencephalogram (HD-EEG) at baseline and after 12 months. The results showed that patients on Crocus had improved Mini-Mental State Examination scores (p = 0.015), while the control group deteriorated. Also, MRI, EEG, and ERP showed improvement in specific domains. This led us to conclude that Crocus is a good choice for management of aMCImd. PMID:27472878

  8. A multicentre randomised, 1-year comparative effectiveness, parallel-group trial protocol of a physical therapy approach compared to corticosteroid injections

    PubMed Central

    Deyle, Gail D; Gill, Norman W; Rhon, Daniel I; Allen, Chris S; Allison, Stephen C; Hando, Ben R; Petersen, Evan J; Dusenberry, Douglas I; Bellamy, Nicholas

    2016-01-01

    Introduction Corticosteroid injections (CSIs) are commonly used as an initial or a primary intervention for knee osteoarthritis (OA). Consistent evidence indicates CSIs offer symptom relief with conflicting reports regarding long-term efficacy. Physical therapy (PT) offers a non-invasive alternative. There is moderate evidence suggesting short-term and long-term symptom relief and functional improvement with PT interventions. Patients with knee OA are more commonly prescribed CSI than PT prior to total joint replacement. UnitedHealthcare and Military Health System data show substantially more total knee replacement patients receive preoperative CSI than PT. There are no studies comparing CSI to a PT approach in individuals with knee OA. The primary objective of this study is to compare the effectiveness of CSI to PT in individuals with knee OA at 1, 2 and 12 months. Methods and analysis We plan to recruit 156 participants meeting established knee OA criteria. Following informed consent, participants will be randomised to receive either CSI or PT. All participants will receive instruction on recommended exercise and weight control strategies plus usual medical care. The CSI intervention consisting of 3 injections and the PT intervention consisting of 8–12 sessions will be spaced over 12 months. Measures of the dependent variables (DVs) will occur at baseline, 4 weeks, 8 weeks, 6 months and 12 months post enrolment. This pragmatic, randomised clinical trial will be a mixed-model 2×5 factorial design. The independent variables are treatment (CSI and PT) and time with five levels from baseline to 1 year. The primary DV is the Western Ontario & McMaster Universities Arthritis Index (WOMAC). We will also compare healthcare utilisation between the 2 groups. Ethics and Dissemination The protocol was approved by the Madigan Army Medical Center Institutional Review Board. The authors intend to publish the results in a peer-reviewed source. Trial Registration

  9. Moxibustion as an adjuvant for benign prostatic hyperplasia with lower urinary tract symptoms: a protocol for a parallel-group, randomised, controlled pilot trial

    PubMed Central

    Lee, Hye-Yoon; Nam, Jong-Kil; Lee, Sang-Don; Lee, Dong-Hoon; Han, Ji-Yeon; Yun, Young-Ju; Lee, Ji-Hye; Park, Hye-lim; Park, Seong-Ha; Kwon, Jung-Nam

    2015-01-01

    Introduction This study aims to explore the feasibility of using moxibustion as a supplementary intervention and to assess the sample size for verifying the effectiveness and safety of integrative treatment involving moxibustion compared with conventional treatment for patients with benign prostatic hyperplasia accompanying moderate to severe lower urinary tract symptoms. Methods and analysis A total of 60 patients diagnosed with benign prostatic hyperplasia by a urologist based on prostate size, prostate-specific antigen and clinical symptoms will participate of their own free will; urologists will monitor the patients and evaluate their symptoms. The patients will be randomised to either a conventional group or an integrative group with a 1:1 allocation according to computer-generated random numbers concealed in opaque, sealed, sequentially numbered envelopes. Watchful waiting or oral medication including α blocker, 5α-reductase inhibitors or antimuscarinic drugs will be offered as conventional treatment. Integrative treatment will include moxibustion therapy in addition to the conventional treatment. The moxibustion therapy will be conducted twice a week for 4 weeks on the bilateral acupoints SP6, LR3 and CV4 by a qualified Korean medical doctor. The primary outcome will be the International Prostate Symptom Score (IPSS) after eight sessions. The secondary outcomes will be the post-void residual urine volume, the maximum urinary flow rate, IPSS, the results of a Short-Form 36-Question Health Survey after 12 weeks, and the patients’ global impression of changes at each visit. Ethics and dissemination Written informed consent will be obtained from all participants. This study was approved by the institutional review boards of both Pusan National University Yangsan Hospital and Pusan National University Korean Medicine Hospital. The trial results will be disseminated through open-access journals and conferences. Trial registration number NCT02051036. PMID

  10. Active control for turbulent premixed flame simulations

    SciTech Connect

    Bell, John B.; Day, Marcus S.; Grcar, Joseph F.; Lijewski, Michael J.

    2004-03-26

    Many turbulent premixed flames of practical interest are statistically stationary. They occur in combustors that have anchoring mechanisms to prevent blow-off and flashback. The stabilization devices often introduce a level of geometric complexity that is prohibitive for detailed computational studies of turbulent flame dynamics. As a result, typical detailed simulations are performed in simplified model configurations such as decaying isotropic turbulence or inflowing turbulence. In these configurations, the turbulence seen by the flame either decays or, in the latter case, increases as the flame accelerates toward the turbulent inflow. This limits the duration of the eddy evolutions experienced by the flame at a given level of turbulent intensity, so that statistically valid observations cannot be made. In this paper, we apply a feedback control to computationally stabilize an otherwise unstable turbulent premixed flame in two dimensions. For the simulations, we specify turbulent in flow conditions and dynamically adjust the integrated fueling rate to control the mean location of the flame in the domain. We outline the numerical procedure, and illustrate the behavior of the control algorithm. We use the simulations to study the propagation and the local chemical variability of turbulent flame chemistry.

  11. ACTIVELY CONTROLLED VORTEX DISPOSAL SYSTEM FOR SLUDGE WASTES

    EPA Science Inventory

    The development of an advanced sludge treatment concept is under way for applications to sludge wastes. The concept integrates primary treatment of sludge in an advanced vortex containment combustor (VCC) with subsequent post treatment in an actively controlled acoustic afterburn...

  12. ACTIVELY CONTROLLED VORTEX DISPOSAL SYSTEM FOR SLUDGE WASTES

    EPA Science Inventory

    The development of an advanced sludge treatment concept is underway for applications to sludge wastes. The concept integrates primary treatment of sludge in an advanced vortex containment combustor (VCC) with subsequent post treatment in an actively controlled acoustic afterburne...

  13. Active controllers and the time duration to learn a task

    NASA Technical Reports Server (NTRS)

    Repperger, D. W.; Goodyear, C.

    1986-01-01

    An active controller was used to help train naive subjects involved in a compensatory tracking task. The controller is called active in this context because it moves the subject's hand in a direction to improve tracking. It is of interest here to question whether the active controller helps the subject to learn a task more rapidly than the passive controller. Six subjects, inexperienced to compensatory tracking, were run to asymptote root mean square error tracking levels with an active controller or a passive controller. The time required to learn the task was defined several different ways. The results of the different measures of learning were examined across pools of subjects and across controllers using statistical tests. The comparison between the active controller and the passive controller as to their ability to accelerate the learning process as well as reduce levels of asymptotic tracking error is reported here.

  14. A double-blind, multicenter, parallel-group trial with 0.05% halobetasol propionate ointment versus 0.1% diflucortolone valerate ointment in patients with severe, chronic atopic dermatitis or lichen simplex chronicus.

    PubMed

    Brunner, N; Yawalkar, S

    1991-12-01

    In a double-blind, parallel-group, multicenter, comparative trial in 120 evaluable patients with chronic, localized atopic dermatitis or lichen simplex chronicus, the success rate (described as "healed" and "marked improvement") was 91.5% in patients treated with halobetasol propionate ointment and 83.6% in those in the diflucortolone valerate treatment group. Of patients treated with halobetasol propionate ointment, 40.7% reported healing within 17 days, whereas of those in the diflucortolone valerate treatment group, 32.8% reported healing within that time. Early onset of therapeutic effect, that is, within 3 days of the start of treatment, was reported in a higher percentage of patients treated with halobetasol propionate ointment than in those treated with diflucortolone valerate ointment (70% versus 59%). Adverse effects at the site of application were less frequently reported in patients belonging to the halobetasol propionate treatment group than in those treated with diflucortolone valerate ointment (3% versus 8%). PMID:1757609

  15. Active control of cantilever-beam vibration

    NASA Astrophysics Data System (ADS)

    Serbyn, M. Roman

    2002-11-01

    A bang-bang control system previously developed for the stabilization of a rigid platform [ISA Trans. 21, 55-59 (1982)] has been adapted to the problem of reducing flexural vibrations of a beam. The electromechanical system develops an appropriate control signal for the actuator from samples of the disturbance by analog and digital signal processing using integrated circuits. The effectiveness of this approach is predicated upon the sampling rate being much higher than the maximum vibration frequency to be silenced. It is also robust with respect to the waveform of the disturbance. Noise reductions of 10-20 dB have been achieved, depending on the bandwidth of the noise. The cantilever, chosen because of its mechanical and theoretical simplicity, provides a good foundation for the study of more complex structures, like airfoils and nonrigid platforms. In both experimental and analytical investigations the emphasis has been on the optimization of control parameters, particularly with regard to the application of the cancellation signal. Reduction in size and cost of the control unit is possible by incorporating the latest technological advances in electronic and electromechanical devices, such as FPGA boards and MEMS components.

  16. Active control technology and the use of multiple control surfaces

    NASA Technical Reports Server (NTRS)

    Hart, J. E.

    1976-01-01

    Needed criteria for active control technology applications in commercial transports are lacking. Criteria for redundancy requirements, believed to be consistent with certification philosophy, are postulated to afford a discussion of the relative value of multiple control surfaces. The control power and frequency bandpass requirements of various active control technology applications are shown to be such that multiple control surfaces offer advantages in minimizing the hydraulic or auxiliary power for the control surface actuators.

  17. Overview of Langley activities in active controls research

    NASA Technical Reports Server (NTRS)

    Abel, I.; Newsom, J. R.

    1981-01-01

    The application of active controls technology to reduce aeroelastic response of aircraft structures offers a potential for significant payoffs in terms of aerodynamic efficiency and weight savings. The activities of the Langley Research Center (laRC) in advancing active controls technology. Activities are categorized into the development of appropriate analysis tools, control law synthesis methodology, and experimental investigations aimed at verifying both analysis and synthesis methodology.

  18. An aeroelastician's perspective of wind tunnel and flight experiences with active control of structural response and stability

    NASA Technical Reports Server (NTRS)

    Hanson, P. W.

    1984-01-01

    Active controls technology is assessed based on a review of most of the wind-tunnel and flight tests and actual applications of active control concepts since the late sixties. The distinction is made between so-called ""rigid-body'' active control functions and those that involve significant modification of structural elastic response or stability. Both areas are reviewed although the focus is on the latter area. The basic goals and major results of the various studies or applications are summarized, and the anticipated use of active controls on current and near-future research and demonstration aircraft is discussed. Some of the ""holes'' remaining in the feasbility/benefits demonstration of active controls technology are examined.

  19. Selected advanced aerodynamic and active control concepts development

    NASA Technical Reports Server (NTRS)

    1981-01-01

    A task for the Energy Efficient Transport program conducted: (1) The design and wind tunnel development of high-aspect-ratio supercritical wings, investigating the cruise speed regime and also high-lift. (2) The preliminary design and evaluation of an aircraft combining a high-aspect-ratio supercritical wing with a winglet. (3) Active Controls: The determination of criteria, configuration, and flying qualities associated with augmented longitudinal stability of a level likely to be acceptable for the next generation transport; and the design of a practical augmentation system. The baseline against which the work was performed and evaluated was the Douglas DC-X-200 twin engine derivative of the DC-10 transport. The supercritical wing development showed that the cruise and buffet requirements could be achieved and that the wing could be designed to realize a sizable advantage over today's technology. Important advances in high lift performance were shown. The design study of an aircraft with supercritical wing and winglet suggested advantages in weight and fuel economy could be realized. The study of augmented stability, conducted with the aid of a motion base simulator, concluded that a negative static margin was acceptable for the baseline unaugmented aircraft.

  20. Application of neural networks to seismic active control

    SciTech Connect

    Tang, Yu

    1995-07-01

    An exploratory study on seismic active control using an artificial neural network (ANN) is presented in which a singledegree-of-freedom (SDF) structural system is controlled by a trained neural network. A feed-forward neural network and the backpropagation training method are used in the study. In backpropagation training, the learning rate is determined by ensuring the decrease of the error function at each training cycle. The training patterns for the neural net are generated randomly. Then, the trained ANN is used to compute the control force according to the control algorithm. The control strategy proposed herein is to apply the control force at every time step to destroy the build-up of the system response. The ground motions considered in the simulations are the N21E and N69W components of the Lake Hughes No. 12 record that occurred in the San Fernando Valley in California on February 9, 1971. Significant reduction of the structural response by one order of magnitude is observed. Also, it is shown that the proposed control strategy has the ability to reduce the peak that occurs during the first few cycles of the time history. These promising results assert the potential of applying ANNs to active structural control under seismic loads.

  1. Development of Active Control within Working Memory: Active Retrieval versus Monitoring in Children

    ERIC Educational Resources Information Center

    Blain-Brière, Bénédicte; Bouchard, Caroline; Bigras, Nathalie; Cadoret, Geneviève

    2014-01-01

    This study aimed to compare children's performance on two mnemonic functions that engage the lateral prefrontal cortex. Brain imaging studies in adults have shown that the mid-ventrolateral prefrontal cortex is specifically involved in active controlled retrieval, and the mid-dorsolateral prefrontal cortex is specifically involved in…

  2. Randomized, Double-Blinded, Double-Dummy, Active-Controlled, and Multiple-Dose Clinical Study Comparing the Efficacy and Safety of Mulberry Twig (Ramulus Mori, Sangzhi) Alkaloid Tablet and Acarbose in Individuals with Type 2 Diabetes Mellitus

    PubMed Central

    Chen, Yao

    2016-01-01

    Aims. To evaluate the efficacy and safety of mulberry twig alkaloid (SZ-A) tablet compared with acarbose in patients with type 2 diabetes. Methods. This clinical trial enrolled 38 patients who were randomized into two groups (SZ-A: 23; acarbose: 15) and were treated for 24 weeks. Patients and clinical trial staffs were masked to treatment assignment throughout the study. The primary outcome measures were glycated hemoglobin (HbA1c) and 1-hour and 2-hour postprandial and fasting plasma glucose levels from baseline to the end of treatment. Analysis included all patients who completed this study. Results. By the end of this study, HbA1c level in SZ-A group was decreased from baseline significantly (P < 0.001). No significant difference was found when compared with acarbose group (P = 0.652). Similarly, 1-hour and 2-hour postprandial plasma glucose levels in SZ-A group were decreased from baseline statistically (P < 0.05), without any significant differences compared with acarbose group (P = 0.748 and 0.558, resp.). The fasting plasma glucose levels were not significantly changed in both groups. One of 23 patients in SZ-A group (4.76%) and 5 of 15 patients in acarbose group (33.33%) suffered from gastrointestinal adverse events. Conclusions. Compared with acarbose, SZ-A tablet was effective and safe in glycemic control in patients with type 2 diabetes. PMID:27547230

  3. Active control of waves in a cochlear model with subpartitions.

    PubMed Central

    Chadwick, R S; Dimitriadis, E K; Iwasa, K H

    1996-01-01

    Multiscale asymptotic methods developed previously to study macromechanical wave propagation in cochlear models are generalized here to include active control of a cochlear partition having three subpartitions, the basilar membrane, the reticular lamina, and the tectorial membrane. Activation of outer hair cells by stereocilia displacement and/or by lateral wall stretching result in a frequency-dependent force acting between the reticular lamina and basilar membrane. Wavelength-dependent fluid loads are estimated by using the unsteady Stokes' equations, except in the narrow gap between the tectorial membrane and reticular lamina, where lubrication theory is appropriate. The local wavenumber and subpartition amplitude ratios are determined from the zeroth order equations of motion. A solvability relation for the first order equations of motion determines the subpartition amplitudes. The main findings are as follows: The reticular lamina and tectorial membrane move in unison with essentially no squeezing of the gap; an active force level consistent with measurements on isolated outer hair cells can provide a 35-dB amplification and sharpening of subpartition waveforms by delaying dissipation and allowing a greater structural resonance to occur before the wave is cut off; however, previously postulated activity mechanisms for single partition models cannot achieve sharp enough tuning in subpartitioned models. Images Fig. 1 Fig. 2 PMID:8637914

  4. Active control of underground stresses through rock pressurization

    SciTech Connect

    Vandergrift, T.L.

    1995-06-01

    To significantly increase the stability of underground excavations while exploiting the full advantages of confined rock strength, methods must be developed to actively control the distribution of stresses near the excavation. This US Bureau of Mines study examines theoretical and practical aspects of rock pressurization, an active stress control concept that induces compressive stress in the wall rock through repeated hydraulic fracturing with a settable fluid. Numerical analyses performed by incorporating the rock pressurization concept into a variety of boundary-element models indicate that rock pressurization has the potential to improve underground excavation stability in three ways: (1) by relocating stress concentrations away from the weak opening surface to stronger, confined wall rock; (2) by inducing additional stresses in a biaxial stress field to reduce the difference between the principal stress components near the surface of the opening, and (3) by counteracting the tensile stresses induced in the rock around internally loaded openings. Practical aspects of the rock pressurization concept were investigated through a series of hydraulic fracturing experiments. The use of sulfur as a settable fluid for hydraulic fracturing was demonstrated, although problems related to sulfur viscosity suggest that other molten materials, such as wax, may be better suited to practical field application of the rock pressurization concept.

  5. A Randomized, Multi-Center, Single Blind, Active-Controlled, Matched Pairs Clinical Study to Evaluate Prevention of Adhesion Formation and Safety of HyFence in Patients After Endoscopic Sinus Surgery

    PubMed Central

    Chang, Chul; Hong, Sung-Moon; Cho, Jin-Hee; Shim, Sang Yul; Cho, Jung-Sun

    2014-01-01

    Objectives Recurrent mucosal disease and anatomic obstruction are commonly cited causes of failed endoscopic sinus surgery (ESS). Hyaluronic acid (HA) has been reported to reduce scarring and to promote wound healing in sinonasal surgery. HyFence is HA stabilized by 1, 4-butandiol diglycidyl ether, which makes it less-water-soluble and highly viscoelastic. The purpose of this study is to examine the anti-adhesion effect of HyFence after ESS compared to that of HA-CMC (Guardix-Sol). Methods Seventy-four patients with chronic rhinosinusitis who underwent ESS were included in the study. After the ESS procedure, Merocel was placed in the ethmoidectomized areas of the both sides. Five milliliters of Guardix-Sol was then applied to the Merocel of one side and HyFence LV was applied to the other side. The effect of the agents was evaluated at one, two, and four weeks after surgery by endoscopic examination. The severity of adhesion, edema, infection and complications were evaluated. Results There was no significant difference in the incidence of postoperative adhesion between the HyFence group and the Guardix-Sol group (P>0.05). Mean postoperative grades of edema and infection showed no significant difference between groups (P>0.05). There was no significant postoperative complications associated with either anti-adhesion agent (P>0.05). Conclusion HyFence has equivalent anti-adhesion effect compared to Guardix-Sol following ESS. PMID:24587878

  6. Randomized, double-blind, active-controlled study evaluating the safety and immunogenicity of three vaccination schedules and two dose levels of AV7909 vaccine for anthrax post-exposure prophylaxis in healthy adults.

    PubMed

    Hopkins, Robert J; Kalsi, Gurdyal; Montalvo-Lugo, Victor M; Sharma, Mona; Wu, Yukun; Muse, Derek D; Sheldon, Eric A; Hampel, Frank C; Lemiale, Laurence

    2016-04-19

    AV7909 vaccine being developed for post-exposure prophylaxis of anthrax disease may require fewer vaccinations and reduced amount of antigen to achieve an accelerated immune response over BioThrax(®) (Anthrax Vaccine Adsorbed). A phase 2, randomized, double-blind, BioThrax vacccine-controlled study was conducted to evaluate the safety and immunogenicity of three intramuscular vaccination schedules and two dose levels of AV7909 in 168 healthy adults. Subjects were randomized at a 4:3:2:4:2 ratio to 5 groups: (1) AV7909 on Days 0/14; (2) AV7909 on Days 0/28; (3) AV7909 on Days 0/14/28; (4) half dose AV7909 on Days 0/14/28; and (5) BioThrax vaccine on Days 0/14/28. Vaccinations in all groups were well tolerated. The incidences of adverse events (AEs) were 79% for AV7909 subjects and 65% for BioThrax subjects; 92% of AV7909 subjects and 87% of BioThrax subjects having AEs reported Grade 1-2 AEs. No serious AEs were assessed as potentially vaccine-related, and no AEs of potential autoimmune etiology were reported. There was no discernible pattern indicative of a safety concern across groups in the incidence or severity of reactogenicity events. Groups 2-4 achieved success for the primary endpoint, demonstrated by a lower 95% confidence limit of the percentage of subjects with protective toxin neutralizing antibody NF50 values (≥0.56) to be ≥40% at Day 63. Group 1 marginally missed the criterion (lower bound 95% confidence limit of 39.5%). Immune responses were above this threshold for Groups 1, 3 and 4 at Day 28 and all groups at Day 42. Further study of an AV7909 two-dose schedule given 2 weeks apart is warranted in light of the favorable tolerability profile and immunogenicity response relative to three doses of BioThrax vaccine, as well as preliminary data from nonclinical studies indicating similar immune responses correlate with higher survival for AV7909 than BioThrax vaccine. PMID:26979136

  7. Mechanisms of active control in cylindrical fuselage structures

    NASA Technical Reports Server (NTRS)

    Silcox, R. J.; Lester, H. C.; Fuller, C. R.

    1987-01-01

    This paper summarizes ongoing efforts to understand and exploit active control techniques for low frequency noise suppression in aerospace applications. Analytical models are utilized in an effort to understand the mechanisms that govern noise transmission into acoustic spaces enclosed by lightweight structures and to examine the results of experimental implementations of active control schemes. Emphasis is placed on attaining global noise reductions using a minimum number of actuators rather than localized control over many subregions. This program has demonstrated the effect of synchrophasing and interface modal filtering, in limiting the modal density within the acoustic space, and how strong reactive effects may occur in two dimensional geometries. Finally, the performance of active control systems utilizing acoustic and vibration actuators is evaluated. Suppressions of 10 to 30 dB are demonstrated in practice, and performance is discussed in relation to the physical mechanisms and parameters of the system.

  8. Application of cosmetic nail varnish does not affect the antifungal efficacy of amorolfine 5% nail lacquer in the treatment of distal subungual toenail onychomycosis: results of a randomised active-controlled study and in vitro assays.

    PubMed

    Sigurgeirsson, B; Ghannoum, M A; Osman-Ponchet, H; Kerrouche, N; Sidou, F

    2016-05-01

    As onychomycosis is unsightly, this study clinically evaluated whether the antifungal efficacy of amorolfine 5% nail lacquer (NL) was affected by a masking, natural-coloured, cosmetic nail varnish applied 24 h later; in vitro investigations were also performed. Subjects with mild-to-moderate distal subungual toenail onychomycosis were randomised to receive amorolfine 5% NL once weekly with or without cosmetic nail varnish applied 24 h later. After 12-week treatment, antifungal activity of affected toenail clippings was assessed by measurement of zones of inhibition (ZOIs) on Trichophyton mentagrophytes seeded agar plates. Mean diameters were 53.5 mm for the amorolfine 5% NL-alone group (n = 23) and 53.6 mm for amorolfine 5% NL plus cosmetic nail varnish group (n = 25). Also, mycological cultures of subungual debris at week 12 were negative for all subjects in both groups. Most subjects (88%) reported that cosmetic nail varnish masked their infected toenails. Additionally, cadaver human nails coated in vitro with or without cosmetic nail varnish 10 min or 24 h post amorolfine NL application all gave ZOIs on Trichophyton rubrum agar plates representing potent antifungal activity. In conclusion, cosmetic nail varnish applied post amorolfine had no effect on the subungual antifungal activity of amorolfine 5% NL or its penetration through toenails. PMID:26867498

  9. An active control synchronization for two modified Chua circuits

    NASA Astrophysics Data System (ADS)

    Li, Guo-Hui

    2005-03-01

    From modern control theory, an active control method to synchronize two modified Chua circuits with each other, which exhibit chaos, is presented. Some sufficient conditions of linear stability of the chaotic synchronization are obtained from rigorous mathematic justification. On the basis of the state-observer, the controller is analytically deduced using the active control. It is shown that this technique can be applied to achieve synchronization of the two systems with each other, whether they are identical or not. Finally, numerical simulations show the effectiveness of the proposed control scheme.

  10. Impact of active controls technology on structural integrity

    NASA Technical Reports Server (NTRS)

    Noll, Thomas; Austin, Edward; Donley, Shawn; Graham, George; Harris, Terry

    1991-01-01

    This paper summarizes the findings of The Technical Cooperation Program to assess the impact of active controls technology on the structural integrity of aeronautical vehicles and to evaluate the present state-of-the-art for predicting the loads caused by a flight-control system modification and the resulting change in the fatigue life of the flight vehicle. The potential for active controls to adversely affect structural integrity is described, and load predictions obtained using two state-of-the-art analytical methods are given.

  11. Active controls: A look at analytical methods and associated tools

    NASA Technical Reports Server (NTRS)

    Newsom, J. R.; Adams, W. M., Jr.; Mukhopadhyay, V.; Tiffany, S. H.; Abel, I.

    1984-01-01

    A review of analytical methods and associated tools for active controls analysis and design problems is presented. Approaches employed to develop mathematical models suitable for control system analysis and/or design are discussed. Significant efforts have been expended to develop tools to generate the models from the standpoint of control system designers' needs and develop the tools necessary to analyze and design active control systems. Representative examples of these tools are discussed. Examples where results from the methods and tools have been compared with experimental data are also presented. Finally, a perspective on future trends in analysis and design methods is presented.

  12. Some experiences with active control of aeroelastic response

    NASA Technical Reports Server (NTRS)

    Newsom, J. R.; Abel, I.

    1981-01-01

    Flight and wind tunnel tests were conducted and multidiscipline computer programs were developed as part of investigations of active control technology conducted at the NASA Langley Research Center. Unsteady aerodynamics approximation, optimal control theory, optimal controller design, and the Delta wing and DC-10 models are described. The drones for aerodynamics and structural testing (DAST program) for evaluating procedures for aerodynamic loads prediction and the design of active control systems on wings with significant aeroelastic effects is described as well as the DAST model used in the wind tunnel tests.

  13. Advanced aerodynamics and active controls. Selected NASA research

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Aerodynamic and active control concepts for application to commercial transport aircraft are discussed. Selected topics include in flight direct strike lightning research, triply redundant digital fly by wire control systems, tail configurations, winglets, and the drones for aerodynamic and structural testing (DAST) program.

  14. Distributed active control of large flexible space structures

    NASA Technical Reports Server (NTRS)

    Nguyen, C. C.; Baz, A.

    1986-01-01

    This progress report summarizes the research work performed at the Catholic University of America on the research grant entitled Distributed Active Control of Large Flexible Space Structures, funded by NASA/Goddard Space Flight Center, under grant number NAG5-749, during the period of March 15, 1986 to September 15, 1986.

  15. Dynamic-Loads Analysis of Flexible Aircraft With Active Controls

    NASA Technical Reports Server (NTRS)

    Perry, B. I.; Durling, B. J.

    1982-01-01

    Integrated system of stand-along computer programs, DYLOFLEX, analyzes dynamic loads on flexible aircraft with active controls. DYLOFLEX capabilities include calculating dynamic loads due to continuous atmospheric turbulence, discrete gusts, and discrete control inputs. Each of the eight individual DYLOFLEX programs may be used alone or in conjunction with other DYLOFLEX programs.

  16. The Middeck Active Control Experiment (MACE): Identification for robust control

    NASA Astrophysics Data System (ADS)

    Karlov, Valery I.

    Viewgraphs on identification for robust control for the Middeck Active Control Experiment (MACE) are presented. Topics covered include: identification for robust control; three levels of identification; basic elements of the approach; advantages of 'post-ID' model of uncertainty; advantages of optimization; and practical realization.

  17. The Middeck Active Control Experiment (MACE): Identification for robust control

    NASA Technical Reports Server (NTRS)

    Karlov, Valery I.

    1992-01-01

    Viewgraphs on identification for robust control for the Middeck Active Control Experiment (MACE) are presented. Topics covered include: identification for robust control; three levels of identification; basic elements of the approach; advantages of 'post-ID' model of uncertainty; advantages of optimization; and practical realization.

  18. Active control strategy on a catenary-pantograph validated model

    NASA Astrophysics Data System (ADS)

    Sanchez-Rebollo, C.; Jimenez-Octavio, J. R.; Carnicero, A.

    2013-04-01

    Dynamic simulation methods have become essential in the design process and control of the catenary-pantograph system, overall since high-speed trains and interoperability criteria are getting very trendy. This paper presents an original hardware-in-the-loop (HIL) strategy aimed at integrating a multicriteria active control within the catenary-pantograph dynamic interaction. The relevance of HIL control systems applied in the frame of the pantograph is undoubtedly increasing due to the recent and more demanding requirements for high-speed railway systems. Since the loss of contact between the catenary and the pantograph leads to arcing and electrical wear, and too high contact forces cause mechanical wear of both the catenary wires and the strips of the pantograph, not only prescribed but also economic and performance criteria ratify such a relevance. Different configurations of the proportional-integral-derivative (PID) controller are proposed and applied to two different plant systems. Since this paper is mainly focused on the control strategy, both plant systems are simulation models though the methodology is suitable for a laboratory bench. The strategy of control involves a multicriteria optimisation of the contact force and the consumption of the energy supplied by the control force, a genetic algorithm has been applied for this purpose. Thus, the PID controller is fitted according to these conflicting objectives and tested within a nonlinear lumped model and a nonlinear finite element model, being the last one validated against the European Standard EN 50318. Finally, certain tests have been accomplished in order to analyse the robustness of the control strategy. Particularly, the relevance or the plant simulation, the running speed and the instrumentation time delay are studied in this paper.

  19. Semi-active control of a cable-stayed bridge under multiple-support excitations.

    PubMed

    Dai, Ze-Bing; Huang, Jin-Zhi; Wang, Hong-Xia

    2004-03-01

    This paper presents a semi-active strategy for seismic protection of a benchmark cable-stayed bridge with consideration of multiple-support excitations. In this control strategy, Magnetorheological (MR) dampers are proposed as control devices, a LQG-clipped-optimal control algorithm is employed. An active control strategy, shown in previous researches to perform well at controlling the benchmark bridge when uniform earthquake motion was assumed, is also used in this study to control this benchmark bridge with consideration of multiple-support excitations. The performance of active control system is compared to that of the presented semi-active control strategy. Because the MR fluid damper is a controllable energy- dissipation device that cannot add mechanical energy to the structural system, the proposed control strategy is fail-safe in that bounded-input, bounded-output stability of the controlled structure is guaranteed. The numerical results demonstrated that the performance of the presented control design is nearly the same as that of the active control system; and that the MR dampers can effectively be used to control seismically excited cable-stayed bridges with multiple-support excitations. PMID:14727308

  20. The Validation of an Active Control Intervention for Mindfulness Based Stress Reduction (MBSR)

    PubMed Central

    MacCoon, Donal G.; Imel, Zac E.; Rosenkranz, Melissa A.; Sheftel, Jenna G.; Weng, Helen Y.; Sullivan, Jude C.; Bonus, Katherine A.; Stoney, Catherine M.; Salomons, Tim V.; Davidson, Richard J.; Lutz, Antoine

    2011-01-01

    Most of the extant literature investigating the health effects of mindfulness interventions relies on wait-list control comparisons. The current article specifies and validates an active control condition, the Health Enhancement Program (HEP), thus providing the foundation necessary for rigorous investigations of the relative efficacy of Mindfulness Based Stress Reduction (MBSR) and for testing mindfulness as an active ingredient. 63 participants were randomized to either MBSR (n=31) or HEP (n=32). Compared to HEP, MBSR led to reductions in thermal pain ratings in the mindfulness- but not the HEP-related instruction condition (η2=.18). There were significant improvements over time for general distress (η2=.09), anxiety (η2=.08), hostility (η2=.07), and medical symptoms (η2=.14), but no effects of intervention. Practice was not related to change. HEP is an active control condition for MBSR while remaining inert to mindfulness. These claims are supported by results from a pain task. Participant-reported outcomes (PROs) replicate previous improvements to well-being in MBSR, but indicate that MBSR is no more effective than a rigorous active control in improving these indices. These results emphasize the importance of using an active control condition like HEP in studies evaluating the effectiveness of MBSR. PMID:22137364

  1. Multirate Flutter Suppression System Design for the Benchmark Active Controls Technology Wing. Part 2; Methodology Application Software Toolbox

    NASA Technical Reports Server (NTRS)

    Mason, Gregory S.; Berg, Martin C.; Mukhopadhyay, Vivek

    2002-01-01

    To study the effectiveness of various control system design methodologies, the NASA Langley Research Center initiated the Benchmark Active Controls Project. In this project, the various methodologies were applied to design a flutter suppression system for the Benchmark Active Controls Technology (BACT) Wing. This report describes the user's manual and software toolbox developed at the University of Washington to design a multirate flutter suppression control law for the BACT wing.

  2. MIT Middeck Active Control Experiment (MACE): noncollocated payload pointing control

    NASA Astrophysics Data System (ADS)

    MacMartin, Douglas G.; Miller, David W.

    1993-09-01

    The Middeck Active Control Experiment is a space shuttle flight experiment intended to demonstrate high authority active structural control in zero gravity conditions. The prediction of on-orbit closed-loop dynamics is based on analysis and ground testing. The MACE test article is representative of multiple payload platforms, and includes two 2-axis gimballing payloads connected by a flexible bus. The goal of active control is to maintain pointing accuracy of one payload, while the remaining payload is moving independently. Current control results on the ground test article are presented. Multiple input, multiple output controllers are designed based on high order measurement based models. Linear Quadratic Gaussian controllers yield reasonable performance. At high authority, however, these controllers destabilize the actual structure, due to parametric errors in the control design model. A robust control design procedure is required to yield high performance in the presence of these errors.

  3. Active Control Analysis for Aeroelastic Instabilities in Turbomachines

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Srivastava, Rakesh

    2002-01-01

    Turbomachines onboard aircraft operate in a highly complex and harsh environment. The unsteady flowfield inherent to turbomachines leads to several problems associated with safety, stability, performance and noise. In-flight surge or flutter incidents could be catastrophic and impact the safety and reliability of the aircraft. High-Cycle-Fatigue (HCF), on the other hand, can significantly impact safety, readiness and maintenance costs. To avoid or minimize these problems generally a more conservative design method must be initiated which results in thicker blades and a loss of performance. Actively controlled turbomachines have the potential to reduce or even eliminate the instabilities by impacting the unsteady aerodynamic characteristics. By modifying the unsteady aerodynamics, active control may significantly improve the safety and performance especially at off-design conditions, reduce noise, and increase the range of operation of the turbomachine. Active control can also help improve reliability for mission critical applications such as the Mars Flyer. In recent years, HCF has become one of the major issues concerning the cost of operation for current turbomachines. HCF alone accounts for roughly 30% of maintenance cost for the United States Air-Force. Other instabilities (flutter, surge, rotating-stall, etc.) are generally identified during the design and testing phase. Usually a redesign overcomes these problems, often reducing performance and range of operation, and resulting in an increase in the development cost and time. Despite a redesign, the engines do not have the capabilities or means to cope with in-flight unforeseen vibration, stall, flutter or surge related instabilities. This could require the entire fleet worldwide to be stood down for expensive modifications. These problems can be largely overcome by incorporating active control within the turbomachine and its design. Active control can help in maintaining the integrity of the system in

  4. Curve Squeal of Train Wheels, Part 3: Active Control

    NASA Astrophysics Data System (ADS)

    HECKL, MARIA A.; HUANG, X. Y.

    2000-01-01

    This paper presents a new method to annul the squeal noise that is produced by trains traversing a curve. The method is a special form of active control, applied to suppress the bending oscillations of a squealing wheel. It is essentially a feedback system with the following components: sensor, narrowband filter, phase-shifter, amplifier and actuator. The control signal driving the actuator has only a single frequency (set at the filter), and that frequency typically corresponds to one of the bending modes of the wheel. Two versions of the feedback system are considered. In the first version, the actuator exerts a control force on the wheel, and in the second version, the actuator imposes a velocity on the rail. A mathematical model is presented and predictions are made for the performance of both versions. The coupling of the different wheel modes by the control system is discussed. A model rig is described which was used for a practical demonstration of this form of active control. Differences from more conventional forms of active control are pointed out.

  5. Validation of model based active control of combustion instability

    SciTech Connect

    Fleifil, M.; Ghoneim, Z.; Ghoniem, A.F.

    1998-07-01

    The demand for efficient, company and clean combustion systems have spurred research into the fundamental mechanisms governing their performance and means of interactively changing their performance characteristics. Thermoacoustic instability which is frequently observed in combustion systems with high power density, when burning close to the lean flammability limit, or using exhaust gas recirculation to meet more stringent emissions regulations, etc. Its occurrence and/or means to mitigate them passively lead to performance degradation such as reduced combustion efficiency, high local heat transfer rates, increase in the mixture equivalence ratio or system failure due to structural damage. This paper reports on their study of the origin of thermoacoustic instability, its dependence on system parameters and the means of actively controlling it. The authors have developed an analytical model of thermoacoustic instability in premixed combustors. The model combines a heat release dynamics model constructed using the kinematics of a premixed flame stabilized behind a perforated plate with the linearized conservation equations governing the system acoustics. This formulation allows model based controller design. In order to test the performance of the analytical model, a numerical solution of the partial differential equations governing the system has been carried out using the principle of harmonic separation and focusing on the dominant unstable mode. This leads to a system of ODEs governing the thermofluid variables. Analytical predictions of the frequency and growth ate of the unstable mode are shown to be in good agreement with the numerical simulations as well s with those obtained using experimental identification techniques when applied to a laboratory combustor. The authors use these results to confirm the validity of the assumptions used in formulating the analytical model. A controller based on the minimization of a cost function using the LQR technique has

  6. A research program in active control/aeroelasticity in the JIAFS at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Whitesides, J. L.

    1984-01-01

    A control law synthesis methodology for multifunctional active control system to satisfy root-mean-square load and response constraints as well as to meet stability robustness requirements at plant input and output was developed. Modern control theory, singular value analysis and optimization techniques were utilized. All stability and response derivative expressions were derived analytically for sensitivity study. The software is incorporated as an update to the AB/LAD general control design software package PADLOCS.

  7. Active control of sound fields in elastic cylinders by vibrational inputs

    NASA Technical Reports Server (NTRS)

    Jones, J. D.; Fuller, C. R.

    1987-01-01

    An experiment is performed to study the mechanisms of active control of sound fields in elastic cylinders via vibrational outputs. In the present method of control, a vibrational force input was used as the secondary control input to reduce the radiated acoustic field. For the frequencies considered, the active vibration technique provided good global reduction of interior sound even though only one actuator was used.

  8. Robust Multivariable Flutter Suppression for the Benchmark Active Control Technology (BACT) Wind-Tunnel Model

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R.

    1997-01-01

    The Benchmark Active Controls Technology (BACT) project is part of NASA Langley Research Center s Benchmark Models Program for studying transonic aeroelastic phenomena. In January of 1996 the BACT wind-tunnel model was used to successfully demonstrate the application of robust multivariable control design methods (H and -synthesis) to flutter suppression. This paper addresses the design and experimental evaluation of robust multivariable flutter suppression control laws with particular attention paid to the degree to which stability and performance robustness was achieved.

  9. Low-dose dexamethasone as a treatment for women with heavy menstrual bleeding: protocol for response-adaptive randomised placebo-controlled dose-finding parallel group trial (DexFEM)

    PubMed Central

    Warner, P; Weir, C J; Hansen, C H; Douglas, A; Madhra, M; Hillier, S G; Saunders, P T K; Iredale, J P; Semple, S; Walker, B R; Critchley, H O D

    2015-01-01

    Introduction Heavy menstrual bleeding (HMB) diminishes individual quality-of-life and poses substantial societal burden. In HMB endometrium, inactivation of cortisol (by enzyme 11β hydroxysteroid dehydrogenase type 2 (11βHSD2)), may cause local endometrial glucocorticoid deficiency and hence increased angiogenesis and impaired vasoconstriction. We propose that ‘rescue’ of luteal phase endometrial glucocorticoid deficiency could reduce menstrual bleeding. Methods and analysis DexFEM is a double-blind response-adaptive parallel-group placebo-controlled trial in women with HMB (108 to be randomised), with active treatment the potent oral synthetic glucocorticoid dexamethasone, which is relatively resistant to 11βHSD2 inactivation. Participants will be aged over 18 years, with mean measured menstrual blood loss (MBL) for two screening cycles ≥50 mL. The primary outcome is reduction in MBL from screening. Secondary end points are questionnaire assessments of treatment effect and acceptability. Treatment will be for 5 days in the mid-luteal phases of three treatment menstrual cycles. Six doses of low-dose dexamethasone (ranging from 0.2 to 0.9 mg twice daily) will be compared with placebo, to ascertain optimal dose, and whether this has advantage over placebo. Statistical efficiency is maximised by allowing randomisation probabilities to ‘adapt’ at five points during enrolment phase, based on the response data available so far, to favour doses expected to provide greatest additional information on the dose–response. Bayesian Normal Dynamic Linear Modelling, with baseline MBL included as covariate, will determine optimal dose (re reduction in MBL). Secondary end points will be analysed using generalised dynamic linear models. For each dose for all end points, a 95% credible interval will be calculated for effect versus placebo. Ethics and dissemination Dexamethasone is widely used and hence well-characterised safety-wise. Ethical approval has been

  10. Active control of spacecraft potentials at geosynchronous orbit

    NASA Technical Reports Server (NTRS)

    Goldstein, R.; Deforest, S. E.

    1976-01-01

    Tests have been conducted concerning the active control of the potentials of the geosynchronous satellites ATS-5 and ATS-6. The ATS-5 tests show that a simple electron emitter can be used to reduce the magnitude of the potential of a spacecraft which has been charged negatively by the environment. The ATS-6 ion thruster had also a pronounced effect on the potential barrier. In this case, the flux of high-energy primary ions and of low-charge exchange ions produces a space-charge neutralization effect which the electron gun alone cannot achieve.

  11. Active control of excessive sound emission on a mobile device.

    PubMed

    Jeon, Se-Woon; Youn, Dae Hee; Park, Young-cheol; Lee, Gun-Woo

    2015-04-01

    During a phone conversation, loud vocal emission from the far-end to the near-end space can disturb nearby people. In this paper, the possibility of actively controlling such unwanted sound emission using a control source placed on the mobile device is investigated. Two different approaches are tested: Global control, minimizing the potential energy measured along a volumetric space surface, and local control, minimizing the squared sound pressure at a discrete point on the phone. From the test results, both approaches can reduce the unwanted sound emission by more than 6 dB in the frequency range up to 2 kHz. PMID:25920885

  12. Active control rotor model testing at Princeton's Rotorcraft Dynamics Laboratory

    NASA Technical Reports Server (NTRS)

    Mckillip, Robert M., Jr.

    1988-01-01

    A description of the model helicopter rotor tests currently in progress at Princeton's Rotorcraft Dynamics Laboratory is presented. The tests are designed to provide data for rotor dynamic modeling for use with active control system design. The model rotor to be used incoporates the capability for Individual Blade Control (IBC) or Higher Harmonic Control through the use of a standard swashplate on a three bladed hub. Sample results from the first series of tests are presented, along with the methodology used for state and parameter identification. Finally, pending experiments and possible research directions using this model and test facility are outlined.

  13. Microscopy beyond the diffraction limit using actively controlled single molecules

    PubMed Central

    MOERNER, W.E.

    2013-01-01

    Summary In this short review, the general principles are described for obtaining microscopic images with resolution beyond the optical diffraction limit with single molecules. Although it has been known for several decades that single-molecule emitters can blink or turn on and off, in recent work the addition of on/off control of molecular emission to maintain concentrations at very low levels in each imaging frame combined with sequential imaging of sparse subsets has enabled the reconstruction of images with resolution far below the optical diffraction limit. Single-molecule active control microscopy provides a powerful window into information about nanoscale structures that was previously unavailable. PMID:22582796

  14. Experiments on the active control of transitional boundary layers

    NASA Astrophysics Data System (ADS)

    Nelson, P. A.; Rioual, J.-L.; Fisher, M. J.

    Experimental results are presented which demonstrate that the streamwise position of the transition region of a flat plate boundary layer can be actively controlled. The means of control is through the application of suction through the surface of the plate, a progressive increase in suction rate being capable of producing transition at progressively larger distances downstream from the plate leading edge. A simple digital feedback regulator based on an integral control law is shown to be most effective in regulating the position of transition, an error signal being derived from measurements of pressure fluctuations on the surface of the plate.

  15. Selected advanced aerodynamic and active control concepts development

    NASA Technical Reports Server (NTRS)

    1980-01-01

    A summary is presented of results obtained during analysis, design and test activities on six selected technical tasks directed at exploratory improvement of fuel efficiency for new and derivative transports. The work included investigations into the potential offered by natural laminar flow, improved surface coatings and advanced high lift concepts. Similar investigations covering optimum low-energy flight path control, integrated application of active controls and evaluation of primary flight control systems reliability and maintenance are also summarized. Recommendations are included for future work needed to exploit potential advancements.

  16. The impact of active controls technology on the structural integrity of aeronautical vehicles

    NASA Technical Reports Server (NTRS)

    Noll, Thomas E.; Austin, Edward; Donley, Shawn; Graham, George; Harris, Terry; Kaynes, Ian; Lee, Ben; Sparrow, James

    1993-01-01

    The findings of an investigation conducted under the auspices of The Technical Cooperation Program (TTCP) to assess the impact of active controls technology on the structural integrity of aeronautical vehicles and to evaluate the present state-of-the-art for predicting loads caused by a flight-control system modification and the resulting change in the fatigue life of the flight vehicle are summarized. Important points concerning structural technology considerations implicit in applying active controls technology in new aircraft are summarized. These points are well founded and based upon information received from within the aerospace industry and government laboratories, acquired by sponsoring workshops which brought together experts from contributing and interacting technical disciplines, and obtained by conducting a case study to independently assess the state of the technology. The paper concludes that communication between technical disciplines is absolutely essential in the design of future high performance aircraft.

  17. Effect of bonding on the performance of a piezoactuator-based active control system

    NASA Technical Reports Server (NTRS)

    Baz, A.; Poh, S.

    1987-01-01

    The utilization of piezoelectric actuators in controlling the structural vibrations of flexible beams is studied. A Modified Independent Modal Space Control (MIMSC) method is devised to select the optimal location, control gains and excitation voltage of the piezoelectric actuators in a way that would minimize the amplitudes of vibrations of beams to which these actuators are bonded, as well as the input control energy necessary to suppress these vibrations. The presented method accounts for the effects that the piezoelectric actuators and the bonding layers have on changing the elastic and inertial properties of the flexible beams. Numerical examples are presented to illustrate the application of the MIMSC method and to demonstrate the effect of the physical and geometrical properties of the bonding layer on the dynamic performance of the actively controlled beams. The obtained results emphasize the importance of the devised method in designing more realistic active control systems for flexible beams, in particular, and large flexible structures in general.

  18. Vibration reduction in helicopter rotors using an active control surface located on the blade

    NASA Technical Reports Server (NTRS)

    Millott, T. A.; Friedmann, P. P.

    1992-01-01

    A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.

  19. Active Control of Jets in Cross-Flow for Film Cooling Applications

    NASA Technical Reports Server (NTRS)

    Nikitopoulos, Dimitris E.

    2003-01-01

    Jets in cross-flow have applications in film cooling of gas turbine vanes, blades and combustor liners. Their cooling effectiveness depends on the extent to which the cool jet-fluid adheres to the cooled component surface. Lift-off of the cooling jet flow or other mechanisms promoting mixing, cause loss of cooling effectiveness as they allow the hot "free-stream" fluid to come in contact with the component surface. The premise of this project is that cooling effectiveness can be improved by actively controlling (e.9. forcing, pulsing) the jet flow. Active control can be applied to prevent/delay lift-off and suppress mixing. Furthermore, an actively controlled film-cooling system coupled with appropriate sensory input (e.g. temperature or heat flux) can adapt to spatial and temporal variations of the hot-gas path. Thus, it is conceivable that the efficiency of film-cooling systems can be improved, resulting in coolant fluid economy. It is envisioned that Micro Electro-Mechanical Systems (MEMS) will play a role in the realization of such systems. As a first step, a feasibility study will be conducted to evaluate the concept, identify actuation and sensory elements and develop a control strategy. Part of this study will be the design of a proof-of-concept experiment and collection of necessary data.

  20. Active control of combustion instabilities in low NO{sub x} gas turbines

    SciTech Connect

    Zinn, B.T.; Neumeier, Y.

    1995-10-01

    This 3-year research program was initiated in September, 1995, to investigate active control of detrimental combustion instabilities in low NO{sub x} gas turbines (LNGT), which burn natural gas in a lean premixed mode to reduce NO{sub x} emissions. The program will investigate the mechanisms that drive these instabilities. Furthermore, it will study active control systems (ACS) that can effectively prevent the onset of such instabilities and/or reduce their amplitudes to acceptable levels. An understanding of the driving mechanisms will not only guide the development of effective ACS for LNGT but may also lead to combustor design changes (i.e., passive control) that will fully or partially resolve the problem. Initial attempts to stabilize combustors (i.e., chemical rockets) by ACS were reported more than 40 years ago, but were unsuccessful due to lack of adequate sensors, electronics, and actuators for performing the needed control actions. Progress made in recent years in sensor and actuator technology, electronics, and control theory has rekindled interest in developing ACS for unstable combustors. While initial efforts in this area, which focused on active control of instabilities in air breathing combustors, have demonstrated the considerable potential of active control, they have also indicated that more effective observers, controllers, and actuators are needed for practical applications. Considerable progress has been made in the observer and actuator areas by the principal investigators of this program during the past 2 years under an AFOSR program. The developed observer is based upon wavelets theory, and can identify the amplitudes, frequencies, and phases of the five most dominant combustor modes in (virtually) real time. The developed actuator is a fuel injector that uses a novel magneto-strictive material to modulate the fuel flow rate into the combustor.

  1. A Stability Enhancement Method for Centrifugal Compressors using Active Control Casing Treatment System

    NASA Astrophysics Data System (ADS)

    Zhao, Yuanyang; Xiao, Jun; Li, Liansheng; Yang, Qichao; Liu, Guangbin; Wang, Le

    2015-08-01

    The centrifugal compressors are widely used in many fields. When the centrifugal compressors operate at the edge of the surge line, the compressor will be unstable. In addition, if the centrifugal compressor runs at this situation long time, the damage will be occurred on compressor. There are some kinds of method to improve and enlarge the range of the centrifugal compressors, such as inlet guide vane, and casing treatment. For casing treatment method, some structures have been researched, such as holed recirculation, basic slot casing treatment and groove casing treatment. All these researches are the passive methods. This paper present a new stability enhancement method based Active Control Casing Treatment (ACCT). All parts of this new method are introduced in detail. The control strategy of the system is mentioned in the paper. As a research sample, a centrifugal compressor having this system is researched using CFD method. The study focuses on the effect of the active control system on the impeller flow. The vortex in impeller is changed by the active control system. And this leads to the suppression of the extension of vortex blockage in impeller and to contribute to the enhancement of the compressor operating range.

  2. Actively controlling coolant-cooled cold plate configuration

    DOEpatents

    Chainer, Timothy J.; Parida, Pritish R.

    2016-04-26

    Cooling apparatuses are provided to facilitate active control of thermal and fluid dynamic performance of a coolant-cooled cold plate. The cooling apparatus includes the cold plate and a controller. The cold plate couples to one or more electronic components to be cooled, and includes an adjustable physical configuration. The controller dynamically varies the adjustable physical configuration of the cold plate based on a monitored variable associated with the cold plate or the electronic component(s) being cooled by the cold plate. By dynamically varying the physical configuration, the thermal and fluid dynamic performance of the cold plate are adjusted to, for example, optimally cool the electronic component(s), and at the same time, reduce cooling power consumption used in cooling the electronic component(s). The physical configuration can be adjusted by providing one or more adjustable plates within the cold plate, the positioning of which may be adjusted based on the monitored variable.

  3. Multidisciplinary analysis of actively controlled large flexible spacecraft

    NASA Technical Reports Server (NTRS)

    Cooper, Paul A.; Young, John W.; Sutter, Thomas R.

    1986-01-01

    The control of Flexible Structures (COFS) program has supported the development of an analysis capability at the Langley Research Center called the Integrated Multidisciplinary Analysis Tool (IMAT) which provides an efficient data storage and transfer capability among commercial computer codes to aid in the dynamic analysis of actively controlled structures. IMAT is a system of computer programs which transfers Computer-Aided-Design (CAD) configurations, structural finite element models, material property and stress information, structural and rigid-body dynamic model information, and linear system matrices for control law formulation among various commercial applications programs through a common database. Although general in its formulation, IMAT was developed specifically to aid in the evaluation of the structures. A description of the IMAT system and results of an application of the system are given.

  4. Active control technique of fractional-order chaotic complex systems

    NASA Astrophysics Data System (ADS)

    Mahmoud, Gamal M.; Ahmed, Mansour E.; Abed-Elhameed, Tarek M.

    2016-06-01

    Several kinds of synchronization of fractional-order chaotic complex systems are challenging research topics of current interest since they appear in many applications in applied sciences. Our main goal in this paper is to introduce the definition of modified projective combination-combination synchronization (MPCCS) of some fractional-order chaotic complex systems. We show that our systems are chaotic by calculating their Lyapunov exponents. The fractional Lyapunov dimension of the chaotic solutions of these systems is computed. A scheme is introduced to calculate MPCCS of four different (or identical) chaotic complex systems using the active control technique. Special cases of this type, which are projective and anti C-C synchronization, are discussed. Some figures are plotted to show that MPCCS is achieved and its errors approach zero.

  5. Actively controlling coolant-cooled cold plate configuration

    SciTech Connect

    Chainer, Timothy J.; Parida, Pritish R.

    2015-07-28

    A method is provided to facilitate active control of thermal and fluid dynamic performance of a coolant-cooled cold plate. The method includes: monitoring a variable associated with at least one of the coolant-cooled cold plate or one or more electronic components being cooled by the cold plate; and dynamically varying, based on the monitored variable, a physical configuration of the cold plate. By dynamically varying the physical configuration, the thermal and fluid dynamic performance of the cold plate are adjusted to, for example, optimally cool the one or more electronic components, and at the same time, reduce cooling power consumption used in cooling the electronic component(s). The physical configuration can be adjusted by providing one or more adjustable plates within the coolant-cooled cold plate, the positioning of which may be adjusted based on the monitored variable.

  6. Active Control of High-Frequency Combustor Instability Demonstrated

    NASA Technical Reports Server (NTRS)

    DeLaat, John C.; Chang, Clarence T.

    2003-01-01

    To reduce the environmental impact of aerospace propulsion systems, extensive research is being done in the development of lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle. However, these lean-burning combustors have an increased susceptibility to thermoacoustic instabilities-high-pressure oscillations much like sound waves that can cause severe high-frequency vibrations in the combustor. These pressure waves can fatigue the combustor components and even the downstream turbine blades. This can significantly decrease the combustor and turbine safe operating life. Thus, suppression of the thermoacoustic combustor instabilities is an enabling technology for lean, low-emissions combustors. Under the Propulsion and Power Program, the NASA Glenn Research Center in partnership with Pratt & Whitney, United Technologies Research Center, and Georgia Institute of Technology is developing technologies for the active control of combustion instabilities.

  7. Active control of bearing preload using piezoelectric translators

    NASA Technical Reports Server (NTRS)

    Nye, Ted W.

    1990-01-01

    In many spacecraft applications, mechanisms are required to perform precision pointing operations or to sometimes dither about or track a moving object. These mechanisms perform in a predictable and repeatable manner in benign temperature environments. Severe thermal gradients experienced in actual space applications however, cause assemblies to expand and contract around their bearings. This results in unpredictable changes in bearing preload, and hence bearing friction. This becomes a limitation for servos controlling pointing accuracy. Likewise, uncontrollable vibrations may couple into fixed preload (hence, fixed stiffness) mechanisms and limit pointing accuracy. Consequently, a complex problem faced today is how to design mechanisms that remain insensitive to changing thermal and vibrational spacecraft environments. Research presented involves the simplified modeling and test results of an actuator module that used piezoelectrically preload controlled bearings. The feasibility of actively controlling bearing preload was demonstrated. Because bearing friction is related to preload, a thermally active system designed with aluminum components and a 440 C bearing, was friction tested at temperatures ranging from 0 to 70 C (32 to 158 F). Effectiveness of the translators were demonstrated by mapping a controllable friction range throughout tested temperatures. It was learned that constant preload for this system could be maintained over an approximate 44 C (79 F) temperature span. From testing, it was also discovered that at the more deviate temperatures, expansions were so large that radial clearances were taken up and the duplex bearing became radially preloaded. Thus, active control of bearing preload is feasible but may be limited by inherent geometry constraints and materials used in the system.

  8. Active control and sound synthesis--two different ways to investigate the influence of the modal parameters of a guitar on its sound.

    PubMed

    Benacchio, Simon; Mamou-Mani, Adrien; Chomette, Baptiste; Finel, Victor

    2016-03-01

    The vibrational behavior of musical instruments is usually studied using physical modeling and simulations. Recently, active control has proven its efficiency to experimentally modify the dynamical behavior of musical instruments. This approach could also be used as an experimental tool to systematically study fine physical phenomena. This paper proposes to use modal active control as an alternative to sound simulation to study the complex case of the coupling between classical guitar strings and soundboard. A comparison between modal active control and sound simulation investigates the advantages, the drawbacks, and the limits of these two approaches. PMID:27036278

  9. Multirate Flutter Suppression System Design for the Benchmark Active Controls Technology Wing. Part 1; Theory and Design Procedure

    NASA Technical Reports Server (NTRS)

    Mason, Gregory S.; Berg, Martin C.; Mukhopadhyay, Vivek

    2002-01-01

    To study the effectiveness of various control system design methodologies, the NASA Langley Research Center initiated the Benchmark Active Controls Project. In this project, the various methodologies were applied to design a flutter suppression system for the Benchmark Active Controls Technology (BACT) Wing. This report describes a project at the University of Washington to design a multirate suppression system for the BACT wing. The objective of the project was two fold. First, to develop a methodology for designing robust multirate compensators, and second, to demonstrate the methodology by applying it to the design of a multirate flutter suppression system for the BACT wing.

  10. Development of Active Control Method for Supercooling Releasing of Water

    NASA Astrophysics Data System (ADS)

    Mito, Daisuke; Kozawa, Yoshiyuki; Tanino, Masayuki; Inada, Takaaki

    We have tested the prototype ice-slurry generator that enables both production of supercooled water (-2°C) and releasing of its supercooling simultaneously and continuously in a closed piping system. In the experiment, we adopted the irradiation of ultrasonic wave as an active control method of triggering for supercooling releasing, and evaluated the reliability for a practical use compared with the seed ice-crystal trigger. As the results, it has been confirmed that the ultrasonic wave trigger acts assuredly at the same level of degree of supercooling as that by using the seed ice-crystal Trigger. Moreover, it can be found that the ultrasonic wave trigger has the advantage of removing the growing ice-crystals on the pipe wall at the same time. Finally, we have specified the bombardment condition of ultrasonic wave enough to make continuously the ice-slurry in a closed system as the output surface power density > 31.4kW/m2 and the superficial bombardment time > 4.1sec. We have also demonstrated the continuous ice-slurry making for more than 6hours by using the refrigerator system with the practical scale of 88kW.

  11. Recent advances in active control of aircraft cabin noise

    NASA Astrophysics Data System (ADS)

    Mathur, Gopal; Fuller, Christopher

    2002-11-01

    Active noise control techniques can provide significant reductions in aircraft interior noise levels without the structural modifications or weight penalties usually associated with passive techniques, particularly for low frequency noise. Our main objective in this presentation is to give a review of active control methods and their applications to aircraft cabin noise reduction with an emphasis on recent advances and challenges facing the noise control engineer in the practical application of these techniques. The active noise control method using secondary acoustic sources, e.g., loudspeakers, as control sources for tonal noise reduction is first discussed with results from an active noise control flight test demonstration. An innovative approach of applying control forces directly to the fuselage structure using piezoelectric actuators, known as active structural acoustic control (ASAC), to control cabin noise is then presented. Experimental results from laboratory ASAC tests conducted on a full-scale fuselage and from flight tests on a helicopter will be discussed. Finally, a hybrid active/passive noise control approach for achieving significant broadband noise reduction will be discussed. Experimental results of control of broadband noise transmission through an aircraft structure will be presented.

  12. Benchmark Active Controls Technology (BACT) Wing CFD Results

    NASA Technical Reports Server (NTRS)

    Schuster, David M.; Bartels, Robert E.

    2000-01-01

    The Benchmark Active Controls Technology (BACT) wing test (see chapter 8E) provides data for the validation of aerodynamic, aeroelastic, and active aeroelastic control simulation codes. These data provide a rich database for development and validation of computational aeroelastic and aeroservoelastic methods. In this vein, high-level viscous CFD analyses of the BACT wing have been performed for a subset of the test conditions available in the dataset. The computations presented in this section investigate the aerodynamic characteristics of the rigid clean wing configuration as well as simulations of the wing with a static and oscillating aileron and spoiler deflection. Two computational aeroelasticity codes extensively used at NASA Langley Research Center are implemented in this simulation. They are the ENS3DAE and CFL3DAE computational aeroelasticity programs. Both of these methods solve the three-dimensional compressible Navier-Stokes equations for both rigid and flexible vehicles, but they use significantly different approaches to the solution 6f the aerodynamic equations of motion. Detailed descriptions of both methods are presented in the following section.

  13. A design procedure for active control of beam vibrations

    NASA Technical Reports Server (NTRS)

    Dickerson, S. L.; Jarocki, G.

    1983-01-01

    The transverse vibrations of beams is discussed and a methodology for the design of an active damping device is given. The Bernoulli-Euler equation is used to derive a transcendental transfer function, which relates a torque applied at one end of the beam to the rotational position and velocity at that point. The active damping device consists of a wire, a linear actuator and a short torque arm attached to one end of the beam. The action of the actuator varies a tension in the wire and creates a torque which opposes the rotation of the beam and thus damps vibration. A design procedure for such an active damper is given. This procedure shows the relationships and trade-offs between the actuator stroke, power required, stress levels in the wire and beam and the geometry of the beam and wire. It is shown that by consideration of the frequency response at the beam natural frequencies, the aforementioned relationships can be greatly simplified. Similarly, a simple way of estimating the effective damping ratios and eigenvalue locations of actively controlled beams is presented.

  14. Sensitivity method for integrated structure/active control law design

    NASA Technical Reports Server (NTRS)

    Gilbert, Michael G.

    1987-01-01

    The development is described of an integrated structure/active control law design methodology for aeroelastic aircraft applications. A short motivating introduction to aeroservoelasticity is given along with the need for integrated structures/controls design algorithms. Three alternative approaches to development of an integrated design method are briefly discussed with regards to complexity, coordination and tradeoff strategies, and the nature of the resulting solutions. This leads to the formulation of the proposed approach which is based on the concepts of sensitivity of optimum solutions and multi-level decompositions. The concept of sensitivity of optimum is explained in more detail and compared with traditional sensitivity concepts of classical control theory. The analytical sensitivity expressions for the solution of the linear, quadratic cost, Gaussian (LQG) control problem are summarized in terms of the linear regulator solution and the Kalman Filter solution. Numerical results for a state space aeroelastic model of the DAST ARW-II vehicle are given, showing the changes in aircraft responses to variations of a structural parameter, in this case first wing bending natural frequency.

  15. Application of constrained optimization to active control of aeroelastic response

    NASA Technical Reports Server (NTRS)

    Newsom, J. R.; Mukhopadhyay, V.

    1981-01-01

    Active control of aeroelastic response is a complex in which the designer usually tries to satisfy many criteria which are often conflicting. To further complicate the design problem, the state space equations describing this type of control problem are usually of high order, involving a large number of states to represent the flexible structure and unsteady aerodynamics. Control laws based on the standard Linear-Quadratic-Gaussian (LQG) method are of the same high order as the aeroelastic plant. To overcome this disadvantage of the LQG mode, an approach developed for designing low order optimal control laws which uses a nonlinear programming algorithm to search for the values of the control law variables that minimize a composite performance index, was extended to the constrained optimization problem. The method involves searching for the values of the control law variables that minimize a basic performance index while satisfying several inequality constraints that describe the design criteria. The method is applied to gust load alleviation of a drone aircraft.

  16. Adaptive active control of periodic vibration using maglev actuators

    NASA Astrophysics Data System (ADS)

    An, Fengyan; Sun, Hongling; Li, Xiaodong

    2012-04-01

    In this paper, active control of periodic vibration is implemented using maglev actuators which exhibit inherent nonlinear behaviors. A multi-channel feedforward control algorithm is proposed to solve these nonlinear problems, in which maglev actuators are treated as single-input-single-output systems with unknown time-varying nonlinearities. A radial basis function network is used by the algorithm as its controller, whose parameters are adapted only with the model of the linear system in the secondary path. Compared with the strategies in the conventional magnetic-levitation system control as well as nonlinear active noise/vibration control, the proposed algorithm has the advantage that the nonlinear modeling procedure of maglev actuators and the usage of displacement sensors could be both avoided. Numerical simulations and real-time experiments are carried out based on a multiple-degree-of-freedom vibration isolation system. The results show that the proposed algorithm not only could efficiently compensate for the actuators' time-varying nonlinearities, but also has the ability to greatly attenuate the energy of periodic vibration.

  17. Active control of fan noise from a turbofan engine

    NASA Technical Reports Server (NTRS)

    Thomas, Russell H.; Burdisso, Ricardo A.; Fuller, Christopher R.; O'Brien, Walter F.

    1993-01-01

    A three channel active control system is applied to an operational turbofan engine in order to reduce tonal noise produced by both the fan and high pressure compressor. The control approach is the feedforward filtered-x least-mean-square algorithm implemented on a digital signal processing board. Reference transducers mounted on the engine case provides blade passing and harmonics frequency information to the controller. Error information is provided by large area microphones placed in the acoustic far field. In order to minimize the error signal, the controller actuates loudspeakers mounted on the inlet to produce destructive interference. The sound pressure level of the fundamental tone of the fan was reduced using the three channel controller by up to 16 dB over a 60 deg angle about the engine axis. A single channel controller could produce reduction over a 30 deg angle. The experimental results show the control to be robust. Simultaneous control of two tones is done with parallel controllers. The fundamental and the first harmonic tones of the fan were controlled simultaneously with reductions of 12 dBA and 5 dBA, respectively, measured on the engine axis. Simultaneous control was also demonstrated for the fan fundamental and the high pressure compressor fundamental tones.

  18. Active control of fan noise from a turbofan engine

    NASA Technical Reports Server (NTRS)

    Thomas, Russell H.; Burdisso, Ricardo A.; Fuller, Christopher R.; O'Brien, Walter F.

    1994-01-01

    A three-channel active control system is applied to an operational turbofan engine to reduce tonal noise produced by both the fan and the high-pressure compressor. The control approach is the feedforward filtered-x least-mean-square algorithm implemented on a digital signal processing board. Reference transducers mounted on the engine case provide blade passing and harmonics frequency information to the controller. Error information is provided by large area microphones placed in the acoustic far field. To minimize the error signal, the controller actuates loudspeakers mounted on the inlet to produce destructive interference. The sound pressure level of the fundamental tone of the fan was reduced using the three-channel controller by up to 16 dB over a +/- 30-deg angle about the engine axis. A single-channel controller could produce reduction over a +/- 15-deg angle. The experimental results show the control to be robust. Outside of the areas contolled, the levels of the tone actually increased due to the generation of radial modes by the control sources. Simultaneous control of two tones is achieved with parallel controllers. The fundamental and the first harmonic tones of the fan were controlled simultaneously with reductions of 12 and 5 dBA, respectively, measured on the engine axis. Simultaneous control was also demonstrated for the fan fundamental and the high-pressure compressor fundamental tones.

  19. Semi-active control of isolated and damaged structures using online damage detection

    NASA Astrophysics Data System (ADS)

    Amini, Fereidoun; Mohajeri, Seyed Ahmad; Javanbakht, Majd

    2015-10-01

    The idea of using semi-active or active control devices within a base isolation system has been developed recently, since applying this system to building structures has some shortcomings such as the creation of large displacements at the base level and the system's lack of adaptability to different seismic excitations. In this study, an integrated structural health monitoring and semi-active control scheme is proposed to enhance the seismic behavior of damaged isolated structures. The nonlinear behavior of an isolated structure is limited to the isolator level and the superstructure is assumed to remain linear. Then, using an online damage detection algorithm based on identified system Markov parameters and a semi-active fuzzy controller, the damage in the base isolator is mitigated and the seismic response of the structure is reduced. In addition, a magnetorheological damper is utilized as a well-studied semi-active actuator in the control system. The effectiveness of the proposed control system is evaluated through the numerical study of a six-degrees-of-freedom model of base-isolated buildings excited by various near-fault and far-field earthquake records. The results of the simulation show that the integrated algorithm is substantially effective in improving the dynamic behavior of isolated structures and reducing the damage in the isolator.

  20. Active Control of Instabilities in Laminar Boundary Layers-Overview and Concept Validation

    NASA Technical Reports Server (NTRS)

    Joslin, Ronald D.; Erlebacher, Gordon; Hussaini, M. Yoursuff

    1997-01-01

    This paper (the first in a series) focuses on using active-control methods to maintain laminar flow in a region of the flow in which the natural instabilities, if left unattended, lead to turbulent flow. The authors review previous studies that examine wave cancellation (currently the most prominent method) and solve the unsteady, nonlinear Navier-Stokes equations to evaluate this method of controlling instabilities. It is definitively shown that instabilities are controlled by the linear summation of waves (i.e., wave cancellation). Although a mathematically complete method for controlling arbitrary instabilities has been developed, the review, duplication, and physical explanation of previous studies are important steps for providing an independent verification of those studies, for establishing a framework for the work which will involve automated transition control, and for detailing the phenomena by-which the automated studies can be used to expand knowledge of flow control.

  1. Active control of instabilities in laminar boundary-layer flow. Part 1: An overview

    NASA Technical Reports Server (NTRS)

    Joslin, Ronald D.; Erlebacher, Gordon; Hussaini, M. Yousuff

    1994-01-01

    This paper (the first in a series) focuses on using active-control methods to maintain laminar flow in a region of the flow in which the natural instabilities, if left unattended, lead to turbulent flow. The authors review previous studies that examine wave cancellation (currently the most prominent method) and solve the unsteady, nonlinear Navier-Stokes equations to evaluate this method of controlling instabilities. It is definitely shown that instabilities are controlled by the linear summation of waves (i.e., wave cancellation). Although a mathematically complete method for controlling arbitrary instabilities has been developed (but not yet tested), the review, duplication, and physical explanation of previous studies are important steps for providing an independent verification of those studies, for establishing a framework for subsequent work which will involve automated transition control, and for detailing the phenomena by which the automated studies can be used to expand knowledge of flow control.

  2. Active Control of Combustor Instability Shown to Help Lower Emissions

    NASA Technical Reports Server (NTRS)

    DeLaat, John C.; Chang, Clarence T.

    2002-01-01

    In a quest to reduce the environmental impact of aerospace propulsion systems, extensive research is being done in the development of lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle. However, these lean-burning combustors have an increased susceptibility to thermoacoustic instabilities, or high-pressure oscillations much like sound waves, that can cause severe high-frequency vibrations in the combustor. These pressure waves can fatigue the combustor components and even the downstream turbine blades. This can significantly decrease the safe operating life of the combustor and turbine. Thus, suppression of the thermoacoustic combustor instabilities is an enabling technology for lean, low-emissions combustors. Under the Aerospace Propulsion and Power Base Research and Technology Program, the NASA Glenn Research Center, in partnership with Pratt & Whitney and United Technologies Research Center, is developing technologies for the active control of combustion instabilities. With active combustion control, the fuel is pulsed to put pressure oscillations into the system. This cancels out the pressure oscillations being produced by the instabilities. Thus, the engine can have lower pollutant emissions and long life.The use of active combustion instability control to reduce thermo-acoustic-driven combustor pressure oscillations was demonstrated on a single-nozzle combustor rig at United Technologies. This rig has many of the complexities of a real engine combustor (i.e., an actual fuel nozzle and swirler, dilution cooling, etc.). Control was demonstrated through modeling, developing, and testing a fuel-delivery system able to the 280-Hz instability frequency. The preceding figure shows the capability of this system to provide high-frequency fuel modulations. Because of the high-shear contrarotating airflow in the fuel injector, there was some concern that the fuel pulses would be attenuated to the point where they would

  3. Active control for stabilization of neoclassical tearing modes

    SciTech Connect

    Humphreys, D.A.; Ferron, J.R.; La Haye, R.J.; Luce, T.C.; Petty, C.C.; Prater, R.; Welander, A.S.

    2006-05-15

    This work describes active control algorithms used by DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] to stabilize and maintain suppression of 3/2 or 2/1 neoclassical tearing modes (NTMs) by application of electron cyclotron current drive (ECCD) at the rational q surface. The DIII-D NTM control system can determine the correct q-surface/ECCD alignment and stabilize existing modes within 100-500 ms of activation, or prevent mode growth with preemptive application of ECCD, in both cases enabling stable operation at normalized beta values above 3.5. Because NTMs can limit performance or cause plasma-terminating disruptions in tokamaks, their stabilization is essential to the high performance operation of ITER [R. Aymar et al., ITER Joint Central Team, ITER Home Teams, Nucl. Fusion 41, 1301 (2001)]. The DIII-D NTM control system has demonstrated many elements of an eventual ITER solution, including general algorithms for robust detection of q-surface/ECCD alignment and for real-time maintenance of alignment following the disappearance of the mode. This latter capability, unique to DIII-D, is based on real-time reconstruction of q-surface geometry by a Grad-Shafranov solver using external magnetics and internal motional Stark effect measurements. Alignment is achieved by varying either the plasma major radius (and the rational q surface) or the toroidal field (and the deposition location). The requirement to achieve and maintain q-surface/ECCD alignment with accuracy on the order of 1 cm is routinely met by the DIII-D Plasma Control System and these algorithms. We discuss the integrated plasma control design process used for developing these and other general control algorithms, which includes physics-based modeling and testing of the algorithm implementation against simulations of actuator and plasma responses. This systematic design/test method and modeling environment enabled successful mode suppression by the NTM control system upon first-time use in an

  4. Robust semi-active control for uncertain structures and smart dampers

    NASA Astrophysics Data System (ADS)

    Yeganeh Fallah, Arash; Taghikhany, Touraj

    2014-09-01

    Recent developments in semi-active control technology have led to its application in civil infrastructures as an efficient strategy to protect susceptible structures against seismic and wind induced vibration. The reliable and robust performance of semi-active systems depends on the level of uncertainties in the structural parameters as well as on the sensors’ measurement and on smart mechanical dampers. A common source of uncertainties in semi-active control devices is related to the inherent nonlinear nature of these devices, thermal variation, or their malfunctioning. This study deals with the robust H∞ control problem and aims to model different sources of uncertainty. The uncertainty of the structural model and damper force are assumed to be norm bounded random variables. By using linear fractional transformation (LFT), the uncertain part of the system is decoupled from the nominal parameters of the system. The robust H∞ controller is designed to achieve consistent performance in structures including nominal and perturbed dynamics. Additionally, to reduce the uncertainty of the damper force, an inverse model of the magnetorheological (MR) damper is developed based on an adaptive neuro-fuzzy inference system (ANFIS). The robustness of the proposed algorithm is validated by numerical simulations.

  5. Improving the vibration suppression capabilities of a magneto-rheological damper using hybrid active and semi-active control

    NASA Astrophysics Data System (ADS)

    Ullah Khan, Irfan; Wagg, David; Sims, Neil D.

    2016-08-01

    This paper presents a new hybrid active and semi-active control method for vibration suppression in flexible structures. The method uses a combination of a semi-active device and an active control actuator situated elsewhere in the structure to suppress vibrations. The key novelty is to use the hybrid controller to enable the magneto-rheological damper to achieve a performance as close to a fully active device as possible. This is achieved by ensuring that the active actuator can assist the magneto-rheological damper in the regions where energy is required. In addition, the hybrid active and semi-active controller is designed to minimize the switching of the semi-active controller. The control framework used is the immersion and invariance control technique in combination with sliding mode control. A two degree-of-freedom system with lightly damped resonances is used as an example system. Both numerical and experimental results are generated for this system, and then compared as part of a validation study. The experimental system uses hardware-in-the-loop to simulate the effect of both the degrees-of-freedom. The results show that the concept is viable both numerically and experimentally, and improved vibration suppression results can be obtained for the magneto-rheological damper that approach the performance of an active device.

  6. Method and apparatus for actively controlling a micro-scale flexural plate wave device

    DOEpatents

    Dohner, Jeffrey L.

    2001-01-01

    An actively controlled flexural plate wave device provides a micro-scale pump. A method of actively controlling a flexural plate wave device produces traveling waves in the device by coordinating the interaction of a magnetic field with actively controlled currents. An actively-controlled flexural plate wave device can be placed in a fluid channel and adapted for use as a micro-scale fluid pump to cool or drive micro-scale systems, for example, micro-chips, micro-electrical-mechanical devices, micro-fluid circuits, or micro-scale chemical analysis devices.

  7. Enhancing Cognitive Abilities with Comprehensive Training: A Large, Online, Randomized, Active-Controlled Trial

    PubMed Central

    Hardy, Joseph L.; Nelson, Rolf A.; Thomason, Moriah E.; Sternberg, Daniel A.; Katovich, Kiefer; Farzin, Faraz; Scanlon, Michael

    2015-01-01

    Background A variety of studies have demonstrated gains in cognitive ability following cognitive training interventions. However, other studies have not shown such gains, and questions remain regarding the efficacy of specific cognitive training interventions. Cognitive training research often involves programs made up of just one or a few exercises, targeting limited and specific cognitive endpoints. In addition, cognitive training studies typically involve small samples that may be insufficient for reliable measurement of change. Other studies have utilized training periods that were too short to generate reliable gains in cognitive performance. Methods The present study evaluated an online cognitive training program comprised of 49 exercises targeting a variety of cognitive capacities. The cognitive training program was compared to an active control condition in which participants completed crossword puzzles. All participants were recruited, trained, and tested online (N = 4,715 fully evaluable participants). Participants in both groups were instructed to complete one approximately 15-minute session at least 5 days per week for 10 weeks. Results Participants randomly assigned to the treatment group improved significantly more on the primary outcome measure, an aggregate measure of neuropsychological performance, than did the active control group (Cohen’s d effect size = 0.255; 95% confidence interval = [0.198, 0.312]). Treatment participants showed greater improvements than controls on speed of processing, short-term memory, working memory, problem solving, and fluid reasoning assessments. Participants in the treatment group also showed greater improvements on self-reported measures of cognitive functioning, particularly on those items related to concentration compared to the control group (Cohen’s d = 0.249; 95% confidence interval = [0.191, 0.306]). Conclusion Taken together, these results indicate that a varied training program composed of a number of

  8. Active control of sound fields in elastic cylinders by multi-control forces

    NASA Technical Reports Server (NTRS)

    Jones, J. D.; Fuller, C. R.

    1987-01-01

    An unstiffened cylindrical model was used to study the control of sound transmission into aircraft cabins by the use of multi-control forces applied directly to the cylinder wall. External acoustic monopoles were located on each side of the cylinder to approximate the propeller noise source. This allowed the study of a dual control system utilizing multi-control forces in conjunction with synchrophasing of the twin acoustic monopole sources. For acoustic resonant conditions within the cavity, a spatially averaged noise reduction of approximately 30 dB was achieved using the active control system for both in-phase and out-of-phase monopoles; however, effective reduction of the sound field was dependent upon judiciously positioning the control forces for optimal control of the sound field.

  9. Selected advanced aerodynamics and active controls technology concepts development on a derivative B-747

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The feasibility of applying wing tip extensions, winglets, and active control wing load alleviation to the Boeing 747 is investigated. Winglet aerodynamic design methods and high speed wind tunnel test results of winglets and of symmetrically deflected ailerons are presented. Structural resizing analyses to determine weight and aeroelastic twist increments for all the concepts and flutter model test results for the wing with winglets are included. Control law development, system mechanization/reliability studies, and aileron balance tab trade studies for active wing load alleviation systems are discussed. Results are presented in the form of incremental effects on L/D, structural weight, block fuel savings, stability and control, airplane price, and airline operating economics.

  10. In-space technology flight experiments: Middeck 0-gravity Dynamics Experiment (MODE) and Middeck Active Control Experiment (MACE)

    NASA Technical Reports Server (NTRS)

    Venneri, Samuel L.

    1991-01-01

    The topics addressed are covered in viewgraph form. The objective of the Middeck 0-gravity Dynamics Experiment (MODE) programs is to study gravity dependent nonlinearities associated with fluid slosh and truss structure dynamics. MODE provides a reusable facility for on-orbit dynamics testing of small scale test articles in the shirt sleeve environment on the Shuttle middeck. Flight program objective of Middeck Active Control Experiment (MACE) is to study gravity effects on the performance and stability of controlled structures.

  11. Evaluation of active control technology for short haul aircraft. [cost effectiveness

    NASA Technical Reports Server (NTRS)

    Renshaw, J. H.; Bennett, J. A.; Harris, O. C.; Honrath, J. F.; Patterson, R. W.

    1975-01-01

    An evaluation of the economics of short-haul aircraft designed with active controls technology and low wing-loading to achieve short field performance with good ride quality is presented. Results indicate that for such a system incorporating gust load alleviation and augmented stability the direct operating cost is better than for aircraft without active controls.

  12. Modeling and Validation of a Navy A6-Intruder Actively Controlled Landing Gear System

    NASA Technical Reports Server (NTRS)

    Horta, Lucas G.; Daugherty, Robert H.; Martinson, Veloria J.

    1999-01-01

    Concepts for long-range air travel are characterized by airframe designs with long, slender, relatively flexible fuselages. One aspect often overlooked is ground-induced vibration of these aircraft. This paper presents an analytical and experimental study of reducing ground-induced aircraft vibration loads by using actively controlled landing gear. A facility has been developed to test various active landing gear control concepts and their performance, The facility uses a Navy A6 Intruder landing gear fitted with an auxiliary hydraulic supply electronically controlled by servo valves. An analytical model of the gear is presented, including modifications to actuate the gear externally, and test data are used to validate the model. The control design is described and closed-loop test and analysis comparisons are presented.

  13. An active control system for helicopter vibration reduction by higher harmonic pitch

    NASA Technical Reports Server (NTRS)

    Taylor, R. B.; Farrar, F. A.; Miao, W.

    1980-01-01

    An analytical study defining the basic configuration of an active control system to reduce helicopter vibrations is presented. Theoretical results for a nonlinear four-bladed single rotor helicopter simulation are discussed, showing that vibration reductions on the order of 80-90% for airspeeds up to 150 kn can be expected when using a higher harmonic pitch in an active feedback control system. The rotor performance penalty associated with this level of vibration reduction is about 1-3% and the increase in rotor blade stresses is considered to be low. The location of sensor accelerometers proved to be significant for vibration reductions, and it is noted that the RTSA controller is tolerant of sensor signal noise.

  14. Test/analysis comparison of piezoelectric patch local behavior for vibroacoustic active control application

    NASA Astrophysics Data System (ADS)

    Florens, Corine; Balmes, Etienne; Clero, Franck

    2007-04-01

    To predict the effect of active control on aircraft or helicopter trim panels, made with honeycomb sandwich composite, one approach consists in modeling the panel by Finite Element Method. FEM with shell elements for the laminate and volume elements for the core is classically used in industry; in a previous study the homogenized modeling approach has been validated. The aim of the present paper is to make a test/analysis comparison of the dynamic behavior of a honeycomb core sandwich beam actuated by a piezoelectric patch. More precisely, the behavior in the vicinity of the piezoelectric actuator is characterized, in order to validate the modeling approach of honeycomb sandwich composite equipped with piezoelectric patches.

  15. Active control of structurally-coupled sound fields in elastic cylinders by vibrational force inputs

    NASA Technical Reports Server (NTRS)

    Jones, J. D.; Fuller, C. R.

    1990-01-01

    Active control of structurally-coupled sound fields in elastic cylinders is analytically and experimentally studied. The primary (noise) field in the cylinder model is generated by the coupled dynamic response of the shell under loading by a single exterior acoustic source. Control of the interior sound field is achieved by applying vibrational force inputs directly to the shell wall. Action of the point controllers serve to increase the input impedance of select structural modes of the shell which are well-coupled to the interior acoustic cavity, thus substantially reducing sound transmission into the cavity. Spatially-averaged noise reductions in excess of 30 dB are demonstrated for acoustic resonant conditions within the cavity. Twin controller configurations are presented which demonstrate the ability to independently control orthogonal modes of the interior acoustic space. Benefits and drawbacks of this new methodology for noise control are discussed and clearly demonstrated.

  16. Postural stability of older female Scottish country dancers in comparison with physically active controls.

    PubMed

    Dewhurst, Susan; Peacock, Leslie; Bampouras, Theodoros M

    2015-01-01

    Physical activity assists older individuals' functional ability and postural stability. Recently, Scottish country dance (SCD) was reported as being a beneficial form of physical activity for functional ability in older females. This study aims to examine the effect of SCD on postural stability. Scottish country dancers (n = 20) were compared with physically active controls (n = 33) for static postural sway measured on a force platform. The Romberg and Tandem stances were used under 'eyes open' and 'eyes closed' conditions. Ninety-five percent ellipse area and sway velocity were calculated from the center of pressure displacement. Ninety-five percent ellipse area was the same for both groups in all tests. The control group had greater sway velocity for all tests (P < .01) except Tandem eyes closed. SCD participation resulted in similar postural sway as participation in other physical activities, however nondancers may need a greater amount of regulatory activity to maintain balance. PMID:24515979

  17. Active control of sound transmission/radiation from elastic plates by vibration inputs. I - Analysis

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1990-01-01

    Active control of sound radiation from vibrating plates by oscillating forces applied directly to the structure is analytically studied. The model consists of a plane acoustic wave incident on a clamped elastic circular thin plate. Control is achieved by point forces, and quadratic optimization is used to calculate the optimal control gains necessary to minimize a cost function proportional to the radiated acoustic power (the transmitted field). The results show that global attenuation of broadband radiated sound levels for low to mid-range frequencies can be achieved with one or two control forces, irrespective of whether the system is on or off resonance. The efficiency of the control strategy is demonstrated to be related to the nature of the coupling between the plate modes of response and the radiated field.

  18. Combustion instability and active control: Alternative fuels, augmentors, and modeling heat release

    NASA Astrophysics Data System (ADS)

    Park, Sammy Ace

    Experimental and analytical studies were conducted to explore thermo-acoustic coupling during the onset of combustion instability in various air-breathing combustor configurations. These include a laboratory-scale 200-kW dump combustor and a 100-kW augmentor featuring a v-gutter flame holder. They were used to simulate main combustion chambers and afterburners in aero engines, respectively. The three primary themes of this work includes: 1) modeling heat release fluctuations for stability analysis, 2) conducting active combustion control with alternative fuels, and 3) demonstrating practical active control for augmentor instability suppression. The phenomenon of combustion instabilities remains an unsolved problem in propulsion engines, mainly because of the difficulty in predicting the fluctuating component of heat release without extensive testing. A hybrid model was developed to describe both the temporal and spatial variations in dynamic heat release, using a separation of variables approach that requires only a limited amount of experimental data. The use of sinusoidal basis functions further reduced the amount of data required. When the mean heat release behavior is known, the only experimental data needed for detailed stability analysis is one instantaneous picture of heat release at the peak pressure phase. This model was successfully tested in the dump combustor experiments, reproducing the correct sign of the overall Rayleigh index as well as the remarkably accurate spatial distribution pattern of fluctuating heat release. Active combustion control was explored for fuel-flexible combustor operation using twelve different jet fuels including bio-synthetic and Fischer-Tropsch types. Analysis done using an actuated spray combustion model revealed that the combustion response times of these fuels were similar. Combined with experimental spray characterizations, this suggested that controller performance should remain effective with various alternative fuels

  19. Active control of counter-rotating open rotor interior noise in a Dornier 728 experimental aircraft

    NASA Astrophysics Data System (ADS)

    Haase, Thomas; Unruh, Oliver; Algermissen, Stephan; Pohl, Martin

    2016-08-01

    The fuel consumption of future civil aircraft needs to be reduced because of the CO2 restrictions declared by the European Union. A consequent lightweight design and a new engine concept called counter-rotating open rotor are seen as key technologies in the attempt to reach this ambitious goals. Bearing in mind that counter-rotating open rotor engines emit very high sound pressures at low frequencies and that lightweight structures have a poor transmission loss in the lower frequency range, these key technologies raise new questions in regard to acoustic passenger comfort. One of the promising solutions for the reduction of sound pressure levels inside the aircraft cabin are active sound and vibration systems. So far, active concepts have rarely been investigated for a counter-rotating open rotor pressure excitation on complex airframe structures. Hence, the state of the art is augmented by the preliminary study presented in this paper. The study shows how an active vibration control system can influence the sound transmission of counter-rotating open rotor noise through a complex airframe structure into the cabin. Furthermore, open questions on the way towards the realisation of an active control system are addressed. In this phase, an active feedforward control system is investigated in a fully equipped Dornier 728 experimental prototype aircraft. In particular, the sound transmission through the airframe, the coupling of classical actuators (inertial and piezoelectric patch actuators) into the structure and the performance of the active vibration control system with different error sensors are investigated. It can be shown that the active control system achieves a reduction up to 5 dB at several counter-rotating open rotor frequencies but also that a better performance could be achieved through further optimisations.

  20. Active Control of Coupled Wave Propagation in Fluid-Filled Elastic Cylindrical Shells.

    NASA Astrophysics Data System (ADS)

    Brevart, Bertrand Jean

    The vibrational energy propagating in straight fluid-filled elastic pipes is carried by the structure as well as by the internal fluid. This study demonstrates that, whether the propagating energy is predominantly conveyed in the shell or in the fluid, large attenuations of the total power flow may be achieved by using an active control approach. As the shell and fluid motions are fully coupled, the implementation of intrusive sources/sensors in the acoustic field can be also avoided. The approach is based on using radial control forces applied to the outer shell wall and error sensors observing the structural motion. The cylindrical shell is assumed to be infinite, in vacuo or filled with water. The first disturbance source investigated is a propagating free wave of circumferential order n = 0 or n = 1. The control forces are appropriate harmonic line forces radially applied to the structure. The radial displacement of the shell wall at discrete locations downstream of the control forces is minimized using linear quadratic optimal control theory. The attenuation of the total power flow in the system after control is used to study the impact of the fluid on the performance of the control approach. Results for the shell in vacuo are presented for comparison. Considering the breathing mode (n = 0), the fluid decreases the control performance when the disturbance is a structural-type incident wave. Significant reductions of the transmitted power flow can be achieved when the disturbance is a fluid-type of wave. Regarding the beam mode (n = 1), the fluid increases the control performance below the first acoustic cut-off frequency and decreases it above this frequency. The analytical study is then extended to the active control of the pipe vibrations induced by more realistic disturbances such as a point force or an internal monopole source. The point force disturbance addresses the problem of mechanical excitation whereas the internal monopole source directs the

  1. Multirate flutter suppression system design for the Benchmark Active Controls Technology Wing

    NASA Technical Reports Server (NTRS)

    Berg, Martin C.; Mason, Gregory S.

    1994-01-01

    To study the effectiveness of various control system design methodologies, the NASA Langley Research Center initiated the Benchmark Active Controls Project. In this project, the various methodologies will be applied to design a flutter suppression system for the Benchmark Active Controls Technology (BACT) Wing (also called the PAPA wing). Eventually, the designs will be implemented in hardware and tested on the BACT wing in a wind tunnel. This report describes a project at the University of Washington to design a multirate flutter suppression system for the BACT wing. The objective of the project was two fold. First, to develop a methodology for designing robust multirate compensators, and second, to demonstrate the methodology by applying it to the design of a multirate flutter suppression system for the BACT wing. The contributions of this project are (1) development of an algorithm for synthesizing robust low order multirate control laws (the algorithm is capable of synthesizing a single compensator which stabilizes both the nominal plant and multiple plant perturbations; (2) development of a multirate design methodology, and supporting software, for modeling, analyzing and synthesizing multirate compensators; and (3) design of a multirate flutter suppression system for NASA's BACT wing which satisfies the specified design criteria. This report describes each of these contributions in detail. Section 2.0 discusses our design methodology. Section 3.0 details the results of our multirate flutter suppression system design for the BACT wing. Finally, Section 4.0 presents our conclusions and suggestions for future research. The body of the report focuses primarily on the results. The associated theoretical background appears in the three technical papers that are included as Attachments 1-3. Attachment 4 is a user's manual for the software that is key to our design methodology.

  2. Relapse Prevention in Major Depressive Disorder: Mindfulness-Based Cognitive Therapy Versus an Active Control Condition

    PubMed Central

    Shallcross, Amanda J.; Gross, James J.; Visvanathan, Pallavi D.; Kumar, Niketa; Palfrey, Amy; Ford, Brett Q.; Dimidjian, Sona; Shirk, Stephen; Holm-Denoma, Jill; Goode, Kari M.; Cox, Erica; Chaplin, William; Mauss, Iris B.

    2015-01-01

    Objective We evaluated the comparative effectiveness of Mindfulness-based cognitive therapy (MBCT) versus an active control condition (ACC) for depression relapse prevention, depressive symptom reduction, and improvement in life satisfaction. Method Ninety-two participants in remission from Major Depressive Disorder with residual depressive symptoms were randomized to either an 8-week MBCT or a validated ACC that is structurally equivalent to MBCT and controls for non-specific effects (e.g., interaction with a facilitator, perceived social support, treatment outcome expectations). Both interventions were delivered according to their published manuals. Results Intention-to-treat analyses indicated no differences between MBCT and ACC in depression relapse rates or time to relapse over a 60-week follow-up. Both groups experienced significant and equal reductions in depressive symptoms and improvements in life satisfaction. A significant quadratic interaction (group x time) indicated that the pattern of depressive symptom reduction differed between groups. The ACC experienced immediate symptom reduction post-intervention and then a gradual increase over the 60-week follow-up. The MBCT group experienced a gradual linear symptom reduction. The pattern for life satisfaction was identical but only marginally significant. Conclusions MBCT did not differ from an ACC on rates of depression relapse, symptom reduction, or life satisfaction, suggesting that MBCT is no more effective for preventing depression relapse and reducing depressive symptoms than the active components of the ACC. Differences in trajectory of depressive symptom improvement suggest that the intervention-specific skills acquired may be associated with differential rates of therapeutic benefit. This study demonstrates the importance of comparing psychotherapeutic interventions to active control conditions. PMID:26371618

  3. Design verification and fabrication of active control systems for the DAST ARW-2 high aspect ratio wing. Part 2: Appendices

    NASA Technical Reports Server (NTRS)

    Mcgehee, C. R.

    1986-01-01

    This is Part 2-Appendices of a study conducted under Drones for Aerodynamic and Structural Testing (DAST) Program to accomplish the final design and hardware fabrication for four active control systems compatible with and ready for installation in the NASA Aeroelastic Research Wing No. 2 (ARW-2) and Firebee II drone flight test vehicle. The wing structure was designed so that Active Control Systems (ACS) are required in the normal flight envelope by integrating control system design with aerodynamics and structure technologies. The DAST ARW-2 configuration uses flutter suppression, relaxed static stability, and gust and maneuver load alleviation ACS systems, and an automatic flight control system. Performance goals and criteria were applied to individual systems and the systems collectively to assure that vehicle stability margins, flutter margins, flying qualities, and load reductions were achieved.

  4. Design verification and fabrication of active control systems for the DAST ARW-2 high aspect ratio wing, part 1

    NASA Technical Reports Server (NTRS)

    Mcgehee, C. R.

    1986-01-01

    A study was conducted under Drones for Aerodynamic and Structural Testing (DAST) program to accomplish the final design and hardware fabrication for four active control systems compatible with and ready for installation in the NASA Aeroelastic Research Wing No. 2 (ARW-2) and Firebee II drone flight test vehicle. The wing structure was designed so that Active Control Systems (ACS) are required in the normal flight envelope by integrating control system design with aerodynamics and structure technologies. The DAST ARW-2 configuration uses flutter suppression, relaxed static stability, and gust and maneuver load alleviation ACS systems, and an automatic flight control system. Performance goals and criteria were applied to individual systems and the systems collectively to assure that vehicle stability margins, flutter margins, flying qualities and load reductions are achieved.

  5. Test Cases for the Benchmark Active Controls: Spoiler and Control Surface Oscillations and Flutter

    NASA Technical Reports Server (NTRS)

    Bennett, Robert M.; Scott, Robert C.; Wieseman, Carol D.

    2000-01-01

    sets from the first two tests have been chosen for Test Cases for computational comparisons concentrating on static conditions and cases with harmonically oscillating control surfaces. Several flutter Test Cases from both tests have also been included. Some aerodynamic comparisons with the BACT data have been made using computational fluid dynamics codes at the Navier-Stokes level (and in the accompanying chapter SC). Some mechanical and active control studies have been presented. In this report several Test Cases are selected to illustrate trends for a variety of different conditions with emphasis on transonic flow effects. Cases for static angles of attack, static trailing-edge and upper-surface spoiler deflections are included for a range of conditions near those for the oscillation cases. Cases for trailing-edge control and upper-surface spoiler oscillations for a range of Mach numbers, angle of attack, and static control deflections are included. Cases for all three types of flutter instability are selected. In addition some cases are included for dynamic response measurements during forced oscillations of the controls on the flexible mount. An overview of the model and tests is given, and the standard formulary for these data is listed. Some sample data and sample results of calculations are presented. Only the static pressures and the first harmonic real and imaginary parts of the pressures are included in the data for the Test Cases, but digitized time histories have been archived. The data for the Test Cases are also available as separate electronic files.

  6. Active control of shocks and sonic boom ground signal

    NASA Astrophysics Data System (ADS)

    Yagiz, Bedri

    The manipulation of a flow field to obtain a desired change is a much heightened subject. Active flow control has been the subject of the major research areas in fluid mechanics for the past two decades. It offers new solutions for mitigation of shock strength, sonic boom alleviation, drag minimization, reducing blade-vortex interaction noise in helicopters, stall control and the performance maximization of existing designs to meet the increasing requirements of the aircraft industries. Despite the wide variety of the potential applications of active flow control, the majority of studies have been performed at subsonic speeds. The active flow control cases were investigated in transonic speed in this study. Although the active flow control provides significant improvements, the sensibility of aerodynamic performance to design parameters makes it a nontrivial and expensive problem, so the designer has to optimize a number of different parameters. For the purpose of gaining understanding of the active flow control concepts, an automated optimization cycle process was generated. Also, the optimization cycle reduces cost and turnaround time. The mass flow coefficient, location, width and angle were chosen as design parameters to maximize the aerodynamic performance of an aircraft. As the main contribution of this study, a detailed parametric study and optimization process were presented. The second step is to appraise the practicability of weakening the shock wave and thereby reducing the wave drag in transonic flight regime using flow control devices such as two dimensional contour bump, individual jet actuator, and also the hybrid control which includes both control devices together, thereby gaining the desired improvements in aerodynamic performance of the air-vehicle. After this study, to improve the aerodynamic performance, the flow control and shape parameters are optimized separately, combined, and in a serial combination. The remarkable part of all these

  7. Calculation of Hub Loads at Low Airspeeds with Active Control

    NASA Technical Reports Server (NTRS)

    Kottapalli, Sesi

    2007-01-01

    The effect of individual blade control (IBC) on the full-scale, low airspeed, level flight UH-60A oscillatory fixed system 4P hub loads and the rotating system blade bending moments is studied. The effect of a single 3P IBC input has been considered in this analytical study. At the low speed under consideration, it has been found that convergence of the comprehensive analysis is important for obtaining good predictions. Good correlation has been obtained with the measured full-scale wind tunnel data for the shapes of the fixed system 4P hub loads variations with the 3P IBC input phase, and also for the "best" phase of the 3P input (for minimum hub loads). The blade bending moment comparison shows mixed results. The 3P lead lag and the 4P flap bending moment trends with the 3P IBC input phase are reasonably predicted, whereas the 5P lead lag bending moment trend is not predicted well. Finally, the prediction of the baseline (no IBC) bending moments needs further study.

  8. Non-actively controlled double-inverted-pendulum-like dynamics can minimize center of mass acceleration during human quiet standing.

    PubMed

    Suzuki, Yasuyuki; Morimoto, Hiroki; Kiyono, Ken; Morasso, Pietro; Nomura, Taishin

    2015-08-01

    Multiple joint movements during human quiet standing exhibit characteristic inter-joint coordination, shortly referred to as reciprocal relationship, in which angular acceleration of the hip joint is linearly and negatively correlated with that of the ankle joint (antiphase coordination) and, moreover, acceleration of the center of mass (CoM) of the double-inverted-pendulum (DIP) model of the human body is close to zero constantly. A question considered in this study is whether the reciprocal relationship is established by active neural control of the posture, or rather it is a biomechanical consequence of non-actively controlled body dynamics. To answer this question, we consider a DIP model of quiet standing, and show that the reciprocal relationship always holds by Newton's second law applied to the DIP model with human anthropometric dimensions, regardless of passive and active joint torque patterns acting on the ankle and hip joints. We then show that characteristic frequencies included in experimental sway trajectories with the reciprocal relationship match with harmonics of the eigenfrequency of the stable antiphase eigenmode of the non-actively controlled DIP-like unstable body dynamics. The results suggest that non-actively controlled DIP-like mechanical dynamics is a major cause of the minimization of the CoM acceleration during quiet standing, which is consistent with a type of control strategy that allows switching off active neural control intermittently for suitable periods of time during quiet standing. PMID:26736538

  9. An active control system for the turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Lew, James

    This thesis presents the development process and the experimental results of a system constructed to apply real-time control to the structures of the turbulent boundary layer region in order to reduce surface shear stress. The system is composed of three main components: an array of MEMS surface shear stress, tauw sensors; a MEMS flap actuator; and a control logic which integrates the hardware components together into a closed system. The objective of this system is to reduce the stress contained in streak-like regions of high tauw. The sensor array, used to image the tauw distribution, is an extension of the thermal based tauw sensor developed by Jiang. Numerous studies have been performed using this device, the results of which have validated its performance. For this study, a new temperature compensation methodology, based on the surface temperature of the sensor chip, was employed in order to account for possible temperature variations at the wall surface. The actuator, a pneumatically driven flap, is developed as part of the present research. The device is, in essence, a 3 mm x 1 mm cantilever beam that sits on top of an inflatable diaphragm and is capable of actuation frequencies of over 200 Hz and amplitudes of over .11 mm. When it is oscillated in the open loop mode, the effect over one cycle of motion is an average reduction by as much as 2.5% in tauw in the region immediately downstream. A neural network is employed to identify the streak-like regions of interest. Results have shown that this network is successful in identifying the streak-like regions of interest. The control logic employs this network in a predictive, feed-forward scheme to determine the appropriate actuator response. Offline studies have shown that under optimal conditions, the signature of the streak-like regions can be eliminated. Online results conform well to the offline predictions. While unable to achieve the optimal conditions, online experiments show that the system is capable

  10. Active Control of Flow Separation Over an Airfoil

    NASA Technical Reports Server (NTRS)

    Ravindran, S. S.

    1999-01-01

    Designing an aircraft without conventional control surfaces is of interest to aerospace community. In this direction, smart actuator devices such as synthetic jets have been proposed to provide aircraft maneuverability instead of control surfaces. In this article, a numerical study is performed to investigate the effects of unsteady suction and blowing on airfoils. The unsteady suction and blowing is introduced at the leading edge of the airfoil in the form of tangential jet. Numerical solutions are obtained using Reynolds-Averaged viscous compressible Navier-Stokes equations. Unsteady suction and blowing is investigated as a means of separation control to obtain lift on airfoils. The effect of blowing coefficients on lift and drag is investigated. The numerical simulations are compared with experiments from the Tel-Aviv University (TAU). These results indicate that unsteady suction and blowing can be used as a means of separation control to generate lift on airfoils.

  11. Active Control of Liner Impedance by Varying Perforate Orifice Geometry

    NASA Technical Reports Server (NTRS)

    Ahuji, K. K.; Gaeta, R. J., Jr.

    2000-01-01

    The present work explored the feasibility of controlling the acoustic impedance of a resonant type acoustic liner. This was accomplished by translating one perforate over another of the same porosity creating a totally new perforate that had an intermediate porosity. This type of adjustable perforate created a variable orifice perforate whose orifices were non-circular. The key objective of the present study was to quantify, the degree of attenuation control that can be achieved by applying such a concept to the buried septum in a two-degree-of-freedom (2DOF) acoustic liner. An additional objective was to examine the adequacy of the existing impedance models to explain the behavior of the unique orifice shapes that result from the proposed silding perforate concept. Different orifice shapes with equivalent area were also examined to determine if highly non-circular orifices had a significant impact on the impedance.

  12. Selected topics on the active control of helicopter aeromechanical and vibration problems

    NASA Technical Reports Server (NTRS)

    Friedmann, Peretz P.

    1994-01-01

    This paper describes in a concise manner three selected topics on the active control of helicopter aeromechanical and vibration problems. The three topics are as follows: (1) the active control of helicopter air-resonance using an LQG/LTR approach; (2) simulation of higher harmonic control (HHC) applied to a four bladed hingeless helicopter rotor in forward flight; and (3) vibration suppression in forward flight on a hingeless helicopter rotor using an actively controlled, partial span, trailing edge flap, which is mounted on the blade. Only a few selected illustrative results are presented. The results obtained clearly indicate that the partial span, actively controlled flap has considerable potential for vibration reduction in helicopter rotors.

  13. The W. M. Keck Telescope segmented primary mirror active control system

    SciTech Connect

    Jared, R.C.; Arthur, A.A.; Andreae, S.; Biocca, A.; Cohen, R.W.; Fuertes, J.M.; Franck, J.; Gabor, G.; Llacer, J.; Mast, T.; Meng, J.; Merrick, T.; Minor, R.; Nelson, J.; Orayani, M.; Salz, P.; Schaefer, B.; Witebsky, C.

    1989-07-01

    The ten meter diameter primary mirror of the W. M. Keck Telescope is a mosaic of thirty-six hexagonal mirrors. An active control system stabilizes the primary mirror. The active control system uses 168 measurements of the relative positions of adjacent mirror segments and 3 measurements of the primary mirror position in the telescope structure to control the 108 degrees of freedom needed to stabilize the figure and position of the primary mirror. The components of the active control system are relative position sensors, electronics, computers, actuators that position the mirrors, and software. The software algorithms control the primary mirror, perform star image stacking, emulate the segments, store and fit calibration data, and locate hardware defects. We give an overview of the active control system, its functional requirements and test measurements. 12 refs.

  14. Effect of the probiotic strain Bifidobacterium animalis subsp. lactis, BB-12®, on defecation frequency in healthy subjects with low defecation frequency and abdominal discomfort: a randomised, double-blind, placebo-controlled, parallel-group trial.

    PubMed

    Eskesen, Dorte; Jespersen, Lillian; Michelsen, Birgit; Whorwell, Peter J; Müller-Lissner, Stefan; Morberg, Cathrine M

    2015-11-28

    The aim of the present study was to investigate the effect of Bifidobacterium animalis subsp. lactis, BB-12®, on two primary end points - defecation frequency and gastrointestinal (GI) well-being - in healthy adults with low defecation frequency and abdominal discomfort. A total of 1248 subjects were included in a randomised, double-blind, placebo-controlled trial. After a 2-week run-in period, subjects were randomised to 1 or 10 billion colony-forming units/d of the probiotic strain BB-12® or a matching placebo capsule once daily for 4 weeks. Subjects completed a diary on bowel habits, relief of abdominal discomfort and symptoms. GI well-being, defined as global relief of abdominal discomfort, did not show significant differences. The OR for having a defecation frequency above baseline for ≥50% of the time was 1·31 (95% CI 0·98, 1·75), P=0·071, for probiotic treatment overall. Tightening the criteria for being a responder to an increase of ≥1 d/week for ≥50 % of the time resulted in an OR of 1·55 (95% CI 1·22, 1·96), P=0·0003, for treatment overall. A treatment effect on average defecation frequency was found (P=0·0065), with the frequency being significantly higher compared with placebo at all weeks for probiotic treatment overall (all P<0·05). Effects on defecation frequency were similar for the two doses tested, suggesting that a ceiling effect was reached with the one billion dose. Overall, 4 weeks' supplementation with the probiotic strain BB-12® resulted in a clinically relevant benefit on defecation frequency. The results suggest that consumption of BB-12® improves the GI health of individuals whose symptoms are not sufficiently severe to consult a doctor (ISRCTN18128385). PMID:26382580

  15. Long-term efficacy and safety of rabeprazole in patients taking low-dose aspirin with a history of peptic ulcers: a phase 2/3, randomized, parallel-group, multicenter, extension clinical trial

    PubMed Central

    Fujishiro, Mitsuhiro; Higuchi, Kazuhide; Kato, Mototsugu; Kinoshita, Yoshikazu; Iwakiri, Ryuichi; Watanabe, Toshio; Takeuchi, Toshihisa; Sugisaki, Nobuyuki; Okada, Yasushi; Ogawa, Hisao; Arakawa, Tetsuo; Fujimoto, Kazuma

    2015-01-01

    A 24-week, double-blind, clinical trial of rabeprazole for the prevention of recurrent peptic ulcers caused by low-dose aspirin (LDA) has been reported, but trials for longer than 24 weeks have not been reported. The aim of this study is to assess the long-term efficacy and safety of rabeprazole for preventing peptic ulcer recurrence on LDA therapy. Eligible patients had a history of peptic ulcers on long-term LDA (81 or 100 mg/day) therapy. Patients with no recurrence of peptic ulcers at the end of the 24-week double-blind phase with rabeprazole (10- or 5-mg once daily) or teprenone (50 mg three times daily) entered the extension phase. Rabeprazole doses were maintained for a maximum of 76 weeks, including the double-blind 24-week period and the extension phase period (long-term rabeprazole 10- and 5-mg groups). Teprenone was randomly switched to rabeprazole 10 or 5 mg for a maximum of 52 weeks in the extension phase (newly-initiated rabeprazole 10- and 5-mg groups). The full analysis set consisted of 151 and 150 subjects in the long-term rabeprazole 10- and 5-mg groups, respectively, and the cumulative recurrence rates of peptic ulcers were 2.2 and 3.7%, respectively. Recurrent peptic ulcers were not observed in the newly-initiated rabeprazole 10- and 5-mg groups. No bleeding ulcers were reported. No clinically significant safety findings, including cardiovascular events, emerged. The use of long-term rabeprazole 10- and 5-mg once daily prevents the recurrence of peptic ulcers in subjects on low-dose aspirin therapy, and both were well-tolerated. PMID:26060354

  16. Simultaneous BVI noise and vibration reduction in rotorcraft using actively-controlled flaps and including performance considerations

    NASA Astrophysics Data System (ADS)

    Patt, Daniel A.

    This work presents the development and application of an active control approach for reduction of both vibration and noise induced by helicopter rotor blade vortex interaction (BVI). Control is implemented through single or dual actively controlled flaps (ACFs) on each blade. Low-speed helicopter flight is prone to severe BVI, resulting in elevated vibration and noise levels. Existing research has suggested that when some form of active control is used to reduce vibration, noise will increase and vice versa. The present research achieves simultaneous reduction of noise and vibration, and also investigates the physical sources of the observed reduction. The initial portion of this work focused on developing a tool for simulating helicopter noise and vibrations in the BVI flight regime. A method for predicting compressible unsteady blade surface pressure distribution on rotor blades was developed and combined with an enhanced free-wake model and an acoustic prediction tool with provisions for blade flexibility. These elements were incorporated within an aeroelastic analysis featuring fully coupled flap-lag-torsional blade dynamics. Subsequently, control algorithms were developed that were effective for reducing noise and vibration even in the nonlinear BVI flight regime; saturation limits were incorporated constraining flap deflections to specified limits. The resulting simulation was also validated with a wide range of experimental data, achieving excellent correlation. Finally, a number of active control studies were performed. Multi-component vibration reductions of 40--80% could be achieved, while incurring a small noise penalty. Noise was reduced using an onboard feedback microphone; reductions of 4--10 dB on the advancing side were observed on a plane beneath the rotor when using dual flaps. Finally, simultaneous noise and vibration reduction was studied. A reduction of about 5 dB in noise on the advancing side combined with a 60% reduction in vibration was

  17. An active control strategy for achieving weak radiator structures

    SciTech Connect

    Naghshineh, K. . Acoustics and Radar Technology Lab.); Koopmann, G.H. . Center for Acoustics and Vibration)

    1994-01-01

    A general control strategy is presented for active suppression of total radiated sound power from harmonically excited structures based on the measurement of their response. Using the measured response of the structure together with knowledge of its structural mobility, and equivalent primary excitation force is found at discrete points along the structure. Using this equivalent primary force and performing a quadratic optimization of the power radiated form the structure, a set of control forces is found at selected points on the structure that results in minimum radiated sound power. A numerical example of this strategy is presented for a simply supported beam in a rigid baffle excited by a harmonic plane wave incident at an oblique angle. A comparison of the response of the beam with and without control forces shows a large reduction in the controlled response displacement magnitude. In addition, as the result of the action of the control forces, the magnitude of the wave number spectrum of the beam's response in the supersonic region is decreased substantially. The effect of the number and location of the actuators on reductions in sound power level is also studied. The actuators located at the anti-nodes of structural modes within the supersonic region together with those located near boundaries are found to be the most effective in controlling the radiation of sound from a structure.

  18. Active control of structures using macro-fiber composite (MFC)

    NASA Astrophysics Data System (ADS)

    Kovalovs, A.; Barkanov, E.; Gluhihs, S.

    2007-12-01

    This paper presents the use of macro-fiber composites (MFC) for vibration reduces of structures. The MFC consist of polyimid films with IDE-electrodes that are glued on the top and the bottom of rectangular piezoceramic fibers. The interdigitated electrodes deliver the electric field required to activate the piezoelectric effect in the fibers and allows to invoke the stronger longitudinal piezoelectric effect along the length of the fibers. When this actuator embedded in a surface or attached to flexible structures, the MFC actuator provides distributed solid-state deflection and vibration control. The major advantages of the piezoelectric fibre composite actuators are their high performance, flexibility, and durability when compared with the traditional piezoceramic (PZT) actuators. In addition, the ability of MFC devices to couple the electrical and mechanical fields is larger than in monolithic PZT. In this study, we showed the experimental results that an MFC could be used as actuator to find modal parameters and reduce vibration for structures such as an aluminium beam and metal music plate. Two MFC actuators were attached to the surfaces of test subjects. First MFC actuator used to supply a signal as exciter of vibration and second MFC show his application for reduction of vibration in the range of resonance frequencies. Experimental results of aluminium beam with MFC actuators compared with finite element model which modelled in ANSYS software. The applied voltage is modelled as a thermal load according to thermal analogy for MFC. The experimental and numerical results presented in this paper confirm the potential of MFC for use in the vibration control of structures.

  19. Active control of panel vibrations induced by boundary-layer flow

    NASA Technical Reports Server (NTRS)

    Chow, Pao-Liu

    1991-01-01

    Some problems in active control of panel vibration excited by a boundary layer flow over a flat plate are studied. In the first phase of the study, the optimal control problem of vibrating elastic panel induced by a fluid dynamical loading was studied. For a simply supported rectangular plate, the vibration control problem can be analyzed by a modal analysis. The control objective is to minimize the total cost functional, which is the sum of a vibrational energy and the control cost. By means of the modal expansion, the dynamical equation for the plate and the cost functional are reduced to a system of ordinary differential equations and the cost functions for the modes. For the linear elastic plate, the modes become uncoupled. The control of each modal amplitude reduces to the so-called linear regulator problem in control theory. Such problems can then be solved by the method of adjoint state. The optimality system of equations was solved numerically by a shooting method. The results are summarized.

  20. Semi-active control of the rocking motion of monolithic art objects

    NASA Astrophysics Data System (ADS)

    Ceravolo, Rosario; Pecorelli, Marica Leonarda; Zanotti Fragonara, Luca

    2016-07-01

    The seismic behaviour of many art objects and obelisks can be analysed in the context of the seismic response of rigid blocks. Starting from the pioneering works by Housner, a large number of analytical studies of the rigid block dynamics were proposed. In fact, despite its apparent simplicity, the motion of a rigid block involves a number of complex dynamic phenomena such as impacts, sliding, uplift and geometric nonlinearities. While most of the current strategies to avoid toppling consist in preventing rocking motion, in this paper a novel semi-active on-off control strategy for protecting monolithic art objects was investigated. The control procedure under study follows a feedback-feedforward scheme that is realised by switching the stiffness of the anchorages located at the two lower corner of the block between two values. Overturning spectra have been calculated in order to clarify the benefits of applying a semi-active control instead of a passive control strategy. In accordance with similar studies, the numerical investigation took into account the dynamic response of blocks with different slenderness and size subject to one-sine pulse excitation.

  1. Active control of the nucleation temperature enhances freezing survival of multipotent mesenchymal stromal cells.

    PubMed

    Lauterboeck, L; Hofmann, N; Mueller, T; Glasmacher, B

    2015-12-01

    Cryopreservation is a technique that has been extensively used for storage of multipotent mesenchymal stromal cells (MSCs) in regenerative medicine. Therefore, improving current cryopreservation procedures in terms of increasing cell viability and functionality is important. In this study, we optimized the cryopreservation protocol of MSCs derived from the common marmoset Callithrix jacchus (cj), which can be used as a non-human primate model in various pathological and transplantation studies and have a great potential for regenerative medicine. We have investigated the effect of the active control of the nucleation temperature using induced nucleation at a broad range of temperatures and two different dimethylsulfoxide concentrations (Me2SO, 5% (v/v) and 10%, (v/v)) to evaluate the overall effect on the viability, metabolic activity and recovery of cells after thawing. Survival rate and metabolic activity displayed an optimum when ice formation was induced at -10 °C. Cryomicroscopy studies indicated differences in ice crystal morphologies as well as differences in intracellular ice formation with different nucleation temperatures. High subzero nucleation temperatures resulted in larger extracellular ice crystals and cellular dehydration, whereas low subzero nucleation temperatures resulted in smaller ice crystals and intracellular ice formation. PMID:26499840

  2. Fire ants actively control spacing and orientation within self-assemblages.

    PubMed

    Foster, Paul C; Mlot, Nathan J; Lin, Angela; Hu, David L

    2014-06-15

    To overcome obstacles and survive harsh environments, fire ants link their bodies together to form self-assemblages such as rafts, bridges and bivouacs. Such structures are examples of self-assembling and self-healing materials, as ants can quickly create and break links with one another in response to changes in their environment. Because ants are opaque, the arrangement of the ants within these three-dimensional networks was previously unknown. In this experimental study, we applied micro-scale computed tomography, or micro-CT, to visualize the connectivity, arrangement and orientation of ants within an assemblage. We identified active and geometric mechanisms that ants use to obtain favorable packing properties with respect to well-studied packing of inert objects such as cylinders. Ants use their legs to push against their neighbors, doubling their spacing relative to random packing of cylinders. These legs also permit active control of their orientation, an ability ants use to arrange themselves perpendicularly rather than in parallel. Lastly, we found an important role of ant polymorphism in promoting self-aggregation: a large distribution of ant sizes permits small ants to fit between the legs of larger ants, a phenomenon that increases the number of average connections per ant. These combined mechanisms lead to low packing fraction and high connectivity, which increase raft buoyancy and strength during flash floods. PMID:24920836

  3. Active control of all-fibre graphene devices with electrical gating.

    PubMed

    Lee, Eun Jung; Choi, Sun Young; Jeong, Hwanseong; Park, Nam Hun; Yim, Woongbin; Kim, Mi Hye; Park, Jae-Ku; Son, Suyeon; Bae, Sukang; Kim, Sang Jin; Lee, Kwanil; Ahn, Yeong Hwan; Ahn, Kwang Jun; Hong, Byung Hee; Park, Ji-Yong; Rotermund, Fabian; Yeom, Dong-Il

    2015-01-01

    Active manipulation of light in optical fibres has been extensively studied with great interest because of its compatibility with diverse fibre-optic systems. While graphene exhibits a strong electro-optic effect originating from its gapless Dirac-fermionic band structure, electric control of all-fibre graphene devices remains still highly challenging. Here we report electrically manipulable in-line graphene devices by integrating graphene-based field effect transistors on a side-polished fibre. Ion liquid used in the present work critically acts both as an efficient gating medium with wide electrochemical windows and transparent over-cladding facilitating light-matter interaction. Combined study of unique features in gate-variable electrical transport and optical transition at monolayer and randomly stacked multilayer graphene reveals that the device exhibits significant optical transmission change (>90%) with high efficiency-loss figure of merit. This subsequently modifies nonlinear saturable absorption characteristics of the device, enabling electrically tunable fibre laser at various operational regimes. The proposed device will open promising way for actively controlled optoelectronic and nonlinear photonic devices in all-fibre platform with greatly enhanced graphene-light interaction. PMID:25897687

  4. Active control of all-fibre graphene devices with electrical gating

    PubMed Central

    Lee, Eun Jung; Choi, Sun Young; Jeong, Hwanseong; Park, Nam Hun; Yim, Woongbin; Kim, Mi Hye; Park, Jae-Ku; Son, Suyeon; Bae, Sukang; Kim, Sang Jin; Lee, Kwanil; Ahn, Yeong Hwan; Ahn, Kwang Jun; Hong, Byung Hee; Park, Ji-Yong; Rotermund, Fabian; Yeom, Dong-Il

    2015-01-01

    Active manipulation of light in optical fibres has been extensively studied with great interest because of its compatibility with diverse fibre-optic systems. While graphene exhibits a strong electro-optic effect originating from its gapless Dirac-fermionic band structure, electric control of all-fibre graphene devices remains still highly challenging. Here we report electrically manipulable in-line graphene devices by integrating graphene-based field effect transistors on a side-polished fibre. Ion liquid used in the present work critically acts both as an efficient gating medium with wide electrochemical windows and transparent over-cladding facilitating light–matter interaction. Combined study of unique features in gate-variable electrical transport and optical transition at monolayer and randomly stacked multilayer graphene reveals that the device exhibits significant optical transmission change (>90%) with high efficiency-loss figure of merit. This subsequently modifies nonlinear saturable absorption characteristics of the device, enabling electrically tunable fibre laser at various operational regimes. The proposed device will open promising way for actively controlled optoelectronic and nonlinear photonic devices in all-fibre platform with greatly enhanced graphene–light interaction. PMID:25897687

  5. Semi-active control of helicopter vibration using controllable stiffness and damping devices

    NASA Astrophysics Data System (ADS)

    Anusonti-Inthra, Phuriwat

    Semi-active concepts for helicopter vibration reduction are developed and evaluated in this dissertation. Semi-active devices, controllable stiffness devices or controllable orifice dampers, are introduced; (i) in the blade root region (rotor-based concept) and (ii) between the rotor and the fuselage as semi-active isolators (in the non-rotating frame). Corresponding semi-active controllers for helicopter vibration reduction are also developed. The effectiveness of the rotor-based semi-active vibration reduction concept (using stiffness and damping variation) is demonstrated for a 4-bladed hingeless rotor helicopter in moderate- to high-speed forward flight. A sensitivity study shows that the stiffness variation of root element can reduce hub vibrations when proper amplitude and phase are used. Furthermore, the optimal semi-active control scheme can determine the combination of stiffness variations that produce significant vibration reduction in all components of vibratory hub loads simultaneously. It is demonstrated that desired cyclic variations in properties of the blade root region can be practically achieved using discrete controllable stiffness devices and controllable dampers, especially in the flap and lag directions. These discrete controllable devices can produce 35--50% reduction in a composite vibration index representing all components of vibratory hub loads. No detrimental increases are observed in the lower harmonics of blade loads and blade response (which contribute to the dynamic stresses) and controllable device internal loads, when the optimal stiffness and damping variations are introduced. The effectiveness of optimal stiffness and damping variations in reducing hub vibration is retained over a range of cruise speeds and for variations in fundamental rotor properties. The effectiveness of the semi-active isolator is demonstrated for a simplified single degree of freedom system representing the semi-active isolation system. The rotor

  6. Stall inception and the prospects for active control in four high-speed compressors

    SciTech Connect

    Day, I.J.; Breuer, T.; Escuret, J.; Cherrett, M.; Wilson, A.

    1999-01-01

    As part of a European collaborative project, four high-speed compressors were tested to investigate the generic features of stall inception in aero-engine type compressors. Tests were run over the full speed range to identify the design and operating parameters that influence the stalling process. A study of data analysis techniques was also conducted in the hope of establishing early warning of stall. The work presented here is intended to relate the physical happenings in the compressor to the signals that would be received by an active stall control system. The measurements show a surprising range of stall-related disturbances and suggest that spike-type stall inception is a feature of low-speed operation while modal activity is clearest in the midspeed range. High-frequency disturbances were detected at both ends of the speed range and nonrotating stall, a new phenomenon, was detected in three out of the four compressors. The variety of the stalling patterns, and the ineffectiveness of the stall warning procedures, suggests that the ultimate goal of a flightworthy active control system remains some way off.

  7. In-flight simulation of high agility through active control: Taming complexity by design

    NASA Technical Reports Server (NTRS)

    Padfield, Gareth D.; Bradley, Roy

    1993-01-01

    The motivation for research into helicopter agility stems from the realization that marked improvements relative to current operational types are possible, yet there is a dearth of useful criteria for flying qualities at high performance levels. Several research laboratories are currently investing resources in developing second generation airborne rotorcraft simulators. The UK's focus has been the exploitation of agility through active control technology (ACT); this paper reviews the results of studies conducted to date. The conflict between safety and performance in flight research is highlighted and the various forms of safety net to protect against system failures are described. The role of the safety pilot, and the use of actuator and flight envelope limiting are discussed. It is argued that the deep complexity of a research ACT system can only be tamed through a requirement specification assembled using design principles and cast in an operational simulation form. Work along these lines conducted at DRA is described, including the use of the Jackson System Development method and associated Ada simulation.

  8. Improved training of neural networks for the nonlinear active control of sound and vibration.

    PubMed

    Bouchard, M; Paillard, B; Le Dinh, C T

    1999-01-01

    Active control of sound and vibration has been the subject of a lot of research in recent years, and examples of applications are now numerous. However, few practical implementations of nonlinear active controllers have been realized. Nonlinear active controllers may be required in cases where the actuators used in active control systems exhibit nonlinear characteristics, or in cases when the structure to be controlled exhibits a nonlinear behavior. A multilayer perceptron neural-network based control structure was previously introduced as a nonlinear active controller, with a training algorithm based on an extended backpropagation scheme. This paper introduces new heuristical training algorithms for the same neural-network control structure. The objective is to develop new algorithms with faster convergence speed (by using nonlinear recursive-least-squares algorithms) and/or lower computational loads (by using an alternative approach to compute the instantaneous gradient of the cost function). Experimental results of active sound control using a nonlinear actuator with linear and nonlinear controllers are presented. The results show that some of the new algorithms can greatly improve the learning rate of the neural-network control structure, and that for the considered experimental setup a neural-network controller can outperform linear controllers. PMID:18252535

  9. Vehicle design considerations for active control application to subsonic transport aircraft

    NASA Technical Reports Server (NTRS)

    Hofmann, L. G.; Clement, W. F.

    1974-01-01

    The state of the art in active control technology is summarized. How current design criteria and airworthiness regulations might restrict application of this emerging technology to subsonic CTOL transports of the 1980's are discussed. Facets of active control technology considered are: (1) augmentation of relaxed inherent stability; (2) center-of-gravity control; (3) ride quality control; (4) load control; (5) flutter control; (6) envelope limiting, and (7) pilot interface with the control system. A summary and appraisal of the current state of the art, design criteria, and recommended practices, as well as a projection of the risk in applying each of these facets of active control technology is given. A summary of pertinent literature and technical expansions is included.

  10. Synthesis of active controls for flutter suppression on a flight research wing

    NASA Technical Reports Server (NTRS)

    Abel, I.; Perry, B., III; Murrow, H. N.

    1977-01-01

    This paper describes some activities associated with the preliminary design of an active control system for flutter suppression capable of demonstrating a 20% increase in flutter velocity. Results from two control system synthesis techniques are given. One technique uses classical control theory, and the other uses an 'aerodynamic energy method' where control surface rates or displacements are minimized. Analytical methods used to synthesize the control systems and evaluate their performance are described. Some aspects of a program for flight testing the active control system are also given. This program, called DAST (Drones for Aerodynamics and Structural Testing), employs modified drone-type vehicles for flight assessments and validation testing.

  11. Current and Future Research in Active Control of Lightweight, Flexible Structures Using the X-56 Aircraft

    NASA Technical Reports Server (NTRS)

    Ryan, John J.; Bosworth, John T.; Burken, John J.; Suh, Peter M.

    2014-01-01

    The X-56 Multi-Utility Technology Testbed aircraft system is a versatile experimental research flight platform. The system was primarily designed to investigate active control of lightweight flexible structures, but is reconfigurable and capable of hosting a wide breadth of research. Current research includes flight experimentation of a Lockheed Martin designed active control flutter suppression system. Future research plans continue experimentation with alternative control systems, explore the use of novel sensor systems, and experiments with the use of novel control effectors. This paper describes the aircraft system, current research efforts designed around the system, and future planned research efforts that will be hosted on the aircraft system.

  12. Ultrafast active control of localized surface plasmon resonances in silicon bowtie antennas.

    PubMed

    Berrier, Audrey; Ulbricht, Ronald; Bonn, Mischa; Rivas, Jaime Gómez

    2010-10-25

    Localized surface plasmon polaritons (LSPPs) provide an efficient means of achieving extreme light concentration. In recent years, their active control has become a major aspiration of plasmonic research. Here, we demonstrate direct control of semiconductor bowtie antennas, enabling active excitation of LSPPs, at terahertz (THz) frequencies. We modify the LSPPs by ultrafast optical modulation of the free carrier density in the plasmonic structure itself, allowing for active control of the semiconductor antennas on picosecond timescales. Moreover, this control enables the manipulation of the field intensity enhancements in ranges of four orders of magnitude. PMID:21164664

  13. Development of weight and cost estimates for lifting surfaces with active controls

    NASA Technical Reports Server (NTRS)

    Anderson, R. D.; Flora, C. C.; Nelson, R. M.; Raymond, E. T.; Vincent, J. H.

    1976-01-01

    Equations and methodology were developed for estimating the weight and cost incrementals due to active controls added to the wing and horizontal tail of a subsonic transport airplane. The methods are sufficiently generalized to be suitable for preliminary design. Supporting methodology and input specifications for the weight and cost equations are provided. The weight and cost equations are structured to be flexible in terms of the active control technology (ACT) flight control system specification. In order to present a self-contained package, methodology is also presented for generating ACT flight control system characteristics for the weight and cost equations. Use of the methodology is illustrated.

  14. Active Control of Sound Field Using State-Space Model and Feedback Control Theory: a Numerical Simulation.

    NASA Astrophysics Data System (ADS)

    Wu, Zhen

    Active sound filed control techniques have received growing attention since they provide alternative solutions to low-frequency sound control, where the conventional passive methods have not been very successful. They have wide industrial and military applications such as noise reduction, room acoustics design, acoustic measurements, underwater acoustic camouflage, etc. An appropriate model of an acoustical system serves as the basis of control law synthesis and active control system design. A classical system model describes the dynamics of an acoustic system in a view of input/output relation through transfer functions. On the other hand, a time-domain based state-space model equivalently describes the system dynamics in terms of internal system variables and provides a direct physical insight of active control of sound. Furthermore, based on a state-space model, one can take advantage of modern control analysis and synthesis tools to design an optimal control system for broadband, global sound absorption. This thesis explores state-space feedback control in unbounded acoustic systems. State-space models are developed for unbounded one-dimensional acoustic systems using a finite-difference method with special boundary treatments. State feedback control algorithms including state estimations are developed using optimal control theory (LQG). Numerical simulation results of the closed-loop system responses demonstrate the optimal performance of active control systems considering the trade-off between the high reflection reduction and limited sensing/actuating power. Two numerical examples, an active underwater sound absorbing coating system, and an active noise control system in a duct, are studied. For the active underwater sound absorbing system, a feedback control system involving two sensors and one actuator is designed. Numerical simulation of the closed-loop response indicates a substantial and broadband reflection (echo) reduction for this design. A variety

  15. Active Control of Panel Vibrations Induced by a Boundary Layer Flow

    NASA Technical Reports Server (NTRS)

    Chow, Pao-Liu

    1998-01-01

    In recent years, active and passive control of sound and vibration in aeroelastic structures have received a great deal of attention due to many potential applications to aerospace and other industries. There exists a great deal of research work done in this area. Recent advances in the control of sound and vibration can be found in the several conference proceedings. In this report we will summarize our research findings supported by the NASA grant NAG-1-1175. The problems of active and passive control of sound and vibration has been investigated by many researchers for a number of years. However, few of the articles are concerned with the sound and vibration with flow-structure interaction. Experimental and numerical studies on the coupling between panel vibration and acoustic radiation due to flow excitation have been done by Maestrello and his associates at NASA/Langley Research Center. Since the coupled system of nonlinear partial differential equations is formidable, an analytical solution to the full problem seems impossible. For this reason, we have to simplify the problem to that of the nonlinear panel vibration induced by a uniform flow or a boundary-layer flow with a given wall pressure distribution. Based on this simplified model, we have been able to study the control and stabilization of the nonlinear panel vibration, which have not been treated satisfactorily by other authors. The vibration suppression will clearly reduce the sound radiation power from the panel. The major research findings will be presented in the next three sections. In Section II we shall describe our results on the boundary control of nonlinear panel vibration, with or without flow excitation. Section III is concerned with active control of the vibration and sound radiation from a nonlinear elastic panel. A detailed description of our work on the parametric vibrational control of nonlinear elastic panel will be presented in Section IV. This paper will be submitted to the Journal

  16. Active control of Boundary Layer Separation & Flow Distortion in Adverse Pressure Gradient Flows via Supersonic Microjets

    NASA Technical Reports Server (NTRS)

    Alvi, Farrukh S.; Gorton, Susan (Technical Monitor)

    2005-01-01

    Inlets to aircraft propulsion systems must supply flow to the compressor with minimal pressure loss, flow distortion or unsteadiness. Flow separation in internal flows such as inlets and ducts in aircraft propulsion systems and external flows such as over aircraft wings, is undesirable as it reduces the overall system performance. The aim of this research has been to understand the nature of separation and more importantly, to explore techniques to actively control this flow separation. In particular, the use of supersonic microjets as a means of controlling boundary layer separation was explored. The geometry used for the early part of this study was a simple diverging Stratford ramp, equipped with arrays of supersonic microjets. Initial results, based on the mean surface pressure distribution, surface flow visualization and Planar Laser Scattering (PLS) indicated a reverse flow region. We implemented supersonic microjets to control this separation and flow visualization results appeared to suggest that microjets have a favorable effect, at least to a certain extent. However, the details of the separated flow field were difficult to determine based on surface pressure distribution, surface flow patterns and PLS alone. It was also difficult to clearly determine the exact influence of the supersonic microjets on this flow. In the latter part of this study, the properties of this flow-field and the effect of supersonic microjets on its behavior were investigated in further detail using 2-component (planar) Particle Image Velocimetry (PIV). The results clearly show that the activation of microjets eliminated flow separation and resulted in a significant increase in the momentum of the fluid near the ramp surface. Also notable is the fact that the gain in momentum due to the elimination of flow separation is at least an order of magnitude larger (two orders of magnitude larger in most cases) than the momentum injected by the microjets and is accomplished with very

  17. a New Active Control Strategy for Wind-Turbine Blades Under Off-Design Conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Ri-Kui; Wu, Jie-Zhi; Chen, Shi-Yi

    A new active control strategy for wind-turbine blades under off-design conditions has been investigated in this paper. According to our previous work, in comparison with the traditional straight leading-edge blade, a new kind of bionic blades with a sinusoidal leading edge can significantly enhance the turbine's power output at high speed inflows. However, the wavy leading-edge shape is unfavorable under the design operating conditions since an early boundary-layer separation is inevitable for a wind-turbine blade because of the geometric disturbances of the leading-edge tubercles. But for the present active control, the deflect in wavy leading-edge blades can be eliminated by introducing a series of small flat delta wings as the control units, since delta wings can also generate powerful leading-edge vortices. As a preliminary test, our numerical results show that, the shaft-torque fluctuation in the turbine's stall region can be improved from 27.8% for a straight leading-edge blade (no control) to 8.9% for the present active control; and by adjusting the control parameters, the control units nearly have not any negative effect on the blade's shaft torque under the design conditions. We believe that, as an auxiliary tool of the conventional control strategies, the present active control approach may be favorable to generate a more stable and more controllable power output for wind turbines under all operating conditions (even in the yawed inflows).

  18. An electronic control for an electrohydraulic active control landing gear for the F-4 aircraft

    NASA Technical Reports Server (NTRS)

    Ross, I.

    1982-01-01

    A controller for an electrohydraulic active control landing gear was developed for the F-4 aircraft. A controller was modified for this application. Simulation results indicate that during landing and rollout over repaired bomb craters the active gear effects a force reduction, relative to the passive gear, or approximately 70%.

  19. Integrated Application of Active Controls (IAAC) Technology to an Advanced Subsonic Transport: Project Plan

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The state of the art of active controls technology (ACT) and a recommended ACT development program plan are reviewed. The performance benefits and cost of ownership of an integrated application of ACT to civil transport aircraft is to be assessed along with the risk and laboratory and/or flight experiments designed to reduce the technical risks to a commercially acceptable level.

  20. Improvements to the FATOLA computer program including added actively controlled landing gear subroutines

    NASA Technical Reports Server (NTRS)

    Mall, G. H.

    1983-01-01

    Modifications to a multi-degree-of-freedom flexible aircraft take-off and landing analysis (FATOLA) computer program, including a provision for actively controlled landing gears to expand the programs simulation capabilities, are presented. Supplemental instructions for preparation of data and for use of the modified program are included.

  1. Stochastic optimal semi-active control of hysteretic systems by using a magneto-rheological damper

    NASA Astrophysics Data System (ADS)

    Cheng, H.; Zhu, W. Q.; Ying, Z. G.

    2006-06-01

    A stochastic optimal semi-active control strategy for stochastically excited hysteretic systems by using a magneto-rheological (MR) damper is proposed. The dynamics of both the hysteretic system and the MR damper is characterized by using the Bouc-Wen hysteretic model. The control force produced by the damper is split into a passive part and a semi-active part. The passive part is combined with the uncontrolled system to form a passively controlled system. Then the system is converted into an equivalent nonlinear non-hysteretic stochastic system, from which a partially averaged Itô stochastic differential equation is derived by using the stochastic averaging method of the energy envelope. For the ergodic control problem, a dynamical programming equation is established based on the stochastic dynamical programming principle and solved to yield the optimal semi-active control law. The fully averaged Itô equation is obtained by substituting the optimal semi-active control force into the partially averaged Itô equation and completing the averaging. Finally, the response of the semi-actively controlled system is obtained from solving the Fokker-Planck-Kolmogorov equation associated with the fully averaged Itô equation. The efficacy of the proposed control strategy is illustrated by the numerical results and comparison with clipped LQG control for an example.

  2. Active controls for flutter suppression and gust alleviation in supersonic aircraft. [YF-17 flutter model

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1980-01-01

    Results of work done on active controls on the modified YF-17 flutter model are summarized. The basic derivation of a suitable control law is discussed. It is shown that discrepencies found between analysis and wind tunnel tests originate from the lack of proper implementation of the desired control law. Program capabilities are described.

  3. Vibration reduction in helicopter rotors using an actively controlled partial span trailing edge flap located on the blade

    NASA Technical Reports Server (NTRS)

    Millott, T. A.; Friedmann, P. P.

    1994-01-01

    This report describes an analytical study of vibration reduction in a four-bladed helicopter rotor using an actively controlled, partial span, trailing edge flap located on the blade. The vibration reduction produced by the actively controlled flap (ACF) is compared with that obtained using individual blade control (IBC), in which the entire blade is oscillated in pitch. For both cases a deterministic feedback controller is implemented to reduce the 4/rev hub loads. For all cases considered, the ACF produced vibration reduction comparable with that obtained using IBC, but consumed only 10-30% of the power required to implement IBC. A careful parametric study is conducted to determine the influence of blade torsional stiffness, spanwise location of the control flap, and hinge moment correction on the vibration reduction characteristics of the ACF. The results clearly demonstrate the feasibility of this new approach to vibration reduction. It should be emphasized than the ACF, used together with a conventional swashplate, is completely decoupled from the primary flight control system and thus it has no influence on the airworthiness of the helicopter. This attribute is potentially a significant advantage when compared to IBC.

  4. Handling qualities of a wide-body transport airplane utilizing Pitch Active Control Systems (PACS) for relaxed static stability application

    NASA Technical Reports Server (NTRS)

    Grantham, William D.; Person, Lee H., Jr.; Brown, Philip W.; Becker, Lawrence E.; Hunt, George E.; Rising, J. J.; Davis, W. J.; Willey, C. S.; Weaver, W. A.; Cokeley, R.

    1985-01-01

    Piloted simulation studies have been conducted to evaluate the effectiveness of two pitch active control systems (PACS) on the flying qualities of a wide-body transport airplane when operating at negative static margins. These two pitch active control systems consisted of a simple 'near-term' PACS and a more complex 'advanced' PACS. Eight different flight conditions, representing the entire flight envelope, were evaluated with emphasis on the cruise flight conditions. These studies were made utilizing the Langley Visual/Motion Simulator (VMS) which has six degrees of freedom. The simulation tests indicated that (1) the flying qualities of the baseline aircraft (PACS off) for the cruise and other high-speed flight conditions were unacceptable at center-of-gravity positions aft of the neutral static stability point; (2) within the linear static stability flight envelope, the near-term PACS provided acceptable flying qualities for static stabilty margins to -3 percent; and (3) with the advanced PACS operative, the flying qualities were demonstrated to be good (satisfactory to very acceptable) for static stabilty margins to -20 percent.

  5. On the numerical simulation of flutter and its suppression by active control

    SciTech Connect

    Dong, B.; Mook, D.T.

    1994-12-31

    The classic problem of predicting the motion (flutter) of a rigid airfoil mounted on an elastic support in a steady freestream is revisited. In the classic approach, the equations of motion were linearized, the supports were linear springs, the motion was assumed to be periodic, the aerodynamic loads were predicted by Wagner`s function, and the solution was obtained in the so-called frequency domain. In the present approach, the equations of motion are in their fully nonlinear form, the supports may be nonlinear springs, the motion is not assumed to be periodic, the loads are predicted by a general unsteady vorticity-panel method, and the solution is obtained in the so-called time domain. After it is demonstrated that the present approach predicts the onset of flutter and the post-flutter behavior for flat-plate as well as thick airfoils, the airfoil -is modified by the addition of a flap at the trailing edge. The flap is part of an actively controlled servomechanism, and it is demonstrated that flutter can be readily controlled with very little effort by a variety of feedback-control laws. In the present approach, emphasis is placed on considering the airfoil, its supports, the flowing air and the control/servo mechanism collectively to be a single dynamic system. All the equations of motion and control laws are solved simultaneously and interactively; thus, complete interactions among the various subsystems are captured. The present simulation of an oscillating airfoil provides some characteristics of the flutter phenomenon that were missed in previous studies: for example, it is shown that, in the absence of flaps, the motion in heave (the translational part of the motion) is responsible for adding energy to (exciting) the structural subsystem while the motion in pitch is responsible for extracting energy from (damping) the structural subsystem. Below the critical speed, there is more dissipation than excitation and hence all initial disturbances decay.

  6. Active Control of Cell Size Generates Spatial Detail during Plant Organogenesis

    PubMed Central

    Serrano-Mislata, Antonio; Schiessl, Katharina; Sablowski, Robert

    2015-01-01

    Summary How cells regulate their dimensions is a long-standing question [1, 2]. In fission and budding yeast, cell-cycle progression depends on cell size, although it is still unclear how size is assessed [3, 4, 5]. In animals, it has been suggested that cell size is modulated primarily by the balance of external signals controlling growth and the cell cycle [1], although there is evidence of cell-autonomous control in cell cultures [6, 7, 8, 9]. Regardless of whether regulation is external or cell autonomous, the role of cell-size control in the development of multicellular organisms remains unclear. Plants are a convenient system to study this question: the shoot meristem, which continuously provides new cells to form new organs, maintains a population of actively dividing and characteristically small cells for extended periods [10]. Here, we used live imaging and quantitative, 4D image analysis to measure the sources of cell-size variability in the meristem and then used these measurements in computer simulations to show that the uniform cell sizes seen in the meristem likely require coordinated control of cell growth and cell cycle in individual cells. A genetically induced transient increase in cell size was quickly corrected by more frequent cell division, showing that the cell cycle was adjusted to maintain cell-size homeostasis. Genetically altered cell sizes had little effect on tissue growth but perturbed the establishment of organ boundaries and the emergence of organ primordia. We conclude that meristem cells actively control their sizes to achieve the resolution required to pattern small-scale structures. PMID:26526374

  7. Active control of acoustic field-of-view in a biosonar system.

    PubMed

    Yovel, Yossi; Falk, Ben; Moss, Cynthia F; Ulanovsky, Nachum

    2011-09-01

    Active-sensing systems abound in nature, but little is known about systematic strategies that are used by these systems to scan the environment. Here, we addressed this question by studying echolocating bats, animals that have the ability to point their biosonar beam to a confined region of space. We trained Egyptian fruit bats to land on a target, under conditions of varying levels of environmental complexity, and measured their echolocation and flight behavior. The bats modulated the intensity of their biosonar emissions, and the spatial region they sampled, in a task-dependant manner. We report here that Egyptian fruit bats selectively change the emission intensity and the angle between the beam axes of sequentially emitted clicks, according to the distance to the target, and depending on the level of environmental complexity. In so doing, they effectively adjusted the spatial sector sampled by a pair of clicks-the "field-of-view." We suggest that the exact point within the beam that is directed towards an object (e.g., the beam's peak, maximal slope, etc.) is influenced by three competing task demands: detection, localization, and angular scanning-where the third factor is modulated by field-of-view. Our results suggest that lingual echolocation (based on tongue clicks) is in fact much more sophisticated than previously believed. They also reveal a new parameter under active control in animal sonar-the angle between consecutive beams. Our findings suggest that acoustic scanning of space by mammals is highly flexible and modulated much more selectively than previously recognized. PMID:21931535

  8. Performance-based semi-active control algorithm for protecting base isolated buildings from near-fault earthquakes

    NASA Astrophysics Data System (ADS)

    Mehrparvar, Behnam; Khoshnoudian, Taramarz

    2012-03-01

    Base isolated structures have been found to be at risk in near-fault regions as a result of long period pulses that may exist in near-source ground motions. Various control strategies, including passive, active and semi-active control systems, have been investigated to overcome this problem. This study focuses on the development of a semi-active control algorithm based on several performance levels anticipated from an isolated building during different levels of ground shaking corresponding to various earthquake hazard levels. The proposed performance-based algorithm is based on a modified version of the well-known semi-active skyhook control algorithm. The proposed control algorithm changes the control gain depending on the level of shaking imposed on the structure. The proposed control system has been evaluated using a series of analyses performed on a base isolated benchmark building subjected to seven pairs of scaled ground motion records. Simulation results show that the newly proposed algorithm is effective in improving the structural and nonstructural performance of the building for selected earthquakes.

  9. Analytical design and evaluation of an active control system for helicopter vibration reduction and gust response alleviation

    NASA Technical Reports Server (NTRS)

    Taylor, R. B.; Zwicke, P. E.; Gold, P.; Miao, W.

    1980-01-01

    An analytical study was conducted to define the basic configuration of an active control system for helicopter vibration and gust response alleviation. The study culminated in a control system design which has two separate systems: narrow band loop for vibration reduction and wider band loop for gust response alleviation. The narrow band vibration loop utilizes the standard swashplate control configuration to input controller for the vibration loop is based on adaptive optimal control theory and is designed to adapt to any flight condition including maneuvers and transients. The prime characteristics of the vibration control system is its real time capability. The gust alleviation control system studied consists of optimal sampled data feedback gains together with an optimal one-step-ahead prediction. The prediction permits the estimation of the gust disturbance which can then be used to minimize the gust effects on the helicopter.

  10. Optimal finite-element-based design of actively controlled smart composite structures under uncertainties

    NASA Astrophysics Data System (ADS)

    Orisamolu, Irewole R.; Koko, Tamunoiyala S.; Akpan, Unyime O.; Smith, Malcolm J.

    1998-07-01

    This paper presents a novel integrated formulation and robust computational tool that can be efficiently employed for the design and analysis of actively controlled smart composite structural systems. The modeling simulation capabilities account for the coupling between thermal, mechanical and electric fields within the framework of an integrated structure/control strategy. The paper also reports the formulation and implementation of an optimization capability for the design and tailoring of smart structural systems. Finally, probabilistic and fuzzy models for rationally and systematically accounting for the uncertainties in structural, control, material, and load parameters are presented. The capabilities are packaged in a comprehensive and user- friendly software system (SMARTCOM) that can be readily applied for cost-effective design or response characterization of actively controlled smart structures.

  11. Active control of static pressure drop caused by hydraulic servo-actuator engage

    SciTech Connect

    Janlovic, J.

    1994-12-31

    Pressure drop caused by propagation of expansion waves in the source pipeline of fast high cyclic hydraulic actuator produces possible anomalies in its function. To prevent pressure drop it is possible to minimize wave effects by active control of actuator servo-valve throttle leakage. In the paper is presented synthesis of possible discrete active control of hydraulic actuator and its servo-valve for prevention expansion wave pressure drop. Control synthesis is based on static pressure increasing with decreasing of fluid flow velocity, which can be realized by lower throttle leakage. Some of the effects of assumed control are shown on corresponding diagrams of control valve throttle motion, piston displacement and its corresponding linear velocity.

  12. Active Control of Airspring Secondary Suspension for Improving Ride Comfort in Presence of Random Track Irregularity

    NASA Astrophysics Data System (ADS)

    Alfi, Stefano; Bruni, Stefano; Gialleonardo, Egidio Di; Facchinetti, Alan

    The aim of this paper is to explore the possible benefits brought by the use of active control of the airspring secondary suspension for high speed railway vehicles; in this regard, active control is applied to reduce the vertical and pitch carbody oscillations in the low frequency range, according to the concept of skyhook damping. A concept is developed for the active airspring suspension, and a numerical model is derived for the vehicle equipped with the active suspension. The results obtained show that the use of active suspension control offers an important improvement of ride quality, by far larger than that achievable with semi-active suspensions. On the other hand, the issue of air consumption is outlined as a critical point of the proposed concept, requiring further research.

  13. Benefits assessment of active control technology and related cockpit technology for rotorcraft

    NASA Technical Reports Server (NTRS)

    Hampton, B. J.

    1982-01-01

    Two main-rotor active control concepts, one incorporating multicyclic actuators located just below the swashplate, and the other providing for the actuators and power supplies to be located in the rotating frame are considered. Each design concept is integrated with cockpit controllers and displays appropriate to the actuation concept in each case. The benefits of applying the defined ACT/RCT concepts to rotorcraft are quantified by comparison to the baseline model 412 helicopter. These benefits include, in the case of one active control concept; (1) up to 91% reduction in 4/rev hub shears; (2) a flight safety failure rate of 1.96 x 10 to the 8th power failures per flight-hour; (3) rotating controls/rotor hub drag reduction of 40%; (4) a 9% reduction in control system weight; and (5) vibratory deicing. The related cockpit concept reduces pilot workload for critical mission segments as much as 178% visual and 25% manual.

  14. Mixed Tracking and Projective Synchronization of 5D Hyperchaotic System Using Active Control

    NASA Astrophysics Data System (ADS)

    Ojo, Kayode; Ogunjo, Samuel T.; Williams, Oluwafemi

    2013-08-01

    This paper examines mixed tracking control and hy- brid synchronization of two identical 5-D hyperchaotic Lorenz systems via active control technique. The de- signed control functions for the mixed tracking enable each of the system state variables to stabilize at differ- ent chosen positions as well as control each state vari- ables of the system to track different desired smooth function of time. Also, the active control technique is used to design control functions which achieve projec- tive synchronization between the slave state variables and the master state variables. We also show that the coupling strength is inversely proportional to the syn- chronization time. Numerical simulations are carried out to validate the effectiveness of the analytical tech- nique.

  15. Research on the Calculated Methods of Active Control Value for Antenna Panel Deformations under Gravity

    NASA Astrophysics Data System (ADS)

    Fu, L.; Zhong, W. Y.; Qiao, H. H.; Liu, G. X.; Qian, H. L.

    2015-07-01

    The methods of ideal reflector surface, two-parameter, five-parameter, and six-parameter best-fit paraboloid are presented in this paper. Based on these methods, the adjustment values of gravity deformations are calculated for the main reflector of large-scale Cassegrain antenna. Accordingly, the positions of subreflector are corrected, and the effects of offset-focus on electric performance are also analyzed. Taking Shanghai 65 m antenna as a research object, the adjustment values of actuator and hexapod, the accuracy of the main reflector surface, and the pointing error after offsetting the focus are contrasted. As a result, the method of six-parameter best-fit paraboloid is ideal to calculate active control value for antenna panels after the effects of feed defocus have been adjusted and modified. The results offer data for the active control of antenna.

  16. ACFA 2020 - An FP7 project on active control of flexible fuel efficient aircraft configurations

    NASA Astrophysics Data System (ADS)

    Maier, R.

    2013-12-01

    This paper gives an overview about the project ACFA 2020 which is funded by the European Commission within the 7th framework program. The acronym ACFA 2020 stands for Active Control for Flexible Aircraft 2020. The project is dealing with the design of highly fuel efficient aircraft configurations and, in particular, on innovative active control concepts with the goal to reduce loads and structural weight. Major focus lays on blended wing body (BWB) aircraft. Blended wing body type aircraft configurations are seen as the most promising future concept to fulfill the so-called ACARE (Advisory Council for Aeronautics Research in Europe) vision 2020 goals in regards to reduce fuel consumption and external noise. The paper discusses in some detail the overall goals and how they are addressed in the workplan. Furthermore, the major achievements of the project are outlined and a short outlook on the remaining work is given.

  17. Dynamics and control of multipayload platforms - The Middeck Active Control Experiment (MACE)

    NASA Technical Reports Server (NTRS)

    Miller, David W.; Crawley, Edward F.; De Luis, Javier

    1990-01-01

    A flight experiment entitled the Middeck Active Control Experiment (MACE) proposed by the Space Engineering Research Center (SERC) at the Massachusetts Institute of Technology is described. The objective of this program is to investigate and validate the modeling of the dynamics of an actively controlled flexible, articulating, multibody platform free floating in zero gravity. A rationale and experimental approach for the program are presented. The rationale shows that on-orbit testing, coupled with ground testing and a strong analytical program, is necessary in order to fully understand both how flexibility of the platform affects the pointing problem, as well as how gravity perturbs this structural flexibility causing deviations between 1-and 0-gravity behavior. The experimental approach captures the essential physics of multibody platforms, by identifying the appropriate attributes, tests, and performance metrics of the test article, and defines the tests required to successfully validate the analytical framework.

  18. Dynamics and control of multipayload platforms. The middeck active control experiment (MACE)

    NASA Astrophysics Data System (ADS)

    Miller, David W.; de Luis, Javier; Crawley, Edward F.

    A flight experiment entitled the Middeck Active Control Experiment (MACE) proposed by the Space Engineering Research Center (SERC) at the Massachusetts Institute of Technology is described. The objective of this program is to investigate and validate the modeling of the dynamics of an actively controlled flexible, articulating, multibody platform free floating in zero gravity. A rationale and experimental approach for the program are presented. The rationale shows that on-orbit testing, coupled with ground testing and a strong analytical program, is necessary in order to fully understand both how flexibility of the platform affects the pointing problem, as well as how gravity perturbs this structural flexibility causing deviations between 1-and 0-gravity behavior. The experimental approach captures the essential physics of multibody platforms, by identifying the appropriate attributes, tests, and performance metrics of the test article, and defines the tests required to successfully validate the analytical framework.

  19. An electric control for an electrohydraulic active control aircraft landing gear

    NASA Technical Reports Server (NTRS)

    Ross, I.; Edson, R.

    1979-01-01

    An electronic controller for an electrohydraulic active control aircraft landing gear was developed. Drop tests of a modified gear from a 2722 Kg (6000 lbm) class of airplane were conducted to illustrate controller performance. The results indicate that the active gear effects a force reduction, relative to that of the passive gear, from 9 to 31 percent depending on the aircraft sink speed and the static gear pressure.

  20. A Digital Program for Calculating the Interaction Between Flexible Structures, Unsteady Aerodynamics and Active Controls

    NASA Technical Reports Server (NTRS)

    Peele, E. L.; Adams, W. M., Jr.

    1979-01-01

    A computer program, ISAC, is described which calculates the stability and response of a flexible airplane equipped with active controls. The equations of motion relative to a fixed inertial coordinate system are formulated in terms of the airplane's rigid body motion and its unrestrained normal vibration modes. Unsteady aerodynamic forces are derived from a doublet lattice lifting surface theory. The theoretical basis for the program is briefly explained together with a description of input data and output results.

  1. Selected advanced aerodynamics and active controls technology concepts development on a derivative B-747 aircraft

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Analytical design and wind tunnel test evaluations covering the feasibility of applying wing tip extensions, winglets, and active control wing had alleviation to the model B747 are described. Aerodynamic improvement offered by wing tip extension and winglet individually, and the combined aerodynamic and weight improvements when wing load alleviation is combined with the tip extension or the winglet are evaluated. Results are presented in the form of incremental effects on weight mission range, fuel usage, cost, and airline operating economics.

  2. Active control of a 30 m ring interferometric telescope primary mirror.

    PubMed

    Dai, Yichun; Liu, Zhong; Jin, Zhenyu; Xu, Jun; Lin, Jing

    2009-02-01

    The active control of a primary mirror for a ring aperture segmented telescope is different from that of a full aperture segmented telescope. Two active maintenance proposals for the ring telescope designed from the segmented patterns are outlined. We present a preliminary calculation of noise propagation and analysis of primary mirror mode characteristics for each proposal. The modulation transfer functions (MTFs) of the primary mirror corresponding to each maintenance method at several typical working wavelengths are also simulated. PMID:19183591

  3. Control law design to meet constraints using SYNPAC-synthesis package for active controls

    NASA Technical Reports Server (NTRS)

    Adams, W. M., Jr.; Tiffany, S. H.

    1982-01-01

    Major features of SYNPAC (Synthesis Package for Active Controls) are described. SYNPAC employs constrained optimization techniques which allow explicit inclusion of design criteria (constraints) in the control law design process. Interrelationships are indicated between this constrained optimization approach, classical and linear quadratic Gaussian design techniques. Results are presented that were obtained by applying SYNPAC to the design of a combined stability augmentation/gust load alleviation control law for the DAST ARW-2.

  4. Experimental Active Control of Automotive Disc Brake Rotor Squeal Using Dither

    NASA Astrophysics Data System (ADS)

    CUNEFARE, K. A.; GRAF, A. J.

    2002-02-01

    This paper presents an experimental investigation into the application of “dither” control for the active control and suppression of automobile disc brake squeal. Dither control is characterized by the application of a control effort at a frequency higher than the disturbance to be controlled. In the particular system considered here, a vibro-acoustic analysis of a disc brake system during squeal determined the acoustic squeal signature to be emanating from the brake rotor. This squeal was eliminated, and could even be prevented from occurring, through the application of a harmonic force with a frequency higher than the squeal frequency. The harmonic force was generated by a stack of piezoelectric elements placed within the brake's caliper piston. The harmonic force represented a small variation about the mean clamping force exerted by the brake upon the rotor. The high-frequency vibration in the brake system due to the action of the control system was not heard if an ultrasonic control frequency was used. More importantly, the active control system is shown to be able to prevent squeal from even occurring. This gives rise to a possible active control system integrated into the brake system of automobiles to prevent squeal.

  5. Semi-active control of floor isolation system using MR-damper

    NASA Astrophysics Data System (ADS)

    Lin, Pei-Yang; Loh, Chin-Hsiung

    2008-03-01

    This paper presents the performance evaluation of a semi-active controlled floor isolation system for earthquake reduction. The floor isolation system consists of a rolling pendulum system and a semi-active controlled MR damper. The modified Bouc-Wen model is used to represent the behavior of the MR damper. A serious of performance test of the MR damper is made and been used for system identification. Two contrasting control methods including LQR with continuous-optimal control and Fuzzy Logic control are experimentally investigated as potential algorithms and comparisons are made from the results. Unlike the clipped-optimal control, LQR with continuous-optimal control can output the continuous command voltage to control the MR damper, and get smoother control effect. A three-story steel structure with the floor isolation system on the 2nd floor is tested on the shake table. Scaled historical near- and far-field seismic records are employed to examine controller performance with respect to frequency content and PGA level. Experimental results show that both control algorithms can suppress the acceleration of the isolated floor during small and large PGA levels, and alleviate both displacement and acceleration simultaneously in larger, near-field events. Both control algorithms are adaptive and robust to various intensity of excitation. This investigation demonstrates the feasibility and capabilities of a smart semi-active controlled floor-isolation system.

  6. Active Control of the Forced and Transient Response of a Finite Beam. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Post, John Theodore

    1989-01-01

    When studying structural vibrations resulting from a concentrated source, many structures may be modelled as a finite beam excited by a point source. The theoretical limit on cancelling the resulting beam vibrations by utilizing another point source as an active controller is explored. Three different types of excitation are considered, harmonic, random, and transient. In each case, a cost function is defined and minimized for numerous parameter variations. For the case of harmonic excitation, the cost function is obtained by integrating the mean squared displacement over a region of the beam in which control is desired. A controller is then found to minimize this cost function in the control interval. The control interval and controller location are continuously varied for several frequencies of excitation. The results show that control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam, but control over a subregion may be obtained even between resonant frequencies at the cost of increasing the vibration outside of the control region. For random excitation, the cost function is realized by integrating the expected value of the displacement squared over the interval of the beam in which control is desired. This is shown to yield the identical cost function as obtained by integrating the cost function for harmonic excitation over all excitation frequencies. As a result, it is always possible to reduce the cost function for random excitation whether controlling the entire beam or just a subregion, without ever increasing the vibration outside the region in which control is desired. The last type of excitation considered is a single, transient pulse. A cost function representative of the beam vibration is obtained by integrating the transient displacement squared over a region of the beam and over all time. The form of the controller is chosen a priori as either one or two delayed pulses. Delays

  7. Use of active control systems to improve bending and rotor flapping response of a tilt rotor VTOL airplane

    NASA Technical Reports Server (NTRS)

    Whitaker, H. P.; Cheng, Y.

    1975-01-01

    The results are summarized of an analytical study of the use of active control systems for the purpose of reducing the root mean square response of wing vertical bending and rotor flapping to atmospheric turbulence for a tilt-rotor VTOL airplane. Only the wing/rotor assembly was considered so that results of a wind tunnel test program would be applicable in a subsequent phase of the research. The capabilities and limitations of simple single feedback configurations were identified, and the most promising multiloop feedback configurations were then investigated. Design parameters were selected so as to minimize either wing bending or rotor flapping response. Within the constraints imposed by practical levels of feedback gains and complexity and by considerations of safety, reduction in response due to turbulence of the order of 30 to 50 percent is predicted using the rotor longitudinal cyclic and a trailing edge wing flap as control effectors.

  8. Active control of residual tool marks for freeform optics functionalization by novel biaxial servo assisted fly cutting.

    PubMed

    Zhu, Zhiwei; To, Suet; Zhang, Shaojian

    2015-09-01

    The inherent residual tool marks (RTM) with particular patterns highly affect optical functions of the generated freeform optics in fast tool servo or slow tool servo (FTS/STS) diamond turning. In the present study, a novel biaxial servo assisted fly cutting (BSFC) method is developed for flexible control of the RTM to be a functional micro/nanotexture in freeform optics generation, which is generally hard to achieve in FTS/STS diamond turning. In the BSFC system, biaxial servo motions along the z-axis and side-feeding directions are mainly adopted for primary surface generation and RTM control, respectively. Active control of the RTM from the two aspects, namely, undesired effect elimination or effective functionalization, are experimentally demonstrated by fabricating a typical F-theta freeform surface with scattering homogenization and two functional microstructures with imposition of secondary phase gratings integrating both reflective and diffractive functions. PMID:26368889

  9. Mindfulness Training Alters Emotional Memory Recall Compared to Active Controls: Support for an Emotional Information Processing Model of Mindfulness

    PubMed Central

    Roberts-Wolfe, Douglas; Sacchet, Matthew D.; Hastings, Elizabeth; Roth, Harold; Britton, Willoughby

    2012-01-01

    Objectives: While mindfulness-based interventions have received widespread application in both clinical and non-clinical populations, the mechanism by which mindfulness meditation improves well-being remains elusive. One possibility is that mindfulness training alters the processing of emotional information, similar to prevailing cognitive models of depression and anxiety. The aim of this study was to investigate the effects of mindfulness training on emotional information processing (i.e., memory) biases in relation to both clinical symptomatology and well-being in comparison to active control conditions. Methods: Fifty-eight university students (28 female, age = 20.1 ± 2.7 years) participated in either a 12-week course containing a “meditation laboratory” or an active control course with similar content or experiential practice laboratory format (music). Participants completed an emotional word recall task and self-report questionnaires of well-being and clinical symptoms before and after the 12-week course. Results: Meditators showed greater increases in positive word recall compared to controls [F(1, 56) = 6.6, p = 0.02]. The meditation group increased significantly more on measures of well-being [F(1, 56) = 6.6, p = 0.01], with a marginal decrease in depression and anxiety [F(1, 56) = 3.0, p = 0.09] compared to controls. Increased positive word recall was associated with increased psychological well-being (r = 0.31, p = 0.02) and decreased clinical symptoms (r = −0.29, p = 0.03). Conclusion: Mindfulness training was associated with greater improvements in processing efficiency for positively valenced stimuli than active control conditions. This change in emotional information processing was associated with improvements in psychological well-being and less depression and anxiety. These data suggest that mindfulness training may improve well-being via changes in emotional information processing. Future

  10. A randomized controlled trial comparing the effects of yoga to an active control on ambulatory blood pressure in individuals with Pre- and Stage 1 Hypertension

    PubMed Central

    Hagins, Marshall; Rundle, Andrew; Consedine, Nathan S.; Khalsa, Sat Bir S.

    2013-01-01

    The purpose of this study was to compare the effects of yoga to an active control (non-aerobic exercise) in individuals with pre- and Stage 1 hypertension. A randomized clinical trial was performed using two arms: 1) yoga and 2) active control. Primary outcomes were 24-hour, day and night ambulatory systolic and diastolic blood pressures. Within-group and between-group analyses were performed using paired t-tests and repeated measures ANOVAs (time x group), respectively. Eighty-four participants enrolled with 68 participants completing the trial. Within-group analyses found 24-hour diastolic, night diastolic, and mean arterial pressure all significantly reduced in the yoga group (−3.93, −4.7, −4.23 mmHg, respectively) but no significant within-group changes in the active control group. Direct comparisons of the yoga intervention to the control group found a single blood pressure variable (diastolic night) to be significantly different (p =.038). This study has demonstrated that a yoga intervention can lower blood pressure in patients with mild hypertension. Although this study was not adequately powered to show between-group differences, the size of the yoga-induced blood pressure reduction we observed appears to justify performing a definitive trial of this intervention to test whether it can provide meaningful therapeutic value for the management of hypertension. PMID:24387700

  11. A randomized controlled trial comparing the effects of yoga with an active control on ambulatory blood pressure in individuals with prehypertension and stage 1 hypertension.

    PubMed

    Hagins, Marshall; Rundle, Andrew; Consedine, Nathan S; Khalsa, Sat Bir S

    2014-01-01

    The purpose of this study was to compare the effects of yoga with an active control (nonaerobic exercise) in individuals with prehypertension and stage 1 hypertension. A randomized clinical trial was performed using two arms: (1) yoga and (2) active control. Primary outcomes were 24-hour day and night ambulatory systolic and diastolic blood pressures. Within-group and between-group analyses were performed using paired t tests and repeated-measures analysis of variance (time × group), respectively. Eighty-four participants enrolled, with 68 participants completing the trial. Within-group analyses found 24-hour diastolic, night diastolic, and mean arterial pressure all significantly reduced in the yoga group (-3.93, -4.7, -4.23 mm Hg, respectively) but no significant within-group changes in the active control group. Direct comparisons of the yoga intervention with the control group found a single blood pressure variable (diastolic night) to be significantly different (P=.038). This study has demonstrated that a yoga intervention can lower blood pressure in patients with mild hypertension. Although this study was not adequately powered to show between-group differences, the size of the yoga-induced blood pressure reduction appears to justify performing a definitive trial of this intervention to test whether it can provide meaningful therapeutic value for the management of hypertension. PMID:24387700

  12. Biologically-inspired robust and adaptive multi-sensor fusion and active control

    NASA Astrophysics Data System (ADS)

    Khosla, Deepak; Dow, Paul A.; Huber, David J.

    2009-04-01

    In this paper, we describe a method and system for robust and efficient goal-oriented active control of a machine (e.g., robot) based on processing, hierarchical spatial understanding, representation and memory of multimodal sensory inputs. This work assumes that a high-level plan or goal is known a priori or is provided by an operator interface, which translates into an overall perceptual processing strategy for the machine. Its analogy to the human brain is the download of plans and decisions from the pre-frontal cortex into various perceptual working memories as a perceptual plan that then guides the sensory data collection and processing. For example, a goal might be to look for specific colored objects in a scene while also looking for specific sound sources. This paper combines three key ideas and methods into a single closed-loop active control system. (1) Use high-level plan or goal to determine and prioritize spatial locations or waypoints (targets) in multimodal sensory space; (2) collect/store information about these spatial locations at the appropriate hierarchy and representation in a spatial working memory. This includes invariant learning of these spatial representations and how to convert between them; and (3) execute actions based on ordered retrieval of these spatial locations from hierarchical spatial working memory and using the "right" level of representation that can efficiently translate into motor actions. In its most specific form, the active control is described for a vision system (such as a pantilt- zoom camera system mounted on a robotic head and neck unit) which finds and then fixates on high saliency visual objects. We also describe the approach where the goal is to turn towards and sequentially foveate on salient multimodal cues that include both visual and auditory inputs.

  13. a Stochastic Optimal Semi-Active Control Strategy for Er/mr Dampers

    NASA Astrophysics Data System (ADS)

    Ying, Z. G.; Zhu, W. Q.; Soong, T. T.

    2003-01-01

    A stochastic optimal semi-active control strategy for randomly excited systems using electrorheological/magnetorheological (ER/MR) dampers is proposed. A system excited by random loading and controlled by using ER/MR dampers is modelled as a controlled, stochastically excited and dissipated Hamiltonian system with n degrees of freedom. The control forces produced by ER/MR dampers are split into a passive part and an active part. The passive control force is further split into a conservative part and a dissipative part, which are combined with the conservative force and dissipative force of the uncontrolled system, respectively, to form a new Hamiltonian and an overall passive dissipative force. The stochastic averaging method for quasi-Hamiltonian systems is applied to the modified system to obtain partially completed averaged Itô stochastic differential equations. Then, the stochastic dynamical programming principle is applied to the partially averaged Itô equations to establish a dynamical programming equation. The optimal control law is obtained from minimizing the dynamical programming equation subject to the constraints of ER/MR damping forces, and the fully completed averaged Itô equations are obtained from the partially completed averaged Itô equations by replacing the control forces with the optimal control forces and by averaging the terms involving the control forces. Finally, the response of semi-actively controlled system is obtained from solving the final dynamical programming equation and the Fokker-Planck-Kolmogorov equation associated with the fully completed averaged Itô equations of the system. Two examples are given to illustrate the application and effectiveness of the proposed stochastic optimal semi-active control strategy.

  14. Development of a microcontrolled bioinstrumentation system for active control of leg prostheses.

    PubMed

    Delis, Alberto Lopez; da Rocha, Adson Ferreira; Dos Santos, Icaro; Sene, Iwens Gervasio; Salomoni, Sauro; Borges, Geovany Araujo

    2008-01-01

    This article describes the design of a microcontrolled bioinstrumentation system for active control of leg prostheses, using 4-channel electromyographic signal (EMG) detection and a single-channel electrogoniometer. The system is part of a control and instrumentation architecture in which a master processor controls the tasks of slave microcontrollers, through a RS-485 interface. Several signal processing methods are integrated in the system, for feature extraction (Recursive Least Squares), feature projection (Self Organizing Maps), and pattern classification (Levenberg-Marquardt Neural Network). The acquisition of EMG signals and additional mechanical information could help improving the precision in the control of leg prostheses. PMID:19163184

  15. Multilayer Active Control For Structural Damping And Optical-Path Regulation

    NASA Technical Reports Server (NTRS)

    Rahman, Zahidul H.; Spanos, John T.; Fanson, James L.

    1995-01-01

    Two active-control concepts incorporated into system for suppression of vibrations in truss structure and regulation of length of optical path on structure to nanometer level. Optical-path-length-control subsystem contains two feedback control loops to obtain active damping in wide amplitude-and-frequency range. Concept described in more detail in number of previous articles, including "Stabilizing Optical-Path Length on a Vibrating Structure" (NPO-19040), "Controllable Optical Delay Line for Stellar Interferometry" (NPO-18686), "Test Bed for Control of Optical-Path Lengths" (NPO-18487).

  16. Multichannel active control of nonlinear noise processes using diagonal structure bilinear FXLMS algorithm

    NASA Astrophysics Data System (ADS)

    Chen, Dong; Yuan, Ding; Li, Tan; Sidan, Du

    2015-12-01

    A novel nonlinear adaptive algorithm named as diagonal structure bilinear filtered-x least mean square (DBFXLMS) for multichannel nonlinear active noise control is proposed in this paper. The performances of the proposed algorithm are shown below and the computational complexity is compared with the second-order Volterra filtered-x LMS (VFXLMS) algorithm and the filtered-s least mean square (FSLMS) algorithm, in terms of normalized mean square error (NMSE), for multichannel active control of nonlinear noise processes. Both the simulations and the computational complexity analyses demonstrate that the proposed method has an improvement as compared to the proposed algorithms.

  17. An active control logic to improve the fatigue strength of smart flexible structures

    NASA Astrophysics Data System (ADS)

    Ambrosio, Pasquale; Braghin, Francesco; Resta, Ferruccio; Ripamonti, Francesco

    2013-04-01

    In general active vibration control intrinsically implies a fatigue damage reduction. Anyway, this assumption is not always verified. In these cases it is possible to deeper investigate the fatigue phenomena on smart flexible structures and their reduction from a control point of view. In this article, to identify the problem main parameters, a simplified interpretation of fatigue damage is given using the frequency analysis framework. Then, the active control logic is defined as an optimization problem with a quadratic functional taking into account the previously cited parameters. Finally, because of non-linearity of fatigue phenomenon, an adaptive approach is applied and a numerical/experimental validation is carried out.

  18. Active control synthesis for flexible space structures excited by persistent disturbances

    NASA Technical Reports Server (NTRS)

    Wie, Bong; Gonzalez, Marcelo

    1990-01-01

    Both classical and state-space synthesis methods for active control of flexible space structures in the presence of persistent disturbances are presented. The methods exploit the so-called internal model principle for asymptotic disturbance rejection. A generic example of flexible space structures is used to illustrate the simplicity of the proposed design methodologies. The concept of a disturbance rejection filter dipole is introduced from a classical control viewpoint. It is shown that the proposed design methods will invariably make use of non-minimum-phase compensation for a class of noncolocated control problems. The need for tradeoffs between performance and parameter robustness is discussed.

  19. Modeling the Benchmark Active Control Technology Wind-Tunnel Model for Application to Flutter Suppression

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R.

    1996-01-01

    This paper describes the formulation of a model of the dynamic behavior of the Benchmark Active Controls Technology (BACT) wind-tunnel model for application to design and analysis of flutter suppression controllers. The model is formed by combining the equations of motion for the BACT wind-tunnel model with actuator models and a model of wind-tunnel turbulence. The primary focus of this paper is the development of the equations of motion from first principles using Lagrange's equations and the principle of virtual work. A numerical form of the model is generated using values for parameters obtained from both experiment and analysis. A unique aspect of the BACT wind-tunnel model is that it has upper- and lower-surface spoilers for active control. Comparisons with experimental frequency responses and other data show excellent agreement and suggest that simple coefficient-based aerodynamics are sufficient to accurately characterize the aeroelastic response of the BACT wind-tunnel model. The equations of motion developed herein have been used to assist the design and analysis of a number of flutter suppression controllers that have been successfully implemented.

  20. Semi-active control of a sandwich beam partially filled with magnetorheological elastomer

    NASA Astrophysics Data System (ADS)

    Dyniewicz, Bartłomiej; Bajkowski, Jacek M.; Bajer, Czesław I.

    2015-08-01

    The paper deals with the semi-active control of vibrations of structural elements. Elastomer composites with ferromagnetic particles that act as magnetorheological fluids are used. The damping coefficient and the shear modulus of the elastomer increases when it is exposed to an electro-magnetic field. The control of this process in time allows us to reduce vibrations more effectively than if the elastomer is permanently exposed to a magnetic field. First the analytical solution for the vibrations of a sandwich beam filled with an elastomer is given. Then the control problem is defined and applied to the analytical formula. The numerical solution of the minimization problem results in a periodic, perfectly rectangular control function if free vibrations are considered. Such a temporarily acting magnetic field is more efficient than a constantly acting one. The surplus reaches 20-50% or more, depending on the filling ratio of the elastomer. The resulting control was verified experimentally in the vibrations of a cantilever sandwich beam. The proposed semi-active control can be directly applied to engineering vibrating structural elements, for example helicopter rotors, aircraft wings, pads under machines, and vehicles.

  1. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Program review

    NASA Technical Reports Server (NTRS)

    1986-01-01

    This report summarizes the Integrated Application of Active Controls (IAAC) Technology to an Advanced Subsonic Transport Project, established as one element of the NASA/Boeing Energy Efficient Transport Technology Program. The performance assessment showed that incorporating ACT into an airplane designed to fly approximately 200 passengers approximately 2,000 nmi could yield block fuel savings from 6 to 10 percent at the design range. The principal risks associated with incorporating these active control functions into a commercial airplane are those involved with the ACT system implementation. The Test and Evaluation phase of the IAAC Project focused on the design, fabrication, and test of a system that implemented pitch axis fly-by-wire, pitch axis augmentation, and wing load alleviation. The system was built to be flight worthy, and was planned to be experimentally flown on the 757. The system was installed in the Boeing Digital Avionics Flight Controls Laboratory (DAFCL), where open loop hardware and software tests, and a brief examination of a direct drive valve (DDV) actuation concept were accomplished. The IAAC Project has shown that ACT can be beneficially incorporated into a commercial transport airplane. Based on the results achieved during the testing phase, there appears to be no fundamental reason(s) that would preclude the commercial application of ACT, assuming an appropriate development effort is included.

  2. The MODE family of on-orbit experiments: The Middeck Active Control Experiment (MACE)

    NASA Technical Reports Server (NTRS)

    Crawley, Edward F.; Miller, David W.; Deluis, Javier; Waldman, Mel; Bicos, Andy

    1990-01-01

    A flight experiment entitled the Middeck Active Control Experiment (MACE), proposed by the Space Engineering Research Center (SERC) at the Massachusetts Institute of Technology, is described. This is the second in a family of flight experiments being developed at MIT. The first is the Middeck 0-Gravity Dynamics Experiment (MODE) which investigates the nonlinear behavior of contained fluids and truss structures in zero gravity. The objective of the MACE program is to investigate and validate the modeling of the dynamics of an actively controlled flexible, articulating, multibody platform free floating in zero gravity. A rationale and experimental approach for the program are presented. The rationale shows that on-orbit testing, coupled with ground testing and a strong analytical program, is necessary in order to fully understand both how flexibility of the platform affects the pointing problem, as well as how gravity perturbs this structural flexibility causing deviations between 1- and 0-gravity behavior. The experimental approach captures the essential physics of multibody platforms, by identifying the appropriate attributes, tests, and performance metrics of the test article and defines the tests required to successfully validate the analytical framework.

  3. The MODE family of on-orbit experiments: The Middeck Active Control Experiment (MACE)

    NASA Astrophysics Data System (ADS)

    Crawley, Edward F.; Miller, David W.; Deluis, Javier; Waldman, Mel; Bicos, Andy

    1990-12-01

    A flight experiment entitled the Middeck Active Control Experiment (MACE), proposed by the Space Engineering Research Center (SERC) at the Massachusetts Institute of Technology, is described. This is the second in a family of flight experiments being developed at MIT. The first is the Middeck 0-Gravity Dynamics Experiment (MODE) which investigates the nonlinear behavior of contained fluids and truss structures in zero gravity. The objective of the MACE program is to investigate and validate the modeling of the dynamics of an actively controlled flexible, articulating, multibody platform free floating in zero gravity. A rationale and experimental approach for the program are presented. The rationale shows that on-orbit testing, coupled with ground testing and a strong analytical program, is necessary in order to fully understand both how flexibility of the platform affects the pointing problem, as well as how gravity perturbs this structural flexibility causing deviations between 1- and 0-gravity behavior. The experimental approach captures the essential physics of multibody platforms, by identifying the appropriate attributes, tests, and performance metrics of the test article and defines the tests required to successfully validate the analytical framework.

  4. A Randomized Controlled Pilot Trial of Classroom-Based Mindfulness Meditation Compared to an Active Control Condition in 6th Grade Children

    PubMed Central

    Britton, Willoughby B.; Lepp, Nathaniel E.; Niles, Halsey F.; Rocha, Tomas; Fisher, Nathan; Gold, Jonathan

    2014-01-01

    Children in the United States are at risk for numerous psychological problems, such as anxiety, attention problems, and mood disorders, and are underserved by current mental health provisions. The current study is a pilot trial to examine the effects of a nonelective, classroom-based, teacher-implemented, mindfulness meditation intervention on standard clinical measures of mental health and affect in middle school children. A total of 101 healthy sixth-grade students (55 boys and 46 girls) were randomized to either an Asian history course with daily mindfulness meditation practice (intervention group) or an African history course with a matched experiential activity (active control group). Self-reported data was collected by administering the Youth Self Report (YSR), a modified Spielberger State-Trait Anxiety Inventory, and the Cognitive and Affective Mindfulness Measure -Revised before and after 6 weeks of meditation or active control condition. Both meditators and active controls decreased significantly on the YSR Internalizing Problems, Externalizing Problems, and Attention Problems subscales but did not differ in the extent of their improvements. Both groups also showed comparable improvements on measures in affect. Meditators were significantly less likely to develop suicidal ideation or thoughts of self-harm than controls. Improvements in affect were correlated with increases in mindfulness in meditators but not controls. These results suggest that mindfulness training may yield both unique and nonspecific benefits that are shared by other novel activities. PMID:24930819

  5. Active Control of Inlet Noise on the JT15D Turbofan Engine

    NASA Technical Reports Server (NTRS)

    Smith, Jerome P.; Hutcheson, Florence V.; Burdisso, Ricardo A.; Fuller, Chris R.

    1999-01-01

    This report presents the key results obtained by the Vibration and Acoustics Laboratories at Virginia Tech over the year from November 1997 to December 1998 on the Active Noise Control of Turbofan Engines research project funded by NASA Langley Research Center. The concept of implementing active noise control techniques with fuselage-mounted error sensors is investigated both analytically and experimentally. The analytical part of the project involves the continued development of an advanced modeling technique to provide prediction and design guidelines for application of active noise control techniques to large, realistic high bypass engines of the type on which active control methods are expected to be applied. Results from the advanced analytical model are presented that show the effectiveness of the control strategies, and the analytical results presented for fuselage error sensors show good agreement with the experimentally observed results and provide additional insight into the control phenomena. Additional analytical results are presented for active noise control used in conjunction with a wavenumber sensing technique. The experimental work is carried out on a running JT15D turbofan jet engine in a test stand at Virginia Tech. The control strategy used in these tests was the feedforward Filtered-X LMS algorithm. The control inputs were supplied by single and multiple circumferential arrays of acoustic sources equipped with neodymium iron cobalt magnets mounted upstream of the fan. The reference signal was obtained from an inlet mounted eddy current probe. The error signals were obtained from a number of pressure transducers flush-mounted in a simulated fuselage section mounted in the engine test cell. The active control methods are investigated when implemented with the control sources embedded within the acoustically absorptive material on a passively-lined inlet. The experimental results show that the combination of active control techniques with fuselage

  6. An overview of possible and not-so-possible tasks for active control of sound and vibration

    NASA Astrophysics Data System (ADS)

    von Flotow, Andreas H.

    1991-05-01

    While such passive approaches to helicopter sound and vibration control as vibration isolation/acoustic blocking, damping/acoustic absorption, and tuned absorbers, can be actively implemented and enhanced, active control methods transcend these possibilities. A survey is presently conducted of the literature generated by active-control research in recent years, with a view to emerging opportunities that do not risk instability, excessive development and production costs, and undue complexity.

  7. Weak-light solitons and their active control in a parity-time-symmetric atomic system

    NASA Astrophysics Data System (ADS)

    Hang, Chao; Huang, Guoxiang

    2015-04-01

    We propose a realistic physical scheme to produce one-dimensional and two-dimensional weak-light solitons in an atomic system with PT symmetry. The system we suggest is a cold three-level atomic gas with two species and is driven by control and probe laser fields. We show that by the interference of two Raman resonances a highly adjustable probe-field refractive index with PT symmetry in one and two dimensions can be realized. We further show that it is possible to produce various light solitons when the weak nonlinearity of the probe field is taken into account. Due to the resonant character of the system, the light solitons obtained in one and two dimensions have extremely low light power (at the level of nanowatts). In addition, we demonstrate that the stability of these light solitons can be actively controlled via PT phase transition of the system.

  8. A universal setup for active control of a single-photon detector

    NASA Astrophysics Data System (ADS)

    Liu, Qin; Lamas-Linares, Antía; Kurtsiefer, Christian; Skaar, Johannes; Makarov, Vadim; Gerhardt, Ilja

    2014-01-01

    The influence of bright light on a single-photon detector has been described in a number of recent publications. The impact on quantum key distribution (QKD) is important, and several hacking experiments have been tailored to fully control single-photon detectors. Special attention has been given to avoid introducing further errors into a QKD system. We describe the design and technical details of an apparatus which allows to attack a quantum-cryptographic connection. This device is capable of controlling free-space and fiber-based systems and of minimizing unwanted clicks in the system. With different control diagrams, we are able to achieve a different level of control. The control was initially targeted to the systems using BB84 protocol, with polarization encoding and basis switching using beamsplitters, but could be extended to other types of systems. We further outline how to characterize the quality of active control of single-photon detectors.

  9. Active control of thermoacoustic amplification in a thermo-acousto-electric engine

    NASA Astrophysics Data System (ADS)

    Olivier, Come; Penelet, Guillaume; Poignand, Gaelle; Lotton, Pierrick

    2014-05-01

    In this paper, a new approach is proposed to control the operation of a thermoacoustic Stirling electricity generator. This control basically consists in adding an additional acoustic source to the device, connected through a feedback loop to a reference microphone, a phase-shifter, and an audio amplifier. Experiments are performed to characterize the impact of the feedback loop (and especially that of the controlled phase-shift) on the overall efficiency of the thermal to electric energy conversion performed by the engine. It is demonstrated that this external forcing of thermoacoustic self-sustained oscillations strongly impacts the performance of the engine, and that it is possible under some circumstances to improve the efficiency of the thermo-electric transduction, compared to the one reached without active control. Applicability and further directions of investigation are also discussed.

  10. Development of selected advanced aerodynamics and active control concepts for commercial transport aircraft

    NASA Technical Reports Server (NTRS)

    Taylor, A. B.

    1984-01-01

    Work done under the Energy Efficient Transport project in the field of advanced aerodynamics and active controls is summarized. The project task selections focused on the following: the investigation of long-duct nacelle shape variation on interference drag; the investigation of the adequacy of a simple control law for the elastic modes of a wing; the development of the aerodynamic technology at cruise and low speed of high-aspect-ratio supercritical wings of high performance; and the development of winglets for a second-generation jet transport. All the tasks involved analysis and substantial wind tunnel testing. The winglet program also included flight evaluation. It is considered that the technology base has been built for the application of high-aspect-ratio supercritical wings and for the use of winglets on second-generation transports.

  11. Control and switching synchronization of fractional order chaotic systems using active control technique.

    PubMed

    Radwan, A G; Moaddy, K; Salama, K N; Momani, S; Hashim, I

    2014-01-01

    This paper discusses the continuous effect of the fractional order parameter of the Lü system where the system response starts stable, passing by chaotic behavior then reaching periodic response as the fractional-order increases. In addition, this paper presents the concept of synchronization of different fractional order chaotic systems using active control technique. Four different synchronization cases are introduced based on the switching parameters. Also, the static and dynamic synchronizations can be obtained when the switching parameters are functions of time. The nonstandard finite difference method is used for the numerical solution of the fractional order master and slave systems. Many numeric simulations are presented to validate the concept for different fractional order parameters. PMID:25685479

  12. Large segmented UV-optical space telescope using a Hybrid Sensor Active Control (HSAC) architecture

    NASA Astrophysics Data System (ADS)

    Feinberg, Lee D.; Dean, Bruce; Hyde, Tupper; Oegerle, Bill; Bolcar, Matthew R.; Smith, J. Scott

    2009-08-01

    Future large UV-optical space telescopes offer new and exciting windows of scientific parameter space. These telescopes can be placed at L2 and borrow heavily from the James Webb Space Telescope (JWST) heritage. For example, they can have similar deployment schemes, hexagonal mirrors, and use Wavefront Sensing and Control (WFSC) technologies developed for JWST. However, a UV-optical telescope requires a 4x improvement in wavefront quality over JWST to be diffraction-limited at 500 nm. Achieving this tolerance would be difficult using a passive thermal architecture such as the one employed on JWST. To solve this problem, our team has developed a novel Hybrid Sensor Active Control (HSAC) architecture that provides a cost effective approach to building a segmented UV-optical space telescope. In this paper, we show the application of this architecture to the ST-2020 mission concept and summarize the technology development requirements.

  13. Modified independent modal space control method for active control of flexible systems

    NASA Technical Reports Server (NTRS)

    Baz, A.; Poh, S.

    1987-01-01

    A modified independent modal space control (MIMSC) method is developed for designing active vibration control systems for large flexible structures. The method accounts for the interaction between the controlled and residual modes. It incorporates also optimal placement procedures for selecting the optimal locations of the actuators in the structure in order to minimize the structural vibrations as well as the actuation energy. The MIMSC method relies on an important feature which is based on time sharing of a small number of actuators, in the modal space, to control effectively a large number of modes. Numerical examples are presented to illustrate the application of the method to generic flexible systems. The results obtained suggest the potential of the devised method in designing efficient active control systems for large flexible structures.

  14. A universal setup for active control of a single-photon detector

    SciTech Connect

    Liu, Qin; Skaar, Johannes; Lamas-Linares, Antía; Kurtsiefer, Christian; Makarov, Vadim; Gerhardt, Ilja

    2014-01-15

    The influence of bright light on a single-photon detector has been described in a number of recent publications. The impact on quantum key distribution (QKD) is important, and several hacking experiments have been tailored to fully control single-photon detectors. Special attention has been given to avoid introducing further errors into a QKD system. We describe the design and technical details of an apparatus which allows to attack a quantum-cryptographic connection. This device is capable of controlling free-space and fiber-based systems and of minimizing unwanted clicks in the system. With different control diagrams, we are able to achieve a different level of control. The control was initially targeted to the systems using BB84 protocol, with polarization encoding and basis switching using beamsplitters, but could be extended to other types of systems. We further outline how to characterize the quality of active control of single-photon detectors.

  15. A universal setup for active control of a single-photon detector.

    PubMed

    Liu, Qin; Lamas-Linares, Antía; Kurtsiefer, Christian; Skaar, Johannes; Makarov, Vadim; Gerhardt, Ilja

    2014-01-01

    The influence of bright light on a single-photon detector has been described in a number of recent publications. The impact on quantum key distribution (QKD) is important, and several hacking experiments have been tailored to fully control single-photon detectors. Special attention has been given to avoid introducing further errors into a QKD system. We describe the design and technical details of an apparatus which allows to attack a quantum-cryptographic connection. This device is capable of controlling free-space and fiber-based systems and of minimizing unwanted clicks in the system. With different control diagrams, we are able to achieve a different level of control. The control was initially targeted to the systems using BB84 protocol, with polarization encoding and basis switching using beamsplitters, but could be extended to other types of systems. We further outline how to characterize the quality of active control of single-photon detectors. PMID:24517746

  16. Motion-base simulator results of advanced supersonic transport handling qualities with active controls

    NASA Technical Reports Server (NTRS)

    Feather, J. B.; Joshi, D. S.

    1981-01-01

    Handling qualities of the unaugmented advanced supersonic transport (AST) are deficient in the low-speed, landing approach regime. Consequently, improvement in handling with active control augmentation systems has been achieved using implicit model-following techniques. Extensive fixed-based simulator evaluations were used to validate these systems prior to tests with full motion and visual capabilities on a six-axis motion-base simulator (MBS). These tests compared the handling qualities of the unaugmented AST with several augmented configurations to ascertain the effectiveness of these systems. Cooper-Harper ratings, tracking errors, and control activity data from the MBS tests have been analyzed statistically. The results show the fully augmented AST handling qualities have been improved to an acceptable level.

  17. Development and flight evaluation of an augmented stability active controls concept with a small tail

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Parasite drag reduction evaluation is composed of wind tunnel tests with a standard L-1011 tail and two reduced area tail configurations. Trim drag reduction is evaluated by rebalancing the airplane for relaxed static stability. This is accomplished by pumping water to tanks in the forward and aft of the airplane to acheive desired center of gravity location. Also, the L-1011 is modified to incorporate term and advanced augmented systems. By using advanced wings and aircraft relaxed static stability significant fuel savings can be realized. An airplane's dynamic stability becomes more sensitive for decreased tail size, relaxed static stability, and advanced wing configurations. Active control pitch augmentation will be used to acheive the required handling qualities. Flight tests will be performed to evaluate the pitch augmentation systems. The effect of elevator downrig on stabilizer/elevator hinge moments will be measured. For control system analysis, the normal acceleration feedback and pitch rate feedback are analyzed.

  18. Extended flight evaluation of a near-term pitch active control system

    NASA Technical Reports Server (NTRS)

    Guinn, Wiley A.; Willey, Craig S.; Chong, Michael G.

    1983-01-01

    Fuel savings can be achieved by moving the center of gravity of an aircraft aft which reduces the static stability margin and consequently the trim drag. However, flying qualities of an aircraft with relaxed static stability can be significantly degraded. The flying qualities can be restored by using a pitch active control system (PACS). This report documents the work accomplished during a follow-on program (see NASA CR-165951 for initial program report) to perform extended flight tests of a near-term PACS. The program included flying qualities analyses, piloted flight simulation tests, aircraft preparation and flight tests to demonstrate that the near-term PACS provided good flying qualities within the linear static stability envelope to a negative 3% static stability margin.

  19. Robust controllers for the Middeck Active Control Experiment using Popov controller synthesis

    NASA Technical Reports Server (NTRS)

    How, Jonathan P.; Hall, Steven R.

    1993-01-01

    Recent work in robust control with real parameter uncertainties has focused on absolute stability and its connections to real mu theory. In particular, the research has investigated the Popov stability criterion and its associated Lur'e-Postnikov Liapunov functions. State space representations of this Popov stability analysis tests are included in an H2 design formulation to provide a powerful technique for robust controller synthesis. This synthesis approach uses a state space optimization procedure to design controllers that minimize an overbound of an H2 cost functional and satisfy stability analysis tests based on the Popov multiplier. The controller and stability multiplier coefficients are optimized simultaneously, which avoids the iteration and curve-fitting procedures required by the D-K algorithm of mu synthesis. While previous work has demonstrated this synthesis approach on benchmark control problems, the purpose of this paper is to use Popov controller synthesis to design robust compensators for the Middeck Active Control Experiment (MACE).

  20. Active control of bending vibrations in thick bars using PZT stack actuators

    SciTech Connect

    Redmond, J.; Parker, G.; Barney, P.; Rodeman, R.

    1995-07-01

    An experimental investigation into active control of bending vibrations in thick bar and plate-like structural elements is described. This work is motivated by vibration problems in machine tools and photolithography machines that require greater control authority than available from conventional surface mounted PZT patches or PVDF films. Focus of this experiment is a cantilevered circular steel bar in which PZT stacks are mounted in cutouts near the bar root. Axially aligned and offset from the neutral axis, these actuators control the bending vibrations by generating moments in the bar through their compressive loads. A Positive Feedback control law is used to significantly augment the damping in the first bending mode. Implications of the experimental results for machine tool stability enhancement are discussed.

  1. Active control of sound transmission/radiation from elastic plates by vibration inputs. II - Experiments

    NASA Technical Reports Server (NTRS)

    Metcalf, V. L.; Fuller, C. R.; Silcox, R. J.; Brown, D. E.

    1992-01-01

    Actively controlled harmonic force inputs were applied experimentally to reduce the sound transmitted through an elastic circular plate. The control implementation used a time domain least mean square adaptive algorithm with two error sensors. The control forces were applied directly to the plate by point force vibration inputs, while the error information and performance were measured in the radiated acoustic field by microphones. Test cases were also performed in which the error sensors were accelerometers mounted on the plate. When accelerometers were used as error sensors, the controller performance was degraded; leading to the conclusion that minimizing plate motion does not necessarily lead to an associated decrease in radiated sound levels. In contrast, the results show excellent attenuation of the transmitted sound field when microphone error sensors were used. This result was consistent over a range of frequencies. In addition, the experimental results are compared to previously derived analytical results and the effect of using a point or global minimization scheme is discussed.

  2. Active control of asymmetric conical flow using spinning and rotatory oscillations

    NASA Technical Reports Server (NTRS)

    Kandil, Osama A.; Sharaf El-Din, Hazem H.; Liu, C. H.

    1993-01-01

    The effectiveness of active control on asymmetric flows around circular cones is investigated computationally using cone spinning and rotatory oscillation around its axis. The investigation uses the time-accurate solution of the unsteady, compressible, full Navier-Stokes equations with the implicit, upwind, flux-difference splitting, finite-volume scheme. The present solutions are obtained under the locally-conical-flow assumption in order to understand the flow physics using very fine grids for reasonable flow resolution at low computational cost. For all the computational solutions, a grid of 241 x 81 x 2 points in the wrap-around, normal and axial directions, respectively, is used. The grid is spinning or oscillating rigidly with the cone according to its motion and the kinematical and dynamical boundary conditions are modified accordingly. The computational applications include the effects of uniform spinning rates and periodic rotatory oscillations at different amplitudes and frequencies on the flow asymmetry.

  3. Toward the Active Control of Heat Transfer in the Hot Gas Path of Gas Turbines

    NASA Technical Reports Server (NTRS)

    Oertling, Jeremiah E.

    2003-01-01

    The work at NASA this summer has focused on assisting the Professor's project, namely "Toward the Active Control of Heat Transfer in the Hot Gas Path of Gas Turbines." The mode of controlling the Heat Transfer that the project focuses on is film cooling. Film cooling is used in high temperature regions of a gas turbine and extends the life of the components exposed to these extreme temperatures. A "cool" jet of air is injected along the surface of the blade and this layer of cool air shields the blade from the high temperatures. Cool is a relative term. The hot gas path temperatures reach on the order of 1500 to 2000 K. The "coo" air is on the order of 700 to 1000 K. This cooler air is bled off of an appropriate compressor stage. The next parameter of interest is the jet s position and orientation in the flow-field.

  4. Application of active control landing gear technology to the A-10 aircraft

    NASA Technical Reports Server (NTRS)

    Ross, I.; Edson, R.

    1983-01-01

    Two concepts which reduce the A-10 aircraft's wing/gear interface forces as a result of applying active control technology to the main landing gear are described. In the first concept, referred to as the alternate concept a servovalve in a closed pressure control loop configuration effectively varies the size of the third stage spool valve orifice which is embedded in the strut. This action allows the internal energy in the strut to shunt hydraulic flow around the metering orifice. The command signal to the loop is reference strut pressure which is compared to the measured strut pressure, the difference being the loop error. Thus, the loop effectively varies the spool valve orifice size to maintain the strut pressure, and therefore minimizes the wing/gear interface force referenced.

  5. Active controls for flutter suppression and gust alleviation in supersonic aircraft

    NASA Technical Reports Server (NTRS)

    Nissim, E.; Lottati, I.

    1980-01-01

    Application is made in the present paper of the recently developed relaxed aerodynamic energy concept and synthesis techniques to the definition of appropriate active control systems for the low-speed flutter model of the B-2707-300 supersonic cruise airplane. The effectiveness of the resulting activated systems is analytically tested for flutter suppression, wing root bending moment alleviation, and ride control (fuselage accelerations). The results obtained indicate that considerable increase in flutter speeds can be obtained by the various control systems, using a single trailing-edge control. In all cases, the flutter suppression control system led to a substantial reduction in both wing root bending moments and in fuselage and wing accelerations.

  6. Active control for vibration suppression in a flexible beam using a modal domain optical fiber sensor

    NASA Technical Reports Server (NTRS)

    Cox, D. E.; Lindner, D. K.

    1991-01-01

    An account is given of the use of a modal-domain (MD) fiber-optic sensor as an active control system component for vibration suppression, whose output is proportional to the integral of the axial strain along the optical fiber. When an MD sensor is attached to, or embedded in, a flexible structure, it senses the strain in the structure along its gage length. On the basis of the present integration of the sensor model into a flexible-structure model, it becomes possible to design a control system with a dynamic compensator which adds damping to the low-order modes of the flexible structure. This modeling procedure has been experimentally validated.

  7. Neural Substrates Underlying the Passive Observation and Active Control of Translational Egomotion

    PubMed Central

    Chen, Ching-fu; Sereno, Martin I.

    2015-01-01

    Moving or static obstacles often get in the way while walking in daily life. Avoiding obstacles involves both perceptual processing of motion information and controlling appropriate defensive movements. Several higher-level motion areas, including the ventral intraparietal area (VIP), medial superior temporal area, parieto-insular vestibular cortex (PIVC), areas V6 and V6A, and cingulate sulcus visual area, have been identified in humans by passive viewing of optic flow patterns that simulate egomotion and object motion. However, the roles of these areas in the active control of egomotion in the real world remain unclear. Here, we used functional magnetic resonance imaging (fMRI) to map the neural substrates underlying the passive observation and active control of translational egomotion in humans. A wide-field virtual reality environment simulated a daily scenario where doors randomly swing outward while walking in a hallway. The stimuli of door-dodging events were essentially the same in two event-related fMRI experiments, which compared passive and active dodges in response to swinging doors. Passive dodges were controlled by a computer program, while active dodges were controlled by the subject. Passive dodges activated several higher-level areas distributed across three dorsal motion streams in the temporal, parietal, and cingulate cortex. Active dodges most strongly activated the temporal–vestibular stream, with peak activation located in the right PIVC. Other higher-level motion areas including VIP showed weaker to no activation in active dodges. These results suggest that PIVC plays an active role in sensing and guiding translational egomotion that moves an observer aside from impending obstacles. PMID:25762672

  8. Neural substrates underlying the passive observation and active control of translational egomotion.

    PubMed

    Huang, Ruey-Song; Chen, Ching-Fu; Sereno, Martin I

    2015-03-11

    Moving or static obstacles often get in the way while walking in daily life. Avoiding obstacles involves both perceptual processing of motion information and controlling appropriate defensive movements. Several higher-level motion areas, including the ventral intraparietal area (VIP), medial superior temporal area, parieto-insular vestibular cortex (PIVC), areas V6 and V6A, and cingulate sulcus visual area, have been identified in humans by passive viewing of optic flow patterns that simulate egomotion and object motion. However, the roles of these areas in the active control of egomotion in the real world remain unclear. Here, we used functional magnetic resonance imaging (fMRI) to map the neural substrates underlying the passive observation and active control of translational egomotion in humans. A wide-field virtual reality environment simulated a daily scenario where doors randomly swing outward while walking in a hallway. The stimuli of door-dodging events were essentially the same in two event-related fMRI experiments, which compared passive and active dodges in response to swinging doors. Passive dodges were controlled by a computer program, while active dodges were controlled by the subject. Passive dodges activated several higher-level areas distributed across three dorsal motion streams in the temporal, parietal, and cingulate cortex. Active dodges most strongly activated the temporal-vestibular stream, with peak activation located in the right PIVC. Other higher-level motion areas including VIP showed weaker to no activation in active dodges. These results suggest that PIVC plays an active role in sensing and guiding translational egomotion that moves an observer aside from impending obstacles. PMID:25762672

  9. Active Control of a Moving Noise SOURCE—EFFECT of Off-Axis Source Position

    NASA Astrophysics Data System (ADS)

    GUO, J.; PAN, J.; HODGSON, M.

    2002-03-01

    An optimally arranged multiple-channel active-control system is known to be able to create a large quiet zone in free space for a stationary primary noise source. When the primary noise source moves, the active control of the noise becomes much more difficult, as the primary noise field changes with time in space. In this case, the controller of the control system must respond fast enough to compensate for the change; much research has been focused on this issue. In this paper, it is shown that a moving source also causes difficulties from an acoustical perspective. A moving source not only changes continuously the strengths and phases of the sound field in the space, but also changes the wavefront of the primary sound field continuously. It is known that the efficiency of active noise control is determined mainly by the wavefront matching between the primary and control fields. To keep the control system effective in the case of a moving source, the wavefront of the control field needs to change, in order to continuously match the primary-wavefront change. This paper shows that there are limitations to the control-wavefront change. An optimally pre-arranged, multiple-channel control system is not able to construct a matching wavefront when the primary source moves outside a certain range. In other words, the control system is still able to create a large quiet zone only when the primary source moves within a range around the central axis of the control system. Both the location and the size of the quiet zone change with the location of the primary source.

  10. Cognitive-affective neural plasticity following active-controlled mindfulness intervention

    PubMed Central

    Allen, Micah; Dietz, Martin; Blair, Karina S.; van Beek, Martijn; Rees, Geraint; Vestergaard-Poulsen, Peter; Lutz, Antoine; Roepstorff, Andreas

    2015-01-01

    Mindfulness meditation is a set of attention-based, regulatory and self-inquiry training regimes. Although the impact of mindfulness meditation training (MT) on self-regulation is well established, the neural mechanisms supporting such plasticity are poorly understood. MT is thought to act on attention through interoceptive salience and attentional control mechanisms, but until now conflicting evidence from behavioral and neural measures has made it difficult to distinguish the role of these mechanisms. To resolve this question we conducted a fully randomized 6-week longitudinal trial of MT, explicitly controlling for cognitive and treatment effects with an active control group. We measured behavioral metacognition and whole-brain Blood Oxygenation Level Dependent (BOLD) signals using functional MRI during an affective Stroop task before and after intervention. Although both groups improved significantly on a response-inhibition task, only the MT group showed reduced affective Stroop conflict. Moreover, the MT group displayed greater dorsolateral prefrontal cortex (DLPFC) responses during executive processing, consistent with increased recruitment of top-down mechanisms to resolve conflict. In contrast, we did not observe overall group by time interactions on negative affect-related RTs or BOLD responses. However, only participants with the greatest amount of MT practice showed improvements in response-inhibition and increased recruitment of dorsal anterior cingulate cortex (dACC), medial prefrontal cortex (mPFC), and right anterior insula during negative valence processing. Collectively our findings highlight the importance of active control in MT research, and indicate unique neural mechanisms for progressive stages of mindfulness training. PMID:23115195

  11. TH-C-19A-02: Characterization of An Actively Controlled Graphite Probe Calorimeter

    SciTech Connect

    Renaud, J; Sarfehnia, A; Seuntjens, J

    2014-06-15

    Purpose: To construct and experimentally evaluate the performance of a miniature probe-format graphite calorimeter (GPC) with built-in active control. The GPC is the first ever calorimeter designed specifically for routine clinical use. Methods: The original GPC design, developed as part of our previous work, was modified to accommodate a micro-thin, resistive heating element and sensing thermistors embedded in the outermost graphite layer. A software-based process control loop was written to maintain a predefined set point temperature throughout the detector by precisely modulating the current flowing through the resistive element. Continuous feedback is provided to the controller by the additional thermistors. A functioning prototype was constructed in-house and operated in adiabatic mode in a 6 MV photon beam. Ten sets of measurements of varying duration (10 to 60 seconds) and repetition rate (200 to 600 MU/min) were analyzed. Reproducibility, linearity and dose rate dependence were assessed. Results: A total of 47 individual measurements were performed using the active GPC. The reproducibility, defined here as the sample standard deviation weighted across all 10 measurement sets, was found to be 0.37%. Similarly, the standard error (type A uncertainty) was 0.17%. Linearity was quantified by plotting signal as a function of monitor units delivered at 600 MU/min. The adjusted R-square of the resulting linear fit was 0.9996. Dose rate dependence, evaluated as the change in normalized response (signal/MU) as a function of repetition rate, was found to be statistically insignificant. Conclusions: The incorporation of active control has resulted in a marked improvement in the GPC's reproducibility and it allows the user to now perform measurements within minutes of setup. With this refinement, it is estimated that the overall standard uncertainty in the absolute determination of dose to water is 1%, making the GPC comparable to a calibrated ionization chamber. This

  12. Skyhook-based semi-active control of full-vehicle suspension with magneto-rheological dampers

    NASA Astrophysics Data System (ADS)

    Zhang, Hailong; Wang, Enrong; Min, Fuhong; Subash, Rakheja; Su, Chunyi

    2013-05-01

    The control study of vehicle semi-active suspension with magneto-rheological (MR) dampers has been attracted much attention internationally. However, a simple, real time and easy implementing semi-active controller has not been proposed for the MR full-vehicle suspension system, and a systematic analysis method has not been established for evaluating the multi-objective suspension performances of MR full-vehicle vertical, pitch and roll motions. For this purpose, according to the 7-degree of freedom (DOF) full-vehicle dynamic system, a generalized 7-DOF MR and passive full-vehicle dynamic model is set up by employing the modified Bouc-wen hysteretic force-velocity ( F-v) model of the MR damper. A semi-active controller is synthesized to realize independent control of the four MR quarter-vehicle sub-suspension systems in the full-vehicle, which is on the basis of the proposed modified skyhook damping scheme of MR quarter-vehicle sub-suspension system. The proposed controller can greatly simplify the controller design complexity of MR full-vehicle suspension and has merits of easy implementation in real application, wherein only absolute velocities of sprung and unsprung masses with reference to the road surface are required to measure in real time when the vehicle is moving. Furthermore, a systematic analysis method is established for evaluating the vertical, pitch and roll motion properties of both MR and passive full-vehicle suspensions in a more realistic road excitation manner, in which the harmonic, rounded pulse and real road measured random signals with delay time are employed as different road excitations inserted on the front and rear two wheels, by considering the distance between front and rear wheels in full-vehicle. The above excitations with different amplitudes are further employed as the road excitations inserted on left and right two wheels for evaluating the roll motion property. The multi-objective suspension performances of ride comfort and

  13. Active Control of Rotating Stall Demonstrated for a Multistage Compressor With Inlet Distortion

    NASA Technical Reports Server (NTRS)

    VanSchalkwyk, Christian; Bright, Michelle M.; Suder, Kenneth L.; Straziar, Anthony J.; Thorp, Scott A.

    2001-01-01

    Aircraft compressors can suffer debilitating consequences as a result of rotating stall and surge events caused by inlet distortions. This is particularly true of aircraft during takeoff, when the compressor is operating at peak performance close to the surge line. Significant research has been conducted by the NASA Glenn Research Center in the area of compressor stability enhancement through active and passive control methods. Most recently, an experiment was conducted at the Wright Patterson Air Force Base Research Laboratory on a two-stage fan with inlet guide vanes and inlet distortion. In this joint Small Business Innovation Research effort between Scientific Systems and Glenn, control of rotating stall was demonstrated in a multistage transonic fan. This twostage fan with inlet guide vanes was tested under clean and distorted inlet conditions. The compressor was also configured with a circumferential distortion screen capable of 180 of distortion and with 14 high-velocity injectors upstream of the first rotor. Twelve of these injectors could oscillate up to frequencies of 450 Hz. The additional two injectors were located next to each other and were used in concert with each other as a single, on/off, high-authority actuator. In a first test of injection in this multistage environment, 12 of the valves were opened 50 percent of their full stroke to assess steady injection through the compressor. This baseline injection is shown in the compressor characteristic of the following figure, and stall margin improvements are tracked from this baseline condition. The compressor was then tested with clean inlet conditions using 12 injectors and active control. Pressure disturbances were tracked before rotating stall, and a constant gain control scheme reduced the stalling mass flow by 10.8 percent over the baseline. With the distortion screen present in the inlet, a pole-zero cancellation control scheme was used to achieve a 6.4-percent decrease in stalling mass flow

  14. Active control of the tip vortex: an experimental investigation on the performance characteristics of a model turbine

    NASA Astrophysics Data System (ADS)

    Anik, E.; Abdulrahim, A.; Ostovan, Y.; Mercan, B.; Uzol, O.

    2014-06-01

    This study is part of an on-going experimental research campaign that focuses on the active control of the tip leakage/vortex characteristics of a model horizontal axis wind turbine rotor using tip injection. This paper presents both baseline (no-injection) data as well as data with tip injection, concentrating on the effects of tip injection on power and thrust variations with the Tip Speed Ratio (TSR). The experiments are conducted by placing a specially designed 3-bladed model wind turbine rotor at the exit of a 1.7 m diameter open-jet wind tunnel. The rotor blades are non-linearly twisted and tapered with NREL S826 airfoil profile all along the span. The nacelle, hub and the blades are specifically designed to allow pressurized air to pass through and get injected from the blade tips while the rotor is rotating. Baseline results show that the general trends are as expected for a small wind turbine and the maximum power coefficient is reached at around TSR=4.5. Results with injection show that the tip injection has significant effect on the power and thrust coefficients in comparison to the baseline data, especially at TSR values higher than the max CP TSR value. Both coefficients seem to be significantly increased due to tip injection and the max CP TSR value also gets shifted to a slightly higher TSR value. Tip injection seems to have no significant effect for TSR values less than 3.5.

  15. Active control of sound radiation from a vibrating rectangular panel by sound sources and vibration inputs - An experimental comparison

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.; Hansen, C. H.; Snyder, S. D.

    1991-01-01

    Active control of sound radiation from a rectangular panel by two different methods has been experimentally studied and compared. In the first method a single control force applied directly to the structure is used with a single error microphone located in the radiated acoustic field. Global attenuation of radiated sound was observed to occur by two main mechanisms. For 'on-resonance' excitation, the control force had the effect of increasing the total panel input impedance presented to the nosie source, thus reducing all radiated sound. For 'off-resonance' excitation, the control force tends not significantly to modify the panel total response amplitude but rather to restructure the relative phases of the modes leading to a more complex vibration pattern and a decrease in radiation efficiency. For acoustic control, the second method, the number of acoustic sources required for global reduction was seen to increase with panel modal order. The mechanism in this case was that the acoustic sources tended to create an inverse pressure distribution at the panel surface and thus 'unload' the panel by reducing the panel radiation impedance. In general, control by structural inputs appears more effective than control by acoustic sources for structurally radiated noise.

  16. Nonlinear dynamic response and active control of fiber metal laminated plates with piezoelectric actuators and sensors in unsteady temperature field

    NASA Astrophysics Data System (ADS)

    Shao, Xuefei; Fu, Yiming; Chen, Yang

    2015-05-01

    Based on the higher order shear deformation theory and the geometric nonlinear theory, the nonlinear motion equations, to which the effects of the positive and negative piezoelectric and the thermal are introduced by piezoelectric fiber metal laminated (FML) plates in an unsteady temperature, are established by Hamilton’s variational principle. Then, the control algorithm of negative-velocity feedback is applied to realize the vibration control of the piezoelectric FML plates. During the solving process, firstly, the formal functions of the displacements that fulfilled the boundary conditions are proposed. Then, heat conduction equations and nonlinear differential equations are dealt with using the differential quadrature (DQ) and Galerkin methods, respectively. On the basis of the previous processing, the time domain is dispersed by the Newmark-β method. Finally, the whole problem can be investigated by the iterative method. In the numerical examples, the influence of the applied voltage, the temperature loading and geometric parameters on the nonlinear dynamic response of the piezoelectric FML plates is analyzed. Meanwhile, the effect of feedback control gain and the position of the piezoelectric layer, the initial deflection and the external temperature on the active control effect of the piezoelectric layers has been studied. The model development and the research results can serve as a basis for nonlinear vibration analysis of the FML structures.

  17. Low-Frequency Sound Field Control in a Reverberant Room with a Single Active Controller Source.

    NASA Astrophysics Data System (ADS)

    Bullock, John Drayton, Jr.

    The operation of a single active controller source in a reverberant room has been investigated. The system consists of a controlled transducer source and a near-source microphone, with electronics arranged as a closed feedback loop. The controller system responds to a single source placed arbitrarily in the room. A theoretical analysis is presented based on the two port model of the controller transducer interfaced to an equivalent description of the reverberant room. The room acoustic transfer impedances between the active controller, room exciter source, near controller pressure sensor, and an arbitrary point in the reverberant sound field are described by a Green's function model. To minimize resonant effects of the controller piston diaphragm, a second control feedback loop using a diaphragm mounted accelerometer was added to the pressure control loop. Examples of the controller system operation were drawn from a computer model. Experimental data were gathered in a test reverberation room at the Applied Research Laboratory of The Pennsylvania State University. This investigation has brought forth three factors which define the limits on wide band control loop gain. They are (i) the position of an accelerometer on the controller diaphragm, (ii) the spacing between the controller and pressure sensor microphone, and (iii) the first mode frequency and the Q of the controller diaphragm. These system and transducer constraints can introduce instability in the control system. The controller system operation in the room has been modeled as a lumped element ideal piston using a flow graph representation. Additional loops on the graph are used to represent non-ideal transducer aberrations, and to define the pressure at various points in the room. Four cases for controller operation have been defined based on the proximity of the room source, the pressure sensor, and the controller. Two of these are important for practical applications: (i) the sensor microphone and

  18. Regarding "Semi-active control of the rocking motion of monolithic art objects" [Journal of Sound and Vibration, 374 (2016) 1-16

    NASA Astrophysics Data System (ADS)

    Cartmell, Matthew P.

    2016-09-01

    The Editor wishes to make the reader aware that the paper "Semi-active control of the rocking motion of monolithic art objects" by R. Ceravolo, M.L. Pecorelli, and L.Z. Fragonara, did not contain a direct citation of the fundamental and original work by D. Konstantinidis and N. Makris entitled "Experimental and analytical studies on the seismic response of free-standing and anchored laboratory equipment", Report No. PEER 2005/07. Pacific Earthquake Engineering Research (PEER) Center, University of California, Berkeley, 2005. The Editor regrets that this omission was not noted at the time that the above paper was accepted and published.

  19. Active Control of Jet Noise Using Observable Inferred Decomposition and Large Window PIV

    NASA Astrophysics Data System (ADS)

    Berger, Zachary; Berry, Matthew; Low, Kerwin; Cordier, Laurent; Noack, Bernd; Gogineni, Sivaram; Glauser, Mark

    2012-11-01

    In this investigation, we seek to find sources of noise created in the near-region of a highly subsonic jet, with a nozzle diameter of 2''. Using large window PIV alongside simultaneous hydrodynamic and acoustic pressure, we focus on observing flow structures created in the collapse of the potential core. Correlations can be made between the low-dimensional velocity field (using POD) and the far-field acoustics in an effort to identify loud modes in the flow. An advanced reduced order model known as Observable Inferred Decomposition (OID) is used to form closed-loop controllers for noise reduction in the far-field. With this technique, we find low-dimensional representations of near-field velocity and far-field pressure - finding a linear mapping between the two fields. Then, we obtain acoustically optimized modes in the flow field and seek to drive these modes to zero using active control strategies. For flow control, synthetic jet actuators are used as shear layer excitation. A large range of tests are explored, varying Mach number and flow control configurations. Finally, large PIV windows will allow us to investigate several diameters of the flow field in the streamwise plane.

  20. Active control of a flexible structure using a modal positive position feedback controller

    NASA Technical Reports Server (NTRS)

    Poh, S.; Baz, A.

    1990-01-01

    The feasibility of a new Modal Positive Position Feedback (MPPF) strategy in controlling the vibration of a complex flexible structure using a single piezo-electric active structural member is demonstrated. The control strategy generates its control forces by manipulating only the modal position signals of the structure to provide a damping action to undamped modes. This is in contrast to conventional modal controllers that rely in their operation on negative feedback of both the modal position and velocity. The proposed strategy is very simple to design and implement as it designs the controller at the uncoupled modal level and utilizes simple first order filters to achieve the Positive Position Feedback effect. The performance of the new strategy is enhanced by augmenting it with a time sharing strategy to share a small number of actuators between larger number of modes. The effectiveness of the new strategy is validated experimentally on a flexible box-type structure that has four bays and its first two bending modes are 2.015 and 6.535 Hz respectively. A single piezo-electric actuator is utilized as an active structural member to control several transverse bending modes of the structure. The performance of the active control system is determined in the time and the frequency domains. The results are compared with those obtained when using the Independent Modal Space Control (IMSC) of Meirovitch. The experimental results suggest the potential of the proposed strategy as a viable means for controlling the vibration of large flexible structures in real time.

  1. Active control of a flexible structure using a modal positive position feedback controller

    NASA Technical Reports Server (NTRS)

    Poh, S.; Baz, A.

    1990-01-01

    The feasibility of a new Modal Positive Position Feedback (MPPF) strategy in controlling the vibration of a complex flexible structure using a single piezo-electric active structural member is demonstrated. The control strategy generates its control forces by manipulating only the modal position signals of the structure to provide a damping action to undamped modes. This is in contrast to conventional modal controllers that rely in their operation on negative feedback of both the modal position and velocity. The proposed strategy is very simple to design and implement as it designs the controller at the uncoupled modal level and utilizes simple first order filters to achieve the Positive Position Feedback effect. The performance of the new strategy is enhanced by augmenting it with a time sharing strategy to share a small number of actuators between larger number of modes. The effectiveness of the new strategy is validated experimentally on a flexible box-type structure that has four bays and its first two bending modes are 2.015 and 6.535 Hz, respectively. A single piezo-electric actuator is utilized as an active structural member to control several transverse bending modes of the structure. The performance of the active control system is determined in the time and the frequency domains. The results are compared with those obtained when using the Independent Modal Space Control (IMSC) of Meirovitch. The experimental results suggest the potential of the proposed strategy as a viable means for controlling the vibration of large flexible structures in real time.

  2. A Design Methodology for Rapid Implementation of Active Control Systems Across Lean Direct Injection Combustor Platforms

    NASA Technical Reports Server (NTRS)

    Baumann, William T.; Saunders, William R.; Vandsburger, Uri; Saus, Joseph (Technical Monitor)

    2003-01-01

    The VACCG team is comprised of engineers at Virginia Tech who specialize in the subject areas of combustion physics, chemical kinetics, dynamics and controls, and signal processing. Currently, the team's work on this NRA research grant is designed to determine key factors that influence combustion control performance through a blend of theoretical and experimental investigations targeting design and demonstration of active control for three different combustors. To validiate the accuracy of conclusions about control effectiveness, a sequence of experimental verifications on increasingly complex lean, direct injection combustors is underway. During the work period January 1, 2002 through October 15, 2002, work has focused on two different laboratory-scale combustors that allow access for a wide variety of measurements. As the grant work proceeds, one key goal will be to obtain certain knowledge about a particular combustor process using a minimum of sophisticated measurements, due to the practical limitations of measurements on full-scale combustors. In the second year, results obtained in the first year will be validated on test combustors to be identified in the first quarter of that year. In the third year, it is proposed to validate the results at more realistic pressure and power levels by utilizing the facilities at the Glenn Research Center.

  3. Active control of the acoustic boundary conditions of combustion test rigs

    NASA Astrophysics Data System (ADS)

    Bothien, Mirko R.; Moeck, Jonas P.; Oliver Paschereit, Christian

    2008-12-01

    In the design process of burners for gas turbines, new burner generations are generally tested in single or multi burner combustion test rigs. With these experiments, computational fluid dynamics, and finite element calculations, the burners' performance in the full-scale engine is sought to be predicted. Especially, information about the thermoacoustic behaviour and the emission characteristics is very important. As the thermoacoustics strongly depend on the acoustic boundary conditions of the system, it is obvious that test rig conditions should match, or be close to those of the full-scale engine. This is, however, generally not the case. Hence, if the combustion process in the test rig is stable at certain operating conditions, it may show unfavourable dynamics at the same conditions in the engine. In this work, a method is proposed which uses an active control scheme to manipulate the acoustic boundary conditions of the test rig. Using this method, the boundary conditions can be continuously modified, ranging from anechoic to fully reflecting in a broad frequency range. The concept is applied to an atmospheric combustion test rig with a swirl-stabilized burner. It is shown that the test rig's properties can be tuned to correspond to those of the full-scale engine. For example, the test rig length can be virtually extended, thereby introducing different resonance frequencies, without having to implement any hardware changes. Furthermore, the acoustic boundary condition can be changed to that of a choked flow without actually needing the flow to be choked.

  4. Seismic protection of frame structures via semi-active control: modeling and implementation issues

    NASA Astrophysics Data System (ADS)

    Gattulli, Vincenzo; Lepidi, Marco; Potenza, Francesco

    2009-12-01

    Theoretical and practical issues concerning the multi-faceted task of mitigating the latero-torsional seismic response of a prototypal frame structure with asymmetric mass distribution are approached. Chevron braces with embedded magnetorheological dampers acting on the interstory drift are used to ensure additional energy dissipation. The semi-active control strategy employed to govern the modification of the damper characteristics via feedback is based on the selection of optimal forces according to a H2/LQG criterion, with respect to which the actual forces are regulated by a clipped-optimal logic. A dynamic observer is used to estimate the state through a non-collocated placement of the acceleration sensors. Several aspects to be addressed throughout the complex process including the design, modelization, and implementation phases of semi-active protection systems are discussed. Finally, experimental results obtained to mitigate the motion induced by ground excitation in a large-scale laboratory prototype, simulating the seismic response of a two-story building, are summarized.

  5. Active Control of High Frequency Combustion Instability in Aircraft Gas-Turbine Engines

    NASA Technical Reports Server (NTRS)

    Corrigan, Bob (Technical Monitor); DeLaat, John C.; Chang, Clarence T.

    2003-01-01

    Active control of high-frequency (greater than 500 Hz) combustion instability has been demonstrated in the NASA single-nozzle combustor rig at United Technologies Research Center. The combustor rig emulates an actual engine instability and has many of the complexities of a real engine combustor (i.e. actual fuel nozzle and swirler, dilution cooling, etc.) In order to demonstrate control, a high-frequency fuel valve capable of modulating the fuel flow at up to 1kHz was developed. Characterization of the fuel delivery system was accomplished in a custom dynamic flow rig developed for that purpose. Two instability control methods, one model-based and one based on adaptive phase-shifting, were developed and evaluated against reduced order models and a Sectored-1-dimensional model of the combustor rig. Open-loop fuel modulation testing in the rig demonstrated sufficient fuel modulation authority to proceed with closed-loop testing. During closed-loop testing, both control methods were able to identify the instability from the background noise and were shown to reduce the pressure oscillations at the instability frequency by 30%. This is the first known successful demonstration of high-frequency combustion instability suppression in a realistic aero-engine environment. Future plans are to carry these technologies forward to demonstration on an advanced low-emission combustor.

  6. Effectiveness enhancement of a cycloidal wind turbine by individual active control of blade motion

    NASA Astrophysics Data System (ADS)

    Hwang, In Seong; Lee, Yun Han; Kim, Seung Jo

    2007-04-01

    In this paper, a research for the effectiveness enhancement of a Cycloidal Wind Turbine by individual active control of blade motion is described. To improve the performance of the power generation system, which consists of several straight blades rotating about axis in parallel direction, the cycloidal blade system and the individual active blade control method are adopted. It has advantages comparing with horizontal axis wind turbine or conventional vertical axis wind turbine because it maintains optimal blade pitch angles according to wind speed, wind direction and rotor rotating speed to produce high electric power at any conditions. It can do self-starting and shows good efficiency at low wind speed and complex wind condition. Optimal blade pitch angle paths are obtained through CFD analysis according to rotor rotating speed and wind speed. The individual rotor blade control system consists of sensors, actuators and microcontroller. To realize the actuating device, servo motors are installed to each rotor blade. Actuating speed and actuating force are calculated to compare with the capacities of servo motor, and some delays of blade pitch angles are corrected experimentally. Performance experiment is carried out by the wind blowing equipment and Labview system, and the rotor rotates from 50 to 100 rpm according to the electric load. From this research, it is concluded that developing new vertical axis wind turbine, Cycloidal Wind Turbine which is adopting individual active blade pitch control method can be a good model for small wind turbine in urban environment.

  7. Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

    NASA Technical Reports Server (NTRS)

    Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

    1994-01-01

    An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

  8. Three Dimensional Solution of Pneumatic Active Control of Forebody Vortex Asymmetry

    NASA Technical Reports Server (NTRS)

    Kandil, Osama A.; SharafEl-Din, Hazem H.; Liu, C. H.

    1995-01-01

    Pneumatic active control of asymmetric vortical flows around a slender pointed forebody is investigated using the three dimensional solution for the compressible thin-layer Navier-Stokes equation. The computational applications cover the normal and tangential injection control of asymmetric flows around a 5 degree semi-apex angle cone at a 40 degree angle of attack, 1.4 freestream Mach number and 6 x 10(exp 6) freestream Reynolds number (based on the cone length). The effective tangential angle range of 67.5 approaches minus 67.5 degrees is used for both normal and tangential ports of injection. The effective axial length of injection is varied from 0.03 to 0.05. The computational solver uses the implicit, upwind, flux difference splitting finite volume scheme, and the grid consists of 161 x 55 x 65 points in the wrap around, normal and axial directions, respectively. The results show that tangential injection is more effective than normal injection.

  9. Structural sensing of interior sound for active control of noise in structural-acoustic cavities.

    PubMed

    Bagha, Ashok K; Modak, S V

    2015-07-01

    This paper proposes a method for structural sensing of acoustic potential energy for active control of noise in a structural-acoustic cavity. The sensing strategy aims at global control and works with a fewer number of sensors. It is based on the established concept of radiation modes and hence does not add too many states to the order of the system. Acoustic potential energy is sensed using a combination of a Kalman filter and a frequency weighting filter with the structural response measurements as the inputs. The use of Kalman filter also makes the system robust against measurement noise. The formulation of the strategy is presented using finite element models of the system including that of sensors and actuators so that it can be easily applied to practical systems. The sensing strategy is numerically evaluated in the framework of Linear Quadratic Gaussian based feedback control of interior noise in a rectangular box cavity with a flexible plate with single and multiple pairs of piezoelectric sensor-actuator patches when broadband disturbances act on the plate. The performance is compared with an "acoustic filter" that models the complete transfer function from the structure to the acoustic domain. The sensing performance is also compared with a direct estimation strategy. PMID:26233001

  10. Inverse eigenvalue problems in vibration absorption: Passive modification and active control

    NASA Astrophysics Data System (ADS)

    Mottershead, John E.; Ram, Yitshak M.

    2006-01-01

    The abiding problem of vibration absorption has occupied engineering scientists for over a century and there remain abundant examples of the need for vibration suppression in many industries. For example, in the automotive industry the resolution of noise, vibration and harshness (NVH) problems is of extreme importance to customer satisfaction. In rotorcraft it is vital to avoid resonance close to the blade passing speed and its harmonics. An objective of the greatest importance, and extremely difficult to achieve, is the isolation of the pilot's seat in a helicopter. It is presently impossible to achieve the objectives of vibration absorption in these industries at the design stage because of limitations inherent in finite element models. Therefore, it is necessary to develop techniques whereby the dynamic of the system (possibly a car or a helicopter) can be adjusted after it has been built. There are two main approaches: structural modification by passive elements and active control. The state of art of the mathematical theory of vibration absorption is presented and illustrated for the benefit of the reader with numerous simple examples.

  11. Active Control of Turbulent Boundary Layer Induced Sound Radiation from Multiple Aircraft Panels

    NASA Technical Reports Server (NTRS)

    Gibbs, Gary P.; Cabell, Randolph H.

    2002-01-01

    The objective of this work is to experimentally investigate active structural acoustic control of turbulent boundary layer (TBL) induced sound radiation from multiple panels on an aircraft sidewall. One possible approach for controlling sound radiation from multiple panels is a multi-input/multi-output scheme which considers dynamic coupling between the panels. Unfortunately, this is difficult for more than a few panels, and is impractical for a typical aircraft which contains several hundred such panels. An alternative is to implement a large number of independent control systems. Results from the current work demonstrate the feasibility of reducing broadband radiation from multiple panels utilizing a single-input/single-output (SISO) controller per bay, and is the first known demonstration of active control of TBL induced sound radiation on more than two bays simultaneously. The paper compares sound reduction for fully coupled control of six panels versus independent control on each panel. An online adaptive control scheme for independent control is also demonstrated. This scheme will adjust for slow time varying dynamic systems such as fuselage response changes due to aircraft pressurization, etc.

  12. Physical mechanisms of active control of sound transmission through rib stiffened double-panel structure

    NASA Astrophysics Data System (ADS)

    Ma, Xiyue; Chen, Kean; Ding, Shaohu; Yu, Haoxin

    2016-06-01

    This paper presents an analytical investigation on physical mechanisms of actively controlling sound transmission through a rib stiffened double-panel structure using point source in the cavity. The combined modal expansion and vibro-acoustic coupling methods are applied to establish the theoretical model of such active structure. Under the condition of minimizing radiated power of the radiating ribbed plate, the physical mechanisms are interpreted in detail from the point of view of modal couplings similar as that used in existed literatures. Results obtained demonstrate that the rule of sound energy transmission and the physical mechanisms for the rib stiffened double-panel structure are all changed, and affected by the coupling effects of the rib when compared with the analytical results obtained for unribbed double-panel case. By taking the coupling effects of the rib into considerations, the cavity modal suppression and rearrangement mechanisms obtained in existed investigations are modified and supplemented for the ribbed plate case, which gives a clear interpretation for the physical nature involved in the active rib stiffened double-panel structure.

  13. ECCD-induced tearing mode stabilization via active control in coupled NIMROD/GENRAY HPC simulations

    NASA Astrophysics Data System (ADS)

    Jenkins, Thomas; Kruger, S. E.; Held, E. D.; Harvey, R. W.

    2012-10-01

    Actively controlled electron cyclotron current drive (ECCD) applied within magnetic islands formed by neoclassical tearing modes (NTMs) has been shown to control or suppress these modes. In conjunction with ongoing experimental efforts, the development and verification of integrated numerical models of this mode stabilization process is of paramount importance in determining optimal NTM stabilization strategies for ITER. In the advanced model developed by the SWIM Project, the equations/closures of extended (not reduced) MHD contain new terms arising from 3D (not toroidal or bounce-averaged) RF-induced quasilinear diffusion. The quasilinear operator formulation models the equilibration of driven current within the island using the same extended MHD dynamics which govern the physics of island formation, yielding a more accurate and self-consistent picture of 3D island response to RF drive. Results of computations which model ECRF deposition using ray tracing, assemble the 3D quasilinear operator from ray/profile data, and calculate the resultant forces within the extended MHD code will be presented. We also discuss the efficacy of various numerical active feedback control systems, which gather data from synthetic diagnostics to dynamically trigger and spatially align RF fields.

  14. Active control of ECCD-induced tearing mode stabilization in coupled NIMROD/GENRAY HPC simulations

    NASA Astrophysics Data System (ADS)

    Jenkins, Thomas; Kruger, Scott; Held, Eric

    2013-10-01

    Actively controlled ECCD applied in or near magnetic islands formed by NTMs has been successfully shown to control/suppress these modes, despite uncertainties in island O-point locations (where induced current is most stabilizing) relative to the RF deposition region. Integrated numerical models of the mode stabilization process can resolve these uncertainties and augment experimental efforts to determine optimal ITER NTM stabilization strategies. The advanced SWIM model incorporates RF effects in the equations/closures of extended MHD as 3D (not toroidal or bounce-averaged) quasilinear diffusion coefficients. Equilibration of driven current within the island geometry is modeled using the same extended MHD dynamics governing the physics of island formation, yielding a more accurate/self-consistent picture of island response to RF drive. Additionally, a numerical active feedback control system gathers data from synthetic diagnostics to dynamically trigger & spatially align the RF fields. Computations which model the RF deposition using ray tracing, assemble the 3D QL operator from ray & profile data, calculate the resultant xMHD forces, and dynamically realign the RF to more efficiently stabilize modes are presented; the efficacy of various control strategies is also discussed. Supported by the SciDAC Center for Extended MHD Modeling (CEMM); see also https://cswim.org.

  15. Active control of noise on the source side of a partition to increase its sound isolation

    NASA Astrophysics Data System (ADS)

    Tarabini, Marco; Roure, Alain; Pinhede, Cedric

    2009-03-01

    This paper describes a local active noise control system that virtually increases the sound isolation of a dividing wall by means of a secondary source array. With the proposed method, sound pressure on the source side of the partition is reduced using an array of loudspeakers that generates destructive interference on the wall surface, where an array of error microphones is placed. The reduction of sound pressure on the incident side of the wall is expected to decrease the sound radiated into the contiguous room. The method efficiency was experimentally verified by checking the insertion loss of the active noise control system; in order to investigate the possibility of using a large number of actuators, a decentralized FXLMS control algorithm was used. Active control performances and stability were tested with different array configurations, loudspeaker directivities and enclosure characteristics (sound source position and absorption coefficient). The influence of all these parameters was investigated with the factorial design of experiments. The main outcome of the experimental campaign was that the insertion loss produced by the secondary source array, in the 50-300 Hz frequency range, was close to 10 dB. In addition, the analysis of variance showed that the active noise control performance can be optimized with a proper choice of the directional characteristics of the secondary source and the distance between loudspeakers and error microphones.

  16. Three-dimensional rearrangement of single atoms using actively controlled optical microtraps.

    PubMed

    Lee, Woojun; Kim, Hyosub; Ahn, Jaewook

    2016-05-01

    We propose and demonstrate three-dimensional rearrangements of single atoms. In experiments performed with single 87Rb atoms in optical microtraps actively controlled by a spatial light modulator, we demonstrate various dynamic rearrangements of up to N = 9 atoms including rotation, 2D vacancy filling, guiding, compactification, and 3D shuffling. With the capability of a phase-only Fourier mask to generate arbitrary shapes of the holographic microtraps, it was possible to place single atoms at arbitrary geometries of a few μm size and even continuously reconfigure them by conveying each atom. For this purpose, we loaded a series of computer-generated phase masks in the full frame rate of 60 Hz of the spatial light modulator, so the animation of phase mask transformed the holographic microtraps in real time, driving each atom along the assigned trajectory. Possible applications of this method of transformation of single atoms include preparation of scalable quantum platforms for quantum computation, quantum simulation, and quantum many-body physics. PMID:27137595

  17. Development and flight evaluation of an augmented stability active controls concept with a small horizontal tail

    NASA Technical Reports Server (NTRS)

    Rising, J. J.; Kairys, A. A.; Maass, C. A.; Siegart, C. D.; Rakness, W. L.; Mijares, R. D.; King, R. W.; Peterson, R. S.; Hurley, S. R.; Wickson, D.

    1982-01-01

    A limited authority pitch active control system (PACS) was developed for a wide body jet transport (L-1011) with a flying horizontal stabilizer. Two dual channel digital computers and the associated software provide command signals to a dual channel series servo which controls the stabilizer power actuators. Input sensor signals to the computer are pitch rate, column-trim position, and dynamic pressure. Control laws are given for the PACS and the system architecture is defined. The piloted flight simulation and vehicle system simulation tests performed to verify control laws and system operation prior to installation on the aircraft are discussed. Modifications to the basic aircraft are described. Flying qualities of the aircraft with the PACS on and off were evaluated. Handling qualities for cruise and high speed flight conditions with the c.g. at 39% mac ( + 1% stability margin) and PACS operating were judged to be as good as the handling qualities with the c.g. at 25% (+15% stability margin) and PACS off.

  18. Middeck Active Control Experiment Reflight (MACE II): lessons learned and reflight status

    NASA Astrophysics Data System (ADS)

    Ninneman, Ronald R.; Denoyer, Keith K.

    2000-06-01

    The Air Force Research Laboratory (AFRL) is sponsoring the Middeck Active Control Experiment Reflight (MACE II) Program. MACE II is a manned space experiment that evaluates the capabilities of adaptive control of flexible structures in the zero-g environment of the space shuttle's Middeck. MACE II has grown out of lessons learned from the original MACE flight and from AFRL sponsored structural control experiments. Previous experiments required extensive testing and 'tuning' for their particular test environment to meet their performance expectations. Such a process is too inefficient to be seriously considered for operational systems, especially space-based systems where access is limited. MACE II takes the next logical step by evaluating the capability of adaptive structural control algorithms AFRL has assembled a team of five small businesses and universities to develop and evaluate several adaptive control methodologies. In addition, AFRL has recruited a second science team led by the Massachusetts Institute of Technology to evaluate control system for time-varying and geometrically nonlinear systems. This paper is an overview of the AFRL science team only.

  19. Active control of the forced and transient response of a finite beam. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Post, John T.

    1990-01-01

    Structural vibrations from a point force are modelled on a finite beam. This research explores the theoretical limit on controlling beam vibrations utilizing another point source as an active controller. Three different types of excitation are considered, harmonic, random, and transient. For harmonic excitation, control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam. Control over a subregion may be obtained even between resonant frequencies at the cost of increasing the vibration outside of the control region. For random excitation, integrating the expected value of the displacement squared over the required interval, is shown to yield the identical cost function as obtained by integrating the cost function for harmonic excitation over all excitation frequencies. As a result, it is always possible to reduce the cost function for random excitation whether controlling the entire beam or just a subregion, without ever increasing the vibration outside the region in which control is desired. The last type of excitation considered is a single, transient pulse. The form of the controller is specified as either one or two delayed pulses, thus constraining the controller to be casual. The best possible control is examined while varying the region of control and the controller location. It is found that control is always possible using either one or two control pulses.

  20. Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

    NASA Technical Reports Server (NTRS)

    Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

    1996-01-01

    An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

  1. A semi-active control suspension system for railway vehicles with magnetorheological fluid dampers

    NASA Astrophysics Data System (ADS)

    Wei, Xiukun; Zhu, Ming; Jia, Limin

    2016-07-01

    The high-speed train has achieved great progress in the last decades. It is one of the most important modes of transportation between cities. With the rapid development of the high-speed train, its safety issue is paid much more attention than ever before. To improve the stability of the vehicle with high speed, extra dampers (i.e. anti-hunting damper) are used in the traditional bogies with passive suspension system. However, the curving performance of the vehicle is undermined due to the extra lateral force generated by the dampers. The active suspension systems proposed in the last decades attempt to solve the vehicle steering issue. However, the active suspension systems need extra actuators driven by electrical power or hydraulic power. There are some implementation and even safety issues which are not easy to be overcome. In this paper, an innovative semi-active controlled lateral suspension system for railway vehicles is proposed. Four magnetorheological fluid dampers are fixed to the primary suspension system of each bogie. They are controlled by online controllers for enhancing the running stability on the straight track line on the one hand and further improving the curving performance by controlling the damper force on the other hand. Two control strategies are proposed in the light of the pure rolling concept. The effectiveness of the proposed strategies is demonstrated by SIMPACK and Matlab co-simulation for a full railway vehicle with two conventional bogies.

  2. Contributions of the Transonic Dynamics Tunnel to the Testing of Active Control of Aeroelastic Response

    NASA Technical Reports Server (NTRS)

    Perry, Boyd, III; Noll, Thomas E.; Scott, Robert C.

    2000-01-01

    By the 1960s, researchers began to investigate the feasibility of using active controls technology (ACT) for increasing the capabilities of military and commercial aircraft. Since then many researchers, too numerous to mention, have investigated and demonstrated the usefulness of ACT for favorably modifying the aeroelastic response characteristics of flight vehicles. As a result, ACT entered the limelight as a viable tool for answering some very difficult design questions and had the potential for obtaining structural weight reductions optimizing maneuvering performance, and satisfying the multimission requirements being imposed on future military and commercial aircraft designs. Over the past 40 years, the NASA Langley Research Center (LaRC) has played a major role in developing ACT in part by its participation in many wind-tunnel programs conducted in the Transonic Dynamics Tunnel (TDT). These programs were conducted for the purposes of: (1) establishing concept feasibility; (2) demonstrating proof of concept; and (3) providing data for validating new modeling, analysis, and design methods. This paper provides an overview of the ACT investigations conducted in the TDT. For each program discussed herein, the objectives of the effort, the testing techniques, the test results, any, signIficant findings, and the lessons learned with respect to ACT testing are presented.

  3. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transpot project-demonstration act system definition

    NASA Technical Reports Server (NTRS)

    Hanks, G. W.; Shomber, H. A.; Crumb, C. B.; Flora, C. C.; Macdonald, K. A. B.; Smith, R. D.; Sassi, A. P.; Dorwart, R. J.

    1982-01-01

    The 1985 ACT airplane is the Final Active Controls Technology (ACT) Airplane with the addition of three-axis fly by wire. Thus it retains all the efficiency features of the full ACT system plus the weight and cost savings accruing from deletion of the mechanical control system. The control system implements the full IAAC spectrum of active controls except flutter-mode control, judged essentially nonbeneficial, and incorporates new control surfaces called flaperons to make the most of wing-load alleviation. This redundant electronic system is conservatively designed to preserve the extreme reliability required of crucial short-period pitch augmentation, which provides more than half of the fuel savings.

  4. Long-term safety evaluation of bimatoprost ophthalmic solution 0.03%: a pooled analysis of six double-masked, randomized, active-controlled clinical trials

    PubMed Central

    Wirta, David; VanDenburgh, Amanda M; Weng, Emily; Whitcup, Scott M; Kurstjens, Sef; Beddingfield, Frederick C

    2011-01-01

    Background: Bimatoprost ophthalmic solution 0.03% was approved in the US for reducing intraoccular pressure (IOP) based on two double-masked, active-controlled clinical trials. Four additional long-term studies (≥12 months) were conducted; however, the aggregate safety profile of the six studies has not been reported. Methods: Adverse events (AEs) were pooled from six double-masked, active-controlled, long-term clinical trials in which subjects received bimatoprost 0.03% once daily (QD) or twice daily (BID) as an eyedrop. AE terms were converted to MedDRA (V.11.0) Preferred Terms and analyzed. Results: In total, 1409 patients received more than one dose of bimatoprost 0.03% QD or BID. Most AEs were mild in severity and reported by 86.7% (QD) and 94.8% (BID) of subjects (≤12 months of treatment). AEs reported through month 12 (aggregate incidence of ≥5%) were conjunctival hyperemia, increased eyelash growth, eye pruritus, periocular skin hyperpigmentation, eye irritation, dry eye, and hypertrichosis. AE onset was generally reported within four months of treatment. The cumulative incidence of common AEs in the QD treatment group at 24–48 months was similar to that measured at 12 months of treatment. Conclusion: Bimatoprost 0.03% has a favorable safety and tolerability profile as characterized by six long-term studies. Common AEs were due to the known pharmacological activity of bimatoprost and reversible with treatment cessation. PMID:21691584

  5. Using the decision ladder to understand road user decision making at actively controlled rail level crossings.

    PubMed

    Mulvihill, Christine M; Salmon, Paul M; Beanland, Vanessa; Lenné, Michael G; Read, Gemma J M; Walker, Guy H; Stanton, Neville A

    2016-09-01

    Rail level crossings (RLXs) represent a key strategic risk for railways worldwide. Despite enforcement and engineering countermeasures, user behaviour at RLXs can often confound expectations and erode safety. Research in this area is limited by a relative absence of insights into actual decision making processes and a focus on only a subset of road user types. One-hundred and sixty-six road users (drivers, motorcyclists, cyclists and pedestrians) completed a diary entry for each of 457 naturalistic encounters with RLXs when a train was approaching. The final eligible sample comprised 94 participants and 248 encounters at actively controlled crossings where a violation of the active warnings was possible. The diary incorporated Critical Decision Method probe questions, which enabled user responses to be mapped onto Rasmussen's decision ladder. Twelve percent of crossing events were non-compliant. The underlying decision making was compared to compliant events and a reference decision model to reveal important differences in the structure and type of decision making within and between road user groups. The findings show that engineering countermeasures intended to improve decision making (e.g. flashing lights), may have the opposite effect for some users because the system permits a high level of flexibility for circumvention. Non-motorised users were more likely to access information outside of the warning signals because of their ability to achieve greater proximity to the train tracks and the train itself. The major conundrum in resolving these issues is whether to restrict the amount of time and information available to users so that it cannot be used for circumventing the system or provide more information to help users make safe decisions. PMID:27184305

  6. Active control of coupled dynamic response of TLP hull and tendon

    SciTech Connect

    Yoshida, Koichiro; Suzuki, Hideyuki; Nam, D.; Hineno, Motohiro; Ishida, Shigeki

    1994-12-31

    This paper presents an active control of coupled dynamic responses of the hull and the tendon of TLP. In a deepwater TLP, the restoring force becomes smaller and the natural frequency of the system decreases with increasing water depth. There is a possibility that the dynamic response of tendon, which is induced by the hull motion, can be significant. Furthermore the motion of TLP due to wave drifting force can be comparable or larger than wave induced motion. This low-frequency response can be controlled by conventional DPS thrusters. The operability is improved and the tendon and the riser are protected from structural damage. The low-frequency motion is induced by small wave drifting force and can be controlled by small control force. The first order wave force is very large and control of this high-frequency response is not practical. The control method is optimal control and the low-frequency hull motion and the bending strain of the tendon are controlled. The high-frequency response is removed from the control system by low pass filters. The effectiveness of control is verified by experiment with a 1/100 scale model of JOIA (Japan Ocean Industries Association)-TLP. The hull motion is measured by an ultrasonic ranging sensor and the control force is generated by two thrusters built in the TLP model. Average control force required for the control is about 1/200 of the hull weight, which is slightly larger than the value of the conventional DPS thrust of a semi-submersible.

  7. No Sustained Attention Differences in a Longitudinal Randomized Trial Comparing Mindfulness Based Stress Reduction versus Active Control

    PubMed Central

    MacCoon, Donal G.; MacLean, Katherine A.; Davidson, Richard J.; Saron, Clifford D.; Lutz, Antoine

    2014-01-01

    Background Mindfulness Based Stress Reduction (MBSR) is a secular form of meditation training. The vast majority of the extant literature investigating the health effects of mindfulness interventions relies on wait-list control comparisons. Previous studies have found that meditation training over several months is associated with improvements in cognitive control and attention. Methodology/Principal Findings We used a visual continuous performance task (CPT) to test the effects of eight weeks of mindfulness training on sustained attention by comparing MBSR to the Health Enhancement Program (HEP), a structurally equivalent, active control condition in a randomized, longitudinal design (ClinicalTrials.gov, NCT01301105) focusing on a non-clinical population typical of MBSR participants. Researchers were blind to group assignment. 63 community participants were randomized to either MBSR (n = 31) or HEP (n = 32). CPT analyses were conducted on 29 MBSR participants and 25 HEP participants. We predicted that MBSR would improve visual discrimination ability and sustained attention over time on the CPT compared to HEP, with more home practice associated with greater improvements. Our hypotheses were not confirmed but we did find some evidence for improved visual discrimination similar to effects in partial replication of other research. Our study had sufficient power to demonstrate that intervention groups do not differ in their improvement over time in sustained attention performance. One of our primary predictions concerning the effects of intervention on attentional fatigue was significant but not interpretable. Conclusions Attentional sensitivity is not affected by mindfulness practice as taught in MBSR, but it is unclear whether mindfulness might positively affect another aspect of attention, vigilance. These results also highlight the relevant procedural modifications required by future research to correctly investigate the role of sustained attention in

  8. A mathematical model of an active control landing gear for load control during impact and roll-out

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.; Carden, H. D.

    1976-01-01

    A mathematical model of an active control landing gear (ACOLAG) was developed and programmed for operation on a digital computer. The mathematical model includes theoretical subsonic aerodynamics; first-mode wing bending and torsional characteristics; oleo-pneumatic shock strut with fit and binding friction; closed-loop, series-hydraulic control; empirical tire force-deflection characteristics; antiskid braking; and sinusoidal or random runway roughness. The mathematical model was used to compute the loads and motions for a simulated vertical drop test and a simulated landing impact of a conventional (passive) main landing gear designed for a 2268-kg (5000-lbm) class airplane. Computations were also made for a simply modified version of the passive gear including a series-hydraulic active control system. Comparison of computed results for the passive gear with experimental data shows that the active control landing gear analysis is valid for predicting the loads and motions of an airplane during a symmetrical landing. Computed results for the series-hydraulic active control in conjunction with the simply modified passive gear show that 20- to 30-percent reductions in wing force, relative to those occurring with the modified passive gear, can be obtained during the impact phase of the landing. These reductions in wing force could result in substantial increases in fatigue life of the structure.

  9. Capabilities and applications of a computer program system for dynamic loads analyses of flexible airplanes with active controls /DYLOFLEX/

    NASA Technical Reports Server (NTRS)

    Perry, B., III; Goetz, R. C.; Kroll, R. I.; Miller, R. D.

    1979-01-01

    This paper describes and illustrates the capabilities of the DYLOFLEX Computer Program System. DYLOFLEX is an integrated system of computer programs for calculating dynamic loads of flexible airplanes with active control systems. A brief discussion of the engineering formulation for each of the nine DYLOFLEX programs is described. The capabilities of the system are illustrated by the analyses of two example configurations.

  10. Multi-domain computerized cognitive training program improves performance of bookkeeping tasks: a matched-sampling active-controlled trial

    PubMed Central

    Lampit, Amit; Ebster, Claus; Valenzuela, Michael

    2014-01-01

    Cognitive skills are important predictors of job performance, but the extent to which computerized cognitive training (CCT) can improve job performance in healthy adults is unclear. We report, for the first time, that a CCT program aimed at attention, memory, reasoning and visuo-spatial abilities can enhance productivity in healthy younger adults on bookkeeping tasks with high relevance to real-world job performance. 44 business students (77.3% female, mean age 21.4 ± 2.6 years) were assigned to either (a) 20 h of CCT, or (b) 20 h of computerized arithmetic training (active control) by a matched sampling procedure. Both interventions were conducted over a period of 6 weeks, 3–4 1-h sessions per week. Transfer of skills to performance on a 60-min paper-based bookkeeping task was measured at three time points—baseline, after 10 h and after 20 h of training. Repeated measures ANOVA found a significant Group X Time effect on productivity (F = 7.033, df = 1.745; 73.273, p = 0.003) with a significant interaction at both the 10-h (Relative Cohen's effect size = 0.38, p = 0.014) and 20-h time points (Relative Cohen's effect size = 0.40, p = 0.003). No significant effects were found on accuracy or on Conners' Continuous Performance Test, a measure of sustained attention. The results are discussed in reference to previous findings on the relationship between brain plasticity and job performance. Generalization of results requires further study. PMID:25120510

  11. Multi-domain computerized cognitive training program improves performance of bookkeeping tasks: a matched-sampling active-controlled trial.

    PubMed

    Lampit, Amit; Ebster, Claus; Valenzuela, Michael

    2014-01-01

    Cognitive skills are important predictors of job performance, but the extent to which computerized cognitive training (CCT) can improve job performance in healthy adults is unclear. We report, for the first time, that a CCT program aimed at attention, memory, reasoning and visuo-spatial abilities can enhance productivity in healthy younger adults on bookkeeping tasks with high relevance to real-world job performance. 44 business students (77.3% female, mean age 21.4 ± 2.6 years) were assigned to either (a) 20 h of CCT, or (b) 20 h of computerized arithmetic training (active control) by a matched sampling procedure. Both interventions were conducted over a period of 6 weeks, 3-4 1-h sessions per week. Transfer of skills to performance on a 60-min paper-based bookkeeping task was measured at three time points-baseline, after 10 h and after 20 h of training. Repeated measures ANOVA found a significant Group X Time effect on productivity (F = 7.033, df = 1.745; 73.273, p = 0.003) with a significant interaction at both the 10-h (Relative Cohen's effect size = 0.38, p = 0.014) and 20-h time points (Relative Cohen's effect size = 0.40, p = 0.003). No significant effects were found on accuracy or on Conners' Continuous Performance Test, a measure of sustained attention. The results are discussed in reference to previous findings on the relationship between brain plasticity and job performance. Generalization of results requires further study. PMID:25120510

  12. Active control of surge in centrifugal compressors using magnetic thrust bearing actuation

    NASA Astrophysics Data System (ADS)

    Sanadgol, Dorsa

    This research presents a new method for active surge control in centrifugal compressors with unshrouded impellers using a magnetic thrust bearing to modulate the impeller tip clearance. Magnetic bearings offer the potential for active control of flow instabilities. This capability is highly dependent on the sensitivity of the compressor characteristics to blade tip clearance. If the position of the shaft can be actuated with sufficient authority and speed, the induced pressure modulation makes control of surge promising. The active nature of the magnetic bearing system makes the real-time static and dynamic positioning of the rotor and therefore modulation of the impeller tip clearance possible. A theoretical model is first established that describes the sensitivity of the centrifugal compressor characteristic curve to tip clearance variations induced by axial motion of the rotor. Results from simulation of the nonlinear model for a single stage high-speed centrifugal compressor show that using the proposed control method, mass flow and pressure oscillations associated with compressor surge are quickly suppressed with acceptable tip clearance excursions, typically less than 20% of the available clearance. It is shown that it is possible to produce adequate axial excursions in the clearance between the impeller blades and the adjacent stationary shroud using a magnetic thrust bearing with practical levels of drive voltage. This surge control method would allow centrifugal compressors to reliably and safely operate with a wider range than is currently done in the field. The principal advantage of the proposed approach over conventional surge control methods lies in that, in machines already equipped with magnetic bearing, the method can potentially be implemented by simply modifying controller software. This dispenses with the need to introduce additional hardware, permitting adaptation of existing machinery at virtually no cost. In addition, since the controller is

  13. Does the Five Facet Mindfulness Questionnaire measure what we think it does? Construct validity evidence from an active controlled randomized clinical trial.

    PubMed

    Goldberg, Simon B; Wielgosz, Joseph; Dahl, Cortland; Schuyler, Brianna; MacCoon, Donal S; Rosenkranz, Melissa; Lutz, Antoine; Sebranek, Chad A; Davidson, Richard J

    2016-08-01

    The current study attempted a rigorous test of the construct validity of a widely used self-report measure of dispositional mindfulness, the Five Facet Mindfulness Questionnaire (FFMQ), within the context of an active controlled randomized trial (n = 130). The trial included three arms: mindfulness-based stress reduction (MBSR), an active control condition that did not include instruction in mindfulness meditation (Health Enhancement Program [HEP]), and a waitlist control condition. Partial evidence for the convergent validity of the FFMQ was shown in correlations at baseline between FFMQ facets and measures of psychological symptoms and psychological well-being. In addition, facets of the FFMQ were shown to increase over the course of an MBSR intervention relative to a waitlist control condition. However, the FFMQ failed to show discriminant validity. Specifically, facets of the FFMQ were shown to increase over the course of the HEP intervention relative to the waitlist control condition. MBSR and HEP, in contrast, did not differ in changes in FFMQ score over time. Implications of these findings for the measurement and theory of mindfulness and MBSR are discussed. (PsycINFO Database Record PMID:26460893

  14. Qualitative comparison of calculated turbulence responses with wind-tunnel measurements for a DC-10 derivative wing with an active control system

    NASA Technical Reports Server (NTRS)

    Perry, B., III

    1981-01-01

    Comparisons are presented analytically predicted and experimental turbulence responses of a wind tunnel model of a DC-10 derivative wing equipped with an active control system. The active control system was designed for the purpose of flutter suppression, but it had additional benefit of alleviating gust loads (wing bending moment) by about 25%. Comparisions of various wing responses are presented for variations in active control system parameters and tunnel speed. The analytical turbulence responses were obtained using DYLOFLEX, a computer program for dynamic loads analyses of flexible airplanes with active controls. In general, the analytical predictions agreed reasonably well with the experimental data.

  15. Survey of Applications of Active Control Technology for Gust Alleviation and New Challenges for Lighter-weight Aircraft

    NASA Technical Reports Server (NTRS)

    Regan, Christopher D.; Jutte, Christine V.

    2012-01-01

    This report provides a historical survey and assessment of the state of the art in the modeling and application of active control to aircraft encountering atmospheric disturbances in flight. Particular emphasis is placed on applications of active control technologies that enable weight reduction in aircraft by mitigating the effects of atmospheric disturbances. Based on what has been learned to date, recommendations are made for addressing gust alleviation on as the trend for more structurally efficient aircraft yields both lighter and more flexible aircraft. These lighter more flexible aircraft face two significant challenges reduced separation between rigid body and flexible modes, and increased sensitivity to gust encounters due to increased wing loading and improved lift to drag ratios. The primary audience of this paper is engineering professionals new to the area of gust load alleviation and interested in tackling the multifaceted challenges that lie ahead for lighter-weight aircraft.

  16. Development and flight evaluation of active controls in the L-1011. [including wing load alleviation and stability augmentation

    NASA Technical Reports Server (NTRS)

    Johnston, J. F.; Urie, D. M.

    1978-01-01

    Active controls in the Lockheed L-1011 for increased energy efficiency are discussed. Active wing load alleviation for extended span, increased aspect ratio, and active stability augmentation with a smaller tail for reduced drag and weight are among the topics considered. Flight tests of active wing load alleviation on the baseline aircraft and moving-base piloted simulation developing criteria for stability augmentation are described.

  17. Dose Response Effects of Lisdexamfetamine Dimesylate Treatment in Adults with ADHD: An Exploratory Study

    ERIC Educational Resources Information Center

    Faraone, Stephen V.; Spencer, Thomas J.; Kollins, Scott H.; Glatt, Stephen J.; Goodman, David

    2012-01-01

    Objective: To explore dose-response effects of lisdexamfetamine dimesylate (LDX) treatment for ADHD. Method: This was a 4-week, randomized, double-blinded, placebo-controlled, parallel-group, forced-dose titration study in adult participants, aged 18 to 55 years, meeting "Diagnostic and Statistical Manual of Mental Disorders" (4th ed., text rev.)…

  18. Alleviation of whirl-flutter on a joined-wing tilt-rotor aircraft configuration using active controls

    NASA Technical Reports Server (NTRS)

    Vanaken, Johannes M.

    1991-01-01

    The feasibility of using active controls to delay the onset of whirl-flutter on a joined-wing tilt rotor aircraft was investigated. The CAMRAD/JA code was used to obtain a set of linear differential equations which describe the motion of the joined-wing tilt-rotor aircraft. The hub motions due to wing/body motion is a standard input to CAMRAD/JA and were obtained from a structural dynamics model of a representative joined-wing tilt-rotor aircraft. The CAMRAD/JA output, consisting of the open-loop system matrices, and the airframe free vibration motion were input to a separate program which performed the closed-loop, active control calculations. An eigenvalue analysis was performed to determine the flutter stability of both open- and closed-loop systems. Sensor models, based upon the feedback of pure state variables and based upon hub-mounted sensors, providing physically measurable accelerations, were evaluated. It was shown that the onset of tilt-rotor whirl-flutter could be delayed from 240 to above 270 knots by feeding back vertical and span-wise accelerations, measured at the rotor hub, to the longitudinal cyclic pitch. Time response calculations at a 270-knot cruise condition showed an active cyclic pitch control level of 0.009 deg, which equates to a very acceptable 9 pound active-control force applied at the rotor hub.

  19. Active control of primary mirror of an orbiting telescope with thermal excitation

    NASA Technical Reports Server (NTRS)

    Hill, J. L.; Youngblood, J. N.

    1974-01-01

    The generalization is presented that was made to model a layered structure of a kind that represents a light-weighted mirror. This theory is presented along with the strategy for error suppression. The results of a variety of error-suppression studies are also presented. The computer programs for all parts of this study are included.

  20. Flutter suppression and gust alleviation using active controls - Review of developments and applications based on the aerodynamic energy concept

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1978-01-01

    The state of the art of the aerodynamic energy concept, involving the use of active controls for flutter suppression, is reviewed. Applications of the concept include the suppression of external-store flutter of three different configurations of the YF-17 flutter model using a single trailing edge control surface activated by a single fixed-gain control law. Consideration is also given to some initial results concerning the flutter suppression of the 1/20 scale low speed wind-tunnel model of the Boeing 2707-300 supersonic transport using an activated trailing edge control surface.

  1. 77 FR 37059 - Draft Guidance for Industry on Active Controls in Studies To Demonstrate Effectiveness of a New...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-20

    ... Demonstrate Effectiveness of a New Animal Drug for Use in Companion Animals; Availability AGENCY: Food and... Demonstrate Effectiveness of a New Animal Drug for Use in Companion Animals.'' This draft guidance advises... of new animal drugs for use in companion animals. The intent of the guidance is to...

  2. 78 FR 63477 - Guidance for Industry on Active Controls in Studies To Demonstrate Effectiveness of a New Animal...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-24

    ... INFORMATION: I. Background In the Federal Register of June 20, 2012 (77 FR 37059), FDA published the notice of... Demonstrate Effectiveness of a New Animal Drug for Use in Companion Animals; Availability AGENCY: Food and... Effectiveness of a New Animal Drug for Use in Companion Animals.'' This guidance advises industry on the use...

  3. Integrated application of active controls (IAAC) technology to an advanced subsonic transport project. Conventional baseline configuration study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Characteristics of the U.S. domestic fleet were evaluated to determine the mission characteristics that would have the most impact on U. S. transport fuel use in the future. This resulted in selection of a 197-passenger (plus cargo), about 3710-km (2000 nmi) mission. The existing data base was reviewed and additional analysis was conducted as necessary to complete the technical descriptions. The resulting baseline configuration utilizes a double-lobe, but nearly circular, body with seven-abreast seating. External characteristics feature an 8.71 aspect ratio, 31.5-degree sweep wing, a T-tail empennage, and a dual CF6-6D2, wing-mounted engine arrangement. It provides for 22 LD-2 or 11 LD-3 containers plus bulk cargo in the lower lobe. Passenger/cargo loading, servicing provisions, taxi/takeoff speeds, and field length characteristics are all compatible with accepted airline operations and regulatory provisions. The baseline configuration construction uses conventional aluminum structure except for advanced aluminum alloys and a limited amount of graphite epoxy secondary structure. Modern systems are used, including advanced guidance, navigation, and controls which emphasize application of digital electronics and advanced displays.

  4. Passive vs. Active Control of Rhythmic Ball Bouncing: The Role of Visual Information

    ERIC Educational Resources Information Center

    Siegler, Isabelle A.; Bardy, Benoit G.; Warren, William H.

    2010-01-01

    The simple task of bouncing a ball on a racket offers a model system for studying how human actors exploit the physics and information of the environment to control their behavior. Previous work shows that people take advantage of a passively stable solution for ball bouncing but can also use perceptual information to actively stabilize bouncing.…

  5. Active control of primary mirror of an orbiting telescope with thermal excitation

    NASA Technical Reports Server (NTRS)

    Hill, J. L.; Youngblood, J. N.

    1973-01-01

    The results of a study of the feasibility of an active method of surface error control using thermal elements are presented. It is shown that the control effort of the thermal elements is sufficient for the purpose, and that such benefits as low cost, low weight, and high reliability may be achieved in conjunction with a significant reduction in the mirror surface error figure.

  6. Analysis of frequency noise in ultra-stable optical oscillators with active control of residual amplitude modulation

    NASA Astrophysics Data System (ADS)

    Li, Liufeng; Shen, Hui; Bi, Jin; Wang, Chun; Lv, Shasha; Chen, Lisheng

    2014-12-01

    Two 1,064-nm Nd:YAG lasers frequency stabilized by high-finesse optical cavities are developed to investigate various noise mechanisms in ultra-stable optical oscillators. Active control of residual amplitude modulation using a separate sensing path is implemented and its effectiveness in the presence of a resonant optical cavity is theoretically analyzed and experimentally verified by measuring the rejection ratios in optical heterodyne beat between a perturbed laser and a stable reference. Laser frequency noises originated from vibration, residual amplitude modulation, quantum-limited shot noise, and electronic noise are experimentally analyzed. With active control, residual amplitude modulation is suppressed to below 1 × 10-6 at 0.02-1,000 s, reaching a minimum of 2 × 10-7 at ~2 s. A frequency stability of 2 × 10-15 is obtained from 0.1 to 10 s, and the optical heterodyne beat of the two Nd:YAG lasers shows 1-Hz linewidth with a measurement time of 4.096 s. In addition, the experimentally determined linewidths agree well with the calculation according to a simplified relationship between the linewidth and the underlying flicker noise that modulates the laser frequency.

  7. Analysis of frequency noise in ultra-stable optical oscillators with active control of residual amplitude modulation

    NASA Astrophysics Data System (ADS)

    Li, Liufeng; Shen, Hui; Bi, Jin; Wang, Chun; Lv, Shasha; Chen, Lisheng

    2014-09-01

    Two 1,064-nm Nd:YAG lasers frequency stabilized by high-finesse optical cavities are developed to investigate various noise mechanisms in ultra-stable optical oscillators. Active control of residual amplitude modulation using a separate sensing path is implemented and its effectiveness in the presence of a resonant optical cavity is theoretically analyzed and experimentally verified by measuring the rejection ratios in optical heterodyne beat between a perturbed laser and a stable reference. Laser frequency noises originated from vibration, residual amplitude modulation, quantum-limited shot noise, and electronic noise are experimentally analyzed. With active control, residual amplitude modulation is suppressed to below 1 × 10-6 at 0.02-1,000 s, reaching a minimum of 2 × 10-7 at ~2 s. A frequency stability of 2 × 10-15 is obtained from 0.1 to 10 s, and the optical heterodyne beat of the two Nd:YAG lasers shows 1-Hz linewidth with a measurement time of 4.096 s. In addition, the experimentally determined linewidths agree well with the calculation according to a simplified relationship between the linewidth and the underlying flicker noise that modulates the laser frequency.

  8. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Final ACT configuration evaluation

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The Final ACT Configuration Evaluation Task of the Integrated Application of Active Controls (IAAC) technology project within the energy efficient transport program is summarized. The Final ACT Configuration, through application of Active Controls Technology (ACT) in combination with increased wing span, exhibits significant performance improvements over the conventional baseline configuration. At the design range for these configurations, 3590 km, the block fuel used is 10% less for the Final ACT Configuration, with significant reductions in fuel usage at all operational ranges. Results of this improved fuel usage and additional system and airframe costs and the complexity required to achieve it were analyzed to determine its economic effects. For a 926 km mission, the incremental return on investment is nearly 25% at 1980 fuel prices. For longer range missions or increased fuel prices, the return is greater. The technical risks encountered in the Final ACT Configuration design and the research and development effort required to reduce these risks to levels acceptable for commercial airplane design are identified.

  9. Immobilization of Yarrowia lipolytica lipase Ylip2 for the biocatalytic synthesis of phytosterol ester in a water activity controlled reactor.

    PubMed

    Cui, Caixia; Guan, Nan; Xing, Chen; Chen, Biqiang; Tan, Tianwei

    2016-10-01

    In this work, phytosterol ester was synthesized using Yarrowia lipolytica lipase Ylip2 that had been immobilized on inorganic support in a solvent-free system and reacted in a computer-aided water activity controlled bioreactor. The immobilization of Ylip2 on celite led to a remarkable increase in the phytosterol conversion compared to that of free lipase. An investigation of the reaction conditions were oleic acid as the fatty acid variety, 10,000U/g substrate, and a temperature of 50°C for phytosterol ester synthesis. Controlling of the water activity at a set point was accomplished by the introduction of dry air through the reaction medium at a digital feedback controlled flow rate. For the esterification of phytosterol ester, a low (15%) water activity resulted in a considerable improvement in phytosterol conversion (91.1%) as well as a decreased reaction time (78h). Furthermore, Ylip2 lipase immobilized on celite retained 90% esterification activity for the synthesis of phytosterol oleate after reused 8 cycles, while free lipase was only viable for 5 batches with 90% esterification activity remained. Finally, the phytosterol oleate space time yield increased from 1.65g/L/h with free lipase to 2.53g/L/h with immobilized lipase. These results illustrate that the immobilized Yarrowia lipolytica lipase Ylip2 in a water activity controlled reactor has great potential for the application in phytosterol esters synthesis. PMID:27416561

  10. Structural Acoustic Characteristics of Aircraft and Active Control of Interior Noise

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1998-01-01

    The reduction of aircraft cabin sound levels to acceptable values still remains a topic of much research. The use of conventional passive approaches has been extensively studied and implemented. However performance limits of these techniques have been reached. In this project, new techniques for understanding the structural acoustic behavior of aircraft fuselages and the use of this knowledge in developing advanced new control approaches are investigated. A central feature of the project is the Aircraft Fuselage Test Facility at Va Tech which is based around a full scale Cessna Citation III fuselage. The work is divided into two main parts; the first part investigates the use of an inverse technique for identifying dominant fuselage vibrations. The second part studies the development and implementation of active and active-passive techniques for controlling aircraft interior noise.

  11. Attenuation of empennage buffet response through active control of damping using piezoelectric material

    NASA Technical Reports Server (NTRS)

    Heeg, Jennifer; Miller, Jonathan M.; Doggett, Robert V., Jr.

    1993-01-01

    Dynamic response and damping data obtained from buffet studies conducted in a low-speed wind tunnel by using a simple, rigid model attached to spring supports are presented. The two parallel leaf spring supports provided a means for the model to respond in a vertical translation mode, thus simulating response in an elastic first bending mode. Wake-induced buffeting flow was created by placing an airfoil upstream of the model of that the wake of the airfoil impinged on the model. Model response was sensed by a strain gage mounted on one of the springs. The output signal from the strain gage was fed back through a control law implemented on a desktop computer. The processed signals were used to 'actuate' a piezoelectric bending actuator bonded to the other spring in such a way as to add damping as the model responded. The results of this 'proof-of-concept' study show that the piezoelectric actuator was effective in attenuating the wake-induced buffet response over the range of parameters investigated.

  12. Linearized Model of an Actively Controlled Cable for a Carlina Diluted Telescope

    NASA Astrophysics Data System (ADS)

    Andersen, T.; Le Coroller, H.; Owner-Petersen, M.; Dejonghe, J.

    2014-04-01

    The Carlina thinned pupil telescope has a focal unit (``gondola'') suspended by cables over the primary mirror. To predict the structural behavior of the gondola system, a simulation building block of a single cable is needed. A preloaded cable is a strongly non-linear system and can be modeled either with partial differential equations or non-linear finite elements. Using the latter, we set up an iteration procedure for determination of the static cable form and we formulate the necessary second-order differential equations for such a model. We convert them to a set of first-order differential equations (an ``ABCD''-model). Symmetrical in-plane eigenmodes and ``axial'' eigenmodes are the only eigenmodes that play a role in practice for a taut cable. Using the model and a generic suspension, a parameter study is made to find the influence of various design parameters. We conclude that the cable should be as stiff and thick as practically possible with a fairly high preload. Steel or Aramid are suitable materials. Further, placing the cable winches on the gondola and not on the ground does not provide significant advantages. Finally, it seems that use of reaction-wheels and/or reaction-masses will make the way for more accurate control of the gondola position under wind load. An adaptive stage with tip/tilt/piston correction for subapertures together with a focus and guiding system for freezing the fringes must also be studied.

  13. Efficiency improvement of a new vertical axis wind turbine by individual active control of blade motion

    NASA Astrophysics Data System (ADS)

    Hwang, In Seong; Min, Seung Yong; Jeong, In Oh; Lee, Yun Han; Kim, Seung Jo

    2006-03-01

    In this paper, a research for the performance improvement of the straight-bladed vertical axis wind turbine is described. To improve the performance of the power generation system, which consists of several blades rotating about axis in parallel direction, the cycloidal blade system and the individual active blade control system are adopted, respectively. Both methods are variable pitch system. For cycloidal wind turbine, aerodynamic analysis is carried out by changing pitch angle and phase angle based on the cycloidal motion according to the change of wind speed and wind direction, and control mechanism using the cycloidal blade system is realized for 1kw class wind turbine. By this method, electrical power is generated about 30% higher than wind turbine using fixed pitch angle method. And for more efficient wind turbine, individual pitch angle control of each blade is studied. By maximizing the tangential force in each rotating blade at the specific rotating position, optimal pitch angle variation is obtained. And several airfoil shapes of NACA 4-digit and NACA 6-series are studied. Aerodynamic analysis shows performance improvement of 60%. To realize this motion, sensing and actuating system is designed.

  14. Preparation time modulates pro-active control and enhances task conflict in task switching.

    PubMed

    Kalanthroff, Eyal; Henik, Avishai

    2014-03-01

    Performance in the Stroop task reflects two conflicts--informational (between the incongruent word and ink color) and task (between relevant color naming and irrelevant word reading). Neuroimaging findings support the existence of task conflict in congruent trials. A behavioral indication for task conflict--Stroop reverse facilitation--was found in previous studies under low task-control conditions. Task switching also causes reduction in task control because the task set frequently changes. We hypothesized that it would be harder to efficiently manage task conflicts in switching situations and, specifically, as cue-target interval (CTI) decreases. This suggestion was examined in two experiments using a combined Stroop task-switching design. We found a large interference effect and reverse facilitation that decreased with elongation of CTI. Results imply that task switching reduces pro-active task control and thereby enhances the informational and the task conflicts. This calls for a revision of recent control models to include task conflict. PMID:23712333

  15. Active control of a large deformable mirror for future E-ELT

    NASA Astrophysics Data System (ADS)

    Gasmi, R.; Le Bihan, D.; Dournaux, J. L.; Sinquin, J. C.; Jagourel, P.

    2010-07-01

    Increasing dimensions of ground based telescopes and adaptive optics needs for these instruments require wide deformable mirrors with a high number of actuators to compensate the effects of the atmospheric turbulence on the wave fronts. The new dimensions and characteristics of these deformable mirrors lead to the apparition of structural vibrations, which may reduce the rejection band width of the adaptive optics control loop. The aim of this paper is the study of the dynamic behavior of a 1-meter prototype of E-ELT's deformable mirror in order to identify its eigenmodes and to propose some ways to control its vibrations. We first present the first eigenmodes of the structure determined by both finite element analysis and experimental modal analysis. Then we present the frequency response of the prototype to a tilt excitation to estimate the effects of its vibrations on the adaptive optics loop. Finally we suggest a method to control the dynamics of the deformable mirror.

  16. Effect of Baduanjin exercise on cognitive function in older adults with mild cognitive impairment: study protocol for a randomised controlled trial

    PubMed Central

    Zheng, Guohua; Huang, Maomao; Li, Shuzhen; Li, Moyi; Xia, Rui; Zhou, Wenji; Tao, Jing; Chen, Lidian

    2016-01-01

    Introduction Mild cognitive impairment (MCI) is an intermediate stage between the cognitive changes of normal aging and dementia characterised by a reduction in memory and/or other cognitive processes. An increasing number of studies have indicated that regular physical activity/exercise may have beneficial association with cognitive function of older adults with or without cognitive impairment. As a traditional Chinese Qigong exercise, Baduanjin may be even more beneficial in promoting cognitive ability in older adults with MCI, but the evidence is still insufficient. The main purpose of this study is to investigate the effect of Baduanjin exercise on neuropsychological outcomes of community-dwelling older adults with MCI, and to explore its mechanism of action from neuroimaging based on functional MRI (fMRI) and cerebrovascular function. Methods and analysis The design of this study is a randomised, controlled trial with three parallel groups in a 1:1:1 allocation ratio with allocation concealment and assessor blinding. A total of 135 participants will be enrolled and randomised to the 24-week Baduanjin exercise intervention, 24-week brisk walking intervention and 24-week usual physical activity control group. Global cognitive function and the specific domains of cognition (memory, processing speed, executive function, attention and verbal learning and memory) will be assessed at baseline and 9, 17, 25 and 37 weeks after randomisation, while the structure and function of brain regions related to cognitive function and haemodynamic variables of the brain will be measured by fMRI and transcranial Doppler, respectively, at baseline and 25 and 37 weeks after randomisation. Ethics and dissemination Ethics approval was given by the Medical Ethics Committee of the Second People's Hospital of Fujian Province (approval number 2014-KL045-02). The findings will be disseminated through peer-reviewed publications and at scientific conferences. Trial registration number

  17. Reduced-order modeling and active control of dry-low-emission combustion

    NASA Astrophysics Data System (ADS)

    Yi, Tongxun

    This dissertation is a complementary experimental and theoretical investigation of combustion instability and lean blowout (LBO) in dry-low-emission (DLE) gas turbine engines, aiming to understand the fundamental mechanisms and shed light on active combustion control. Combustion instability involves complicated physicochemical processes, and many of the underlying mechanisms remain unknown, despite extensive research in the past several decades. A practical control system must be able to achieve satisfactory control performances in the presence of large uncertainties, large variations, and even unknown system dynamics. Toward this goal, an observer-based controller, capable of attenuating multiple unstable modes with unknown characteristics, is developed. A mechanism suitable for online prediction of the safety margin to the onset of combustion instability is presented, which does not require knowing the unstable frequencies. The shortage of a reliable, high-frequency, proportional fuel actuator is a major technical challenge for active combustion control. A complementary theoretical and experimental study is performed on a pump-style, high-frequency, magnetostrictive fuel actuator. Improvements to the fuel setup have been made according to the model predictions, which have been experimentally shown to be beneficial to combustion instability control. The second part of this dissertation is about modeling, prediction, and control of lean blowout. The experimentally observed, "intensified", low frequency, near-LBO combustion oscillations have been used as incipient LBO precursors, and are characterized as low-dimension chaotic behavior in the present study. The normalized chemiluminescence RMS and the normalized cumulative duration of LBO precursor events are recommended for LBO prediction in generic gas turbine engines. Linear stability analysis shows that, with decreasing equivalence ratios, a complex conjugate pair of eigenvalues emerges from three negative real

  18. From tunable core-shell nanoparticles to plasmonic drawbridges: Active control of nanoparticle optical properties

    PubMed Central

    Byers, Chad P.; Zhang, Hui; Swearer, Dayne F.; Yorulmaz, Mustafa; Hoener, Benjamin S.; Huang, Da; Hoggard, Anneli; Chang, Wei-Shun; Mulvaney, Paul; Ringe, Emilie; Halas, Naomi J.; Nordlander, Peter; Link, Stephan; Landes, Christy F.

    2015-01-01

    The optical properties of metallic nanoparticles are highly sensitive to interparticle distance, giving rise to dramatic but frequently irreversible color changes. By electrochemical modification of individual nanoparticles and nanoparticle pairs, we induced equally dramatic, yet reversible, changes in their optical properties. We achieved plasmon tuning by oxidation-reduction chemistry of Ag-AgCl shells on the surfaces of both individual and strongly coupled Au nanoparticle pairs, resulting in extreme but reversible changes in scattering line shape. We demonstrated reversible formation of the charge transfer plasmon mode by switching between capacitive and conductive electronic coupling mechanisms. Dynamic single-particle spectroelectrochemistry also gave an insight into the reaction kinetics and evolution of the charge transfer plasmon mode in an electrochemically tunable structure. Our study represents a highly useful approach to the precise tuning of the morphology of narrow interparticle gaps and will be of value for controlling and activating a range of properties such as extreme plasmon modulation, nanoscopic plasmon switching, and subnanometer tunable gap applications. PMID:26665175

  19. Substrate lability and plant activity controls greenhouse gas release from Neotropical peatland

    NASA Astrophysics Data System (ADS)

    Sjogersten, Sofie; Hoyos, Jorge; Lomax, Barry; Turner, Ben; Wright, Emma

    2014-05-01

    Almost one third of global CO2 emissions resulting from land use change and substantial CH4 emissions originate from tropical peatlands. However, our understanding of the controls of CO2 and CH4 release from tropical peatlands are limited. The aim of this study was to investigate the role of peat lability and the activity of the vegetation on gas release using a combination of field and laboratory experiments. We demonstrated that peat lability constrained CH4 production to the surface peat under anaerobic conditions. The presence of plants shifted the C balance from a C source to a C sink with respect to CO2 while the activity of the root system strongly influenced CH4 emissions through its impact on soil O2 inputs. Both field and laboratory data suggest a coupling between the photosynthetic activity of the vegetation and the release of both CO2 and CH4 following the circadian rhythm of the dominant plant functional types. Forest clearance for agriculture resulted in elevated CH4 release, which we attribute in part to the cessation of root O2 inputs to the peat. We conclude that high emissions of CO2 and CH4 from forested tropical peatlands are likely driven by labile C inputs from the vegetation but that root O2 release may limit CH4 emissions.

  20. PLIF Visualization of Active Control of Hypersonic Boundary Layers Using Blowing

    NASA Technical Reports Server (NTRS)

    Bathel, Brett F.; Danehy, Paul M.; Inman, Jennifer A.; Alderfer, David W.; Berry, Scott A.

    2008-01-01

    Planar laser-induced fluorescence (PLIF) imaging was used to visualize the boundary layer flow on a 1/3-scale Hyper-X forebody model. The boundary layer was perturbed by blowing out of orifices normal to the model surface. Two blowing orifice configurations were used: a spanwise row of 17-holes spaced at 1/8 inch, with diameters of 0.020 inches and a single-hole orifice with a diameter of 0.010 inches. The purpose of the study was to visualize and identify laminar and turbulent structures in the boundary layer and to make comparisons with previous phosphor thermography measurements of surface heating. Jet penetration and its influence on the boundary layer development was also examined as was the effect of a compression corner on downstream boundary layer transition. Based upon the acquired PLIF images, it was determined that global surface heating measurements obtained using the phosphor thermography technique provide an incomplete indicator of transitional and turbulent behavior of the corresponding boundary layer flow. Additionally, the PLIF images show a significant contribution towards transition from instabilities originating from the underexpanded jets. For this experiment, a nitric oxide/nitrogen mixture was seeded through the orifices, with nitric oxide (NO) serving as the fluorescing gas. The experiment was performed in the 31-inch Mach 10 Air Tunnel at NASA Langley Research Center.

  1. Glow Discharge Plasma Active Control of Separation at Low Pressure Turbine Conditions.

    NASA Astrophysics Data System (ADS)

    Hultgren, Lennart S.; Ashpis, David E.

    2002-11-01

    Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modern low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2%) and high (2.5%) free-stream turbulence intensities are set using passive grids. The base flow includes closed separation bubbles and non-reattaching separated flow, and is thoroughly documented using single-wire constant-temperature anemometry and static surface pressure measurements. A spanwise-oriented phased-plasma-array actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the controlled flow are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control.

  2. Active control of panel vibrations induced by a boundary layer flow

    NASA Technical Reports Server (NTRS)

    Chow, Pao-Liu

    1995-01-01

    The problems of active and passive control of sound and vibration has been investigated by many researchers for a number of years. However, few of the articles are concerned with the sound and vibration with flow-structure interaction. Experimental and numerical studies on the coupling between panel vibration and acoustic radiation due to flow excitation have been done by Maestrello and his associates at NASA/Langley Research Center. Since the coupled system of nonlinear partial differential equations is formidable, an analytical solution to the full problem seems impossible. For this reason, we have to simplify the problem to that of the nonlinear panel vibration induced by a uniform flow or a boundary-layer flow with a given wall pressure distribution. Based on this simplified model, we have been able to consider the control and stabilization of the nonlinear panel vibration, which have not been treated satisfactorily by other authors. Although the sound radiation has not been included, the vibration suppression will clearly reduce the sound radiation power from the panel. The major research findings are presented in three sections. In section two we describe results on the boundary control of nonlinear panel vibration, with or without flow excitation. Sections three and four are concerned with some analytical and numerical results in the optimal control of the linear and nonlinear panel vibrations, respectively, excited by the flow pressure fluctuations. Finally, in section five, we draw some conclusions from research findings.

  3. Design of an actively controlled steerable needle with tendon actuation and FBG-based shape sensing.

    PubMed

    van de Berg, Nick J; Dankelman, Jenny; van den Dobbelsteen, John J

    2015-06-01

    This work presents a new steerable needle to facilitate active steering toward predefined target locations. It focuses on mechanical aspects and design choices in relation to the observed response in a tissue phantom. Tip steering with two rotational degrees of freedom was achieved by a tendon actuated ball joint mechanism. During insertion, the flexible cannula bends as a result of asymmetric tip-tissue interaction forces. The stylet was equipped with fiber Bragg gratings to measure the needle shape and tip position during use. A PI-controller was implemented to facilitate steering to predefined targets. During the validation study, nine targets were defined at a depth of 100 mm below the gelatin surface. One was located below the insertion point, the others at a radial offset of 30 mm in each of the eight principle steering directions. Per location, six repetitions were performed. The targeting accuracy was 6.2 ± 1.4 mm (mean ± std). The steering precision was 2.6 ± 1.1 mm. The ability to steer with this new needle steering approach is presented and the mechanical characteristics are discussed for this representative subset of steering directions. PMID:25922213

  4. [Behavior of various activity-controlled cardiac pacemakers in treadmill stress tests with variable slopes].

    PubMed

    Matula, M; Hölzer, K; Zitzmann, E; Schön, H; Alt, E

    1993-02-01

    New activity pacemaker systems with the principle of sensing low-frequency acceleration in the anterior-posterior axis are currently under clinical evaluation. We compared the pacemaker system Relay, which represents this new generation of accelerometer controlled devices, with conventional activity systems sensing pressure and vibration. Ten pacemaker patients with implanted Activitrax, Sensolog or Relay pacemakers and 10 healthy volunteers with externally strapped-on pacemakers were studied. The aim was to evaluate the systems' ability to distinguish different workloads during graded treadmill testing with changes in speed and/or slope. The rate adaption of the new acceleration sensing pacemakers was found to be more adequate compared to vibration and pressure-sensing pacemakers when only the slope of the treadmill was varied. The acceleration-sensing pacemaker adjusted its rate according to the workload largely independent from the type of stress (n.s.). With the vibration and pressure-sensing pacemakers, however, significant differences (p < 0.05) were seen between rate adaption in the two stress test modes. The new generation of acceleration-sensing pacemakers has certain advantages over conventional vibration-sensitive systems in terms of a higher sensitivity to varying workloads and higher specificity to the type of exercise performed. PMID:8465563

  5. High Temperature Superconducting Magnets with Active Control for Attraction Levitation Transport Applications

    NASA Technical Reports Server (NTRS)

    Jones, Harry; Jenkins, Richard G.; Goodall, Roger M.; Macleod, Colin; ElAbbar, Abdallah A.; Campbell, Archie M.

    1996-01-01

    A research program, involving 3 British universities, directed at quantifying the controllability of High Temperature Superconducting (HTS) magnets for use in attraction levitation transport systems will be described. The work includes measurement of loss mechanisms for iron cored HTS magnets which need to produce a flux density of approx. 1 tesla in the airgap between the magnet poles and a ferromagnetic rail. This flux density needs to be maintained and this is done by introducing small variations of the magnet current using a feedback loop, at frequencies up to 10 Hz to compensate for load changes, track variation etc. The test magnet assemblies constructed so far will be described and the studies and modelling of designs for a practical levitation demonstrator (using commercially obtained HTS tape) will be discussed with particular emphasis on how the field distribution and its components, e.g., the component vector normal to the broad face of the tape, can radically affect design philosophy compared to the classical electrical engineering approach. Although specifically aimed at levitation transport the controllability data obtained have implications for a much wider range of applications.

  6. Deriving plasma densities in tenuous plasma regions, with the spacecraft potential under active control

    NASA Astrophysics Data System (ADS)

    Andriopoulou, M.; Nakamura, R.; Torkar, K.; Baumjohann, W.; Hoelzl, B.

    2015-11-01

    Variations of the floating potential on spacecraft are often used to derive plasma densities, complementing the plasma instrument measurements. All spacecraft of the Cluster mission are equipped with Active Spacecraft POtential Control (ASPOC) instruments that control the spacecraft potential. Although the ASPOC operation increases the accuracy of electric field and plasma measurements, it prevents a direct use of the spacecraft potential variations to derive plasma densities. In this work we develop a new reconstruction method of uncontrolled spacecraft potential from controlled spacecraft potential data and a derived photoelectron curve, using multispacecraft observations. We assume that the same curve governs the plasma environment for the spacecraft with ASPOC on and off. The current work focuses on reconstructions in the magnetotail region. The period that was more extensively studied was the one from August to October 2003, when the spacecraft were close to each other, while results from the periods of August-October 2001, 2002, and 2004, when the Cluster spacecraft had their apogee in the magnetotail region, are also presented. In this way, we investigate how the photoelectron curve varies at different time intervals and also how the reconstruction results are modified when the distance between the spacecraft is increasing. Finally, by using the reconstructed results, we proceed by estimating the plasma densities and we discuss the uncertainties of such estimations. While, on average, spacecraft potential measurements are successfully reconstructed, plasma and solar activity variations on short timescales seem to affect the reconstructions, requiring in some cases more detailed analysis in order to achieve results with higher accuracy. Moreover, there are some limitations while deriving results in very tenuous plasma regions due to increased uncertainties in some of the scientific measurements used there. The results and the methods developed for this work

  7. Effects of Elevated Free-Stream Turbulence on Active Control of a Separation Bubble

    NASA Technical Reports Server (NTRS)

    Ashpis, D. (Technical Monitor); Halfon, E.; Nishri, B.; Seifert, A.; Wygnanski, I.

    2004-01-01

    The Effects of elevated free-stream turbulence (FST) on the natural and periodically excited separation bubbles were studied experimentally, due to the relevance of this flow to low-pressure turbine blades at low Reynolds numbers. A bubble was formed at the leading edge of a flat plate and the FST level was altered by placing a grid across the flow at different locations upstream of the plate. The mixing across the separated shear-layer, forming the free boundary of the bubble, increased due to the elevated FST and due to nominally two-dimensional periodic excitation, both flattening and shortening the bubble. Periodic excitation at frequencies that were at least an order of magnitude lower than those associated with the initial shear-layer instability, were very effective at low FST, because the amplitudes of the excitation frequency and its harmonic were amplified over the bubble. High frequency excitation (F+ 3, based on the length of the baseline low FST bubble) had a major effect close to the separation location, while farther downstream the excited fluctuations rapidly decayed in the reattachment region. Low frequency excitation, that generated waves comparable to the length of the unperturbed bubble (F+ 1) were less effective and their magnitude decayed at a slower rate downstream of reattachment. An increase in the level of the FST reduced the net effect of the periodic excitation on the mixing enhancement and subsequent reattachment process, probably due to a destructive interference between the nominally 2D excitation and the random (in space and time) FST, reducing the spanwise coherence and therefore the effectiveness of the current control strategy. However, even at the reduced effectiveness of 2D periodic excitation at elevated FST, it accelerated the reattachment process and the recovery rate of the reattached boundary layer, enhancing the boundary layer resistance to repeat separation and reducing its momentum loss further downstream.

  8. Low-dimensional techniques for active control of high-speed jet aeroacoustics

    NASA Astrophysics Data System (ADS)

    Pinier, Jeremy

    The present study is focused on the development of an empirical low-order dynamical system (LODS) of a Mach 0.6 high-speed axisymmetric jet to be ultimately used for closed-loop flow control. An identification method is implemented to solve for the coefficients of the ordinary differential equation (ODE) describing the evolution of the flow. This ODE is derived from a Galerkin projection of the Navier-Stokes equations onto a basis of proper orthogonal decomposition (POD) eigenfunctions. An extensive database of the velocity and acceleration fields is therefore needed to be used as "training" data for the dynamical system. A dual-time particle image velocimetry (DT-PIV) experiment is designed and carried out to measure velocity and Eulerian acceleration in cross-flow planes from 3 to 10 jet diameters downstream. The setup comprises two stereoscopic PIV systems that sample velocity at two consecutive instants, the time separation being carefully chosen to resolve the scales of interest in the flow. POD is applied and the resulting low order dynamical system is exposed and its dynamics are validated against data previously measured in this flow. A preliminary experiment measuring and correlating the near-field to the far-field pressure is carried out to identify the most sound productive region in the jet, where the DT-PIV experiment focuses, and to give insight into the nature of the propagative sound sources. The results of this experiment lead to the understanding that the axisymmetric mode (azimuthal Fourier mode 0) of the near pressure field is the best propagator to the far-field, which can guide flow control strategies for noise reduction. With this result in mind, synthetic-jet based actuators are designed to be able to provide hydrodynamic perturbations at the nozzle exit to exploit the non-propagative nature of the higher azimuthal modes. The three main aspects of this work (dynamical system development, sound source identification and flow control device

  9. Weak-light rogue waves, breathers, and their active control in a cold atomic gas via electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Liu, Junyang; Hang, Chao; Huang, Guoxiang

    2016-06-01

    We propose a scheme to demonstrate the existence of optical Peregrine rogue waves and Akhmediev and Kuznetsov-Ma breathers and realize their active control via electromagnetically induced transparency (EIT). The system we suggest is a cold, Λ -type three-level atomic gas interacting with a probe and a control laser fields and working under EIT condition. We show that, based on EIT with an incoherent optical pumping, which can be used to cancel optical absorption, (1+1)-dimensional optical Peregrine rogue waves, Akhmediev breathers, and Kuznetsov-Ma breathers can be generated with very low light power. In addition, we demonstrate that the Akhmediev and Kuznetsov-Ma breathers in (2+1)-dimensions obtained can be actively manipulated by using an external magnetic field. As a result, these breathers can display trajectory deflections and bypass obstacles during propagation.

  10. Robotic Arm Manipulator Using Active Control for Sample Acquisition and Transfer, and Passive Mode for Surface Compliance

    NASA Technical Reports Server (NTRS)

    Liu, Jun; Underhill, Michael L.; Trease, Brian P.; Lindemann, Randel A.

    2010-01-01

    A robotic arm that consists of three joints with four degrees of freedom (DOF) has been developed. It can carry an end-effector to acquire and transfer samples by using active control and comply with surface topology in a passive mode during a brief surface contact. The three joints are arranged in such a way that one joint of two DOFs is located at the shoulder, one joint of one DOF is located at the elbow, and one joint of one DOF is located at the wrist. Operationally, three DOFs are moved in the same plane, and the remaining one on the shoulder is moved perpendicular to the other three for better compliance with ground surface and more flexibility of sample handling. Three out of four joints are backdriveable, making the mechanism less complex and more cost effective

  11. Final design and fabrication of an active control system for flutter suppression on a supercritical aeroelastic research wing

    NASA Technical Reports Server (NTRS)

    Hodges, G. E.; Mcgehee, C. R.

    1981-01-01

    The final design and hardware fabrication was completed for an active control system capable of the required flutter suppression, compatible with and ready for installation in the NASA aeroelastic research wing number 1 (ARW-1) on Firebee II drone flight test vehicle. The flutter suppression system uses vertical acceleration at win buttock line 1.930 (76), with fuselage vertical and roll accelerations subtracted out, to drive wing outboard aileron control surfaces through appropriate symmetric and antisymmetric shaping filters. The goal of providing an increase of 20 percent above the unaugmented vehicle flutter velocity but below the maximum operating condition at Mach 0.98 is exceeded by the final flutter suppression system. Results indicate that the flutter suppression system mechanical and electronic components are ready for installation on the DAST ARW-1 wing and BQM-34E/F drone fuselage.

  12. Active control of massively separated high-speed/base flows with electric arc plasma actuators

    NASA Astrophysics Data System (ADS)

    DeBlauw, Bradley G.

    The current project was undertaken to evaluate the effects of electric arc plasma actuators on high-speed separated flows. Two underlying goals motivated these experiments. The first goal was to provide a flow control technique that will result in enhanced flight performance for supersonic vehicles by altering the near-wake characteristics. The second goal was to gain a broader and more sophisticated understanding of these complex, supersonic, massively-separated, compressible, and turbulent flow fields. The attainment of the proposed objectives was facilitated through energy deposition from multiple electric-arc plasma discharges near the base corner separation point. The control authority of electric arc plasma actuators on a supersonic axisymmetric base flow was evaluated for several actuator geometries, frequencies, forcing modes, duty cycles/on-times, and currents. Initially, an electric arc plasma actuator power supply and control system were constructed to generate the arcs. Experiments were performed to evaluate the operational characteristics, electromagnetic emission, and fluidic effect of the actuators in quiescent ambient air. The maximum velocity induced by the arc when formed in a 5 mm x 1.6 mm x 2 mm deep cavity was about 40 m/s. During breakdown, the electromagnetic emission exhibited a rise and fall in intensity over a period of about 340 ns. After breakdown, the emission stabilized to a near-constant distribution. It was also observed that the plasma formed into two different modes: "high-voltage" and "low-voltage". It is believed that the plasma may be switching between an arc discharge and a glow discharge for these different modes. The two types of plasma do not appear to cause substantial differences on the induced fluidic effects of the actuator. In general, the characterization study provided a greater fundamental understanding of the operation of the actuators, as well as data for computational model comparison. Preliminary investigations

  13. Design, construction, and operation of an actively controlled deep-sea CO2 enrichment experiment using a cabled observatory system

    NASA Astrophysics Data System (ADS)

    Kirkwood, William J.; Walz, Peter M.; Peltzer, Edward T.; Barry, James P.; Herlien, Robert A.; Headley, Kent L.; Kecy, Chad; Matsumoto, George I.; Maughan, Thom; O'Reilly, Thomas C.; Salamy, Karen A.; Shane, Farley; Brewer, Peter G.

    2015-03-01

    We describe the design, testing, and performance of an actively controlled deep-sea Free Ocean CO2 Enrichment (dp-FOCE) system for the execution of seafloor experiments relating to the impacts of ocean acidification on natural ecosystems. We used the 880 m deep MARS (Monterey Accelerated Research System) cable site offshore Monterey Bay, California for this work, but the Free Ocean CO2 Enrichment (FOCE) system concept is designed to be scalable and can be modified to be used in a wide variety of ocean depths and locations. The main frame is based on a flume design with active thruster control of flow and a central experimental chamber. The unit was allowed to free fall to the seafloor and connected to the cable node by remotely operated vehicle (ROV) manipulation. For operation at depth we designed a liquid CO2 containment reservoir which provided the CO2 enriched working fluid as ambient seawater was drawn through the reservoir beneath the more buoyant liquid CO2. Our design allowed for the significant lag time associated with the hydration of the dissolved CO2 molecule, resulting in an e-folding time, τ, of 97 s between fluid injection and pH sensing at the mean local T=4.31±0.14 °C and pHT of 7.625±0.011. The system maintained a pH offset of ~0.4 pH units compared to the surrounding ocean for a period of ~1 month. The unit allows for the emplacement of deep-sea animals for testing. We describe the components and software used for system operation and show examples of each. The demonstrated ability for active control of experimental systems opens new possibilities for deep-sea biogeochemical perturbation experiments of several kinds and our developments in open source control systems software and hardware described here are applicable to this end.

  14. Effects of actuator limits in bifurcation control with applications to active control of fluid instabilities in turbomachinery

    NASA Astrophysics Data System (ADS)

    Wang, Yong

    Bifurcations are ubiquitous in engineering applications. Subcritical bifurcations are typically associated with hysteresis and catastrophic instability inception, while supercritical bifurcations are usually associated with gradual and more benign instability inception. With the assumption that the bifurcating modes are linearly unstabilizable, we give a constructive procedure of designing feedback laws to change the criticality of bifurcations from subcritical to supercritical. Algebraic necessary and sufficient conditions are obtained under which the criticality of a simple steady-state or Hopf bifurcation can be changed to supercritical by a smooth feedback. The effects of magnitude saturation, bandwidth, and rate limits are important issues in control engineering. We give qualitative estimates of the region of attraction to the stabilized bifurcating equilibrium/periodic orbits under these constraints. We apply the above theoretical results to the Moore-Greitzer model in active control of rotating stall and surge in gas turbine engines. Though linear stabilizability can be achieved using distributed actuation, it limits the practical usefulness due to considerations of affordability and reliability. On the other hand, simple but practically promising actuation schemes such as outlet bleed valves, a couple of air injectors, and magnetic bearings will make the system loss of linear stabilizability, thus the control design becomes a challenging task. The above mentioned theory in bifurcation stabilization can be applied to these cases. We analyze the effects of magnitude and rate saturations in active control of rotating stall using bleed valves. Analytic formulas are obtained for the operability enhancement as a function of system parameters, noise level, and actuator magnitude and rate limits. The formulas give good qualitative predictions when compared with experiments. Our conclusion is that actuator magnitude and rate limits are serious limiting factors in

  15. Inappropriate statistical method in a parallel-group randomized controlled trial results in unsubstantiated conclusions.

    PubMed

    Dimova, Rositsa B; Allison, David B

    2016-01-01

    The conclusions of Cassani et al. in the January 2015 issue of Nutrition Journal (doi: 10.1186/1475-2891-14-5 ) cannot be substantiated by the analysis reported nor by the data themselves. The authors ascribed the observed decrease in inflammatory markers to the components of flaxseed and based their conclusions on within-group comparisons made between the final and the baseline measurements separately in each arm of the randomized controlled trial. However, this is an improper approach and the conclusions of the paper are invalid. A correct analysis of the data shows no such effects. PMID:27265269

  16. Fluoroscopic Caudal Epidural Injections in Managing Post Lumbar Surgery Syndrome: Two-Year Results of a Randomized, Double-Blind, Active-Control Trial

    PubMed Central

    Manchikanti, Laxmaiah; Singh, Vijay; Cash, Kimberly A.; Pampati, Vidyasagar; Datta, Sukdeb

    2012-01-01

    Study Design: A randomized, active control, double-blind trial. Objective: To evaluate the effectiveness of fluoroscopically directed caudal epidural injections with or without steroids in managing chronic low back and lower extremity pain secondary to post lumbar surgery syndrome. Summary of Background Data: There is a paucity of evidence concerning caudal epidural injections for managing chronic persistent low back pain with or without lower extremity pain caused by post lumbar surgery syndrome. Methods: This active control randomized study included 140 patients with 70 patients in each group. Group I received 0.5% lidocaine, 10 mL; Group II received 9 mL of 0.5% lidocaine mixed with 1 mL of 6 mg of nonparticulate betamethasone. The multiple outcome measures included the numeric rating scale, the Oswestry Disability Index 2.0, employment status, and opioid intake with assessments at 3, 6, 12, 18, and 24 months posttreatment. Primary outcome was defined as at least 50% improvement in pain and Oswestry Disability Index scores. Patients with a positive response to the first 2 procedures with at least 3 weeks of relief were considered to be successful. All others were considered as failures. Results: Overall in Group I, 53% and 47% of the patients and in Group II, 59% and 58% of the patients, showed significant improvement with reduction in pain scores and disability index at 12 months and 24 months. In contrast, in the successful groups, significant pain relief and improvement in function were observed in 70% and 62% of Group I at one and 2 years; in 75% and 69% of Group II at one and 2 years. The results in the successful group showed that at the end of the first year patients experienced approximately 38 weeks of relief and at the end of 2 years Group I had 62 weeks and Group II had 68 weeks of relief. Overall total relief for 2 years was 48 weeks in Group I and 54 weeks in Group II. The average procedures in the successful groups were at 4 in one year and 6 at

  17. Active control of convection

    SciTech Connect

    Bau, H.H.

    1995-12-31

    Using stability theory, numerical simulations, and in some instances experiments, it is demonstrated that the critical Rayleigh number for the bifurcation (1) from the no-motion (conduction) state to the motion state and (2) from time-independent convection to time-dependent, oscillatory convection in the thermal convection loop and Rayleigh-Benard problems can be significantly increased or decreased. This is accomplished through the use of a feedback controller effectuating small perturbations in the boundary data. The controller consists of sensors which detect deviations in the fluid`s temperature from the motionless, conductive values and then direct actuators to respond to these deviations in such a way as to suppress the naturally occurring flow instabilities. Actuators which modify the boundary`s temperature/heat flux are considered. The feedback controller can also be used to control flow patterns and generate complex dynamic behavior at relatively low Rayleigh numbers.

  18. Immunogenicity and safety assessment of a trivalent, inactivated split influenza vaccine in Korean children: Double-blind, randomized, active-controlled multicenter phase III clinical trial

    PubMed Central

    Han, Seung Beom; Rhim, Jung-Woo; Shin, Hye Jo; Lee, Soo Young; Kim, Hyun-Hee; Kim, Jong-Hyun; Lee, Kyung-Yil; Ma, Sang Hyuk; Park, Joon Soo; Kim, Hwang Min; Kim, Chun Soo; Kim, Dong Ho; Choi, Young Youn; Cha, Sung-Ho; Hong, Young Jin; Kang, Jin Han

    2015-01-01

    A multicenter, double-blind, randomized, active-control phase III clinical trial was performed to assess the immunogenicity and safety of a trivalent, inactivated split influenza vaccine. Korean children between the ages of 6 months and 18 y were enrolled and randomized into a study (study vaccine) or a control vaccine group (commercially available trivalent, inactivated split influenza vaccine) in a 5:1 ratio. Antibody responses were determined using hemagglutination inhibition assay, and post-vaccination immunogenicity was assessed based on seroconversion and seroprotection rates. For safety assessment, solicited local and systemic adverse events up to 28 d after vaccination and unsolicited adverse events up to 6 months after vaccination were evaluated. Immunogenicity was assessed in 337 and 68 children of the study and control groups. In the study vaccine group, seroconversion rates against influenza A/H1N1, A/H3N2, and B strains were 62.0% (95% CI: 56.8–67.2), 53.4% (95% CI: 48.1–58.7), and 54.9% (95% CI: 48.1–60.2), respectively. The corresponding seroprotection rates were 95.0% (95% CI: 92.6–97.3), 93.8% (95% CI: 91.2–96.4), and 95.3% (95% CI: 93.0–97.5). The lower 95% CI limits of the seroconversion and seroprotection rates were over 40% and 70%, respectively, against all strains. Seroconversion and seroprotection rates were not significantly different between the study and control vaccine groups. Furthermore, the frequencies of adverse events were not significantly different between the 2 vaccine groups, and no serious vaccination-related adverse events were noted. In conclusion, the study vaccine exhibited substantial immunogenicity and safety in Korean children and is expected to be clinically effective. PMID:25875868

  19. Immunogenicity and safety assessment of a trivalent, inactivated split influenza vaccine in Korean children: Double-blind, randomized, active-controlled multicenter phase III clinical trial.

    PubMed

    Han, Seung Beom; Rhim, Jung-Woo; Shin, Hye Jo; Lee, Soo Young; Kim, Hyun-Hee; Kim, Jong-Hyun; Lee, Kyung-Yil; Ma, Sang Hyuk; Park, Joon Soo; Kim, Hwang Min; Kim, Chun Soo; Kim, Dong Ho; Choi, Young Youn; Cha, Sung-Ho; Hong, Young Jin; Kang, Jin Han

    2015-01-01

    A multicenter, double-blind, randomized, active-control phase III clinical trial was performed to assess the immunogenicity and safety of a trivalent, inactivated split influenza vaccine. Korean children between the ages of 6 months and 18 y were enrolled and randomized into a study (study vaccine) or a control vaccine group (commercially available trivalent, inactivated split influenza vaccine) in a 5:1 ratio. Antibody responses were determined using hemagglutination inhibition assay, and post-vaccination immunogenicity was assessed based on seroconversion and seroprotection rates. For safety assessment, solicited local and systemic adverse events up to 28 d after vaccination and unsolicited adverse events up to 6 months after vaccination were evaluated. Immunogenicity was assessed in 337 and 68 children of the study and control groups. In the study vaccine group, seroconversion rates against influenza A/H1N1, A/H3N2, and B strains were 62.0% (95% CI: 56.8-67.2), 53.4% (95% CI: 48.1-58.7), and 54.9% (95% CI: 48.1-60.2), respectively. The corresponding seroprotection rates were 95.0% (95% CI: 92.6-97.3), 93.8% (95% CI: 91.2-96.4), and 95.3% (95% CI: 93.0-97.5). The lower 95% CI limits of the seroconversion and seroprotection rates were over 40% and 70%, respectively, against all strains. Seroconversion and seroprotection rates were not significantly different between the study and control vaccine groups. Furthermore, the frequencies of adverse events were not significantly different between the 2 vaccine groups, and no serious vaccination-related adverse events were noted. In conclusion, the study vaccine exhibited substantial immunogenicity and safety in Korean children and is expected to be clinically effective. PMID:25875868

  20. A comparative study of DA-9601 and misoprostol for prevention of NSAID-associated gastroduodenal injury in patients undergoing chronic NSAID treatment.

    PubMed

    Lee, Oh Young; Kang, Dae-Hwan; Lee, Dong Ho; Chung, Il-Kwun; Jang, Jae Young; Jang, Jae-Young; Kim, Jin-Il; Cho, Jin-Woong; Rew, Jong-Sun; Lee, Kang-Moon; Kim, Kyoung Oh; Choi, Myung-Gyu; Lee, Sang-Woo; Lee, Soo-Teik; Kim, Tae-Oh; Shin, Yong-Woon; Seol, Sang-Yong

    2014-10-01

    Misoprostol is reported to prevent non-steroidal anti-inflammatory drug (NSAID)-associated gastroduodenal complications. There is, however, limited information regarding the efficacy of DA-9601 in this context. We performed a comparative study on the relative efficacy of DA-9601 and misoprostol for prevention of NSAID-associated complications. In this multicenter, double-blinded, active-controlled, stratified randomized, parallel group, non-inferiority trial, 520 patients who were to be treated with an NSAID (aceclofenac, 100 mg, twice daily) over a 4-week period were randomly assigned to groups for coincidental treatment with DA-9601 (60 mg, thrice daily) (236 patients for full analysis) or misoprostol (200 μg, thrice daily) (242 patients for full analysis). [corrected]. The primary endpoint was the gastric protection rate, and secondary endpoints were the duodenal protection rate and ulcer incidence rate. Endpoints were assessed by endoscopy after the 4-week treatment period. Drug-related adverse effects, including gastrointestinal (GI) symptoms, were also compared. At week 4, the gastric protection rates with DA-9601 and misoprostol were 81.4 % (192/236) and 89.3 % (216/242), respectively. The difference between the groups was -14.2 %, indicating non-inferiority of DA-9601 to misoprostol. Adverse event rates were not different between the two groups; however, the total scores for GI symptoms before and after administration were significantly lower in the DA-9601 group than in the misoprostol group (-0.2 ± 2.8 vs 1.2 ± 3.2; p < 0.0001). DA-9601 is as effective as misoprostol in preventing NSAID-associated gastroduodenal complications, and has a superior adverse GI effect profile. PMID:24871787

  1. A randomized controlled pilot trial of classroom-based mindfulness meditation compared to an active control condition in sixth-grade children.

    PubMed

    Britton, Willoughby B; Lepp, Nathaniel E; Niles, Halsey F; Rocha, Tomas; Fisher, Nathan E; Gold, Jonathan S

    2014-06-01

    The current study is a pilot trial to examine the effects of a nonelective, classroom-based, teacher-implemented, mindfulness meditation intervention on standard clinical measures of mental health and affect in middle school children. A total of 101 healthy sixth-grade students (55 boys, 46 girls) were randomized to either an Asian history course with daily mindfulness meditation practice (intervention group) or an African history course with a matched experiential activity (active control group). Self-reported measures included the Youth Self Report (YSR), a modified Spielberger State-Trait Anxiety Inventory, and the Cognitive and Affective Mindfulness Measure -Revised. Both groups decreased significantly on clinical syndrome subscales and affect but did not differ in the extent of their improvements. Meditators were significantly less likely to develop suicidal ideation or thoughts of self-harm than controls. These results suggest that mindfulness training may yield both unique and non-specific benefits that are shared by other novel activities. PMID:24930819

  2. Numerical modeling of multi-mode active control of turbofan tonal noise using a boundary element method

    NASA Astrophysics Data System (ADS)

    Ireland, Laralee Gordon

    A numerical model was developed to investigate the possibility of implementing active control (ANC) to minimize noise radiation from high-bypass turbofan engines. Previous experimental work on the NASA Glenn Research Center active noise control fan (ANCF) was encouraging, but the question remained whether the modal approach investigated could be effective on real engines. The engine model developed for this research project uses an indirect boundary element method, implemented with Sysnoise, and a multi-mode Newton's algorithm, implemented with MATLAB(TM), to simulate the active control. Noise from the inlet was targeted. Both the experimental and numerical results based on the NASA ANCF simplified cylindrical engine geometry indicate overall reductions in the m = 2 component of the noise. Reductions obtained at the numerical sensor rings range from 17 dB to 63 dB and at a plane in the duct inlet, -8 dB to 33 dB. Rings mounted on the inlet duct are unable to accurately predict the total reduction of the inlet field, but the controller is still able to effectively reduce the total acoustic field. Generally, one sensor ring and one actuator ring per propagating mode were necessary to control the inlet field. At frequencies close to the cut-off frequency of a mode, an additional sensor and actuator ring were needed to adequately control the inlet field due to the evanescent mode. A more realistic, but still axisymmetric, engine geometry based on the GE CF6-80C engine was developed and the same algorithm used. Reductions obtained at the sensor rings range from 4 dB to 56 dB and at the duct inlet plane, from 12 dB to 26 dB. The overall far field noise radiation from the engine remained unchanged (0.4 dB) or decreased slightly (3.6 dB). The inlet noise was controlled at all frequencies but the noise from the exhaust was increased. The effect of inlet control on the exhaust radiation suggests the need for a controller that targets both the inlet and exhaust noise

  3. First description of a musculoskeletal linkage in an adipose fin: innovations for active control in a primitively passive appendage.

    PubMed

    Stewart, Thomas A; Hale, Melina E

    2013-01-01

    Adipose fins are enigmatic appendages found between the dorsal and caudal fins of some teleostean fishes. Long thought to be vestigial, degenerate second dorsal fins, remnants of the primitive gnathostome condition, adipose fins have since been recognized as novel morphologies. Unique among the fins of extant fishes, adipose fins have uniformly been described as passive structures, with no associated musculature. Here we provide the first description of a musculoskeletal linkage in an adipose fin, identified in the sun catfish Horabagrus brachysoma. Modified supracarinalis posterior muscles insert from the dorsal midline anterior to the adipose fin by tendons onto the fin base. An additional pair of posterior adipose-fin muscles also inserts upon the fin base and lay posterolateral to the fin, superficial to the axial muscle. This musculoskeletal linkage is an evolutionary innovation, a novel mechanism for controlling adipose-fin movement. These muscles appear to exemplify two approaches by which fins evolve to be actively controlled. We hypothesize that the anterior muscles arose through co-option of an existing fin linkage, while the posterior muscles originated as de novo fin muscles. These findings present adipose fins as a rich system within which to explore the evolution of novel vertebrate appendages. PMID:23135670

  4. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Test act system validation

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The primary objective of the Test Active Control Technology (ACT) System laboratory tests was to verify and validate the system concept, hardware, and software. The initial lab tests were open loop hardware tests of the Test ACT System as designed and built. During the course of the testing, minor problems were uncovered and corrected. Major software tests were run. The initial software testing was also open loop. These tests examined pitch control laws, wing load alleviation, signal selection/fault detection (SSFD), and output management. The Test ACT System was modified to interface with the direct drive valve (DDV) modules. The initial testing identified problem areas with DDV nonlinearities, valve friction induced limit cycling, DDV control loop instability, and channel command mismatch. The other DDV issue investigated was the ability to detect and isolate failures. Some simple schemes for failure detection were tested but were not completely satisfactory. The Test ACT System architecture continues to appear promising for ACT/FBW applications in systems that must be immune to worst case generic digital faults, and be able to tolerate two sequential nongeneric faults with no reduction in performance. The challenge in such an implementation would be to keep the analog element sufficiently simple to achieve the necessary reliability.

  5. Active Control of the Operating Temperature in a Loop Heat Pipe with Two Evaporators and Two Condensers

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Birur, Gaj; Powers, Edward I. (Technical Monitor)

    2001-01-01

    The operating temperature of a loop heat pipe (LHP) with multiple evaporators is a function of the total heat load, heat load distribution among evaporators, condenser temperature and ambient temperature. Because of the many variables involved, the operating temperature also showed more hystereses than an LHP with a single evaporator. Tight temperature control can be achieved by controlling its compensation chamber (CC) temperatures at the desired set point. This paper describes a test program on active control of the operating temperature in an LHP with two evaporators and two condensers. Temperature control was achieved by heating one or both CC's. Tests performed included start-up, power cycle, sink temperature cycle, CC temperature cycle, and capillary limit. Test results show that, regardless one or two CC's were heated to the set point temperature, one of CC's was always flooded with liquid. The loop could operate successfully at the desired set point temperature under most conditions, including some fast transients. At low heat loads, however, the CC temperature could suddenly increase above the set point temperature, possibly due to a sudden change of the vapor content inside the evaporator core.

  6. Sliding mode fault detection and fault-tolerant control of smart dampers in semi-active control of building structures

    NASA Astrophysics Data System (ADS)

    Yeganeh Fallah, Arash; Taghikhany, Touraj

    2015-12-01

    Recent decades have witnessed much interest in the application of active and semi-active control strategies for seismic protection of civil infrastructures. However, the reliability of these systems is still in doubt as there remains the possibility of malfunctioning of their critical components (i.e. actuators and sensors) during an earthquake. This paper focuses on the application of the sliding mode method due to the inherent robustness of its fault detection observer and fault-tolerant control. The robust sliding mode observer estimates the state of the system and reconstructs the actuators’ faults which are used for calculating a fault distribution matrix. Then the fault-tolerant sliding mode controller reconfigures itself by the fault distribution matrix and accommodates the fault effect on the system. Numerical simulation of a three-story structure with magneto-rheological dampers demonstrates the effectiveness of the proposed fault-tolerant control system. It was shown that the fault-tolerant control system maintains the performance of the structure at an acceptable level in the post-fault case.

  7. Semi-active control of piezoelectric coating's underwater sound absorption by combining design of the shunt impedances

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Li, Zhaohui; Huang, Aigen; Li, Qihu

    2015-10-01

    Piezoelectric shunt damping technology has been applied in the field of underwater sound absorption in recent years. In order to achieve broadband echo reduction, semi-active control of sound absorption of multi-layered piezoelectric coating by shunt damping is significant. In this paper, a practical method is proposed to control the underwater sound absorption coefficients of piezoelectric coating layers by combining design of the shunt impedance that allows certain sound absorption coefficients at setting frequencies. A one-dimensional electro-acoustic model of the piezoelectric coating and the backing is established based on the Mason equivalent circuit theory. First, the shunt impedance of the coating is derived under the constraint of sound absorption coefficient at one frequency. Then, taking the 1-3 piezoelectric composite coating as an example, the sound absorption properties of the coating shunted to the designed shunt impedance are investigated. Next, on the basis of that, an iterative method for two constrained frequencies and an optimizing algorithm for multiple constrained frequencies are provided for combining design of the shunt impedances. At last, an experimental sample with four piezoelectric material layers is manufactured, of which the sound absorption coefficients are measured in an impedance tube. The experimental results show good agreement with the finite element simulation results. It is proved that a serial R-L circuit can control the peak frequency, maximum and bandwidth of the sound absorption coefficient and the combining R-L circuits shunted to multiple layers can control the sound absorption coefficients at multiple frequencies.

  8. On-orbit application of H-infinity to the middeck active controls experiment: Overview of results

    NASA Technical Reports Server (NTRS)

    Woods-Vedeler, Jessica A.; Horta, Lucas G.

    1996-01-01

    The Middeck Active Control Experiment (MACE) was successfully completed during the flight of STS-67 in March 1995. MACE provided an on-orbit validation of modem robust control theory and system identification techniques through the testing of a flexible, multi-instrument, science platform in the micro-gravity environment of the Space Shuttle's Middeck. As part of this experiment, H-infinity control design was validated in zero gravity (0-G) environment. The control objective was to isolate a payload sensor from a 5O Hz bandwidth disturbance occurring on the test article. Controllers were designed with the use of finite element models developed using 1 -G measurements and a measurement model obtained by applying system identification techniques to open loop data obtained on orbit. Over 50 single-input, single-output and multi-input, multi-output, single and multi-axis H-infinity control designs were evaluated on-orbit. Up to 19 dB reduction in vibration levels and 25 Hz bandwidth of control were achieved.

  9. Trust-region based instantaneous optimal semi-active control of long-span spatially extended structures with MRF-04K damper

    NASA Astrophysics Data System (ADS)

    Lin, Wei; Li, Zhongxian; Ding, Yang

    2008-12-01

    In the field of civil engineering, magneto rheological fluid (MRF) damper-based semi-active control systems have received considerable attention for use in protecting structures from natural hazards such as strong earthquakes and high winds. In this paper, the MRF damper-based semi-active control system is applied to a long-span spatially extended structure and its feasibility is discussed. Meanwhile, a trust-region method based instantaneous optimal semi-active control algorithm (TIOC) is proposed to improve the performance of the semi-active control system in a multiple damper situation. The proposed TIOC describes the control process as a bounded constraint optimization problem, in which an optimal semiactive control force vector is solved by the trust-region method in every control step to minimize the structural responses. A numerical example of a railway station roof structure installed with MRF-04K dampers is presented. First, a modified Bouc-Wen model is utilized to describe the behavior of the selected MRF-04K damper. Then, two semi-active control systems, including the well-known clipped-optimal controller and the proposed TIOC controller, are considered. Based on the characteristics of the long-span spatially extended structure, the performance of the control system is evaluated under uniform earthquake excitation and travelling-wave excitation with different apparent velocities. The simulation results indicate that the MR fluid damper-based semi-active control systems have the potential to mitigate the responses of full-scale long-span spatially extended structures under earthquake hazards. The superiority of the proposed TIOC controller is demonstrated by comparing its control effectiveness with the clipped-optimal controller for several different cases.

  10. Efficacy and safety of lipegfilgrastim versus pegfilgrastim: a randomized, multicenter, active-control phase 3 trial in patients with breast cancer receiving doxorubicin/docetaxel chemotherapy

    PubMed Central

    2013-01-01

    Background Lipegfilgrastim is a novel glyco-pegylated granulocyte-colony stimulating factor in development for neutropenia prophylaxis in cancer patients receiving chemotherapy. This phase III, double-blind, randomized, active-controlled, noninferiority trial compared the efficacy and safety of lipegfilgrastim versus pegfilgrastim in chemotherapy-naïve breast cancer patients receiving doxorubicin/docetaxel chemotherapy. Methods Patients with high-risk stage II, III, or IV breast cancer and an absolute neutrophil count ≥1.5 × 109 cells/L were randomized to a single 6-mg subcutaneous injection of lipegfilgrastim (n = 101) or pegfilgrastim (n = 101) on day 2 of each 21-day chemotherapy cycle (4 cycles maximum). The primary efficacy endpoint was the duration of severe neutropenia during cycle 1. Results Cycle 1: The mean duration of severe neutropenia for the lipegfilgrastim and pegfilgrastim groups was 0.7 and 0.8 days, respectively (λ = −0.218 [95% confidence interval: –0.498%, 0.062%], p = 0.126), and no severe neutropenia was observed in 56% and 49% of patients in the lipegfilgrastim and pegfilgrastim groups, respectively. All cycles: In the efficacy population, febrile neutropenia occurred in three pegfilgrastim-treated patients (all in cycle 1) and zero lipegfilgrastim-treated patients. Drug-related adverse events in the safety population were reported in 28% and 26% of patients i006E the lipegfilgrastim and pegfilgrastim groups, respectively. Conclusion This study demonstrates that lipegfilgrastim 6 mg is as effective as pegfilgrastim in reducing neutropenia in patients with breast cancer receiving myelosuppressive chemotherapy. Trial Registration Eudra EEACTA200901599910 The study protocol, two global amendments (Nos. 1 and 2), informed consent documents, and other appropriate study-related documents were reviewed and approved by the Ministry of Health of Ukraine Central Ethics Committee and local independent ethics committees

  11. Putting Brain Training to the Test in the Workplace: A Randomized, Blinded, Multisite, Active-Controlled Trial

    PubMed Central

    Borness, Catherine; Proudfoot, Judith; Crawford, John; Valenzuela, Michael

    2013-01-01

    Background Cognitive training (CT) is effective at improving cognitive outcomes in children with and without clinical impairment as well as older individuals. Yet whether CT is of any preventative health benefit to working age adults is controversial. Our objective was therefore to investigate the real-world efficacy of CT in the workplace, involving employees from across the working-age spectrum and addressing many of the design issues that have limited trials to date. Methods and Findings 135 white collar employees of a large Australian public sector organization were randomised to either 16 weeks (20 minutes three times per week) of online CT or an active control (AC) program of equal length and structure. Cognitive, wellbeing and productivity outcome measures were analysed across three timepoints: baseline, immediately after training and 6 months post-training. CT effects on cognitive outcomes were limited, even after planned subgroup analyses of cognitive capacity and age. Unexpectedly, we found that our AC condition, which comprised viewing short documentaries about the natural world, had more impact. Compared to the CT group, 6 months after the end of training, those in the AC group experienced a significant increase in their self-reported Quality of Life (Effect Size g = .34 vs −.15; TIME×GROUP p = .003), decrease in stress levels (g = .22 vs −.19; TIME x GROUP p = .03), and overall improvement in Psychological Wellbeing (g = .32 vs −.06; TIME×GROUP p = .02). Conclusions CT does not appear to positively impact cognition or wellbeing amongst white collar office workers; however, short time-out respite activities may have value in the promotion of psychological wellbeing. Given looming challenges to workplace productivity, further work-based interventional research targeting employee mental health is recommended. Trial Registration This trial was registered with the Australian New Zealand Clinical Trials Registry: ACTRN

  12. Earthquake response reduction of mid-story isolated system due to semi-active control using magnetorheological rotary inertia mass damper

    NASA Astrophysics Data System (ADS)

    Ito, Mai; Yoshida, Shohei; Fujitani, Hideo; Sato, Yusuke

    2015-04-01

    The dynamic characteristics of mid-story isolated buildings and seismic response reduction due to a semi-active control system were investigated using a three-lumped-mass model that simplified the sixteen story building with an isolation layer in the sixth story. A semi-active control method using a rotary inertia mass damper filled with magnetorheological fluid (MR fluid) was proposed. The damper shows both mass amplification effect due to rotational inertia and variable damping effect due to the MR fluid. The damping force is controlled by the strength of the magnetic field that is applied to the MR fluid. It is determined by using the electric current, which is calculated by the proposed semi-active control method based on the velocity of the isolation layer relative to the layer just underneath it. Real-time hybrid tests using an actual damper and simulations using a building model were conducted to check the damper model; the test results were in good agreement with the simulation results. The simulation results suggest that the response displacement of the structure above the isolation layer is significantly reduced, without increasing the response acceleration of the entire structure against near-fault pulse and long-period ground motions. The proposed semi-active control using an MR rotary inertia mass damper was confirmed to be effective for mid-story isolated buildings.

  13. The Role of Thoracic Medial Branch Blocks in Managing Chronic Mid and Upper Back Pain: A Randomized, Double-Blind, Active-Control Trial with a 2-Year Followup

    PubMed Central

    Manchikanti, Laxmaiah; Singh, Vijay; Falco, Frank J. E.; Cash, Kimberly A.; Pampati, Vidyasagar; Fellows, Bert

    2012-01-01

    Study Design. A randomized, double-blind, active-control trial. Objective. To determine the clinical effectiveness of therapeutic thoracic facet joint nerve blocks with or without steroids in managing chronic mid back and upper back pain. Summary of Background Data. The prevalence of thoracic facet joint pain has been established as 34% to 42%. Multiple therapeutic techniques utilized in managing chronic thoracic pain of facet joint origin include medial branch blocks, radiofrequency neurotomy, and intraarticular injections. Methods. This randomized double-blind active controlled trial was performed in 100 patients with 50 patients in each group who received medial branch blocks with local anesthetic alone or local anesthetic and steroids. Outcome measures included the numeric rating scale (NRS), Oswestry Disability Index (ODI), opioid intake, and work status, at baseline, 3, 6, 12, 18, and 24 months. Results. Significant improvement with significant pain relief and functional status improvement of 50% or more were observed in 80% of the patients in Group I and 84% of the patients in Group II at 2-year followup. Conclusions. Therapeutic medial branch blocks of thoracic facets with or without steroids may provide a management option for chronic function-limiting thoracic pain of facet joint origin. PMID:22851967

  14. Shaping frequency response of a vibrating plate for passive and active control applications by simultaneous optimization of arrangement of additional masses and ribs. Part I: Modeling

    NASA Astrophysics Data System (ADS)

    Wrona, Stanislaw; Pawelczyk, Marek

    2016-03-01

    An ability to shape frequency response of a vibrating plate according to precisely defined demands has a very high practical potential. It can be applied to improve acoustic radiation of the plate for required frequencies or enhance acoustic isolation of noise barriers and device casings by using both passive and active control. The proposed method is based on mounting severaladditional ribs and masses (passive and/or active) to the plate surface at locations followed from an optimization process. This paper, Part I, concerns derivation of a mathematical model of the plate with attached elements in the function of their shape and placement. The model is validated by means of simulations and laboratory experiments, and compared with models known from the literature. This paper is followed by a companion paper, Part II, where the optimization process is described. It includes arrangement of passive elements as well as actuators and sensors to improve controllability and observability measures, if active control is concerned.

  15. [Principle of the activity-controlled rate-adaptive cardiac pacemaker: analysis of stress and environment-induced mechanical effects on the human body].

    PubMed

    Alt, E; Matula, M; Theres, H; Heinz, M

    1989-09-01

    Rate-adaptive pacemakers are increasingly becoming part of clinical routine, the most widespread systems being activity-controlled. In order to shed more light on the foundations of mechanical forces which can possibly be utilized for controlling rate-adaptive systems, we conducted tests on six healthy volunteers and six pacemaker patients. With the aid of three orthogonal wide-band linear acceleration pick-ups attached to the body, the mechanical signals were recorded from the three axes during different activities. Along with standardized exercise on bicycle and treadmill ergometers, we tested the influence of household activities and interference influences. The results were analyzed in terms of the amplitude and frequency content of the signals. For walking activities we found a signal amplitude increasing in largely linear fashion with the walking speed, the signal amplitudes being approximately twice as high on the vertical axis as on the other two axes. Exercise on the bicycle ergometer produced mechanical signals of clearly lower amplitude than comparable walking activities. The Fast-Fourier analysis showed amplitude peaks in the low frequency range of 1 to 4 Hz for all forms of physiological exercise, while interference influences showed amplitude peaks mainly in the range above 8 Hz. The use of an acceleration pickup and a corresponding low pass filter might be a way of reducing the effect of nonphysiological interference influences on an activity-controlled pacemaker system. A sensor measuring in the horizontal axis appears to be the most favorable compromise for the various types of exercise. However, due to the considerable difference in signal amplitude for different types of exercise of the same intensity, an activity-controlled pacemaker system cannot entirely meet metabolic conditions and requirements. PMID:2815913

  16. Vertical Tail Buffeting Alleviation Using Piezoelectric Actuators-Some Results of the Actively Controlled Response of Buffet-Affected Tails (ACROBAT) Program

    NASA Technical Reports Server (NTRS)

    Moses, Robert W.

    1997-01-01

    Buffet is an aeroelastic phenomenon associated with high performance aircraft especially those with twin vertical tails. In particular, for the F/A-18 aircraft at high angles of attack, vortices emanating from wing/fuselage leading edge extensions burst, immersing the vertical tails in their wake. The resulting buffet loads on the vertical tails are a concern from fatigue and inspection points of view. Recently, a 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet Affected Tails (ACROBAT) Program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at Mach 0.10. By using single-input-single-output control laws at gains well below the physical limits of the actuators, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. The results herein illustrate that buffet alleviation of vertical tails can be accomplished using simple active control of the rudder or piezoelectric actuators. In fact, as demonstrated herein, a fixed gain single input single output control law that commands piezoelectric actuators may be active throughout the high angle-of-attack maneuver without requiring any changes during the maneuver. Future tests are mentioned for accentuating the international interest in this area of research.

  17. Vertical Tail Buffeting Alleviation Using Piezoelectric Actuators: Some Results of the Actively Controlled Response of Buffet-Affected Tails (ACROBAT) Program

    NASA Technical Reports Server (NTRS)

    Moses, Robert W.

    1997-01-01

    A 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet Affected Tails (ACROBAT) program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at a dynamic pressure of 14 psf. By using single-input-single-output control laws at gains well below the physical limits of the actuators, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. Buffeting alleviation results when using the rudder are presented for comparison. Stability margins indicate that a constant gain setting in the control law may be used throughout the range of angle of attack tested.

  18. Vertical-tail-buffeting alleviation using piezoelectric actuators: some results of the actively controlled response of buffet-affected tails (ACROBAT) program

    NASA Astrophysics Data System (ADS)

    Moses, Robert W.

    1997-05-01

    A 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet Affected Tails program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at a dynamic pressure of 14 psf. By using single-input-single-output control laws at gains well below the physical limits of the actuators, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square values of root strain were reduced by as much as 19 percent. Buffeting alleviation results when using the rudder are presented for comparison. Stability margins indicate that a constant gain setting in the control law may be used throughout the range of angle of attack tested.

  19. The basis for activity controlled rate variable cardiac pacemakers: an analysis of mechanical forces on the human body induced by exercise and environment.

    PubMed

    Alt, E; Matula, M; Theres, H; Heinz, M; Baker, R

    1989-10-01

    We conducted tests on six healthy volunteers and six pacemaker patients. With the aid of three straight line frequency acceleration pickups attached to the body, the mechanical signals were recorded on the three axes during different activities. Along with standardized exercise on bicycle and treadmill ergometers, we tested the influence of household activities and interference influences. The results were analyzed in terms of the amplitude and frequency content of the signals. For walking activities, we found a signal amplitude increasing in a largely linear fashion with the walking speed, the signal amplitudes being approximately twice as high on the vertical axis as on the other two axes. Exercise on the bicycle ergometer produced mechanical signals of clearly lower amplitude than comparable walking activities. The Fast-Fourier analysis showed amplitude peaks in the low frequency range of 1 to 4 Hz for all forms of physiological exercise, while interference influences showed amplitude peaks mainly in the range above 8 Hz. The use of a straight line-frequency acceleration pickup and a corresponding low pass filter might be a way of reducing the effect of unphysiological interference influences on an activity controlled pacemaker system. A sensor measuring on the horizontal axis appears to be the most favorable compromise for the various types of exercise. However, due to the considerable difference in signal amplitude for different types of exercise of the same intensity, an activity controlled pacemaker system cannot entirely meet metabolic conditions and requirements. PMID:2477823

  20. Modeling and Simulations of Olfactory Drug Delivery with Passive and Active Controls of Nasally Inhaled Pharmaceutical Aerosols.

    PubMed

    Si, Xiuhua A; Xi, Jinxiang

    2016-01-01

    There are many advantages of direct nose-to-brain drug delivery in the treatment of neurological disorders. However, its application is limited by the extremely low delivery efficiency (< 1%) to the olfactory mucosa that directly connects the brain. It is crucial to develop novel techniques to deliver neurological medications more effectively to the olfactory region. The objective of this study is to develop a numerical platform to simulate and improve intranasal olfactory drug delivery. A coupled image-CFD method was presented that synthetized the image-based model development, quality meshing, fluid simulation, and magnetic particle tracking. With this method, performances of three intranasal delivery protocols were numerically assessed and compared. Influences of breathing maneuvers, magnet layout, magnetic field strength, drug release position, and particle size on the olfactory dosage were also numerically studied. From the simulations, we found that clinically significant olfactory dosage (up to 45%) were feasible using the combination of magnet layout and selective drug release. A 64 -fold higher delivery of dosage was predicted in the case with magnetophoretic guidance compared to the case without it. However, precise guidance of nasally inhaled aerosols to the olfactory region remains challenging due to the unstable nature of magnetophoresis, as well as the high sensitivity of olfactory dosage to patient-, device-, and particle-related factors. PMID:27285852

  1. Effect of control surface mass unbalance on the stability of a closed-loop active control system

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1989-01-01

    The effects on stability of inertial forces arising from closed-loop activation of mass-unbalanced control surfaces are studied analytically using inertial energy approach, similar to the aerodynamic energy approach used for flutter suppression. The limitations of a single control surface like a leading-edge (LE) control or a trailing-edge (TE) control are demonstrated and compared to the superior combined LE-TE mass unbalanced system. It is shown that a spanwise section for sensor location can be determined which ensures minimum sensitivity to the mode shapes of the aircraft. It is shown that an LE control exhibits compatibility between inertial stabilization and aerodynamic stabilization, and that a TE control lacks such compatibility. The results of the present work should prove valuable, both for the purpose of flutter suppression using mass unbalanced control surfaces, or for the stabilization of structural modes of large space structures by means of inertial forces.

  2. Active control of vortex-induced vibrations of a circular cylinder using windward-suction- leeward-blowing actuation

    NASA Astrophysics Data System (ADS)

    Wang, Chenglei; Tang, Hui; Yu, Simon C. M.; Duan, Fei

    2016-05-01

    This paper studies the control of two-dimensional vortex-induced vibrations (VIVs) of a single circular cylinder at a Reynolds number of 100 using a novel windward-suction-leeward-blowing (WSLB) concept. A lattice Boltzmann method based numerical framework is adopted for this study. Both open-loop and closed-loop controls are implemented. In the open-loop control, three types of actuation arrangements, including the pure suction on the windward side of the cylinder, the pure blowing on the leeward side, and the general WSLB on both sides, are implemented and compared. It is found that the general WSLB is the most effective, whereas the pure suction is the least effective. In the closed-loop control, the proportional (P), integral (I), and proportional-integral (PI) control schemes are applied to adjust the WSLB velocities according to the flow information obtained from a sensor. The effects of four key control parameters including the proportional gain constant, the integral gain constant, the length of data history used for the feedback, and the location of the sensor are investigated. It is found that the use of only P control fails to completely suppress the VIV, the use of only I control can achieve the complete suppression, and the PI control performs the best in terms of both the control effectiveness and efficiency. In the PI control, there exists an optimal length of data history for the feedback, at which the VIV control is the most efficient. There also exist the minimum required WSLB velocities for the VIV suppression, independent of the control schemes. Moreover, it is found that the VIV control is independent of the sensor location.

  3. A piezolaminated composite degenerated shell finite element for active control of structures with distributed piezosensors and actuators

    NASA Astrophysics Data System (ADS)

    Balamurugan, V.; Narayanan, S.

    2008-06-01

    potential difference between the top and bottom surfaces of the piezoelectric layer. Few case studies of composite general shells with piezoelectric sensors and actuators have been considered by modeling them with the above elements and the active vibration control performance has been studied using linear quadratic Gaussian (LQG) control.

  4. Immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine in Chinese healthy population aged >2 years: A randomized, double-blinded, active control, phase III trial.

    PubMed

    Kong, Yujia; Zhang, Wei; Jiang, Zhiwei; Wang, Ling; Li, Chanjuan; Li, Yanping; Xia, Jielai

    2015-01-01

    Streptococcus pneumoniae is an important pathogen causing invasive diseases such as sepsis, meningitis, and pneumonia. Vaccines have become the most effective way to prevent pneumococcal infections. This phase III trial was designed to evaluate the immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine in Chinese healthy population aged >2 years. We conducted a randomized, double-blinded, active-controlled, multicenter trial in which 1660 healthy population (>2 years of age) were randomly assigned in a 1 : 1 ratio to receive 2 intramuscular doses of either the treatment vaccine or the active control vaccine, PNEUMOVAX 23. The surveillance period was 30 days. The primary end point was the 2-fold increase rate of anti-pneumococcal antibody for all 23 included serotypes in each group. In the intention-to-treat cohort, the 2-fold increase rate of anti-pneumococcal antibody for 23 included serotypes varied from 62.47% to 97.01% in the treatment group, and from 51.49% to 95.77% in the control group. According to -10% non-inferiority margin and 95% confidence intervals of rate difference, almost all included serotypes of the treatment group reached non-inferiority to control group except for serotype 6B, the lower limit of rate difference of which was -10.00%, equal to the non-inferiority margin. The 2-fold increase rates of anti-pneumococcal antibody were significantly higher in the treatment group for serotype 2, 3, 4, 10A, 11A and 20. Furthermore, for all 23 serotypes, IgG geometric mean concentrations (GMCs) at day 30 were significantly higher in treatment group for serotype 2, 3, 4, 9 V, 10A, 11A, 15 B, 18C, 19 A, 22 F and 33 F. Higher geometric mean fold increase (GMFI) were also observed in the treatment group correspondingly. Serious adverse events occurred in 3 of 830 participants in the treatment group (0.36%) and 2 of 830 participants in the control group (0.24%). No death occurred during the trial. The frequencies of both solicited and

  5. Geometry sensing through POR1 regulates Rac1 activity controlling early osteoblast differentiation in response to nanofiber diameter.

    PubMed

    Higgins, A M; Banik, B L; Brown, J L

    2015-02-01

    Bone grafting procedures in the United States rely heavily upon autografts and allografts, which are donor-dependent, cause donor site pain, and can transmit disease. Synthetic bone grafts can reduce these risks; however, synthetics lack the bone differentiating (osteoinductive) abilities of auto- and allografts. Achieving innate osteoinductive properties of synthetics through surface modifications is currently under investigation. This study focuses on nanofibers, with emphasis on how fiber diameter and the potential curvature sensor POR1 affect the activation of the signaling molecules Rac1 and Arf1, and leading to expression of alkaline phosphatase (ALP), an osteoinductive marker. Diameters of 0.1, 0.3, and 1.0 μm were compared against a flat control. The highest level of Rac1 activation was achieved on the smallest fibers (0.1 μm), a trend that was lost in POR1 knockdowns. This supports the hypothesis that on small nanofibers, POR1 favorably binds to highly curved cell membranes, which allows Rac1 to subsequently dissociate and activate. When the curvature is insufficient to bind POR1, POR1 binds to inactive Rac1 and competitively inhibits its activation. Arf1 activation followed an opposite trend, with the largest nanofibers exhibiting the highest activity. This trend reinforces the known interaction between Rac1 and Arf1 through the GIT-PIX complex, an Arf1 GAP and Rac1 GEF, respectively. Large, (1.0 μm), nanofibers demonstrated the highest ALP activity, indicating that ALP expression is inversely dependent on Rac1 activation. Knockdown of POR1 resulted in increased ALP activity across the substrates but without regard to the curvature sensing trend seen previously. Thus, POR1 senses curvature and increases Rac1 activity, which negatively regulates bone differentiation. PMID:25539497

  6. Spatio-temporal analysis reveals active control of both task-relevant and task-irrelevant variables

    PubMed Central

    Rácz, Kornelius; Valero-Cuevas, Francisco J.

    2013-01-01

    The Uncontrolled Manifold (UCM) hypothesis and Minimal Intervention principle propose that the observed differential variability across task relevant (i.e., task goals) vs. irrelevant (i.e., in the null space of those goals) variables is evidence of a separation of task variables for efficient neural control, ranked by their respective variabilities (sometimes referred to as hierarchy of control). Support for this comes from spatial domain analyses (i.e., structure of) of kinematic, kinetic, and EMG variability. While proponents admit the possibility of preferential as opposed to strictly uncontrolled variables, such distinctions have only begun to be quantified or considered in the temporal domain when inferring control action. Here we extend the study of task variability during tripod static grasp to the temporal domain by applying diffusion analysis. We show that both task-relevant and task-irrelevant parameters show corrective action at some time scales; and conversely, that task-relevant parameters do not show corrective action at other time scales. That is, the spatial fluctuations of fingertip forces show, as expected, greater ranges of variability in task-irrelevant variables (>98% associated with changes in total grasp force; vs. only <2% in task-relevant changes associated with acceleration of the object). But at some time scales, however, temporal fluctuations of task-irrelevant variables exhibit negative correlations clearly indicative of corrective action (scaling exponents <0.5); and temporal fluctuations of task-relevant variables exhibit neutral and positive correlations clearly indicative of absence of corrective action (scaling exponents ≥0.5). In agreement with recent work in other behavioral contexts, these results propose we revise our understanding of variability vis-á-vis task relevance by considering both spatial and temporal features of all task variables when inferring control action and understanding how the CNS confronts task

  7. TECHNICAL NOTE: Active control for stress intensity of crack-tips under mixed mode by shape memory TiNi fiber epoxy composites

    NASA Astrophysics Data System (ADS)

    Shimamoto, A.; Zhao, H.; Azakami, T.

    2007-06-01

    The paper presented the effectiveness of a shape memory alloy hybrid composite. It was designed to actively suppress stress intensity in the vicinity of a crack-tip. A shape memory alloy (SMA) TiNi fiber reinforced epoxy composite was fabricated based on the proposed design concept and its material and mechanical properties were investigated by photoelastic examinations. The stress intensity factors, KI and KII, at a crack-tip decreased temperatures greater than Af under mixed mode. The phenomenon was caused by the recovery force of the TiNi fiber. The relationship of the stress intensity factors with the prestrain in the SMA fiber as well as with the ambient temperature in an isothermal furnace was clarified. On this basis, the active control for stress intensity by a shape memory composite was discussed.

  8. Accelerated development and flight evaluation of active controls concepts for subsonic transport aircraft. Volume 2: AFT C.G. simulation and analysis

    NASA Technical Reports Server (NTRS)

    Urie, D. M.

    1979-01-01

    Relaxed static stability and stability augmentation with active controls were investigated for subsonic transport aircraft. Analytical and simulator evaluations were done using a contemporary wide body transport as a baseline. Criteria for augmentation system performance and unaugmented flying qualities were evaluated. Augmentation control laws were defined based on selected frequency response and time history criteria. Flying qualities evaluations were conducted by pilots using a moving base simulator with a transport cab. Static margin and air turbulence intensity were varied in test with and without augmentation. Suitability of a simple pitch control law was verified at neutral static margin in cruise and landing flight tasks. Neutral stability was found to be marginally acceptable in heavy turbulence in both cruise and landing conditions.

  9. Accelerated development and flight evaluation of active controls concepts for subsonic transport aircraft. Volume 1: Load alleviation/extended span development and flight tests

    NASA Technical Reports Server (NTRS)

    Johnston, J. F.

    1979-01-01

    Active wing load alleviation to extend the wing span by 5.8 percent, giving a 3 percent reduction in cruise drag is covered. The active wing load alleviation used symmetric motions of the outboard ailerons for maneuver load control (MLC) and elastic mode suppression (EMS), and stabilizer motions for gust load alleviation (GLA). Slow maneuvers verified the MLC, and open and closed-loop flight frequency response tests verified the aircraft dynamic response to symmetric aileron and stabilizer drives as well as the active system performance. Flight tests in turbulence verified the effectiveness of the active controls in reducing gust-induced wing loads. It is concluded that active wing load alleviation/extended span is proven in the L-1011 and is ready for application to airline service; it is a very practical way to obtain the increased efficiency of a higher aspect ratio wing with minimum structural impact.

  10. Parameter Estimation of Actuators for Benchmark Active Control Technology (BACT) Wind Tunnel Model with Analysis of Wear and Aerodynamic Loading Effects

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R.; Fung, Jimmy

    1998-01-01

    This report describes the development of transfer function models for the trailing-edge and upper and lower spoiler actuators of the Benchmark Active Control Technology (BACT) wind tunnel model for application to control system analysis and design. A simple nonlinear least-squares parameter estimation approach is applied to determine transfer function parameters from frequency response data. Unconstrained quasi-Newton minimization of weighted frequency response error was employed to estimate the transfer function parameters. An analysis of the behavior of the actuators over time to assess the effects of wear and aerodynamic load by using the transfer function models is also presented. The frequency responses indicate consistent actuator behavior throughout the wind tunnel test and only slight degradation in effectiveness due to aerodynamic hinge loading. The resulting actuator models have been used in design, analysis, and simulation of controllers for the BACT to successfully suppress flutter over a wide range of conditions.

  11. Dynamically stable, self-similarly evolving, and self-organized states of high beta tokamak and reversed pinch plasmas and advanced active control

    SciTech Connect

    Kondoh, Yoshiomi; Fukasawa, Toshinobu

    2009-11-15

    Generalized simultaneous eigenvalue equations derived from a generalized theory of self-organization are applied to a set of simultaneous equations for two-fluid model plasmas. An advanced active control by using theoretical time constants is proposed by predicting quantities to be controlled. Typical high beta numerical configurations are presented for the ultra low q tokamak plasmas and the reversed-field pinch (RFP) ones in cylindrical geometry by solving the set of simultaneous eigenvalue equations. Improved confinement with no detectable saw-teeth oscillations in tokamak experiments is reasonably explained by the shortest time constant of ion flow. The shortest time constant of poloidal ion flow is shown to be a reasonable mechanism for suppression of magnetic fluctuations by pulsed poloidal current drives in RFP experiments. The bifurcation from basic eigenmodes to mixed ones deduced from stability conditions for eigenvalues is shown to be a good candidate for the experimental bifurcation from standard RFP plasmas to their improved confinement regimes.

  12. Prospective, randomized, and active controlled study of the efficacy of alginic acid and antacid in the treatment of patients with endoscopy-negative reflux disease

    PubMed Central

    Lai, I-Rue; Wu, Ming-Shiang; Lin, Jaw-Town

    2006-01-01

    AIM: To assess the efficacy and safety of a compound containing alginic acid plus antacid (Topaal®) compared to equal-strength antacid (Nacid®) in patients with endoscopy-negative reflux disease (ENRD). METHODS: A total of 121 patients with ENRD were randomized to receive Topaal® (65 patients) or Nacid® (56 patients) for 6 weeks, with a consultation every 3 weeks. The primary end-point assessment was the change in the severity of heartburn as evaluated using a visual analog scale (VAS) at 6 weeks. The secondary end-point assessments were the VAS at 3 weeks, the change of frequency of the reflux symptom, the change of quality of life and the adverse effects. RESULTS: Demographics of randomized subjects in each treatment group were comparable except that the Topaal® group included more males. The baseline characteristics between the groups were similar. After 6 weeks of treatment, the reduction of VAS of heartburn was more prominent in the Topaal® group (-6.29 cm vs -4.11 cm). At the 3rd week, Topaal® group showed greater reduction of VAS for heartburn (P = 0.0016), regurgitation (P = 0.0006), vomiting (P  = 0.0373), and belching (P  <0.0001). The patients of the Topaal® group had lower frequency of heartburn (P  = 0.0015) and pain (P   = 0.0163) at the end of the 6-week treatment period. From the doctor’s point of view, the Topaal® group also showed significant reduction in the severity of heartburn (P   = 0.0020), regurgitation (P   = 0.0081), vomiting (P  = 0.0182), and belching (P   = 0.0018) at the end of the treatment. The improvement of the quality of life was more remarkable in the Topaal® group at the end of the 6-week treatment period (P  < 0.0001). For the adverse effect, there was no difference in both the groups. CONCLUSION: Topaal® is more effective than Nacid® for the treatment of symptoms presented by patients with ENRD. PMID:16521188

  13. Active Control of Fan Noise: Feasibility Study. Volume 6; Theoretical Analysis for Coupling of Active Noise Control Actuator Ring Sources to an Annular Duct with Flow

    NASA Technical Reports Server (NTRS)

    Kraft, R. E.

    1996-01-01

    The objective of this effort is to develop an analytical model for the coupling of active noise control (ANC) piston-type actuators that are mounted flush to the inner and outer walls of an annular duct to the modes in the duct generated by the actuator motion. The analysis will be used to couple the ANC actuators to the modal analysis propagation computer program for the annular duct, to predict the effects of active suppression of fan-generated engine noise sources. This combined program will then be available to assist in the design or evaluation of ANC systems in fan engine annular exhaust ducts. An analysis has been developed to predict the modes generated in an annular duct due to the coupling of flush-mounted ring actuators on the inner and outer walls of the duct. The analysis has been combined with a previous analysis for the coupling of modes to a cylindrical duct in a FORTRAN computer program to perform the computations. The method includes the effects of uniform mean flow in the duct. The program can be used for design or evaluation purposes for active noise control hardware for turbofan engines. Predictions for some sample cases modeled after the geometry of the NASA Lewis ANC Fan indicate very efficient coupling in both the inlet and exhaust ducts for the m = 6 spinning mode at frequencies where only a single radial mode is cut-on. Radial mode content in higher order cut-off modes at the source plane and the required actuator displacement amplitude to achieve 110 dB SPL levels in the desired mode were predicted. Equivalent cases with and without flow were examined for the cylindrical and annular geometry, and little difference was found for a duct flow Mach number of 0.1. The actuator ring coupling program will be adapted as a subroutine to the cylindrical duct modal analysis and the exhaust duct modal analysis. This will allow the fan source to be defined in terms of characteristic modes at the fan source plane and predict the propagation to the arbitrarily-located ANC source plane. The actuator velocities can then be determined to generate the anti-phase mode. The resulting combined fan source/ANC pressure can then be calculated at any desired wall sensor position. The actuator velocities can be determined manually or using a simulation of a control system feedback loop. This will provide a very useful ANC system design and evaluation tool.

  14. Neuronal activity controls transsynaptic geometry.

    PubMed

    Glebov, Oleg O; Cox, Susan; Humphreys, Lawrence; Burrone, Juan

    2016-01-01

    The neuronal synapse is comprised of several distinct zones, including presynaptic vesicle zone (SVZ), active zone (AZ) and postsynaptic density (PSD). While correct relative positioning of these zones is believed to be essential for synaptic function, the mechanisms controlling their mutual localization remain unexplored. Here, we employ high-throughput quantitative confocal imaging, super-resolution and electron microscopy to visualize organization of synaptic subdomains in hippocampal neurons. Silencing of neuronal activity leads to reversible reorganization of the synaptic geometry, resulting in a increased overlap between immunostained AZ and PSD markers; in contrast, the SVZ-AZ spatial coupling is decreased. Bayesian blinking and bleaching (3B) reconstruction reveals that the distance between the AZ-PSD distance is decreased by 30 nm, while electron microscopy shows that the width of the synaptic cleft is decreased by 1.1 nm. Our findings show that multiple aspects of synaptic geometry are dynamically controlled by neuronal activity and suggest mutual repositioning of synaptic components as a potential novel mechanism contributing to the homeostatic forms of synaptic plasticity. PMID:26951792

  15. Neuronal activity controls transsynaptic geometry

    PubMed Central

    Glebov, Oleg O.; Cox, Susan; Humphreys, Lawrence; Burrone, Juan

    2016-01-01

    The neuronal synapse is comprised of several distinct zones, including presynaptic vesicle zone (SVZ), active zone (AZ) and postsynaptic density (PSD). While correct relative positioning of these zones is believed to be essential for synaptic function, the mec