Ohkubo, Yu; Ohno, Tatsuya; Noda, Shin-ei; Kubo, Nobuteru; Nakagawa, Akiko; Kawahara, Masahiro; Abe, Takanori; Kiyohara, Hiroki; Wakatsuki, Masaru; Nakano, Takashi
2013-01-01
The purpose of this study was to evaluate interfractional changes of the minimum dose delivered to 90% of the high-risk clinical target volume (HR-CTV D90) and D2cc of the bladder and rectum during brachytherapy for uterine cervical cancer patients. A total of 52 patients received external beam radiotherapy and high-dose-rate intracavitary brachytherapy (ICBT). For each of four ICBT applications, a pelvic CT scan was performed and the HR-CTV was delineated. Retrospectively, these patients were divided into two groups: (i) the standard dose group with 6 Gy to point A in each ICBT, and (ii) the adaptive dose group with a modified dose to point A to cover the HR-CTV with the 6-Gy isodose line as much as possible. The HR-CTV D90 was assessed in every session, and analyzed as interfractional changes. In the standard dose group, the interfractional changes of the HR-CTV D90 showed a linear increase from the first to the third of the four ICBT (average 6.1, 6.6, 7.0 and 7.1 Gy, respectively). In contrast, those of the adaptive dose group remained almost constant (average 7.2, 7.2, 7.3 and 7.4 Gy, respectively). Especially, in the case of a large HR-CTV volume (≥35 cm3) at first ICBT, the total HR-CTV D90 of the adaptive dose group with brachytherapy was significantly higher than that of the standard dose group. There were no significant differences in total D2cc in bladder and rectum between the two groups. Image-guided adaptive brachytherapy based on interfractional tumor volume change improves the dose to the HR-CTV while keeping rectal and bladder doses within acceptable levels. PMID:23732770
Wang, Yi; Ye, Wei-Jun; Du, Le-Hui; Li, Ai-Ju; Ren, Yu-Feng; Cao, Xin-Ping
2012-01-01
Currently, image-based 3-dimentional (3D) planning brachytherapy allows for a better assessment of gross tumor volume (GTV) and the definition and delineation of target volume in cervix cancer. In this study, we investigated the feasibility of our novel computed tomography (CT)-guided free-hand high-dose-rate interstitial brachytherapy (HDRISBT) technique for cervical cancer by evaluating the dosimetry and preliminary clinical outcome of this approach. Dose-volume histogram (DVH) parameters were analyzed according to the Gynecological GEC-ESTRO Working Group recommendations for image-based 3D treatment in cervical cancer. Twenty cervical cancer patients who underwent CT-guided free-hand HDRISBT between March 2009 and June 2010 were studied. With a median of 5 (range, 4–7) implanted needles for each patient, the median dose of brachytherapy alone delivered to 90% of the target volume (D90) was 45 (range, 33–54) Gyα/β10 for high-risk clinical target volume (HR-CTV) and 30 (range, 20–36) Gyα/β10 for intermediate-risk clinical target volume (IR-CTV). The percentage of the CTV covered by the prescribed dose (V100) of HR-CTV with brachytherapy alone was 81.9%–99.2% (median, 96.7%). With an additional dose of external beam radiotherapy (EBRT), the median D90 was 94 (range, 83–104) Gyα/β10 for HR-CTV and 77 (range, 70–87) Gyα/β10 for IR-CTV; the median dose delivered to 100% of the target volume (D100) was 75 (range, 66–84) Gyα/β10 for HR-CTV and 65 (range, 57–73) Gyα/β10 for IR-CTV. The minimum dose to the most irradiated 2 cc volume (D2cc) was 73–96 (median, 83) Gyα/β3 for the bladder, 64–98 (median, 73) Gyα/β3 for the rectum, and 52–69 (median, 61) Gyα/β3 for the sigmoid colon. After a median follow-up of 15 months (range, 3–24 months), two patients experienced local failure, and 1 showed internal iliac nodal metastasis. Despite the relatively small number of needles used, CT-guided HDRISBT for cervical cancer showed favorable
Schmid, Maximilian P.; Kirisits, Christian; Nesvacil, Nicole; Dimopoulos, Johannes C.A.; Berger, Daniel; Pötter, Richard
2011-01-01
Purpose It has been shown that a cumulative dose of ⩾87 Gy (EQD2) of external beam radiotherapy (EBRT) and image guided adaptive brachytherapy (IGABT) to the high risk clinical target volume (HR CTV) confer a local control rate >95% in locally advanced cervical cancer. This study examines the dose distribution within the HR CTV and intermediate (IR) CTV in patients with cervical cancer treated with definitive EBRT +/− concomitant chemotherapy and MRI-based IGABT between patients with local recurrence (LR) and patients in continuous complete local remission (CCLR). Material and methods From 1998 to 2010, 265 patients were treated with definitive EBRT +/− concomitant chemotherapy and IGABT. Twenty-four LRs were documented. For the statistical analysis all patients with LR were matched to patients in CCLR from our database according to the following criteria: FIGO stage, histology, lymph node status, tumour size and chemotherapy. DVH parameters (D50, D90, D98, D100) were reported for HR CTV and IR CTV. In order to report the minimum dose in the region where the recurrence occurred, the HR CTV/IR CTV were divided into four quadrants on transversal planes. The minimum dose at the HR CTV/IR CTV contour was measured (within the corresponding quadrant closest to the LR) in the treatment planning system. A mean minimum point dose (MPD) was calculated by averaging these measurements on four consecutive slices at the level of the recurrence for each of the 4 brachytherapy fractions. EQD2 doses were calculated by summation of all BT and external beam therapy fractions. For each matched patient in the control group the measurements were performed on the same quadrant and at the same level. Results Sufficient image data were available for 21 LRs. Eight central failures and 13 non-central failures were observed. The mean D90 and D100 for HR CTV were 77 Gy and 61 Gy for patients with LR and 95 Gy and 71 Gy for patients in CCLR, respectively (p < 0.01). The MPD for HR
Pötter, Richard; Haie-Meder, Christine; Van Limbergen, Erik; Barillot, Isabelle; De Brabandere, Marisol; Dimopoulos, Johannes; Dumas, Isabelle; Erickson, Beth; Lang, Stefan; Nulens, An; Petrow, Peter; Rownd, Jason; Kirisits, Christian
2006-01-01
The second part of the GYN GEC ESTRO working group recommendations is focused on 3D dose-volume parameters for brachytherapy of cervical carcinoma. Methods and parameters have been developed and validated from dosimetric, imaging and clinical experience from different institutions (University of Vienna, IGR Paris, University of Leuven). Cumulative dose volume histograms (DVH) are recommended for evaluation of the complex dose heterogeneity. DVH parameters for GTV, HR CTV and IR CTV are the minimum dose delivered to 90 and 100% of the respective volume: D90, D100. The volume, which is enclosed by 150 or 200% of the prescribed dose (V150, V200), is recommended for overall assessment of high dose volumes. V100 is recommended for quality assessment only within a given treatment schedule. For Organs at Risk (OAR) the minimum dose in the most irradiated tissue volume is recommended for reporting: 0.1, 1, and 2 cm3; optional 5 and 10 cm3. Underlying assumptions are: full dose of external beam therapy in the volume of interest, identical location during fractionated brachytherapy, contiguous volumes and contouring of organ walls for >2 cm3. Dose values are reported as absorbed dose and also taking into account different dose rates. The linear-quadratic radiobiological model-equivalent dose (EQD2)-is applied for brachytherapy and is also used for calculating dose from external beam therapy. This formalism allows systematic assessment within one patient, one centre and comparison between different centres with analysis of dose volume relations for GTV, CTV, and OAR. Recommendations for the transition period from traditional to 3D image-based cervix cancer brachytherapy are formulated. Supplementary data (available in the electronic version of this paper) deals with aspects of 3D imaging, radiation physics, radiation biology, dose at reference points and dimensions and volumes for the GTV and CTV (adding to [Haie-Meder C, Pötter R, Van Limbergen E et al. Recommendations from
(125)I monotherapy using D90 implant doses of 180 Gy or greater.
Kao, Johnny; Stone, Nelson N; Lavaf, Amir; Dumane, Vishruta; Cesaretti, Jamie A; Stock, Richard G
2008-01-01
The purpose of this study was to characterize the oncologic results and toxicity profile of patients treated with (125)I implants using the dose delivered to 90% of the gland from the dose-volume histogram (D90) of greater than 144 Gy. From June 1995 to Feb 2005, a total of 643 patients were treated with (125)I monotherapy for T1-T2 prostate cancer with a D90 of 180 Gy or greater (median, 197 Gy; range, 180-267 Gy). Implantations were performed using a real-time ultrasound-guided seed-placement method and intraoperative dosimetry to optimize target coverage and homogeneity by using modified peripheral loading. We analyzed biochemical disease-free survival (bDFS) of 435 patients who had a minimum 2-year prostate-specific antigen follow-up (median follow-up, 6.7 years; range, 2.0-11.1 years). Five-year bDFS rates for the entire cohort using the American Society for Therapeutic Radiology and Oncology and Phoenix definitions were 96.9% and 96.5%, respectively. Using the Phoenix definition, 5-year bDFS rates were 97.3% for low-risk patients and 92.8% for intermediate/high-risk patients. The positive biopsy rate was 4.1%. The freedom rate from Grade 2 or higher rectal bleeding at 5 years was 88.5%. Acute urinary retention occurred in 10.7%, more commonly in patients with high pretreatment International Prostate Symptom Scores (p < 0.01). In patients who were potent before treatment, 73.4% remained potent at 5 years after implantation. Patients with a minimum D90 of 180 Gy had outstanding local control based on prostate-specific antigen control and biopsy data. Toxicity profiles, particularly for long-term urinary and sexual function, were excellent and showed that D90 doses of 180 Gy or greater performed using the technique described were feasible and tolerable.
{sup 125}I Monotherapy Using D90 Implant Doses of 180 Gy or Greater
Kao, Johnny; Stone, Nelson N.; Lavaf, Amir Dumane, Vishruta; Cesaretti, Jamie A.; Stock, Richard G.
2008-01-01
Purpose: The purpose of this study was to characterize the oncologic results and toxicity profile of patients treated with {sup 125}I implants using the dose delivered to 90% of the gland from the dose-volume histogram (D90) of greater than 144 Gy. Methods and Materials: From June 1995 to Feb 2005, a total of 643 patients were treated with {sup 125}I monotherapy for T1-T2 prostate cancer with a D90 of 180 Gy or greater (median, 197 Gy; range, 180-267 Gy). Implantations were performed using a real-time ultrasound-guided seed-placement method and intraoperative dosimetry to optimize target coverage and homogeneity by using modified peripheral loading. We analyzed biochemical disease-free survival (bDFS) of 435 patients who had a minimum 2-year prostate-specific antigen follow-up (median follow-up, 6.7 years; range, 2.0-11.1 years). Results: Five-year bDFS rates for the entire cohort using the American Society for Therapeutic Radiology and Oncology and Phoenix definitions were 96.9% and 96.5%, respectively. Using the Phoenix definition, 5-year bDFS rates were 97.3% for low-risk patients and 92.8% for intermediate/high-risk patients. The positive biopsy rate was 4.1%. The freedom rate from Grade 2 or higher rectal bleeding at 5 years was 88.5%. Acute urinary retention occurred in 10.7%, more commonly in patients with high pretreatment International Prostate Symptom Scores (p < 0.01). In patients who were potent before treatment, 73.4% remained potent at 5 years after implantation. Conclusions: Patients with a minimum D90 of 180 Gy had outstanding local control based on prostate-specific antigen control and biopsy data. Toxicity profiles, particularly for long-term urinary and sexual function, were excellent and showed that D90 doses of 180 Gy or greater performed using the technique described were feasible and tolerable.
Liu, Zhong-Shan; Guo, Jie; Zhao, Yang-Zhi; Lin, Xia; Chen, Bin; Zhang, Ming; Li, Jiang-Ming; Ren, Xiao-Jun; Zhang, Bing-Ya
2016-01-01
Purpose Locally recurring cervical cancer after surgery and adjuvant radiotherapy remains a major therapeutic challenge. This paper presents a new therapeutic technique for such patients: interstitial brachytherapy (BT) guided by real-time three-dimensional (3D) computed tomography (CT). Material and methods Sixteen patients with recurrent cervical cancer after radical surgery and adjuvant external-beam radiotherapy (EBRT) were included in this study. These patients underwent high-dose-rate (HDR) interstitial BT with free-hand placement of metal needles guided by real-time 3D-CT. Six Gy in 6 fractions were prescribed for the high-risk clinical target volume (HR-CTV). D90 and D100 for HR-CTV of BT, and the cumulative D2cc for the bladder, rectum, and sigmoid, including previous EBRT and present BT were analyzed. Treatment-related complications and 3-month tumor-response rates were investigated. Results The mean D90 value for HR-CTV was 52.5 ± 3.3 Gy. The cumulative D2cc for the bladder, rectum, and sigmoid were 85.6 ± 5.8, 71.6 ± 6.4, and 69.6 ± 5.9 Gy, respectively. The mean number of needles was 6.1 ± 1.5, with an average depth of 3.5 ± 0.9 cm for each application. Interstitial BT was associated with minor complications and passable tumor-response rate. Conclusions Interstitial BT guided by real-time 3D-CT for recurrent cervical cancer results in good dose-volume histogram (DVH) parameters. The current technique may be clinically feasible. However, long-term clinical outcomes should be further investigated. PMID:27895683
Takenaka, Tadashi; Yoshida, Ken; Tachiiri, Seiji; Yamazaki,, Hideya; Aramoto, Kazumasa; Furuya, Seiichi; Yoshida, Mineo; Ban, Chiaki; Tanaka, Eiichi; Honda, Kazuya
2012-01-01
To investigate the feasibility of image-based intracavitary brachytherapy (IBICBT) for uterine cervical cancer, we evaluated the dose–volume histograms (DVHs) for the tumor and organs at risk (OARs) and compared results from the IBICBT plan and the standard Manchester system (Manchester plan) in eight patients as a simulation experiment. We performed magnetic resonance imaging (MRI) and computed tomography (CT) following MRI-adapted applicator insertion, then superimposed MR images on the planning CT images to describe the contours of high-risk clinical target volume (HR CTV) and OARs. The median volume of HR CTV was 29 cm3 (range, 21–61 cm3). Median D90 (HR CTV) and V100 (HR CTV) were 116.1% prescribed doses (PD) (90.0–150.8%) and 96.7% (84.2–100%), respectively, for the Manchester plan. In comparison, we confirmed that the median D90 (HR CTV) was 100% PD in the IBICBT plan for all patients. Mean D2cc (bladder) was 101.8% PD for the Manchester plan and 83.2% PD for the IBICBT plan. Mean D2cc (rectum) was 80.1% PD for the Manchester plan and 64.2% PD for the IBICBT plan. Mean D2cc (sigmoid) was 75% PD for the Manchester plan and 57.5% PD for the IBICBT plan. One patient with a large tumor (HR CTV, 61 cm3) showed lower D90 (HR CTV) with the Manchester plan than with the IBICBT plan. The Manchester plan may represent overtreatment for small tumors but insufficient dose distribution for larger tumors. The IBICBT plan could reduce OAR dosage while maintaining adequate tumor coverage. PMID:22843369
Nakagawa, Akiko; Ohno, Tatsuya; Noda, Shin-ei; Kubo, Nobuteru; Kuwako, Keiko; Saitoh, Jun-ichi; Nakano, Takashi
2014-01-01
We investigated the rectal dose-sparing effect and tumor control of a point A dose-reduced plan in patients with Stage I–II cervical cancer (≤4 cm) arising from a small-sized uterus. Between October 2008 and August 2011, 19 patients with Stage I–II cervical cancer (≤4 cm) were treated with external beam radiotherapy (EBRT) for the pelvis and CT-guided brachytherapy. Seven patients were treated with brachytherapy with standard loading of source-dwell positions and a fraction dose of 6 Gy at point A (conventional brachy-plan). The other 12 patients with a small uterus close to the rectum or small intestine were treated with brachytherapy with a point A dose-reduction to match D2cc of the rectum and <6 Gy as the dose constraint (‘point A dose-reduced plan’) instead of the 6-Gy plan at point A (‘tentative 6-Gy plan’). The total doses from EBRT and brachytherapy were added up and normalized to a biological equivalent dose of 2 Gy per fraction (EQD2). The median doses to the high-risk clinical target volume (HR-CTV) D90 in the conventional brachy-plan, tentative 6-Gy plan and point A dose-reduced plan were 62 GyEQD2, 80 GyEQD2 and 64 GyEQD2, respectively. The median doses of rectal D2cc in the corresponding three plans were 42 GyEQD2, 62 GyEQD2 and 51 GyEQD2, respectively. With a median follow-up period of 35 months, three patients developed Grade-1 late rectal complications and no patients developed local recurrence. Our preliminary results suggested that CT-guided brachytherapy using an individualized point A dose-reduced plan might be useful for reducing late rectal complications while maintaining primary tumor control. PMID:24566721
Nakagawa, Akiko; Ohno, Tatsuya; Noda, Shin-ei; Kubo, Nobuteru; Kuwako, Keiko; Saitoh, Jun-Ichi; Nakano, Takashi
2014-07-01
We investigated the rectal dose-sparing effect and tumor control of a point A dose-reduced plan in patients with Stage I-II cervical cancer (≤4 cm) arising from a small-sized uterus. Between October 2008 and August 2011, 19 patients with Stage I-II cervical cancer (≤4 cm) were treated with external beam radiotherapy (EBRT) for the pelvis and CT-guided brachytherapy. Seven patients were treated with brachytherapy with standard loading of source-dwell positions and a fraction dose of 6 Gy at point A (conventional brachy-plan). The other 12 patients with a small uterus close to the rectum or small intestine were treated with brachytherapy with a point A dose-reduction to match D2cc of the rectum and <6 Gy as the dose constraint ('point A dose-reduced plan') instead of the 6-Gy plan at point A ('tentative 6-Gy plan'). The total doses from EBRT and brachytherapy were added up and normalized to a biological equivalent dose of 2 Gy per fraction (EQD2). The median doses to the high-risk clinical target volume (HR-CTV) D90 in the conventional brachy-plan, tentative 6-Gy plan and point A dose-reduced plan were 62 GyEQD2, 80 GyEQD2 and 64 GyEQD2, respectively. The median doses of rectal D2cc in the corresponding three plans were 42 GyEQD2, 62 GyEQD2 and 51 GyEQD2, respectively. With a median follow-up period of 35 months, three patients developed Grade-1 late rectal complications and no patients developed local recurrence. Our preliminary results suggested that CT-guided brachytherapy using an individualized point A dose-reduced plan might be useful for reducing late rectal complications while maintaining primary tumor control.
Asymmetric dose-volume optimization with smoothness control for rotating-shield brachytherapy.
Liu, Yunlong; Flynn, Ryan T; Kim, Yusung; Wu, Xiaodong
2014-11-01
It is important to reduce fluence map complexity in rotating-shield brachytherapy (RSBT) inverse planning to improve delivery efficiency while maintaining plan quality. This study proposes an efficient and effective RSBT dose optimization method which enables to produce smooth fluence maps. Five cervical cancer patients each with a high-risk clinical-target-volume (HR-CTV) larger than 40 cm(3) were considered as the test cases. The RSBT source was a partially shielded electronic brachytherapy source (Xoft Axxent™). The anchor RSBT plans generated by the asymmetric dose-volume optimization with smoothness control (ADOS) method were compared against those produced by the dose-surface optimization (DSO) method and inverse-planning with simulated annealing (IPSA). Either L1-norm or L2-norm was used to measure the smoothness of a fluence map in the proposed ADOS method as one weighted term of the objective function. Uniform dwell-time scaling was applied to all plans such that HR-CTV D90 was maximized without violating the D2cc tolerances of the rectum, bladder, and sigmoid colon. The quality of the anchor plans was measured with HR-CTV D90 of the anchor plans. Single-shielded RSBT [(S-RSBT), RSBT with single, fix sized delivery window] and dynamic-sheilded RSBT [(D-RSBT), RSBT with dynamically varying sized delivery window] delivery plans generated based on the anchor plans were also measured, with delivery time constraints of 10, 20, and 30 min/fraction (fx). The average HR-CTV D90 values of the anchor plans achieved by the ADOS, DSO, and IPSA methods were 111.5, 94.2, and 107.4 Gy, respectively, where the weighting parameter β used in ADOS with L2-norm was set to be 100. By using S-RSBT sequencing and 20 min/fx delivery time, the corresponding D90 values were 88.8, 81.9, and 83.4 Gy; while using D-RSBT sequencing with 20 min/fx delivery time, the corresponding D90 values were 91.4, 88.3, and 78.9 Gy, respectively. The average optimization times for ADOS, DSO, and
Vinod, Shalini K; Lim, Karen; Bell, Lauren; Veera, Jacqueline; Ohanessian, Lucy; Juresic, Ewa; Borok, Nira; Chan, Phillip; Chee, Raphael; Do, Viet; Govindarajulu, Geetha; Sridharan, Swetha; Johnson, Carol; Moses, Daniel; Van Dyk, Sylvia; Holloway, Lois
2017-02-01
Image-based brachytherapy for cervical cancer using MRI has been implemented in Australia and New Zealand. The aims of this study were to measure variability in High-risk CTV (HR-CTV) delineation and evaluate dosimetric consequences of this. Nine radiation oncologists, one radiation therapist and two radiologists contoured HR-CTV on 3T MRI datasets from ten consecutive patients undergoing cervical brachytherapy at a single institution. Contour comparisons were performed using the Dice Similarity Coefficient (DSC) and Mean Absolute Surface Distance (MASD). Two reference contours were created for brachytherapy planning: a Simultaneous Truth and Performance Level Estimation (STAPLE) and a consensus contour (CONSENSUS). Optimized plans (8 Gy) for both these contours were applied to individual participant's contours to assess D90 and D100 coverage of HR CTV. To compare variability in dosimetry, relative standard deviation (rSD) was calculated. Good concordance (mean DSC≥0.7, MASD≤5 mm) was achieved in 8/10 cases when compared to the STAPLE reference and 6/10 cases when compared to the CONSENSUS reference. Greatest variation was visually seen in the cranio-caudal direction. The average mean rSD across all patients was 27% and 34% for the STAPLE HR-CTV D90 and D100, respectively, and 28% and 35% for the CONSENSUS HR-CTV D90 and D100. Delineation uncertainty resulted in an average dosimetric uncertainty of ±1.5-1.6 Gy per fraction based on an 8 Gy prescribed fraction. Delineation of HR-CTV for cervical cancer brachytherapy was consistent amongst observers, suggesting similar interpretation of GEC-ESTRO guidelines. Despite the good concordance, there was dosimetric variation noted, which could be clinically significant. © 2016 The Royal Australian and New Zealand College of Radiologists.
Lupo, Vincenzo; Pascual-Pascual, Samuel I; Sancho, Paula; Calpena, Eduardo; Gutiérrez-Molina, Manuel; Mateo-Martínez, Gonzalo; Espinós, Carmen; Arriola-Pereda, Gema
2015-10-01
Early-onset hereditary motor and sensory neuropathies are rare diseases representing a broad clinical and genetic spectrum. Without a notable familial history, the clinical diagnosis is complicated because acquired causes of peripheral neuropathy, such as inflammatory neuropathies, neuropathies with toxic causes, and nutritional deficiencies, must be considered. We examined the clinical, electrophysiological, and pathologic manifestations of a boy with an initial diagnosis of chronic inflammatory demyelinating polyneuropathy. The progression of the disease despite treatment led to a suspicion of hereditary motor and sensory neuropathy. Genetic testing revealed the presence of the MPZ p.D90E mutation in heterozygosis. To clarify the pathogenicity of this mutation and achieve a conclusive diagnosis, we investigated the MPZ p.D90E mutation through in silico and cellular approaches. This study broadens the clinical phenotype of hereditary motor and sensory neuropathy due to MPZ mutation and emphasises the difficulty of achieving an accurate genetic diagnosis in a sporadic patient to provide an appropriate pharmacologic treatment. © The Author(s) 2015.
Dynamic rotating-shield brachytherapy
Liu, Yunlong; Flynn, Ryan T.; Kim, Yusung; Yang, Wenjun; Wu, Xiaodong
2013-01-01
Purpose: To present dynamic rotating shield brachytherapy (D-RSBT), a novel form of high-dose-rate brachytherapy (HDR-BT) with electronic brachytherapy source, where the radiation shield is capable of changing emission angles during the radiation delivery process. Methods: A D-RSBT system uses two layers of independently rotating tungsten alloy shields, each with a 180° azimuthal emission angle. The D-RSBT planning is separated into two stages: anchor plan optimization and optimal sequencing. In the anchor plan optimization, anchor plans are generated by maximizing the D90 for the high-risk clinical-tumor-volume (HR-CTV) assuming a fixed azimuthal emission angle of 11.25°. In the optimal sequencing, treatment plans that most closely approximate the anchor plans under the delivery-time constraint will be efficiently computed. Treatment plans for five cervical cancer patients were generated for D-RSBT, single-shield RSBT (S-RSBT), and 192Ir-based intracavitary brachytherapy with supplementary interstitial brachytherapy (IS + ICBT) assuming five treatment fractions. External beam radiotherapy doses of 45 Gy in 25 fractions of 1.8 Gy each were accounted for. The high-risk clinical target volume (HR-CTV) doses were escalated such that the D2cc of the rectum, sigmoid colon, or bladder reached its tolerance equivalent dose in 2 Gy fractions (EQD2 with α/β = 3 Gy) of 75 Gy, 75 Gy, or 90 Gy, respectively. Results: For the patients considered, IS + ICBT had an average total dwell time of 5.7 minutes/fraction (min/fx) assuming a 10 Ci192Ir source, and the average HR-CTV D90 was 78.9 Gy. In order to match the HR-CTV D90 of IS + ICBT, D-RSBT required an average of 10.1 min/fx more delivery time, and S-RSBT required 6.7 min/fx more. If an additional 20 min/fx of delivery time is allowed beyond that of the IS + ICBT case, D-RSBT and S-RSBT increased the HR-CTV D90 above IS + ICBT by an average of 16.3 Gy and 9.1 Gy, respectively. Conclusions: For cervical cancer patients, D
Dynamic rotating-shield brachytherapy.
Liu, Yunlong; Flynn, Ryan T; Kim, Yusung; Yang, Wenjun; Wu, Xiaodong
2013-12-01
To present dynamic rotating shield brachytherapy (D-RSBT), a novel form of high-dose-rate brachytherapy (HDR-BT) with electronic brachytherapy source, where the radiation shield is capable of changing emission angles during the radiation delivery process. A D-RSBT system uses two layers of independently rotating tungsten alloy shields, each with a 180° azimuthal emission angle. The D-RSBT planning is separated into two stages: anchor plan optimization and optimal sequencing. In the anchor plan optimization, anchor plans are generated by maximizing the D90 for the high-risk clinical-tumor-volume (HR-CTV) assuming a fixed azimuthal emission angle of 11.25°. In the optimal sequencing, treatment plans that most closely approximate the anchor plans under the delivery-time constraint will be efficiently computed. Treatment plans for five cervical cancer patients were generated for D-RSBT, single-shield RSBT (S-RSBT), and (192)Ir-based intracavitary brachytherapy with supplementary interstitial brachytherapy (IS + ICBT) assuming five treatment fractions. External beam radiotherapy doses of 45 Gy in 25 fractions of 1.8 Gy each were accounted for. The high-risk clinical target volume (HR-CTV) doses were escalated such that the D2cc of the rectum, sigmoid colon, or bladder reached its tolerance equivalent dose in 2 Gy fractions (EQD2 with α∕β = 3 Gy) of 75 Gy, 75 Gy, or 90 Gy, respectively. For the patients considered, IS + ICBT had an average total dwell time of 5.7 minutes∕fraction (min∕fx) assuming a 10 Ci(192)Ir source, and the average HR-CTV D90 was 78.9 Gy. In order to match the HR-CTV D90 of IS + ICBT, D-RSBT required an average of 10.1 min∕fx more delivery time, and S-RSBT required 6.7 min∕fx more. If an additional 20 min∕fx of delivery time is allowed beyond that of the IS + ICBT case, D-RSBT and S-RSBT increased the HR-CTV D90 above IS + ICBT by an average of 16.3 Gy and 9.1 Gy, respectively. For cervical cancer patients, D-RSBT can boost HR-CTV D90
2014-01-01
Background In this study, high risk clinical target volumes (HR-CTVs) according to GEC-ESTRO guideline were contoured retrospectively based on CT images taken at the time of high-dose rate intracavitary brachytherapy (HDR-ICBT) and correlation between clinical outcome and dose of HR-CTV were analyzed. Methods Our study population consists of 51 patients with cervical cancer (Stages IB-IVA) treated with 50 Gy external beam radiotherapy (EBRT) using central shield combined with 2–5 times of 6 Gy HDR-ICBT with or without weekly cisplatin. Dose calculation was based on Manchester system and prescribed dose of 6 Gy were delivered for point A. CT images taken at the time of each HDR-ICBT were reviewed and HR-CTVs were contoured. Doses were converted to the equivalent dose in 2 Gy (EQD2) by applying the linear quadratic model (α/β = 10 Gy). Results Three-year overall survival, Progression-free survival, and local control rate was 82.4%, 85.3% and 91.7%, respectively. Median cumulative dose of HR-CTV D90 was 65.0 Gy (52.7-101.7 Gy). Median length from tandem to the most lateral edge of HR-CTV at the first ICBT was 29.2 mm (range, 18.0-51.9 mm). On univariate analysis, both LCR and PFS was significantly favorable in those patients D90 for HR-CTV was 60 Gy or greater (p = 0.001 and 0.03, respectively). PFS was significantly favorable in those patients maximum length from tandem to edge of HR-CTV at first ICBT was shorter than 3.5 cm (p = 0.042). Conclusion Volume-dose showed a relationship to the clinical outcome in CT based brachytherapy for cervical carcinoma. PMID:24938757
Thunberg, Per; With, Anders; Mordhorst, Louise Bohr; Persliden, Jan
2017-01-01
Purpose Using 3D image-guided adaptive brachytherapy for cervical cancer treatment, it often means that patients are transported and moved during the treatment procedure. The purpose of this study was to determine the intra-fractional longitudinal applicator shift in relation to the high risk clinical target volume (HR-CTV) by comparing geometries at imaging and dose delivery for patients with and without needles. Material and methods Measurements were performed in 33 patients (71 fractions), where 25 fractions were without and 46 were with interstitial needles. Gold markers were placed in the lower part of the cervix as a surrogate for HR-CTV, enabling distance measurements between HR-CTV and the ring applicator. Shifts of the applicator relative to the markers were determined using planning computed tomography (CT) images used for planning, and the radiographs obtained at dose delivery. Differences in the physical D90 for HR-CTV due to applicator shifts were simulated individually in the treatment planning system to provide the relative dose variation. Results The maximum distances of the applicator shifts, in relation to the markers, were 3.6 mm (caudal), and –2.5 mm (cranial). There was a significant displacement of –0.7 mm (SD = 0.9 mm) without needles, while with needles there was no significant shift. The relative dose variation showed a significant increase in D90 HR-CTV of 1.6% (SD = 2.6%) when not using needles, and no significant dose variation was found when using needles. Conclusions The results from this study showed that there was a small longitudinal displacement of the ring applicator and a significant difference in displacement between using interstitial needles or not. PMID:28344604
Yoshida, Ken; Yamazaki, Hideya; Takenaka, Tadashi; Kotsuma, Tadayuki; Yoshida, Mineo; Furuya, Seiichi; Tanaka, Eiichi; Uegaki, Tadaaki; Kuriyama, Keiko; Matsumoto, Hisanobu; Yamada, Shigetoshi; Ban, Chiaki
2010-07-01
Purpose: To investigate the feasibility of our novel image-based high-dose-rate interstitial brachytherapy (HDR-ISBT) for uterine cervical cancer, we evaluated the dose-volume histogram (DVH) according to the recommendations of the Gynecological GEC-ESTRO Working Group for image-based intracavitary brachytherapy (ICBT). Methods and Materials: Between June 2005 and June 2007, 18 previously untreated cervical cancer patients were enrolled. We implanted magnetic resonance imaging (MRI)-available plastic applicators by our unique ambulatory technique. Total treatment doses were 30-36 Gy (6 Gy per fraction) combined with external beam radiotherapy (EBRT). Treatment plans were created based on planning computed tomography with MRI as a reference. DVHs of the high-risk clinical target volume (HR CTV), intermediate-risk CTV (IR CTV), and the bladder and rectum were calculated. Dose values were biologically normalized to equivalent doses in 2-Gy fractions (EQD{sub 2}). Results: The median D90 (HR CTV) and D90 (IR CTV) per fraction were 6.8 Gy (range, 5.5-7.5) and 5.4 Gy (range, 4.2-6.3), respectively. The median V100 (HR CTV) and V100 (IR CTV) were 98.4% (range, 83-100) and 81.8% (range, 64-93.8), respectively. When the dose of EBRT was added, the median D90 and D100 of HR CTV were 80.6 Gy (range, 65.5-96.6) and 62.4 Gy (range, 49-83.2). The D{sub 2cc} of the bladder was 62 Gy (range, 51.4-89) and of the rectum was 65.9 Gy (range, 48.9-76). Conclusions: Although the targets were advanced and difficult to treat effectively by ICBT, MRI-aided image-based ISBT showed favorable results for CTV and organs at risk compared with previously reported image-based ICBT results.
Rotating-shield brachytherapy for cervical cancer
NASA Astrophysics Data System (ADS)
Yang, Wenjun; Kim, Yusung; Wu, Xiaodong; Song, Qi; Liu, Yunlong; Bhatia, Sudershan K.; Sun, Wenqing; Flynn, Ryan T.
2013-06-01
In this treatment planning study, the potential benefits of a rotating shield brachytherapy (RSBT) technique based on a partially-shielded electronic brachytherapy source were assessed for treating cervical cancer. Conventional intracavitary brachytherapy (ICBT), intracavitary plus supplementary interstitial (IS+ICBT), and RSBT treatment plans for azimuthal emission angles of 180° (RSBT-180) and 45° (RSBT-45) were generated for five patients. For each patient, high-risk clinical target volume (HR-CTV) equivalent dose in 2 Gy fractions (EQD2) (α/β = 10 Gy) was escalated until bladder, rectum, or sigmoid colon tolerance EQD2 values were reached. External beam radiotherapy dose (1.8 Gy × 25) was accounted for, and brachytherapy was assumed to have been delivered in 5 fractions. IS+ICBT provided a greater HR-CTV D90 (minimum EQD2 to the hottest 90%) than ICBT. D90 was greater for RSBT-45 than IS+ICBT for all five patients, and greater for RSBT-180 than IS+ICBT for two patients. When the RSBT-45/180 plan with the lowest HR-CTV D90 that was greater than the D90 the ICBT or IS+ICBT plan was selected, the average (range) of D90 increases for RSBT over ICBT and IS+ICBT were 16.2 (6.3-27.2)and 8.5 (0.03-20.16) Gy, respectively. The average (range) treatment time increase per fraction of RSBT was 34.56 (3.68-70.41) min over ICBT and 34.59 (3.57-70.13) min over IS+ICBT. RSBT can increase D90 over ICBT and IS+ICBT without compromising organ-at-risk sparing. The D90 and treatment time improvements from RSBT depend on the patient and shield emission angle.
Hayman, Orla; Muscat, Sarah
2012-01-01
Purpose To evaluate whether Co-60 is equivalent to Ir-192 for HDR cervical brachytherapy, through 3D-DVH dose comparisons in standard and optimised plans. Previous studies have only considered 2D dosimetry, point dose comparisons or identical loading. Typical treatment times and economics are considered. Material and methods Plans were produced for eight cervix patients using Co-60 and Ir-192 sources, CT imaging and IU/two-channel-ring applicator (Eckert Ziegler BEBIG). The comparison was made under two conditions: (A) identical dwell positions and loading, prescribed to Point A and (B) optimised source dwells, prescribed to HR-CTV. This provided a direct comparison of inherent differences and residual differences under typical clinical plan optimisation. The DVH (target and OAR), ICRU reference points and isodose distributions were compared. Typical treatment times and source replacement costs were compared. Results Small differences (p < 0.01) in 3D dosimetry exist when using Co-60 compared to Ir-192, prescribed to Point A with identical loading patterns, particularly 3.3% increase in rectum D2cc. No significant difference was observed in this parameter when prescribing to the HR-CTV using dwell-time optimisation. There was no statistically significant difference in D90 between the two isotopes. Co-60 plans delivered consistently higher V150% (mean +4.4%, p = 0.03) and V400% (mean +11.6%, p < 0.01) compared to Ir-192 in optimised plans. Differences in physical source properties were overwhelmed by geometric effects. Conclusions Co-60 may be used as an effective alternative to Ir-192 for HDR cervix brachytherapy, producing similar plans of equivalent D90, but with logistical benefits. There is a small dose increase along the extension of the source axis when using Co-60 compared to Ir-192, leading to small rectal dose increases for identical loading patterns. This can be eliminated by planning optimisation techniques. Such optimisation may also be associated with
NASA Astrophysics Data System (ADS)
Jamalludin, Z.; Min, U. N.; Ishak, W. Z. Wan; Malik, R. Abdul
2016-03-01
This study presents our preliminary work of the computed tomography (CT) image guided brachytherapy (IGBT) implementation on cervical cancer patients. We developed a protocol in which patients undergo two Magnetic Resonance Imaging (MRI) examinations; a) prior to external beam radiotherapy (EBRT) and b) prior to intra-cavitary brachytherapy for tumour identification and delineation during IGBT planning and dosimetry. For each fraction, patients were simulated using CT simulator and images were transferred to the treatment planning system. The HR-CTV, IR-CTV, bladder and rectum were delineated on CT-based contouring for cervical cancer. Plans were optimised to achieve HR-CTV and IR-CTV dose (D90) of total EQD2 80Gy and 60Gy respectively, while limiting the minimum dose to the most irradiated 2cm3 volume (D2cc) of bladder and rectum to total EQD2 90Gy and 75Gy respectively. Data from seven insertions were analysed by comparing the volume-based with traditional point- based doses. Based on our data, there were differences between volume and point doses of HR- CTV, bladder and rectum organs. As the number of patients having the CT-based IGBT increases from day to day in our centre, it is expected that the treatment and dosimetry accuracy will be improved with the implementation.
Sharma, M; Todor, D; Fields, E
2014-06-01
Purpose: To present a novel method allowing fast, true volumetric optimization of T and O HDR treatments and to quantify its benefits. Materials and Methods: 27 CT planning datasets and treatment plans from six consecutive cervical cancer patients treated with 4–5 intracavitary T and O insertions were used. Initial treatment plans were created with a goal of covering high risk (HR)-CTV with D90 > 90% and minimizing D2cc to rectum, bladder and sigmoid with manual optimization, approved and delivered. For the second step, each case was re-planned adding a new structure, created from the 100% prescription isodose line of the manually optimized plan to the existent physician delineated HR-CTV, rectum, bladder and sigmoid. New, more rigorous DVH constraints for the critical OARs were used for the optimization. D90 for the HR-CTV and D2cc for OARs were evaluated in both plans. Results: Two-step optimized plans had consistently smaller D2cc's for all three OARs while preserving good D90s for HR-CTV. On plans with “excellent” CTV coverage, average D90 of 96% (range 91–102), sigmoid D2cc was reduced on average by 37% (range 16–73), bladder by 28% (range 20–47) and rectum by 27% (range 15–45). Similar reductions were obtained on plans with “good” coverage, with an average D90 of 93% (range 90–99). For plans with inferior coverage, average D90 of 81%, an increase in coverage to 87% was achieved concurrently with D2cc reductions of 31%, 18% and 11% for sigmoid, bladder and rectum. Conclusions: A two-step DVH-based optimization can be added with minimal planning time increase, but with the potential of dramatic and systematic reductions of D2cc for OARs and in some cases with concurrent increases in target dose coverage. These single-fraction modifications would be magnified over the course of 4–5 intracavitary insertions and may have real clinical implications in terms of decreasing both acute and late toxicity.
NASA Astrophysics Data System (ADS)
Ren, Jiyun; Menon, Geetha; Sloboda, Ron
2013-04-01
Although the Manchester system is still extensively used to prescribe dose in brachytherapy (BT) for locally advanced cervix cancer, many radiation oncology centers are transitioning to 3D image-guided BT, owing to the excellent anatomy definition offered by modern imaging modalities. As automatic dose optimization is highly desirable for 3D image-based BT, this study comparatively evaluates the performance of two optimization methods used in BT treatment planning—Nelder-Mead simplex (NMS) and simulated annealing (SA)—for a cervix BT computer simulation model incorporating a Manchester-style applicator. Eight model cases were constructed based on anatomical structure data (for high risk-clinical target volume (HR-CTV), bladder, rectum and sigmoid) obtained from measurements on fused MR-CT images for BT patients. D90 and V100 for HR-CTV, D2cc for organs at risk (OARs), dose to point A, conformation index and the sum of dwell times within the tandem and ovoids were calculated for optimized treatment plans designed to treat the HR-CTV in a highly conformal manner. Compared to the NMS algorithm, SA was found to be superior as it could perform optimization starting from a range of initial dwell times, while the performance of NMS was strongly dependent on their initial choice. SA-optimized plans also exhibited lower D2cc to OARs, especially the bladder and sigmoid, and reduced tandem dwell times. For cases with smaller HR-CTV having good separation from adjoining OARs, multiple SA-optimized solutions were found which differed markedly from each other and were associated with different choices for initial dwell times. Finally and importantly, the SA method yielded plans with lower dwell time variability compared with the NMS method.
Ren, Jiyun; Menon, Geetha; Sloboda, Ron
2013-04-07
Although the Manchester system is still extensively used to prescribe dose in brachytherapy (BT) for locally advanced cervix cancer, many radiation oncology centers are transitioning to 3D image-guided BT, owing to the excellent anatomy definition offered by modern imaging modalities. As automatic dose optimization is highly desirable for 3D image-based BT, this study comparatively evaluates the performance of two optimization methods used in BT treatment planning--Nelder-Mead simplex (NMS) and simulated annealing (SA)--for a cervix BT computer simulation model incorporating a Manchester-style applicator. Eight model cases were constructed based on anatomical structure data (for high risk-clinical target volume (HR-CTV), bladder, rectum and sigmoid) obtained from measurements on fused MR-CT images for BT patients. D90 and V100 for HR-CTV, D2cc for organs at risk (OARs), dose to point A, conformation index and the sum of dwell times within the tandem and ovoids were calculated for optimized treatment plans designed to treat the HR-CTV in a highly conformal manner. Compared to the NMS algorithm, SA was found to be superior as it could perform optimization starting from a range of initial dwell times, while the performance of NMS was strongly dependent on their initial choice. SA-optimized plans also exhibited lower D2cc to OARs, especially the bladder and sigmoid, and reduced tandem dwell times. For cases with smaller HR-CTV having good separation from adjoining OARs, multiple SA-optimized solutions were found which differed markedly from each other and were associated with different choices for initial dwell times. Finally and importantly, the SA method yielded plans with lower dwell time variability compared with the NMS method.
Dimopoulos, Johannes Lang, Stefan; Kirisits, Christian; Fidarova, Elena F.; Berger, Daniel; Georg, Petra; Doerr, Wolfgang; Poetter, Richard
2009-09-01
Purpose: To investigate the value of dose-volume histogram (DVH) parameters for predicting local control in magnetic resonance (MR) image-guided brachytherapy (IGBT) for patients with cervical cancer. Methods and Materials: Our study population consists of 141 patients with cervical cancer (Stages IB-IVA) treated with 45-50 Gy external beam radiotherapy plus four times 7 Gy IGBT with or without cisplatin. Gross tumor volume (GTV), high-risk clinical target volume (HRCTV), and intermediate-risk clinical target volume (IRCTV) were contoured, and DVH parameters (minimum dose delivered to 90% of the volume of interest [D90] and D100) were assessed. Doses were converted to the equivalent dose in 2 Gy (EQD2) by applying the linear quadratic model ({alpha}/{beta} = 10 Gy). Groups were defined for patients with or without local recurrence (LR) in the true pelvis for tumor size at diagnosis (GTV at diagnosis [GTVD] of 2-5 cm (Group 1) or greater than 5 cm (Group 2) and for tumor size response at IGBT (HRCTV) of 2-5 cm (Group 2a) or greater than 5 cm (Group 2b). Results: Eighteen LRs were observed. The most important DVH parameters correlated with LR were the D90 and D100 for HRCTV. Mean D90 and D100 values for HRCTV were 86 {+-} 16 and 65 {+-} 10 Gy, respectively. The D90 for HRCTV greater than 87 Gy resulted in an LR incidence of 4% (3 of 68) compared with 20% (15 of 73) for D90 less than 87 Gy. The effect was most pronounced in the tumor group (Group 2b). Conclusions: We showed an increase in local control in IGBT in patients with cervical cancer with the dose delivered, which can be expressed by the D90 and D100 for HRCTV. Local control rates greater than 95% can be achieved if the D90 (EQD2) for HRCTV is 87 Gy or greater.
Sherertz, T; Ellis, R; Colussi, V; Mislmani, M; Traughber, B; Herrmann, K; Podder, T
2014-06-15
Purpose: To evaluate volumetric coverage of a Mick Radionuclear titanium Split-Ring applicator (SRA) with/without interstitial needle compared to an intracavitary Vienna applicator (VA), interstitial-intracavitary VA, and intracavitary ring and tandem applicator (RTA). Methods: A 57 year-old female with FIGO stage IIB cervical carcinoma was treated following chemoradiotherapy (45Gy pelvic and 5.4Gy parametrial boost) with highdose- rate (HDR) brachytherapy to 30Gy in 5 fractions using a SRA. A single interstitial needle was placed using the Ellis Interstitial Cap for the final three fractions to increase coverage of left-sided gross residual disease identified on 3T-MRI. High-risk (HR) clinical target volume (CTV) and intermediate-risk (IR) CTV were defined using axial T2-weighted 2D and 3D MRI sequences (Philips PET/MRI unit). Organs-at-risks (OARs) were delineated on CT. Oncentra planning system was used for treatment optimization satisfying GEC-ESTRO guidelines for target coverage and OAR constraints. Retrospectively, treatment plans (additional 20 plans) were simulated using intracavitary SRA (without needle), intracavitary VA (without needle), interstitial-intracavitary VA, and intracavitary RTA with this same patient case. Plans were optimized for each fraction to maintain coverage to HR-CTV. Results: Interstitial-intracavitary SRA achieved the following combined coverage for external radiation and brachytherapy (EQD2): D90 HR-CTV =94.6Gy; Bladder-2cc =88.9Gy; Rectum-2cc =65.1Gy; Sigmoid-2cc =48.9Gy; Left vaginal wall (VW) =103Gy, Right VW =99.2Gy. Interstitial-intracavitary VA was able to achieve identical D90 HR-CTV =94.6Gy, yet Bladder-2cc =91.9Gy (exceeding GEC-ESTRO recommendations of 2cc<90Gy) and Left VW =120.8Gy and Right VW =115.5Gy. Neither the SRA nor VA without interstitial needle could cover HR-CTV adequately without exceeding dose to Bladder-2cc. Conventional RTA was unable to achieve target coverage for the HR-CTV >80Gy without severely
Nesvacil, Nicole; Tanderup, Kari; Hellebust, Taran P.; De Leeuw, Astrid; Lang, Stefan; Mohamed, Sandy; Jamema, Swamidas V.; Anderson, Clare; Pötter, Richard; Kirisits, Christian
2013-01-01
Background and purpose To compare the dosimetric impact of organ and target variations relative to the applicator for intracavitary brachytherapy by a multicentre analysis with different application techniques and fractionation schemes. Material and methods DVH data from 363 image/contour sets (120 patients, 6 institutions) were included for 1–6 fractions per patient, with imaging intervals ranging from several hours to ∼20 days. Variations between images acquired within one (intra-application) or between consecutive applicator insertions (inter-application) were evaluated. Dose plans based on a reference MR or CT image series were superimposed onto subsequent image sets and D2cm3 for the bladder, rectum and sigmoid and D90 for HR CTV were recorded. Results For the whole sample, the systematic dosimetric variations for all organs at risk, i.e. mean variations of D2cm3, were found to be minor (<5%), while random variations, i.e. standard deviations were found to be high due to large variations in individual cases. The D2cm3 variations (mean ± 1SD) were 0.6 ± 19.5%, 4.1 ± 21.7% and 1.6 ± 26.8%, for the bladder, rectum and sigmoid. For HR CTV, the variations of D90 were found to be −1.1 ± 13.1% for the whole sample. Grouping of the results by intra- and inter-application variations showed that random uncertainties for bladder and sigmoid were 3–7% larger when re-implanting the applicator for individual fractions. No statistically significant differences between the two groups were detected in dosimetric variations for the HR CTV. Using 20% uncertainty of physical dose for OAR and 10% for HR CTV, the effects on total treatment dose for a 4 fraction HDR schedule at clinically relevant dose levels were found to be 4–8 Gy EQD2 for OAR and 3 Gy EQD2 for HR CTV. Conclusions Substantial variations occur in fractionated cervix cancer BT with higher impact close to clinical threshold levels. The treatment approach has to balance uncertainties for
Fenkell, Louis; Assenholt, Marianne; Nielsen, Soren Kynde; Haie-Meder, Christine; Poetter, Richard; Lindegaard, Jacob; Tanderup, Kari
2011-04-01
Purpose: Midline-blocked boost (MBB) fields are frequently used in the treatment of locally advanced cervical cancer. The purpose of this study was to evaluate the dose contribution from MBBs to tumor and organs at risk. Methods and Materials: Six patients with locally advanced cervical cancer (IIB-IIIB) treated with definitive chemoradiotherapy and magnetic resonance imaging (MRI)-guided brachytherapy were analyzed. A three-phase plan was modeled: 45 Gy (1.8 Gy per fraction) four-field box, 9 Gy (1.8 Gy per fraction) MBB (midline-shielded anteroposterior/posteroanterior fields), and intracavitary MRI-guided brachytherapy boost of 28 Gy (7 Gy per fraction). Midline shields 3, 4, and 5 cm wide were simulated for each patient. Brachytherapy and MBB plans were volumetrically summed. The rectum, sigmoid, and bladder minimum dose in the most exposed 2 cm{sup 3} of an organ at risk (D{sub 2cc}) and high-risk clinical target volume (HR-CTV) and intermediate-risk clinical target volume (IR-CTV) D90 and D100 were evaluated. The intended HR-CTV D90 was 85 Gy or greater, and the intended IR-CTV D90 was greater than 60 Gy. Results: After a 4-cm MBB, HR-CTV D90 remained lower than 85 Gy in all cases (mean, 74 Gy; range, 64-82 Gy). High-risk clinical target volume (85 Gy) coverage increased slightly from 73% (range, 64-82%) to 78% (range, 69-88%). Mean IR-CTV D90 increased from 56 Gy (range, 53-64 Gy) to 62 Gy (range, 59-67 Gy). Intermediate-risk clinical target volume 60-Gy dose coverage increased from 81% (range, 72-96%) to 96% (range, 90-100%). The mean volume irradiated to 85 Gy increased by 14 cm{sup 3} (range, 10-22 cm{sup 3}), whereas the volume irradiated to 60 Gy increased from 276 cm{sup 3} (range, 185-417 cm{sup 3}) to 592 cm{sup 3} (range, 385-807 cm{sup 3}). Bladder, rectum, or sigmoid D{sub 2cc} increased by more than 50% of the boost dose in 4 of 6 patients. Conclusions: Midline-blocked boosts contribute substantial dose to rectum, sigmoid, and bladder D{sub 2cc
Fenkell, Louis; Assenholt, Marianne; Nielsen, Søren Kynde; Haie-Meder, Christine; Pötter, Richard; Lindegaard, Jacob; Tanderup, Kari
2011-04-01
Midline-blocked boost (MBB) fields are frequently used in the treatment of locally advanced cervical cancer. The purpose of this study was to evaluate the dose contribution from MBBs to tumor and organs at risk. Six patients with locally advanced cervical cancer (IIB-IIIB) treated with definitive chemoradiotherapy and magnetic resonance imaging (MRI)-guided brachytherapy were analyzed. A three-phase plan was modeled: 45 Gy (1.8 Gy per fraction) four-field box, 9 Gy (1.8 Gy per fraction) MBB (midline-shielded anteroposterior/posteroanterior fields), and intracavitary MRI-guided brachytherapy boost of 28 Gy (7 Gy per fraction). Midline shields 3, 4, and 5 cm wide were simulated for each patient. Brachytherapy and MBB plans were volumetrically summed. The rectum, sigmoid, and bladder minimum dose in the most exposed 2 cm(3) of an organ at risk (D(2 cc)) and high-risk clinical target volume (HR-CTV) and intermediate-risk clinical target volume (IR-CTV) D90 and D100 were evaluated. The intended HR-CTV D90 was 85 Gy or greater, and the intended IR-CTV D90 was greater than 60 Gy. After a 4-cm MBB, HR-CTV D90 remained lower than 85 Gy in all cases (mean, 74 Gy; range, 64-82 Gy). High-risk clinical target volume (85 Gy) coverage increased slightly from 73% (range, 64-82%) to 78% (range, 69-88%). Mean IR-CTV D90 increased from 56 Gy (range, 53-64 Gy) to 62 Gy (range, 59-67 Gy). Intermediate-risk clinical target volume 60-Gy dose coverage increased from 81% (range, 72-96%) to 96% (range, 90-100%). The mean volume irradiated to 85 Gy increased by 14 cm(3) (range, 10-22 cm(3)), whereas the volume irradiated to 60 Gy increased from 276 cm(3) (range, 185-417 cm(3)) to 592 cm(3) (range, 385-807 cm(3)). Bladder, rectum, or sigmoid D(2 cc) increased by more than 50% of the boost dose in 4 of 6 patients. Midline-blocked boosts contribute substantial dose to rectum, sigmoid, and bladder D(2 cc). HR-CTV dose and 85-Gy coverage remain compromised in large tumors despite MBB. IR-CTV 60
Applicator reconstruction and applicator shifts in 3D MR-based PDR brachytherapy of cervical cancer.
De Leeuw, Astrid A C; Moerland, Marinus A; Nomden, Christel; Tersteeg, Robert H A; Roesink, Judith M; Jürgenliemk-Schulz, Ina M
2009-11-01
To evaluate the methods of applicator reconstruction in 3D MR-based planning for brachytherapy of cervical cancer, and to investigate applicator shifts and changes in DVH parameters during PDR treatment. For each application MR scans with applicator in situ were made: three T2-weighted (4.5 mm slices) Turbo Spin Echo (TSE) scans and a balanced Steady State Free Precession scan (1.5 mm). Three observers tested two applicator reconstruction methods: (A) directly on the bSSFP scan and (B) on a resampled combination of the three T2-weighted scans. For 10 patients MR imaging was repeated on the second day of each PDR fraction to determine applicator shifts and changes in DVH parameters. For both applicator reconstruction methods the interobserver variation for the DVH parameters was comparable (average <1.5% in dose). Differences between the two methods were larger (up to 6.4% for target) and were related to position differences during MR scanning. The average applicator shift relative to the pelvic structures was 5-6 mm into the ventral direction and 3-4 mm cranially. For a single PDR fraction, the average D90 (HR-CTV) on 'day 2' was 0.2 (SD 2.0) Gy lower than that for day 1. The average increase in D(2 cc) (bladder) was 1.0 (SD 3.0) Gy(alphabeta3) for a single PDR fraction. If the effect of both fractions was combined, for 1 patient a total decrease of D90 of 7 Gy(alphabeta10) was found, whereas for another patient the total increase in bladder dose was 12 Gy(alphabeta3). Applicator reconstruction on MR data is feasible. In the overall accuracy during PDR brachytherapy the reconstruction uncertainty is of minor importance. Applicator and/or organ movement during the course of the PDR fraction produce larger uncertainties.
Paton, A M; Chalmers, K E; Coomber, H; Cameron, A L
2012-01-01
Objective The aim of this study was to assess the impact of dose escalation on the proportion of patients requiring MR image-guided optimisation rather than standard Manchester-based CT-guided planning, and the level of escalation achievable. Methods 30 patients with cervical cancer treated with external beam radiotherapy and image-guided brachytherapy (IGBT) had MR images acquired at the first fraction of IGBT. Gross tumour volume and high-risk clinical target volume (HR CTV) were contoured and treatment plans retrospectively produced for a range of total 2-Gy equivalent (EQD2) prescription doses from 66 Gyα/β=10 to 90 Gyα/β=10 (HR CTV D90). Standard Manchester system-style plans were produced, prescribed to point A and then optimised where necessary with the aim of delivering at least the prescription dose to the HR CTV D90 while respecting organ-at-risk (OAR) tolerances. Results Increasing the total EQD2 from 66 Gyα/β=10 to 90 Gyα/β=10 increased the number of plans requiring optimisation from 13.3% to 90%. After optimisation, the number of plans achieving the prescription dose ranged from 93.3% (66 Gyα/β=10) to 63.3% (90 Gyα/β=10) with the mean±standard deviation for HR CTV D90 EQD2 from 78.4±12.4 Gyα/β=10 (66 Gyα/β=10) to 94.1±19.9 Gyα/β=10 (90 Gyα/β=10). Conclusion As doses are escalated, the need for non-standard optimised planning increases, while benefits in terms of increased target doses actually achieved diminish. The maximum achievable target dose is ultimately limited by proximity of OARs. Advances in knowledge This work represents a guide for other centres in determining the highest practicable prescription doses while considering patient throughput and maintaining acceptable OAR doses. PMID:23175490
Kubicky, Charlotte Dai; Yeh, Benjamin M; Lessard, Etienne; Joe, Bonnie N; Speight, Joycelyn L; Pouliot, Jean; Hsu, I-Chow
2008-01-01
To develop a technique using exclusively magnetic resonance imaging (MRI) to perform dwell position identification, targets and organs at risk delineation, and to apply inverse planning dose optimization to high-dose-rate brachytherapy for cervical cancer. We included 15 consecutive women treated with high-dose-rate (HDR) brachytherapy for cervical cancer. All patients underwent MRI after placement of tandem and ring applicator containing a gadodiamide-filled dummy marker. This technique allowed direct visualization of the source pathway and precise definition of the intra-applicator source positions. For each patient, we delineated gross target volume (GTV), high-risk clinical target volume (HR-CTV), and organs at risk on MRI, according to the European Gynecological GEC-ESTRO Working Group definitions. We performed inverse planning simulated annealing (IPSA) and analyzed the dose-volume histograms with the following endpoints: D(90), D(100), and V(100) for GTV and HR-CTV; D0.1 cc, D1 cc, D2 cc for bladder, rectum, and bowel; and dose at Point A. The intra-applicator source pathway was easily visualized on MRI using the gadodiamide-filled marker. IPSA provided excellent target coverage. The mean D(90) and V(100) for HR-CTV were 103+/-5% and 92+/-3%, respectively. IPSA provided excellent bladder sparing. D1 cc and D2 cc of bladder were 73+/-10% and 67+/-10%, respectively. We developed a novel technique that allows direct visualization of the intra-applicator source pathway on MRI. Using this technique, we successfully performed inverse planning directly from MRI.
ERIC Educational Resources Information Center
Ladefoged, Peter
1980-01-01
Summarizes the 16 parameters hypothesized to be necessary and sufficient for linguistic phonetic specifications. Suggests seven parameters affecting tongue shapes, three determining the positions of the lips, one controlling the position of the velum, four varying laryngeal actions, and one controlling respiratory activity. (RL)
Paddle-based rotating-shield brachytherapy
Liu, Yunlong; Flynn, Ryan T.; Kim, Yusung; Dadkhah, Hossein; Bhatia, Sudershan K.; Buatti, John M.; Xu, Weiyu; Wu, Xiaodong
2015-01-01
Purpose: The authors present a novel paddle-based rotating-shield brachytherapy (P-RSBT) method, whose radiation-attenuating shields are formed with a multileaf collimator (MLC), consisting of retractable paddles, to achieve intensity modulation in high-dose-rate brachytherapy. Methods: Five cervical cancer patients using an intrauterine tandem applicator were considered to assess the potential benefit of the P-RSBT method. The P-RSBT source used was a 50 kV electronic brachytherapy source (Xoft Axxent™). The paddles can be retracted independently to form multiple emission windows around the source for radiation delivery. The MLC was assumed to be rotatable. P-RSBT treatment plans were generated using the asymmetric dose–volume optimization with smoothness control method [Liu et al., Med. Phys. 41(11), 111709 (11pp.) (2014)] with a delivery time constraint, different paddle sizes, and different rotation strides. The number of treatment fractions (fx) was assumed to be five. As brachytherapy is delivered as a boost for cervical cancer, the dose distribution for each case includes the dose from external beam radiotherapy as well, which is 45 Gy in 25 fx. The high-risk clinical target volume (HR-CTV) doses were escalated until the minimum dose to the hottest 2 cm3 (D2cm3) of either the rectum, sigmoid colon, or bladder reached their tolerance doses of 75, 75, and 90 Gy3, respectively, expressed as equivalent doses in 2 Gy fractions (EQD2 with α/β = 3 Gy). Results: P-RSBT outperformed the two other RSBT delivery techniques, single-shield RSBT (S-RSBT) and dynamic-shield RSBT (D-RSBT), with a properly selected paddle size. If the paddle size was angled at 60°, the average D90 increases for the delivery plans by P-RSBT on the five cases, compared to S-RSBT, were 2.2, 8.3, 12.6, 11.9, and 9.1 Gy10, respectively, with delivery times of 10, 15, 20, 25, and 30 min/fx. The increases in HR-CTV D90, compared to D-RSBT, were 16.6, 12.9, 7.2, 3.7, and 1.7 Gy10
Mehta, Keyur J; Yaparpalvi, Ravindra; Shankar, Viswanathan; Bodner, William; Garg, Madhur; Rivera, Amanda; Tomé, Wolfgang A.; Kalnicki, Shalom
2016-01-01
Purpose This study assessed the modeled probability of tumor control and organ at risk toxicities in locally advanced cervical cancer in patients treated by external beam radiation plus brachytherapy using intracavitary combined with interstitial brachytherapy (IC/IS) vs. intracavitary brachytherapy (IC) alone. Material and methods Twenty cervical cancer patients with a mean HR-CTV volume of 47.4 cm3 and a mean width of 54 mm were planned with both IC/IS and IC brachytherapy alone. A probit model was utilized to model 3-year (3-yr) local control rate (LC), 3-yr cancer specific survival rate (CSS), and the adverse effect (AE) of the organ at risk by using a modeled data set from multiple institutions. Modeling results were used to estimate the LC, CSS, and AE of the treatments in this study. Results Using the IC/IS technique, an EQD2 increase of 12.3 Gy to D90 (from 76.1 Gy to 88.3 Gy) of HR-CTV is expected to increase 3-yr LC and 3-yr CSS by 12.5%, and 11.0%, respectively. Comparing IC/IS to IC alone, the expected G2+ AE were 7.7% vs. 7.9% for the bladder, and 5.9% vs. 6.8% for the rectum. Conclusions The IC/IS technique improved dose coverage to the HR-CTV without significantly increasing dose to 2 cm3 of the organ at risk (OAR) surrounding it. With different regimens of EBRT combined with BT, IC/IS can be used to increase the probability of LC and CSS, or decrease the risk of AE. PMID:28115959
Badkul, R; McClinton, C; Kumar, P; Mitchell, M
2014-06-01
Purpose: Brachytherapy plays a crucial role in management of cervix cancer. MRI compatible applicators have made it possible to accurately delineate gross-target-volume(GTV) and organs-at-risk(OAR) volumes, as well as directly plan, optimize and adapt dose-distribution for each insertion. We sought to compare DVH of tumor-coverage and OARs to traditional Point-A, ICRU-38 bladder and rectum point-doses for four different planning-techniques. Methods: MRI based 3D-planning was performed on Nucletron-Oncentra-TPS for 3 selected patients with varying tumor-sizes and anatomy. GTV,high-risk-clinical-target-volume(HR-CTV), intermediate-risk-clinical-target-volume(IR-CTV) and OARs: rectum, bladder, sigmoid-colon, vaginal-mucosa were delineated. Three conventionally used techniques: mg-Radium-equivalent(RaEq),equal-dwell-weights(EDW), Medical-College-of-Wisconsin proposed points-optimization (MCWO) and a manual-graphical-optimization(MGO) volume-coverage based technique were applied for each patient. Prescription was 6Gy delivered to point-A in Conventional techniques (RaEq, EDW, MCWO). For MGO, goal was to achieve 90%-coverage (D90) to HR-CTV with prescription-dose. ICRU point doses for rectum and bladder, point-A doses, DVH-doses for HR-CTV-D90,0.1cc-volume(D0.1),1ccvolume( D1),2cc-volume(D2) were collected for all plans and analyzed . Results: Mean D90 for HR-CTV normalized to MGO were 0.89,0.84,0.9,1.0 for EDW, RaEq, MCWO, MGO respectively. Mean point-A doses were 21.7% higher for MGO. Conventional techniques with Point-A prescriptions under covered HR-CTV-D90 by average of 12% as compared to MGO. Rectum, bladder and sigmoid doses were highest in MGO-plans for ICRU points as well as D0.1,D1 and D2 doses. Among conventional-techniques, rectum and bladder ICRU and DVH doses(0.1,1,2cc) were not significantly different (within 7%).Rectum D0.1 provided good estimation of ICRU-rectum-point doses (within 3.9%),rectum D0.1 were higher from 0.8 to 3.9% while bladder D0
Mazeron, R; Petit, C; Rivin, E; Limkin, E; Dumas, I; Maroun, P; Annede, P; Martinetti, F; Seisen, T; Lefkopoulos, D; Chargari, C; Haie-Meder, C
2016-03-01
In locally advanced cervical cancer, the dose delivered results from the sum of external beam radiotherapy and brachytherapy, and is limited by the surrounding organs at risk. The balance between both techniques influences the total dose delivered to the high-risk clinical target volume (HR-CTV). The aim of the present study was to compare the ability of reaching different planning aims after external beam radiotherapy pelvic doses of 45 Gy in 25 fractions or 50.4 Gy in 28 fractions, both considered as standard prescriptions. The optimised plans of 120 patients treated with pelvic chemoradiation followed by magnetic resonance image-guided intracavitary brachytherapy were reviewed. The doses per pulse were calculated, and the number of pulses required to reach the planning aims, or a limiting dose constraint to organs at risk, was calculated. All doses were converted to 2-Gy equivalents. Three scenarios were applied consisting of different sets of planning aims: 85 and 60 Gy for the HR-CTV and the intermediate-risk CTV (IR-CTV) D90 (minimal dose received by 90% of the volume) in scenario 1, 90 and 60 Gy, respectively, for scenarios 2 and 3. For organs at risk, dose constraints were 90, 75 and 75 Gy to the bladder, rectum and sigmoid D2cm(3), respectively, in scenarios 1 and 2, and 80, 65 and 70 Gy in scenario 3. A similar HR-CTV D90 could have been reached in scenarios 1 and 2 according to both pelvic doses. In scenario 3, a higher mean HR-CTV could have been reached in the 45 Gy arm (83.5 ± 8.0 versus 82.4 ± 8.0, P < 0.0001). The mean D2cm(3) of organs at risk was systematically and significantly increased after a delivery of 50.4 Gy to the pelvis, from 0.9 to 2.89 Gy. The proportions of plans reaching planning aims were 85.8, 72.5 and 42.5% after 45 Gy and 85.5, 67.5 and 33.3% after 50.4 Gy according to scenarios 1, 2 and 3, respectively. According to scenario 3, 50.4 Gy, the reachable HR-CTV D90 was higher in 30% of the cases, by 2 Gy in two
NASA Astrophysics Data System (ADS)
Udayashankar, Paniveni
2016-07-01
I study the complexity of supergranular cells using intensity patterns from Kodaikanal solar observatory. The chaotic and turbulent aspect of the solar supergranulation can be studied by examining the interrelationships amongst the parameters characterizing supergranular cells namely size, horizontal flow field, lifetime and physical dimensions of the cells and the fractal dimension deduced from the size data. The findings are supportive of Kolmogorov's theory of turbulence. The Data consists of visually identified supergranular cells, from which a fractal dimension 'D' for supergranulation is obtained according to the relation P α AD/2 where 'A' is the area and 'P' is the perimeter of the supergranular cells. I find a fractal dimension close to about 1.3 which is consistent with that for isobars and suggests a possible turbulent origin. The cell circularity shows a dependence on the perimeter with a peak around (1.1-1.2) x 105 m. The findings are supportive of Kolmogorov's theory of turbulence.
Nesvacil, Nicole; Pötter, Richard; Sturdza, Alina; Hegazy, Neamat; Federico, Mario; Kirisits, Christian
2013-01-01
Purpose To investigate and test the feasibility of adaptive 3D image based BT planning for cervix cancer patients in settings with limited access to MRI, using a combination of MRI for the first BT fraction and planning of subsequent fractions on CT. Material and methods For 20 patients treated with EBRT and HDR BT with tandem/ring applicators two sets of treatment plans were compared. Scenario one is based on the “gold standard” with individual MRI-based treatment plans (applicator reconstruction, target contouring and dose optimization) for two BT applications with two fractions each. Scenario two is based on one initial MRI acquisition with an applicator in place for the planning of the two fractions of the first BT application and reuse of the target contour delineated on MRI for subsequent planning of the second application on CT. Transfer of the target from MRI of the first application to the CT of the second one was accomplished by use of an automatic applicator-based image registration procedure. Individual dose optimization of the second BT application was based on the transferred MRI target volume and OAR structures delineated on CT. DVH parameters were calculated for transferred target structures (virtual dose from MRI/CT plan) and CT-based OAR. The quality of the MRI/CT combination method was investigated by evaluating the CT-based dose distributions on MRI-based target and OAR contours of the same application (real dose from MRI/CT plan). Results The mean difference between the MRI based target volumes (HR CTVMRI2) and the structures transferred from MRI to CT (HR CTVCT2) was −1.7 ± 6.6 cm3 (−2.9 ± 20.4%) with a median of −0.7 cm3. The mean difference between the virtual and the real total D90, based on the MRI/CT combination technique was −1.5 ± 4.3 Gy EQD2. This indicates a small systematic underestimation of the real D90. Conclusions A combination of MRI for first fraction and subsequent CT based planning is feasible and easy
Nesvacil, Nicole; Pötter, Richard; Sturdza, Alina; Hegazy, Neamat; Federico, Mario; Kirisits, Christian
2013-04-01
To investigate and test the feasibility of adaptive 3D image based BT planning for cervix cancer patients in settings with limited access to MRI, using a combination of MRI for the first BT fraction and planning of subsequent fractions on CT. For 20 patients treated with EBRT and HDR BT with tandem/ring applicators two sets of treatment plans were compared. Scenario one is based on the "gold standard" with individual MRI-based treatment plans (applicator reconstruction, target contouring and dose optimization) for two BT applications with two fractions each. Scenario two is based on one initial MRI acquisition with an applicator in place for the planning of the two fractions of the first BT application and reuse of the target contour delineated on MRI for subsequent planning of the second application on CT. Transfer of the target from MRI of the first application to the CT of the second one was accomplished by use of an automatic applicator-based image registration procedure. Individual dose optimization of the second BT application was based on the transferred MRI target volume and OAR structures delineated on CT. DVH parameters were calculated for transferred target structures (virtual dose from MRI/CT plan) and CT-based OAR. The quality of the MRI/CT combination method was investigated by evaluating the CT-based dose distributions on MRI-based target and OAR contours of the same application (real dose from MRI/CT plan). The mean difference between the MRI based target volumes (HR CTVMRI2) and the structures transferred from MRI to CT (HR CTVCT2) was -1.7±6.6 cm(3) (-2.9±20.4%) with a median of -0.7 cm(3). The mean difference between the virtual and the real total D90, based on the MRI/CT combination technique was -1.5±4.3 Gy EQD2. This indicates a small systematic underestimation of the real D90. A combination of MRI for first fraction and subsequent CT based planning is feasible and easy when automatic applicator-based image registration and target transfer
Ren, Juan; Yuan, Wei; Wang, Ruihua; Wang, Qiuping; Li, Yi; Xue, Chaofan; Yan, Yanli; Ma, Xiaowei; Tan, Li; Liu, Zi
2016-01-01
Objective The purpose of this study was to comprehensively compare the 3-dimensional (3D) magnetic resonance imaging (MRI)-guided and conventional 2-dimensional (2D) point A-based intracavitary brachytherapy (BT) planning for cervical cancer with regard to target dose coverage and dosages to adjacent organs-at risk (OARs). Methods A total of 79 patients with cervical cancer were enrolled to receive 2D point A-based BT planning and then immediately to receive 3D planning between October 2011 and April 2013 at the First Hospital Affiliated to Xi’an Jiao Tong University (Xi’an, China). The dose-volume histogram (DVH) parameters for gross tumor volume (GTV), high-risk clinical target volume (HR-CTV), intermediate-risk clinical target volume (IR-CTV) and OARs were compared between the 2D and 3D planning. Results In small tumors, there was no significant difference in most of the DVHs between 2D and 3D planning (all p>0.05). While in big tumors, 3D BT planning significantly increased the DVHs for most of the GTV, HR-CTV and IR-CTV, and some OARs compared with 2D planning (all P<0.05). In 3D planning, DVHs for GTV, HR-CTV, IR-CTV and some OARs were significantly higher in big tumors than in small tumors (all p<0.05). In contrast, in 2D planning, DVHs for almost all of the HR-CTV and IR-CTV were significantly lower in big tumors (all p<0.05). In eccentric tumors, 3D planning significantly increased dose coverage but decreased dosages to OARs compared with 2D planning (p<0.05). In tumors invading adjacent tissues, the target dose coverage in 3D planning was generally significantly higher than in 2D planning (P<0.05); the dosages to the adjacent rectum and bladder were significantly higher but those to sigmoid colon were lower in 3D planning (all P<0.05). Conclusions 3D MRI image-guided BT planning exhibits advantages over 2D planning in a complex way, generally showing advantages for the treatment of cervical cancer except small tumors. PMID:27611853
Multihelix rotating shield brachytherapy for cervical cancer
Dadkhah, Hossein; Kim, Yusung; Wu, Xiaodong; Flynn, Ryan T.
2015-01-01
Purpose: To present a novel brachytherapy technique, called multihelix rotating shield brachytherapy (H-RSBT), for the precise angular and linear positioning of a partial shield in a curved applicator. H-RSBT mechanically enables the dose delivery using only linear translational motion of the radiation source/shield combination. The previously proposed approach of serial rotating shield brachytherapy (S-RSBT), in which the partial shield is rotated to several angular positions at each source dwell position [W. Yang et al., “Rotating-shield brachytherapy for cervical cancer,” Phys. Med. Biol. 58, 3931–3941 (2013)], is mechanically challenging to implement in a curved applicator, and H-RSBT is proposed as a feasible solution. Methods: A Henschke-type applicator, designed for an electronic brachytherapy source (Xoft Axxent™) and a 0.5 mm thick tungsten partial shield with 180° or 45° azimuthal emission angles and 116° asymmetric zenith angle, is proposed. The interior wall of the applicator contains six evenly spaced helical keyways that rigidly define the emission direction of the partial radiation shield as a function of depth in the applicator. The shield contains three uniformly distributed protruding keys on its exterior wall and is attached to the source such that it rotates freely, thus longitudinal translational motion of the source is transferred to rotational motion of the shield. S-RSBT and H-RSBT treatment plans with 180° and 45° azimuthal emission angles were generated for five cervical cancer patients with a diverse range of high-risk target volume (HR-CTV) shapes and applicator positions. For each patient, the total number of emission angles was held nearly constant for S-RSBT and H-RSBT by using dwell positions separated by 5 and 1.7 mm, respectively, and emission directions separated by 22.5° and 60°, respectively. Treatment delivery time and tumor coverage (D90 of HR-CTV) were the two metrics used as the basis for evaluation and
Redefining solubility parameters: the partial solvation parameters.
Panayiotou, Costas
2012-03-21
The present work reconsiders a classical and universally accepted concept of physical chemistry, the solubility parameter. Based on the insight derived from modern quantum chemical calculations, a new definition of solubility parameter is proposed, which overcomes some of the inherent restrictions of the original definition and expands its range of applications. The original single solubility parameter is replaced by four partial solvation parameters reflecting the dispersion, the polar, the acidic and the basic character of the chemical compounds as expressed either in their pure state or in mixtures. Simple rules are adopted for the definition and calculation of these four parameters and their values are tabulated for a variety of common substances. In contrast, however, to the well known Hansen solubility parameters, their design and evaluation does not rely exclusively on the basic rule of "similarity matching" for solubility but it makes also use of the other basic rule of compatibility, namely, the rule of "complementarity matching". This complementarity matching becomes particularly operational with the sound definition of the acidic and basic components of the solvation parameter based on the third σ-moments of the screening charge distributions of the quantum mechanics-based COSMO-RS theory. The new definitions are made in a simple and straightforward manner, thus, preserving the strength and appeal of solubility parameter stemming from its simplicity. The new predictive method has been applied to a variety of solubility data for systems of pharmaceuticals and polymers. The results from quantum mechanics calculations are critically compared with the results from Abraham's acid/base descriptors.
Huq, M. Saiful; Houser, Chris; Beriwal, Sushil; Michalski, Dariusz
2014-01-01
Purpose For patients undergoing external beam radiation therapy (EBRT) and brachytherapy, recommendations for target doses and constraints are based on calculation of the equivalent dose in 2 Gy fractions (EQD2) from each phase. At present, the EBRT dose distribution is assumed to be uniform throughout the pelvis. We performed a preliminary study to determine whether deformable dose distribution mapping from the EBRT onto magnetic resonance (MR) images for the brachytherapy would yield differences in doses for organs at risk (OARs) and high-risk clinical target volume (HR-CTV). Material and methods Nine cervical cancer patients were treated to a total dose of 45 Gy in 25 fractions using intensity-modulated radiation therapy (IMRT), followed by MRI-based 3D high dose rate (HDR) brachytherapy. Retrospectively, the IMRT planning CT images were fused with the MR image for each fraction of brachytherapy using deformable image registration. The deformed IMRT dose onto MR images were converted to EQD2 and compared to the uniform dose assumption. Results For all patients, the EQD2 from the EBRT phase was significantly higher with deformable registration than with the conventional uniform dose distribution assumption. The mean EQD2 ± SD for HR-CTV D90 was 45.7 ± 0.7 Gy vs. 44.3 Gy for deformable vs. uniform dose distribution, respectively (p < 0.001). The dose to 2 cc of the bladder, rectum, and sigmoid was 46.4 ± 1.2 Gy, 46.2 ± 1.0 Gy, and 48.0 ± 2.5 Gy, respectively with deformable dose distribution, and was significantly higher than with uniform dose distribution (43.2 Gy for all OAR, p < 0.001). Conclusions This study reveals that deformed EBRT dose distribution to HR-CTV and OARs in MR images for brachytherapy is technically feasible, and achieves differences compared to a uniform dose distribution. Therefore, the assumption that EBRT contributes the same dose value may need to be carefully investigated further based on deformable image registration. PMID:25097559
Safigholi, H; Soliman, A; Song, W; Han, D; Meigooni, A Soleimani
2015-06-15
Purpose: A novel tungsten alloy shielded, MRI-compatible, direction modulated brachytherapy (DMBT) concept tandem applicator, which enables unprecedented intensity modulation, was used to evaluate treatment plan quality improvement over a conventional tandem. The utility of the 192-Ir and 169-Yb HDR sources, for use with the DMBT applicator, was evaluated. Methods: The total diameter of the DMBT tandem applicator is 6.0 mm, which consists of 5.4-mm diameter tungsten alloy and 0.3 mm thick plastic sheath. The tandem has 6 symmetric peripheral 1.3-mm diameter grooves for the source to travel. MCNPX v.2.6 was used to simulate the 192-Ir and 169-Yb sources inside the DMBT applicator. First, TG-43 source parameters were evaluated. Second, 3D dose matrix with 1 mm3 resolution were imported into an in-house-coded inverse optimization treatment planning program to obtain optimal plans for 19 clinical cases. All plans were compared with the standard tandem and ring plans. Prescription dose was 15.0 Gy. All plans were normalized to receive the same HRCTV D90. Results: Generally, the DMBT tandem (and ring) plans were better than the conventional tandem and ring plans for 192-Ir and 169-Yb HDR sources. The mean data of D2cc for bladder, rectum, and sigmoid were 11.65±2.30 Gy, 7.47±3.05 Gy, and 9.84±2.48 Gy for Ir-192 DMBT tandem, respectively. These data for Yb-169 were 11.67±2.26 Gy, 7.44±3.02 Gy, and 9.83±2.38 Gy, respectively. The HR-CTV D98 and V100 were 16.37±1.86 Gy and 97.37 ± 1.92 Gy for Ir-192 DMBT, respectively. The corresponding values for Yb-169 were 16.43±1.86 Gy, and 97.51 ± 1.91 Gy. Plans with the 169-Yb source generally produced more favorable results where V100 increased by 13.65% while D2cc across all OARs reduced by 0.54% compared with the 192-Ir plans. Conclusion: For the DMBT tandem applicator, 169-Yb source seems to produce more directional beams resulting in increased intensity modulation capacity, thus resulting in more conformal plans.
Tharavichitkul, Ekkasit; Wanwilairat, Somsak; Chitapanarux, Imjai; Kimmig, Bernhard; Dunst, Jürgen; Lorvidhaya, Vicharn
2015-01-01
Starting in 1999, the University Cooperation Platform (UCP) implemented an exchange program of researchers and clinicians/physicists between the Christian-Albrechts-University Kiel in Germany and Chiang Mai University in Thailand, to initiate a sustainable base for long-term development of image-guided brachytherapy and in general for high-technology radiotherapy in Chiang Mai. A series of UCP protocols, based constructively on each other, were performed and evaluated at intermediate term follow-up. The first protocol, addressing computed tomography (CT)-optimized brachytherapy for advanced cervical cancer (n = 17), showed a significant reduction of D2cc for the bladder and sigmoid (p < 0.001) while maintaining a very high dose in D90 high-risk clinical target volume (HR-CTV) in comparison with standard point-based planning. In addition, after a follow-up of 19 months no tumor relapse was observed. The second UCP protocol, testing the impact of magnetic resonance imaging (MRI) guidance (n = 15) in patients with cervical cancer, proved significantly smaller D2cc doses for the bladder, rectum, and sigmoid (p = 0.003, p = 0.015, and p = 0.012), and secured highly curative mean doses in D90 HR-CTV of 99.2 Gy. The acute and late toxicity was excellent without any observed grade 3 or higher morbidity. In the third protocol, the combination of image-guided brachytherapy (IGBT) and whole pelvis intensity-modulated external beam radiotherapy (WP-IMRT) (n = 15) reaffirmed the significant reduction of D2cc doses for the bladder, rectum, and sigmoid (p = 0.001 or p < 0.001) along with high equivalent dose at 2 Gy (EQD2) in the HR-CTV, and demonstrated very low acute therapy-related toxicity in absence of grade 3 morbidity. The implementation of transabdominal ultrasound (TAUS) was the focus of the fourth UCP project aiming a more generous potential use of image-guidance on long-term, and enhancing the quality of soft tissue assessment complementary to conventionally planned
Galalae, Razvan; Tharavichitkul, Ekkasit; Wanwilairat, Somsak; Chitapanarux, Imjai; Kimmig, Bernhard; Dunst, Jürgen; Lorvidhaya, Vicharn
2015-02-01
Starting in 1999, the University Cooperation Platform (UCP) implemented an exchange program of researchers and clinicians/physicists between the Christian-Albrechts-University Kiel in Germany and Chiang Mai University in Thailand, to initiate a sustainable base for long-term development of image-guided brachytherapy and in general for high-technology radiotherapy in Chiang Mai. A series of UCP protocols, based constructively on each other, were performed and evaluated at intermediate term follow-up. The first protocol, addressing computed tomography (CT)-optimized brachytherapy for advanced cervical cancer (n = 17), showed a significant reduction of D2cc for the bladder and sigmoid (p < 0.001) while maintaining a very high dose in D90 high-risk clinical target volume (HR-CTV) in comparison with standard point-based planning. In addition, after a follow-up of 19 months no tumor relapse was observed. The second UCP protocol, testing the impact of magnetic resonance imaging (MRI) guidance (n = 15) in patients with cervical cancer, proved significantly smaller D2cc doses for the bladder, rectum, and sigmoid (p = 0.003, p = 0.015, and p = 0.012), and secured highly curative mean doses in D90 HR-CTV of 99.2 Gy. The acute and late toxicity was excellent without any observed grade 3 or higher morbidity. In the third protocol, the combination of image-guided brachytherapy (IGBT) and whole pelvis intensity-modulated external beam radiotherapy (WP-IMRT) (n = 15) reaffirmed the significant reduction of D2cc doses for the bladder, rectum, and sigmoid (p = 0.001 or p < 0.001) along with high equivalent dose at 2 Gy (EQD2) in the HR-CTV, and demonstrated very low acute therapy-related toxicity in absence of grade 3 morbidity. The implementation of transabdominal ultrasound (TAUS) was the focus of the fourth UCP project aiming a more generous potential use of image-guidance on long-term, and enhancing the quality of soft tissue assessment complementary to conventionally planned
Reporting small bowel dose in cervix cancer high-dose-rate brachytherapy.
Liao, Yixiang; Dandekar, Virag; Chu, James C H; Turian, Julius; Bernard, Damian; Kiel, Krystyna
2016-01-01
Small bowel (SB) is an organ at risk (OAR) that may potentially develop toxicity after radiotherapy for cervix cancer. However, its dose from brachytherapy (BT) is not systematically reported as in other OARs, even with image-guided brachytherapy (IGBT). This study aims to introduce consideration of quantified objectives for SB in BT plan optimization and to evaluate the feasibility of sparing SB while maintaining adequate target coverage. In all, 13 patients were included in this retrospective study. All patients were treated with external beam radiotherapy (EBRT) 45Gy in 25 fractions followed by high dose rate (HDR)-BT boost of 28Gy in 4 fractions using tandem/ring applicator. Magnetic resonance imaging (MRI) and computed tomographic (CT) images were obtained to define the gross tumor volume (GTV), high-risk clinical target volume (HR-CTV) and OARs (rectum, bladder, sigmoid colon, and SB). Treatment plans were generated for each patient using GEC-ESTRO recommendations based on the first CT/MRI. Treatment plans were revised to reduce SB dose when the [Formula: see text] dose to SB was > 5Gy, while maintaining other OAR constraints. For the 7 patients with 2 sets of CT and MRI studies, the interfraction variation of the most exposed SB was analyzed. Plan revisions were done in 6 of 13 cases owing to high [Formula: see text] of SB. An average reduction of 19% in [Formula: see text] was achieved. Meeting SB and other OAR constraints resulted in less than optimal target coverage in 2 patients (D90 of HR-CTV < 77Gyαβ10). The highest interfraction variation was observed for SB at 16 ± 59%, as opposed to 28 ± 27% for rectum and 21 ± 16% for bladder. Prospective reporting of SB dose could provide data required to establish a potential correlation with radiation-induced late complication for SB.
Yoshio, Kotaro; Murakami, Naoya; Morota, Madoka; Harada, Ken; Kitaguchi, Mayuka; Yamagishi, Kentaro; Sekii, Shuhei; Takahashi, Kana; Inaba, Koji; Mayahara, Hiroshi; Ito, Yoshinori; Sumi, Minako; Kanazawa, Susumu; Itami, Jun
2013-01-01
The main purpose of this study was to compare three different treatment plans for locally advanced cervical cancer: (i) the inverse-planning simulated annealing (IPSA) plan for combination brachytherapy (BT) of interstitial and intracavitary brachytherapy, (ii) manual optimization based on the Manchester system for combination-BT, and (iii) the conventional Manchester system using only tandem and ovoids. This was a retrospective study of 25 consecutive implants. The high-risk clinical target volume (HR-CTV) and organs at risk were defined according to the GEC-ESTRO Working Group definitions. A dose of 6 Gy was prescribed. The uniform cost function for dose constraints was applied to all IPSA-generated plans. The coverage of the HR-CTV by IPSA for combination-BT was equivalent to that of manual optimization, and was better than that of the Manchester system using only tandem and ovoids. The mean V100 achieved by IPSA for combination-BT, manual optimization and Manchester was 96 ± 3.7%, 95 ± 5.5% and 80 ± 13.4%, respectively. The mean D100 was 483 ± 80, 487 ± 97 and 335 ± 119 cGy, respectively. The mean D90 was 677 ± 61, 681 ± 88 and 513 ± 150 cGy, respectively. IPSA resulted in significant reductions of the doses to the rectum (IPSA D2cm3: 408 ± 71 cGy vs manual optimization D2cm3: 485 ± 105 cGy; P = 0.03) and the bladder (IPSA D2cm3: 452 ± 60 cGy vs manual optimization D2cm3: 583 ± 113 cGy; P < 0.0001). In conclusion, combination-BT achieved better tumor coverage, and plans using IPSA provided significant sparing of normal tissues without compromising CTV coverage. PMID:23728322
Jaikuna, Tanwiwat; Khadsiri, Phatchareewan; Chawapun, Nisa; Saekho, Suwit
2017-01-01
Purpose To develop an in-house software program that is able to calculate and generate the biological dose distribution and biological dose volume histogram by physical dose conversion using the linear-quadratic-linear (LQL) model. Material and methods The Isobio software was developed using MATLAB version 2014b to calculate and generate the biological dose distribution and biological dose volume histograms. The physical dose from each voxel in treatment planning was extracted through Computational Environment for Radiotherapy Research (CERR), and the accuracy was verified by the differentiation between the dose volume histogram from CERR and the treatment planning system. An equivalent dose in 2 Gy fraction (EQD2) was calculated using biological effective dose (BED) based on the LQL model. The software calculation and the manual calculation were compared for EQD2 verification with pair t-test statistical analysis using IBM SPSS Statistics version 22 (64-bit). Results Two and three-dimensional biological dose distribution and biological dose volume histogram were displayed correctly by the Isobio software. Different physical doses were found between CERR and treatment planning system (TPS) in Oncentra, with 3.33% in high-risk clinical target volume (HR-CTV) determined by D90%, 0.56% in the bladder, 1.74% in the rectum when determined by D2cc, and less than 1% in Pinnacle. The difference in the EQD2 between the software calculation and the manual calculation was not significantly different with 0.00% at p-values 0.820, 0.095, and 0.593 for external beam radiation therapy (EBRT) and 0.240, 0.320, and 0.849 for brachytherapy (BT) in HR-CTV, bladder, and rectum, respectively. Conclusions The Isobio software is a feasible tool to generate the biological dose distribution and biological dose volume histogram for treatment plan evaluation in both EBRT and BT. PMID:28344603
Jaikuna, Tanwiwat; Khadsiri, Phatchareewan; Chawapun, Nisa; Saekho, Suwit; Tharavichitkul, Ekkasit
2017-02-01
To develop an in-house software program that is able to calculate and generate the biological dose distribution and biological dose volume histogram by physical dose conversion using the linear-quadratic-linear (LQL) model. The Isobio software was developed using MATLAB version 2014b to calculate and generate the biological dose distribution and biological dose volume histograms. The physical dose from each voxel in treatment planning was extracted through Computational Environment for Radiotherapy Research (CERR), and the accuracy was verified by the differentiation between the dose volume histogram from CERR and the treatment planning system. An equivalent dose in 2 Gy fraction (EQD2) was calculated using biological effective dose (BED) based on the LQL model. The software calculation and the manual calculation were compared for EQD2 verification with pair t-test statistical analysis using IBM SPSS Statistics version 22 (64-bit). Two and three-dimensional biological dose distribution and biological dose volume histogram were displayed correctly by the Isobio software. Different physical doses were found between CERR and treatment planning system (TPS) in Oncentra, with 3.33% in high-risk clinical target volume (HR-CTV) determined by D90%, 0.56% in the bladder, 1.74% in the rectum when determined by D2cc, and less than 1% in Pinnacle. The difference in the EQD2 between the software calculation and the manual calculation was not significantly different with 0.00% at p-values 0.820, 0.095, and 0.593 for external beam radiation therapy (EBRT) and 0.240, 0.320, and 0.849 for brachytherapy (BT) in HR-CTV, bladder, and rectum, respectively. The Isobio software is a feasible tool to generate the biological dose distribution and biological dose volume histogram for treatment plan evaluation in both EBRT and BT.
HYDROGEN ATOM THERMAL PARAMETERS.
JENSEN, L H; SUNDARALINGAM, M
1964-09-11
Isotropic hydrogen atom thermal parameters for N,N'- hexamethylenebispropionamide have been determined. They show a definite trend and vary from approximately the same as the mean thermal parameters for atoms other than hydrogen near the center of the molecule to appreciably greater for atoms near the end. The indicated trend for this compound, along with other results, provides the basis for a possible explanation of the anomolous values that have been obtained for hydrogen atom thermal parameters.
1989-03-01
Th usr a toente aninteer a thca sms b esta 1 Fp-ocsing 2. Enter P1 values, lwgt, ldig - > 9 Table I give us proper values. Table 1. PARAMETER TABLE...necessary and identify by block number) In this thesis a control systems analysis package is developed using parameter plane methods. It is an interactive...designer is able to choose values of the parameters which provide a good compromise between cost and dynamic behavior. 20 Distribution Availability of
Relations between demographic parameters.
Demetrius, L
1979-05-01
The mean life-expectancy e describes the average prospective life-time of an individual aged zero. This parameter can be explicitly described in terms of the survivorship distribution of the population. The Malthusian parameter r represents the asymptotic growth rate of a population. This parameter can be implicitly expressed in terms of the net-maternity distribution. The parameters e and r incompletely incorporate the age-specific fertility and mortality pattern of a population; distinct populations may have the same growth rate but different net-maternity functions; distinct populations may be characterized by the same mean life expectation but may have different survivorship distributions. This article analyzes a class of parameters called the entropy of a population (Demetrius, 1974a) which distinguishes between net-maternity functions with the same growth rate and also mortality distributions with the same mean life expectation. This class of parameters measures the convexity of the fertility and mortality distributions. This paper analyzes the relations between the entropy parameter and the standard demographic parameters.
Hanada, Takashi; Yorozu, Atsunori; Ohashi, Toshio; Shigematsu, Naoyuki; Maruyama, Koichi
2010-01-01
In the present study, the prostate medium determined from the CT images of 149 patients was developed. The dosimetric parameters such as Λ, g(L)(r) and F(r, θ) used in TG-43U1-based calculation for an iodine-125 ((125)I) brachytherapy-source were examined using Monte Carlo code Geant4. Clinical dosimetry parameters such as the D(90) were evaluated among a subgroup of 50 randomly selected patients who had been treated with permanent brachytherapy between January 2008 and December 2008 at the Tokyo Medical Center. The results show a slight difference in the dose rate constant Λ (within 1.0%). The radial dose function g(L)(r) exhibits a prominent difference in the region over 3 cm, and this difference is maintained within 2.9% in the region close to the source. The calculated values of F(r, θ) for the prostate medium were similar to values for water (within 1%), except in the longitudinal axis. A comparison of D(90) values shows a systematic dose overestimation of 2.8 ± 0.7 Gy in water, where the distribution of the differences can be seen with a spread of 1.8 ± 0.3% compared to that in prostate medium. It was concluded that the introduction of any kind of tissue correction for the TG-43U1-based calculation was not necessary to allow for the differences in elemental compositions and densities between water and prostate medium. PACS number: 87.00.00; 87.55.dk; 87.55.K-; 87.56.B-.
Parameter estimating state reconstruction
NASA Technical Reports Server (NTRS)
George, E. B.
1976-01-01
Parameter estimation is considered for systems whose entire state cannot be measured. Linear observers are designed to recover the unmeasured states to a sufficient accuracy to permit the estimation process. There are three distinct dynamics that must be accommodated in the system design: the dynamics of the plant, the dynamics of the observer, and the system updating of the parameter estimation. The latter two are designed to minimize interaction of the involved systems. These techniques are extended to weakly nonlinear systems. The application to a simulation of a space shuttle POGO system test is of particular interest. A nonlinear simulation of the system is developed, observers designed, and the parameters estimated.
RESRAD parameter sensitivity analysis
Cheng, J.J.; Yu, C.; Zielen, A.J.
1991-08-01
Three methods were used to perform a sensitivity analysis of RESRAD code input parameters -- enhancement of RESRAD by the Gradient Enhanced Software System (GRESS) package, direct parameter perturbation, and graphic comparison. Evaluation of these methods indicated that (1) the enhancement of RESRAD by GRESS has limitations and should be used cautiously, (2) direct parameter perturbation is tedious to implement, and (3) the graphics capability of RESRAD 4.0 is the most direct and convenient method for performing sensitivity analyses. This report describes procedures for implementing these methods and presents a comparison of results. 3 refs., 9 figs., 8 tabs.
NASA Astrophysics Data System (ADS)
Kitano, Ryuichiro; Motono, Ryuji; Nagai, Minoru
2016-12-01
It is often argued that the minimal supersymmetric standard model has O (100 ) free parameters, and the generic parameter region is already excluded by the null observation of the flavor and C P -violating processes as well as the constraints from the LHC experiments. This situation naturally leads us to consider the case where all the dangerous soft supersymmetry breaking terms, such as the scalar masses and scalar couplings, are absent, while only the unified gaugino mass term and the μ term are nonvanishing at the grand unification scale. We revisit this simple situation taking into account the observed Higgs boson mass, 125 GeV. Since the gaugino mass and the μ term are fixed in order to explain the Higgs boson and the Z boson masses, there is no free parameter left in this scenario. We find that there are three independent parameter sets that exist including ones which have not been discussed in the literature. We also find that the abundance of the dark matter can be explained by relic gravitinos which are nonthermally produced as decay products of the supersymmetry particles while satisfying constraints from big bang nucleosynthesis. We discuss the effects of the gravity mediation which generically gives a contribution to the soft terms of the order of the gravitino mass. It turns out that a newly found parameter set is preferable to explain the Higgs boson mass as well as the gravitino dark matter while satisfying the constraints from the electric dipole moments of the electron and the nucleon.
NASA Technical Reports Server (NTRS)
Hocking, W. K.
1989-01-01
The objective of any radar experiment is to determine as much as possible about the entities which scatter the radiation. This review discusses many of the various parameters which can be deduced in a radar experiment, and also critically examines the procedures used to deduce them. Methods for determining the mean wind velocity, the RMS fluctuating velocities, turbulence parameters, and the shapes of the scatterers are considered. Complications with these determinations are discussed. It is seen throughout that a detailed understanding of the shape and cause of the scatterers is important in order to make better determinations of these various quantities. Finally, some other parameters, which are less easily acquired, are considered. For example, it is noted that momentum fluxes due to buoyancy waves and turbulence can be determined, and on occasions radars can be used to determine stratospheric diffusion coefficients and even temperature profiles in the atmosphere.
NASA Technical Reports Server (NTRS)
Iliff, Kenneth W.
1987-01-01
The aircraft parameter estimation problem is used to illustrate the utility of parameter estimation, which applies to many engineering and scientific fields. Maximum likelihood estimation has been used to extract stability and control derivatives from flight data for many years. This paper presents some of the basic concepts of aircraft parameter estimation and briefly surveys the literature in the field. The maximum likelihood estimator is discussed, and the basic concepts of minimization and estimation are examined for a simple simulated aircraft example. The cost functions that are to be minimized during estimation are defined and discussed. Graphic representations of the cost functions are given to illustrate the minimization process. Finally, the basic concepts are generalized, and estimation from flight data is discussed. Some of the major conclusions for the simulated example are also developed for the analysis of flight data from the F-14, highly maneuverable aircraft technology (HiMAT), and space shuttle vehicles.
The Parameters of Postmodernism.
ERIC Educational Resources Information Center
Zurbrugg, Nicholas
Hypothesizing that the tendency to define postmodern culture negatively derives from overliteral and undercritical responses to European theorists, this book of essays identifies the wide parameters of postmodernism. The book demonstrates that the literary and artistic temper of the postmodern condition in Europe and America cannot adequately be…
Phenological Parameters Estimation Tool
NASA Technical Reports Server (NTRS)
McKellip, Rodney D.; Ross, Kenton W.; Spruce, Joseph P.; Smoot, James C.; Ryan, Robert E.; Gasser, Gerald E.; Prados, Donald L.; Vaughan, Ronald D.
2010-01-01
The Phenological Parameters Estimation Tool (PPET) is a set of algorithms implemented in MATLAB that estimates key vegetative phenological parameters. For a given year, the PPET software package takes in temporally processed vegetation index data (3D spatio-temporal arrays) generated by the time series product tool (TSPT) and outputs spatial grids (2D arrays) of vegetation phenological parameters. As a precursor to PPET, the TSPT uses quality information for each pixel of each date to remove bad or suspect data, and then interpolates and digitally fills data voids in the time series to produce a continuous, smoothed vegetation index product. During processing, the TSPT displays NDVI (Normalized Difference Vegetation Index) time series plots and images from the temporally processed pixels. Both the TSPT and PPET currently use moderate resolution imaging spectroradiometer (MODIS) satellite multispectral data as a default, but each software package is modifiable and could be used with any high-temporal-rate remote sensing data collection system that is capable of producing vegetation indices. Raw MODIS data from the Aqua and Terra satellites is processed using the TSPT to generate a filtered time series data product. The PPET then uses the TSPT output to generate phenological parameters for desired locations. PPET output data tiles are mosaicked into a Conterminous United States (CONUS) data layer using ERDAS IMAGINE, or equivalent software package. Mosaics of the vegetation phenology data products are then reprojected to the desired map projection using ERDAS IMAGINE
The Parameters of Postmodernism.
ERIC Educational Resources Information Center
Zurbrugg, Nicholas
Hypothesizing that the tendency to define postmodern culture negatively derives from overliteral and undercritical responses to European theorists, this book of essays identifies the wide parameters of postmodernism. The book demonstrates that the literary and artistic temper of the postmodern condition in Europe and America cannot adequately be…
NASA Astrophysics Data System (ADS)
Messaoud, Deghdak
2010-11-01
In this paper, we study the existence of equilibrium in non-cooperative game with fuzzy parameters. We generalize te results of Larbani and Kacher(2008, 2009) in infinite dimentional spaces. The proof is based on the Browder-Fan fixed point theorem.
Geoengineering design parameters workshop
St. John, C.M. and Associates, Grand Junction, CO ); Kim, Kunsoo . Rockwell Hanford Operations)
1985-12-12
A one-day workshop on the subject of the geotechnical design parameters, in situ stress and rock mass strength, for a nuclear waste repository in basalt was held in Rapid City, South Dakota, on June 25, 1989. A panel comprised of five widely recognized experts in the field of rock mechanics, met to discuss the state of stress at the Hanford Site and the strength of a basalt rock mass. This report summarizes the discussions that took place and presents a set of final position statements developed collaboratively by the panel and the workshop moderator. The report concludes with a set of specific recommendations for future actions considered necessary to adequately define the in situ stress and the rock mass strength at the Hanford Site and to document the position of the Basalt Waste Isolation Project in respect to these two critical design parameters.
Physical Parameter Eclipse Mapping
NASA Astrophysics Data System (ADS)
Vrielmann, S.
The tomographic method Physical Parameter Eclipse Mapping is a tool to reconstruct spatial distributions of physical parameters (like temperatures and surface densities) in accretion discs of cataclysmic variables. After summarizing the method, we apply it to multi-colour eclipse light curves of various dwarf novae and nova-likes like VZ Scl, IP Peg in outburst, UU Aqr, V2051 Oph and HT Cas in order to derive the temperatures (and surface densities) in the disc, the white dwarf temperature, the disc size, the effective temperatures and the viscosities. The results allows us to establish or refine a physical model for the accretion disc. Our maps of HT Cas and V 2051Oph, for example, indicate that the (quiescent) disc must be structured into a cool, optically thick inner disc sandwiched by hot, optically thin chromospheres. In addition, the disc of HT Cas must be patchy with a covering factor of about 40% caused by magnetic activity in the disc.
Ceramic Life Prediction Parameters
1980-05-01
prediction methodology is shown in the form of a flow chart in Fig. 1, and entails material characterization including the two parameter Weibull (volume...temperatures between 1100 and 1250CC, Fig. 24, is interpreted as indicative of blunting of the microcrack due to the viscous flow . It is...retained in two slotted SiC holders by large SiC pins. The SiC holders are retained in water cooled metal adaptors which in turn are attached
Military display performance parameters
NASA Astrophysics Data System (ADS)
Desjardins, Daniel D.; Meyer, Frederick
2012-06-01
The military display market is analyzed in terms of four of its segments: avionics, vetronics, dismounted soldier, and command and control. Requirements are summarized for a number of technology-driving parameters, to include luminance, night vision imaging system compatibility, gray levels, resolution, dimming range, viewing angle, video capability, altitude, temperature, shock and vibration, etc., for direct-view and virtual-view displays in cockpits and crew stations. Technical specifications are discussed for selected programs.
Prediction of psychoacoustic parameters
NASA Astrophysics Data System (ADS)
Genuit, Klaus; Fiebig, Andre
2005-09-01
Noise is defined as an audible sound which either disturbs the silence, or an intentional sound that listening to leads to annoyance. Thus, it is clearly defined that the assignment of noise cannot be reduced to simple determining objective parameters like the A-weighted SPL. The question whether a sound is judged as noise can only be answered after the transformation from the sound event into an hearing event has been accomplished. The evaluation of noise depends on the physical characteristics of the sound event, on the psychoacoustical features of the human ear as well as on the psychological aspects of men. The subjectively felt noise quality depends not only on the A-weighted sound-pressure level, but also on other psychoacoustical parameters such as loudness, roughness, sharpness, etc. The known methods for the prediction of the spatial A-weighted SPL distribution in dependence on the propagation are not suitable to predict psychoacoustic parameters in an adequate way. Especially, the roughness provoked by modulation or the sharpness generated by an accumulation of high, frequent sound energy cannot offhandedly be predicted as distance dependent.
NASA Astrophysics Data System (ADS)
Dashevsky, Ilana
2007-07-01
This proposal tests the new NICMOS non-nominal focus positions, which are implemented in the front-end systems and are specified in the Phase II using the CAMERA-FOCUS=DEFOCUS Optional Parameter. The targets from Proposals 9832 and 11063 are used in this Proposal. The GO Proposal 9832 is an example of how GOs may use the new non-nominal focus implementation for detector 3. Proposal 11063 is the NICMOS focus monitor, which will be used to verify the non-nominal focus for all 3 detectors.
NASA Technical Reports Server (NTRS)
Drysdale, Alan; Sager, John; Wheeler, Ray; Fortson, Russ; Chetirkin, Peter
1993-01-01
The most important Controlled Ecological Life Support System (CELSS) engineering parameters are, in order of decreasing importance, manpower, mass, and energy. The plant component is a significant contributor to the total system equivalent mass. In this report, a generic plant component is described and the relative equivalent mass and productivity are derived for a number of instances taken from the KSC CELSS Breadboard Project data and literature. Typical specific productivities (edible biomass produced over 10 years divided by system equivalent mass) for closed systems are of the order of 0.2.
NASA Technical Reports Server (NTRS)
Drysdale, Alan; Sager, John; Wheeler, Ray; Fortson, Russ; Chetirkin, Peter
1993-01-01
The most important Controlled Ecological Life Support System (CELSS) engineering parameters are, in order of decreasing importance, manpower, mass, and energy. The plant component is a significant contributor to the total system equivalent mass. In this report, a generic plant component is described and the relative equivalent mass and productivity are derived for a number of instances taken from the KSC CELSS Breadboard Project data and literature. Typical specific productivities (edible biomass produced over 10 years divided by system equivalent mass) for closed systems are of the order of 0.2.
Infrared Drying Parameter Optimization
NASA Astrophysics Data System (ADS)
Jackson, Matthew R.
In recent years, much research has been done to explore direct printing methods, such as screen and inkjet printing, as alternatives to the traditional lithographic process. The primary motivation is reduction of the material costs associated with producing common electronic devices. Much of this research has focused on developing inkjet or screen paste formulations that can be printed on a variety of substrates, and which have similar conductivity performance to the materials currently used in the manufacturing of circuit boards and other electronic devices. Very little research has been done to develop a process that would use direct printing methods to manufacture electronic devices in high volumes. This study focuses on developing and optimizing a drying process for conductive copper ink in a high volume manufacturing setting. Using an infrared (IR) dryer, it was determined that conductive copper prints could be dried in seconds or minutes as opposed to tens of minutes or hours that it would take with other drying devices, such as a vacuum oven. In addition, this study also identifies significant parameters that can affect the conductivity of IR dried prints. Using designed experiments and statistical analysis; the dryer parameters were optimized to produce the best conductivity performance for a specific ink formulation and substrate combination. It was determined that for an ethylene glycol, butanol, 1-methoxy 2- propanol ink formulation printed on Kapton, the optimal drying parameters consisted of a dryer height of 4 inches, a temperature setting between 190 - 200°C, and a dry time of 50-65 seconds depending on the printed film thickness as determined by the number of print passes. It is important to note that these parameters are optimized specifically for the ink formulation and substrate used in this study. There is still much research that needs to be done into optimizing the IR dryer for different ink substrate combinations, as well as developing a
Display Parameters and Requirements
NASA Astrophysics Data System (ADS)
Bahadur, Birendra
The following sections are included: * INTRODUCTION * HUMAN FACTORS * Anthropometry * Sensory * Cognitive * Discussions * THE HUMAN VISUAL SYSTEM - CAPABILITIES AND LIMITATIONS * Cornea * Pupil and Iris * Lens * Vitreous Humor * Retina * RODS - NIGHT VISION * CONES - DAY VISION * RODS AND CONES - TWILIGHT VISION * VISUAL PIGMENTS * MACULA * BLOOD * CHOROID COAT * Visual Signal Processing * Pathways to the Brain * Spatial Vision * Temporal Vision * Colour Vision * Colour Blindness * DICHROMATISM * Protanopia * Deuteranopia * Tritanopia * ANOMALOUS TRICHROMATISM * Protanomaly * Deuteranomaly * Tritanomaly * CONE MONOCHROMATISM * ROD MONOCHROMATISM * Using Colour Effectively * COLOUR MIXTURES AND THE CHROMATICITY DIAGRAM * Colour Matching Functions and Chromaticity Co-ordinates * CIE 1931 Colour Space * CIE PRIMARIES * CIE COLOUR MATCHING FUNCTIONS AND CHROMATICITY CO-ORDINATES * METHODS FOR DETERMINING TRISTIMULUS VALUES AND COLOUR CO-ORDINATES * Spectral Power Distribution Method * Filter Method * CIE 1931 CHROMATICITY DIAGRAM * ADDITIVE COLOUR MIXTURE * CIE 1976 Chromaticity Diagram * CIE Uniform Colour Spaces and Colour Difference Formulae * CIELUV OR L*u*v* * CIELAB OR L*a*b* * CIE COLOUR DIFFERENCE FORMULAE * Colour Temperature and CIE Standard Illuminants and source * RADIOMETRIC AND PHOTOMETRIC QUANTITIES * Photopic (Vλ and Scotopic (Vλ') Luminous Efficiency Function * Photometric and Radiometric Flux * Luminous and Radiant Intensities * Incidence: Illuminance and Irradiance * Exitance or Emittance (M) * Luminance and Radiance * ERGONOMIC REQUIREMENTS OF DISPLAYS * ELECTRO-OPTICAL PARAMETERS AND REQUIREMENTS * Contrast and Contrast Ratio * Luminance and Brightness * Colour Contrast and Chromaticity * Glare * Other Aspects of Legibility * SHAPE AND SIZE OF CHARACTERS * DEFECTS AND BLEMISHES * FLICKER AND DISTORTION * ANGLE OF VIEW * Switching Speed * Threshold and Threshold Characteristic * Measurement Techniques For Electro-optical Parameters * RADIOMETRIC
Precision cosmological parameter estimation
NASA Astrophysics Data System (ADS)
Fendt, William Ashton, Jr.
2009-09-01
methods. These techniques will help in the understanding of new physics contained in current and future data sets as well as benefit the research efforts of the cosmology community. Our idea is to shift the computationally intensive pieces of the parameter estimation framework to a parallel training step. We then provide a machine learning code that uses this training set to learn the relationship between the underlying cosmological parameters and the function we wish to compute. This code is very accurate and simple to evaluate. It can provide incredible speed- ups of parameter estimation codes. For some applications this provides the convenience of obtaining results faster, while in other cases this allows the use of codes that would be impossible to apply in the brute force setting. In this thesis we provide several examples where our method allows more accurate computation of functions important for data analysis than is currently possible. As the techniques developed in this work are very general, there are no doubt a wide array of applications both inside and outside of cosmology. We have already seen this interest as other scientists have presented ideas for using our algorithm to improve their computational work, indicating its importance as modern experiments push forward. In fact, our algorithm will play an important role in the parameter analysis of Planck, the next generation CMB space mission.
Cook, J.M.
1995-07-01
Sands and Rees propose an electronic bench measurement of the impulse energy loss of a stored particle bunch to vacuum-chamber components. The components act as the outer conductor of a coaxial line with a thin wire as center conductor. Short pulses are then transmitted through this coaxial system to simulate relativistic particle bunches. Their proposal has since been implemented by several investigators and has become a well-known technique. They derive a first-order approximation to the loss parameter {kappa} for use in these measurements. The purpose of this note is to point out that exact expression for {kappa} is as simple as its first-order approximation and to recommend its use even when {kappa} is small.
Orio, Peter; Wallner, Kent . E-mail: kent.Wallner@med.va.gov; Merrick, Gregory; Herstein, Andrew; Mitsuyama, Paul; Thornton, Ken; Butler, Wayne; Sutlief, Steven
2007-02-01
Purpose: To analyze the role of dosimetric quality parameters in maximizing cancer eradication in higher risk prostate cancer patients treated with palladium (Pd)-103 and supplemental beam radiation. Methods: One-hundred-seventy-nine patients treated with Pd-103 and supplemental beam radiation, with minimum 2 years follow-up prostate-specific antigen (PSA) values and posttreatment computed tomography scans were analyzed. Dosimetric parameters included the V100 (percent of the postimplant volume covered by the prescription dose), the D90 (the minimum dose that covered 90% of the post implant volume), and the treatment margins (the radial distance between the prostatic edge and the prescription isodose). Treatment margins (TMs) were calculated using premarket software. Results: Freedom from biochemical failure was 79% at 3 years, with 92 of the 179 patients (51%) followed beyond 3 years. In comparing patients who did or did not achieve biochemical control, the most striking differences were in biologic factors of pretreatment PSA and Gleason score. The V100, D90, and average TM all showed nonsignificant trends to higher values in patients with biochemical control. In multivariate analysis of each of the three dosimetric parameters against PSA and Gleason score, TM showed the strongest correlation with biochemical control (p = 0.19). Conclusions: For patients with intermediate and high-risk prostate cancer treated with Pd-103 brachytherapy and external beam radiation, biologic factors (PSA and Gleason score) were the most important determinants of cancer eradication. However, there is a trend to better outcomes among patients with higher quality implant parameters, suggesting that attention to implant quality will maximize the likelihood of cure.
Stochastic control system parameter identifiability
NASA Technical Reports Server (NTRS)
Lee, C. H.; Herget, C. J.
1975-01-01
The parameter identification problem of general discrete time, nonlinear, multiple input/multiple output dynamic systems with Gaussian white distributed measurement errors is considered. The knowledge of the system parameterization was assumed to be known. Concepts of local parameter identifiability and local constrained maximum likelihood parameter identifiability were established. A set of sufficient conditions for the existence of a region of parameter identifiability was derived. A computation procedure employing interval arithmetic was provided for finding the regions of parameter identifiability. If the vector of the true parameters is locally constrained maximum likelihood (CML) identifiable, then with probability one, the vector of true parameters is a unique maximal point of the maximum likelihood function in the region of parameter identifiability and the constrained maximum likelihood estimation sequence will converge to the vector of true parameters.
[Acoustical parameters of toys].
Harazin, Barbara
2010-01-01
Toys play an important role in the development of the sight and hearing concentration in children. They also support the development of manipulation, gently influence a child and excite its emotional activities. A lot of toys emit various sounds. The aim of the study was to assess sound levels produced by sound-emitting toys used by young children. Acoustical parameters of noise were evaluated for 16 sound-emitting plastic toys in laboratory conditions. The noise level was recorded at four different distances, 10, 20, 25 and 30 cm, from the toy. Measurements of A-weighted sound pressure levels and noise levels in octave band in the frequency range from 31.5 Hz to 16 kHz were performed at each distance. Taking into consideration the highest equivalent A-weighted sound levels produced by tested toys, they can be divided into four groups: below 70 dB (6 toys), from 70 to 74 dB (4 toys), from 75 to 84 dB (3 toys) and from 85 to 94 dB (3 toys). The majority of toys (81%) emitted dominant sound levels in octave band at the frequency range from 2 kHz to 4 kHz. Sound-emitting toys produce the highest acoustic energy at the frequency range of the highest susceptibility of the auditory system. Noise levels produced by some toys can be dangerous to children's hearing.
Agarwal, P; Sharma, D; Gandhi, A; Binjola, A; Subramani, V; Chander, S
2016-06-15
Purpose: To compare the Accelerated Partial Breast Irradiation (APBI) plan with the normalized basal dose points and 5mm box prescription. Methods: Five patients of APBI were planned twice in Oncentra Master planning TPS (Version 4.3) using TG-43 algorithm. The number of catheters for all the patients was 10 to 16 and implant plane 2 to 3. For planning all catheters were reconstructed. Source loading was done as per HR-CTV contoured. The HR-CTV volume range was from 75cc to 182cc. Plans were normalized in two methods. First all plans were normalized on Basal dose points (PlanA) and second all the plan were normalized on 5mm box (PlanB). The prescription dose (PD) was 35Gy in 10 fractions. All the plans were completely based on normalization and without optimization. Plan evaluation was based on certain parameters coverage Index (CI), dose homogeneity index (DHI), conformity index (COIN), over dose volume index (OI). Results: The average and median of CI for planA was 0.835 and 0.8154, for planB 0.82 and 0.799 respectively. The median and average of DHI for planA was 0.66 and 0.6062, for planB 0.67 and 0.62 respectively. The range of COIN for planA and planB was from 0.58 to 0.65 respectively. The range of OI was from 0.083 to 0.169 for planA and planB. The treatment time in planA was in average 1.13 times more than planB as V150% of HR-CTV in planA was 4–6% more. The ipsilateral lung was getting 30% of PD which was 0.6% to 3.5%. Conclusion: Treatment Planning should be individualized based on implants characteristics. Planning with prescription to basal dose points should be preferred to 5mm box prescription, in order to achieve better DHI and less treatment time.
A study of parameter identification
NASA Technical Reports Server (NTRS)
Herget, C. J.; Patterson, R. E., III
1978-01-01
A set of definitions for deterministic parameter identification ability were proposed. Deterministic parameter identificability properties are presented based on four system characteristics: direct parameter recoverability, properties of the system transfer function, properties of output distinguishability, and uniqueness properties of a quadratic cost functional. Stochastic parameter identifiability was defined in terms of the existence of an estimation sequence for the unknown parameters which is consistent in probability. Stochastic parameter identifiability properties are presented based on the following characteristics: convergence properties of the maximum likelihood estimate, properties of the joint probability density functions of the observations, and properties of the information matrix.
Oliveira, Susana Maria; Teixeira, Nuno José; Fernandes, Lisete; Teles, Pedro; Vieira, Guy; Vaz, Pedro
2014-11-01
The MCNPX code was used to calculate the TG-43U1 recommended parameters in water and prostate tissue in order to quantify the dosimetric impact in 30 patients treated with (125)I prostate implants when replacing the TG-43U1 formalism parameters calculated in water by a prostate-like medium in the planning system (PS) and to evaluate the uncertainties associated with Monte Carlo (MC) calculations. The prostate density was obtained from the CT of 100 patients with prostate cancer. The deviations between our results for water and the TG-43U1 consensus dataset values were -2.6% for prostate V100, -13.0% for V150, and -5.8% for D90; -2.0% for rectum V100, and -5.1% for D0.1; -5.0% for urethra D10, and -5.1% for D30. The same differences between our water and prostate results were all under 0.3%. Uncertainties estimations were up to 2.9% for the gL(r) function, 13.4% for the F(r,θ) function and 7.0% for Λ, mainly due to seed geometry uncertainties. Uncertainties in extracting the TG-43U1 parameters in the MC simulations as well as in the literature comparison are of the same order of magnitude as the differences between dose distributions computed for water and prostate-like medium. The selection of the parameters for the PS should be done carefully, as it may considerably affect the dose distributions. The seeds internal geometry uncertainties are a major limiting factor in the MC parameters deduction. Copyright © 2014. Published by Elsevier Ltd.
Computer program for parameter optimization
NASA Technical Reports Server (NTRS)
Glatt, C. R.; Hague, D. S.
1968-01-01
Flexible, large scale digital computer program was designed for the solution of a wide range of multivariable parameter optimization problems. The program has the ability to solve constrained optimization problems involving up to one hundred parameters.
Subsurface Geotechnical Parameters Report
D. Rigby; M. Mrugala; G. Shideler; T. Davidsavor; J. Leem; D. Buesch; Y. Sun; D. Potyondy; M. Christianson
2003-12-17
The Yucca Mountain Project is entering a the license application (LA) stage in its mission to develop the nation's first underground nuclear waste repository. After a number of years of gathering data related to site characterization, including activities ranging from laboratory and site investigations, to numerical modeling of processes associated with conditions to be encountered in the future repository, the Project is realigning its activities towards the License Application preparation. At the current stage, the major efforts are directed at translating the results of scientific investigations into sets of data needed to support the design, and to fulfill the licensing requirements and the repository design activities. This document addresses the program need to address specific technical questions so that an assessment can be made about the suitability and adequacy of data to license and construct a repository at the Yucca Mountain Site. In July 2002, the U.S. Nuclear Regulatory Commission (NRC) published an Integrated Issue Resolution Status Report (NRC 2002). Included in this report were the Repository Design and Thermal-Mechanical Effects (RDTME) Key Technical Issues (KTI). Geotechnical agreements were formulated to resolve a number of KTI subissues, in particular, RDTME KTIs 3.04, 3.05, 3.07, and 3.19 relate to the physical, thermal and mechanical properties of the host rock (NRC 2002, pp. 2.1.1-28, 2.1.7-10 to 2.1.7-21, A-17, A-18, and A-20). The purpose of the Subsurface Geotechnical Parameters Report is to present an accounting of current geotechnical information that will help resolve KTI subissues and some other project needs. The report analyzes and summarizes available qualified geotechnical data. It evaluates the sufficiency and quality of existing data to support engineering design and performance assessment. In addition, the corroborative data obtained from tests performed by a number of research organizations is presented to reinforce
Bibliography for aircraft parameter estimation
NASA Technical Reports Server (NTRS)
Iliff, Kenneth W.; Maine, Richard E.
1986-01-01
An extensive bibliography in the field of aircraft parameter estimation has been compiled. This list contains definitive works related to most aircraft parameter estimation approaches. Theoretical studies as well as practical applications are included. Many of these publications are pertinent to subjects peripherally related to parameter estimation, such as aircraft maneuver design or instrumentation considerations.
Improved Estimates of Thermodynamic Parameters
NASA Technical Reports Server (NTRS)
Lawson, D. D.
1982-01-01
Techniques refined for estimating heat of vaporization and other parameters from molecular structure. Using parabolic equation with three adjustable parameters, heat of vaporization can be used to estimate boiling point, and vice versa. Boiling points and vapor pressures for some nonpolar liquids were estimated by improved method and compared with previously reported values. Technique for estimating thermodynamic parameters should make it easier for engineers to choose among candidate heat-exchange fluids for thermochemical cycles.
MODFLOW-Style parameters in underdetermined parameter estimation.
D'Oria, Marco; Fienen, Michael N
2012-01-01
In this article, we discuss the use of MODFLOW-Style parameters in the numerical codes MODFLOW_2005 and MODFLOW_2005-Adjoint for the definition of variables in the Layer Property Flow package. Parameters are a useful tool to represent aquifer properties in both codes and are the only option available in the adjoint version. Moreover, for overdetermined parameter estimation problems, the parameter approach for model input can make data input easier. We found that if each estimable parameter is defined by one parameter, the codes require a large computational effort and substantial gains in efficiency are achieved by removing logical comparison of character strings that represent the names and types of the parameters. An alternative formulation already available in the current implementation of the code can also alleviate the efficiency degradation due to character comparisons in the special case of distributed parameters defined through multiplication matrices. The authors also hope that lessons learned in analyzing the performance of the MODFLOW family codes will be enlightening to developers of other Fortran implementations of numerical codes.
Identified Parameters, Parameters of Interest and Their Relationships
ERIC Educational Resources Information Center
San Martin, Ernesto; Gonzalez, Jorge; Tuerlinckx, Francis
2009-01-01
The goal of this commentary is to provide some additional results to the interesting and provocative paper of Maris and Bechger ("On Interpreting the Model Parameters for the Three Parameter Logistic Model," this issue). In this article, the authors have three aims. First, the authors distinguish between three fundamental concepts that are…
MODFLOW-style parameters in underdetermined parameter estimation
D'Oria, Marco D.; Fienen, Michael N.
2012-01-01
In this article, we discuss the use of MODFLOW-Style parameters in the numerical codes MODFLOW_2005 and MODFLOW_2005-Adjoint for the definition of variables in the Layer Property Flow package. Parameters are a useful tool to represent aquifer properties in both codes and are the only option available in the adjoint version. Moreover, for overdetermined parameter estimation problems, the parameter approach for model input can make data input easier. We found that if each estimable parameter is defined by one parameter, the codes require a large computational effort and substantial gains in efficiency are achieved by removing logical comparison of character strings that represent the names and types of the parameters. An alternative formulation already available in the current implementation of the code can also alleviate the efficiency degradation due to character comparisons in the special case of distributed parameters defined through multiplication matrices. The authors also hope that lessons learned in analyzing the performance of the MODFLOW family codes will be enlightening to developers of other Fortran implementations of numerical codes.
MODFLOW-style parameters in underdetermined parameter estimation
D'Oria, M.; Fienen, M.N.
2012-01-01
In this article, we discuss the use of MODFLOW-Style parameters in the numerical codes MODFLOW-2005 and MODFLOW-2005-Adjoint for the definition of variables in the Layer Property Flow package. Parameters are a useful tool to represent aquifer properties in both codes and are the only option available in the adjoint version. Moreover, for overdetermined parameter estimation problems, the parameter approach for model input can make data input easier. We found that if each estimable parameter is defined by one parameter, the codes require a large computational effort and substantial gains in efficiency are achieved by removing logical comparison of character strings that represent the names and types of the parameters. An alternative formulation already available in the current implementation of the code can also alleviate the efficiency degradation due to character comparisons in the special case of distributed parameters defined through multiplication matrices. The authors also hope that lessons learned in analyzing the performance of the MODFLOW family codes will be enlightening to developers of other Fortran implementations of numerical codes. ?? 2011, National Ground Water Association.
Identified Parameters, Parameters of Interest and Their Relationships
ERIC Educational Resources Information Center
San Martin, Ernesto; Gonzalez, Jorge; Tuerlinckx, Francis
2009-01-01
The goal of this commentary is to provide some additional results to the interesting and provocative paper of Maris and Bechger ("On Interpreting the Model Parameters for the Three Parameter Logistic Model," this issue). In this article, the authors have three aims. First, the authors distinguish between three fundamental concepts that are…
Asymmetric dose–volume optimization with smoothness control for rotating-shield brachytherapy
Liu, Yunlong; Flynn, Ryan T.; Kim, Yusung; Wu, Xiaodong
2014-11-01
Purpose: It is important to reduce fluence map complexity in rotating-shield brachytherapy (RSBT) inverse planning to improve delivery efficiency while maintaining plan quality. This study proposes an efficient and effective RSBT dose optimization method which enables to produce smooth fluence maps. Methods: Five cervical cancer patients each with a high-risk clinical-target-volume (HR-CTV) larger than 40 cm{sup 3} were considered as the test cases. The RSBT source was a partially shielded electronic brachytherapy source (Xoft Axxent™). The anchor RSBT plans generated by the asymmetric dose–volume optimization with smoothness control (ADOS) method were compared against those produced by the dose–surface optimization (DSO) method and inverse-planning with simulated annealing (IPSA). Either L{sub 1}-norm or L{sub 2}-norm was used to measure the smoothness of a fluence map in the proposed ADOS method as one weighted term of the objective function. Uniform dwell-time scaling was applied to all plans such that HR-CTV D{sub 90} was maximized without violating the D{sub 2cc} tolerances of the rectum, bladder, and sigmoid colon. The quality of the anchor plans was measured with HR-CTV D{sub 90} of the anchor plans. Single-shielded RSBT [(S-RSBT), RSBT with single, fix sized delivery window] and dynamic-sheilded RSBT [(D-RSBT), RSBT with dynamically varying sized delivery window] delivery plans generated based on the anchor plans were also measured, with delivery time constraints of 10, 20, and 30 min/fraction (fx). Results: The average HR-CTV D{sub 90} values of the anchor plans achieved by the ADOS, DSO, and IPSA methods were 111.5, 94.2, and 107.4 Gy, respectively, where the weighting parameter β used in ADOS with L{sub 2}-norm was set to be 100. By using S-RSBT sequencing and 20 min/fx delivery time, the corresponding D{sub 90} values were 88.8, 81.9, and 83.4 Gy; while using D-RSBT sequencing with 20 min/fx delivery time, the corresponding D{sub 90} values were
Parameter estimation in food science.
Dolan, Kirk D; Mishra, Dharmendra K
2013-01-01
Modeling includes two distinct parts, the forward problem and the inverse problem. The forward problem-computing y(t) given known parameters-has received much attention, especially with the explosion of commercial simulation software. What is rarely made clear is that the forward results can be no better than the accuracy of the parameters. Therefore, the inverse problem-estimation of parameters given measured y(t)-is at least as important as the forward problem. However, in the food science literature there has been little attention paid to the accuracy of parameters. The purpose of this article is to summarize the state of the art of parameter estimation in food science, to review some of the common food science models used for parameter estimation (for microbial inactivation and growth, thermal properties, and kinetics), and to suggest a generic method to standardize parameter estimation, thereby making research results more useful. Scaled sensitivity coefficients are introduced and shown to be important in parameter identifiability. Sequential estimation and optimal experimental design are also reviewed as powerful parameter estimation methods that are beginning to be used in the food science literature.
Han, Ben H; Wallner, Kent; Merrick, Gregory; Badiozamani, Kas; Butler, Wayne
2003-06-01
The purpose of this study was to clarify where observers differ in their interpretation of CT scans, and to relate those differences to clinically relevant dosimetric parameters. Twenty unselected patients treated with I-125 or Pd-103 brachytherapy at the Veterans Affairs Puget Sound Health Care System (VAPSHCS) in 2001 were studied. Patients were implanted with I-125 (7 patients, 0.87 mCi/source) or Pd-103 (13 patients, 2.54 U/source). The number of I-125 sources implanted ranged from 52 to 78. The number of Pd-103 sources implanted ranged from 58-144. Post-implant 3 mm CT images were imported into a laptop running Varian Variseed and sent to the four physician investigators, who outlined the prostate independently. Investigators were not coached specifically for this study, beyond their having read prior reports regarding prostate volume determinations. There was moderate interobserver variability in CT volume determination, with the standard deviations as a percent of the mean ranging from 9% to 29% (median: 17%). An average of 14% of implants (range: 5%-20%) would have been judged inadequate based on a minimum V100 of 80%, versus 24% of implants (range: 5%-45%) being judged inadequate based on a minimum D90 of 90% of prescription dose. The greatest variability was seen in prostate length (median standard deviation: 0.57 cm), due to vagaries in base and apical localization. However, the prostatic width and thickness also varied substantially between observers, with median standard deviations of 0.24 and 0.32 cm, respectively. Treatment margin variability was greatest at the anterior border, with a median standard deviation of 0.21 cm +/- 0.10. We believe that CT-based dosimetry, while influenced by CT interpretation, still provides useful general dosimetric calculations, that are likely to be reproducible enough to provide clinically useful information between institutions. The V100 and TMs are less influenced by interobserver CT interpretation variability than
Methods for Linking Item Parameters.
1981-08-01
of Linking Adequacy ... ........... ... 27 Evaluation of Linking Techniques .. ......... ... 28 Rasch model . ................. 28 Three-parameter...class are models for use when the response is dichotomous (Lord & Novick, 1968; lirnbaum, 1968), models for use when the response is polychotomous... dichotomous ability items of a multiple-choice nature. Two IRT models are appropriate for such items: the three-parameter normal and logistic ogive models
2015-05-27
ParFit is a flexible and extendable framework and library of classes for fitting force-field parameters to data from high-level ab-initio calculations on the basis of deterministic and stochastic algorithms. Currently, the code is fitting MM3 and Merck force-field parameters but could easily extend to other force-field types.
2015-05-27
ParFit is a flexible and extendable framework and library of classes for fitting force-field parameters to data from high-level ab-initio calculations on the basis of deterministic and stochastic algorithms. Currently, the code is fitting MM3 and Merck force-field parameters but could easily extend to other force-field types.
Parameter estimation for distributed parameter models of complex, flexible structures
NASA Technical Reports Server (NTRS)
Taylor, Lawrence W., Jr.
1991-01-01
Distributed parameter modeling of structural dynamics has been limited to simple spacecraft configurations because of the difficulty of handling several distributed parameter systems linked at their boundaries. Although there is other computer software able to generate such models or complex, flexible spacecraft, unfortunately, neither is suitable for parameter estimation. Because of this limitation the computer software PDEMOD is being developed for the express purposes of modeling, control system analysis, parameter estimation and structure optimization. PDEMOD is capable of modeling complex, flexible spacecraft which consist of a three-dimensional network of flexible beams and rigid bodies. Each beam has bending (Bernoulli-Euler or Timoshenko) in two directions, torsion, and elongation degrees of freedom. The rigid bodies can be attached to the beam ends at any angle or body location. PDEMOD is also capable of performing parameter estimation based on matching experimental modal frequencies and static deflection test data. The underlying formulation and the results of using this approach for test data of the Mini-MAST truss will be discussed. The resulting accuracy of the parameter estimates when using such limited data can impact significantly the instrumentation requirements for on-orbit tests.
Parameter justification report for DRSPALL.
Pfeifle, Thomas W.; Hansen, Francis D.; Lord, David L.
2003-10-01
A new conceptual model has been developed for drilling intrusion into the Waste Isolation Pilot Plant. The model is implemented in a new code, DRSPALL, which captures the physics of the spallings release phenomena. The new conceptual model and code required parallel development of a family of parameters that adequately describe the properties of the system. This report introduces the various parameters implemented in the new spallings model, and provides justification for values and ranges of new parameters not currently in the performance assessment database.
Method for estimating solubility parameter
NASA Technical Reports Server (NTRS)
Lawson, D. D.; Ingham, J. D.
1973-01-01
Semiempirical correlations have been developed between solubility parameters and refractive indices for series of model hydrocarbon compounds and organic polymers. Measurement of intermolecular forces is useful for assessment of material compatibility, glass-transition temperature, and transport properties.
Quantum estimation of unknown parameters
NASA Astrophysics Data System (ADS)
Martínez-Vargas, Esteban; Pineda, Carlos; Leyvraz, François; Barberis-Blostein, Pablo
2017-01-01
We discuss the problem of finding the best measurement strategy for estimating the value of a quantum system parameter. In general the optimum quantum measurement, in the sense that it maximizes the quantum Fisher information and hence allows one to minimize the estimation error, can only be determined if the value of the parameter is already known. A modification of the quantum Van Trees inequality, which gives a lower bound on the error in the estimation of a random parameter, is proposed. The suggested inequality allows us to assert if a particular quantum measurement, together with an appropriate estimator, is optimal. An adaptive strategy to estimate the value of a parameter, based on our modified inequality, is proposed.
How many dark energy parameters?
Linder, Eric V.; Huterer, Dragan
2005-05-16
For exploring the physics behind the accelerating universe a crucial question is how much we can learn about the dynamics through next generation cosmological experiments. For example, in defining the dark energy behavior through an effective equation of state, how many parameters can we realistically expect to tightly constrain? Through both general and specific examples (including new parametrizations and principal component analysis) we argue that the answer is 42 - no, wait, two. Cosmological parameter analyses involving a measure of the equation of state value at some epoch (e.g., w_0) and a measure of the change in equation of state (e.g., w') are therefore realistic in projecting dark energy parameter constraints. More elaborate parametrizations could have some uses (e.g., testing for bias or comparison with model features), but do not lead to accurately measured dark energy parameters.
Parameter Estimator for Engineering Systems
2016-10-13
This software model generates vehicle parameter sets for downstream modeling applications using real-world data. Value to users is provided through improvements to modeling activities as a result of decreases in time taken during model development and validation. Currently configured for transportation modeling activities, the software provides initial estimates for multiple fundamental vehicle parameters including mass, coefficient of drag, and tire rolling resistance using real-world drive and duty cycle information as inputs.
Calibrating binary lumped parameter models
NASA Astrophysics Data System (ADS)
Morgenstern, Uwe; Stewart, Mike
2017-04-01
Groundwater at its discharge point is a mixture of water from short and long flowlines, and therefore has a distribution of ages rather than a single age. Various transfer functions describe the distribution of ages within the water sample. Lumped parameter models (LPMs), which are mathematical models of water transport based on simplified aquifer geometry and flow configuration can account for such mixing of groundwater of different age, usually representing the age distribution with two parameters, the mean residence time, and the mixing parameter. Simple lumped parameter models can often match well the measured time varying age tracer concentrations, and therefore are a good representation of the groundwater mixing at these sites. Usually a few tracer data (time series and/or multi-tracer) can constrain both parameters. With the building of larger data sets of age tracer data throughout New Zealand, including tritium, SF6, CFCs, and recently Halon-1301, and time series of these tracers, we realised that for a number of wells the groundwater ages using a simple lumped parameter model were inconsistent between the different tracer methods. Contamination or degradation of individual tracers is unlikely because the different tracers show consistent trends over years and decades. This points toward a more complex mixing of groundwaters with different ages for such wells than represented by the simple lumped parameter models. Binary (or compound) mixing models are able to represent a more complex mixing, with mixing of water of two different age distributions. The problem related to these models is that they usually have 5 parameters which makes them data-hungry and therefore difficult to constrain all parameters. Two or more age tracers with different input functions, with multiple measurements over time, can provide the required information to constrain the parameters of the binary mixing model. We obtained excellent results using tritium time series encompassing
Parameter Estimation Using VLA Data
NASA Astrophysics Data System (ADS)
Venter, Willem C.
The main objective of this dissertation is to extract parameters from multiple wavelength images, on a pixel-to-pixel basis, when the images are corrupted with noise and a point spread function. The data used are from the field of radio astronomy. The very large array (VLA) at Socorro in New Mexico was used to observe planetary nebula NGC 7027 at three different wavelengths, 2 cm, 6 cm and 20 cm. A temperature model, describing the temperature variation in the nebula as a function of optical depth, is postulated. Mathematical expressions for the brightness distribution (flux density) of the nebula, at the three observed wavelengths, are obtained. Using these three equations and the three data values available, one from the observed flux density map at each wavelength, it is possible to solve for two temperature parameters and one optical depth parameter at each pixel location. Due to the fact that the number of unknowns equal the number of equations available, estimation theory cannot be used to smooth any noise present in the data values. It was found that a direct solution of the three highly nonlinear flux density equations is very sensitive to noise in the data. Results obtained from solving for the three unknown parameters directly, as discussed above, were not physical realizable. This was partly due to the effect of incomplete sampling at the time when the data were gathered and to noise in the system. The application of rigorous digital parameter estimation techniques result in estimated parameters that are also not physically realizable. The estimated values for the temperature parameters are for example either too high or negative, which is not physically possible. Simulation studies have shown that a "double smoothing" technique improves the results by a large margin. This technique consists of two parts: in the first part the original observed data are smoothed using a running window and in the second part a similar smoothing of the estimated parameters
Understanding bibliometric parameters and analysis.
Choudhri, Asim F; Siddiqui, Adeel; Khan, Nickalus R; Cohen, Harris L
2015-01-01
Bibliometric parameters have become an important part of modern assessment of academic productivity. These parameters exist for the purpose of evaluating authors (publication count, citation count, h-index, m-quotient, hc-index, e-index, g-index, i-10 [i-n] index) and journals (impact factor, Eigenfactor, article influence score, SCImago journal rank, source-normalized impact per paper). Although in recent years there has been a proliferation of bibliometric parameters, the true meaning and appropriate use of these parameters is generally not well understood. Effective use of existing and emerging bibliometric tools can aid in assessment of academic productivity, including readiness for promotions and other awards. However, if not properly understood, the data can be misinterpreted and may be subject to manipulation. Familiarity with bibliometric parameters will aid in their effective implementation in the review of authors-whether individuals or groups-and journals, as well as their possible use in the promotions review process, maximizing the effectiveness of bibliometric analysis.
Catalogue of HI PArameters (CHIPA)
NASA Astrophysics Data System (ADS)
Saponara, J.; Benaglia, P.; Koribalski, B.; Andruchow, I.
2015-08-01
The catalogue of HI parameters of galaxies HI (CHIPA) is the natural continuation of the compilation by M.C. Martin in 1998. CHIPA provides the most important parameters of nearby galaxies derived from observations of the neutral Hydrogen line. The catalogue contains information of 1400 galaxies across the sky and different morphological types. Parameters like the optical diameter of the galaxy, the blue magnitude, the distance, morphological type, HI extension are listed among others. Maps of the HI distribution, velocity and velocity dispersion can also be display for some cases. The main objective of this catalogue is to facilitate the bibliographic queries, through searching in a database accessible from the internet that will be available in 2015 (the website is under construction). The database was built using the open source `` mysql (SQL, Structured Query Language, management system relational database) '', while the website was built with ''HTML (Hypertext Markup Language)'' and ''PHP (Hypertext Preprocessor)''.
The parameter uncertainty inflation fallacy.
Pernot, Pascal
2017-09-14
Statistical estimation of the prediction uncertainty of physical models is typically hindered by the inadequacy of these models due to various approximations they are built upon. The prediction errors caused by model inadequacy can be handled either by correcting the model's results or by adapting the model's parameter uncertainty to generate prediction uncertainties representative, in a way to be defined, of model inadequacy errors. The main advantage of the latter approach (thereafter called PUI, for Parameter Uncertainty Inflation) is its transferability to the prediction of other quantities of interest based on the same parameters. A critical review of implementations of PUI in several areas of computational chemistry shows that it is biased, in the sense that it does not produce prediction uncertainty bands conforming to model inadequacy errors.
Parameter estimation by genetic algorithms
Reese, G.M.
1993-11-01
Test/Analysis correlation, or structural identification, is a process of reconciling differences in the structural dynamic models constructed analytically (using the finite element (FE) method) and experimentally (from modal test). This is a methodology for assessing the reliability of the computational model, and is very important in building models of high integrity, which may be used as predictive tools in design. Both the analytic and experimental models evaluate the same quantities: the natural frequencies (or eigenvalues, ({omega}{sub i}), and the mode shapes (or eigenvectors, {var_phi}). In this paper, selected frequencies are reconciled in the two models by modifying physical parameters in the FE model. A variety of parameters may be modified such as the stiffness of a joint member or the thickness of a plate. Engineering judgement is required to identify important frequencies, and to characterize the uncertainty of the model design parameters.
The parameter uncertainty inflation fallacy
NASA Astrophysics Data System (ADS)
Pernot, Pascal
2017-09-01
Statistical estimation of the prediction uncertainty of physical models is typically hindered by the inadequacy of these models due to various approximations they are built upon. The prediction errors caused by model inadequacy can be handled either by correcting the model's results or by adapting the model's parameter uncertainty to generate prediction uncertainties representative, in a way to be defined, of model inadequacy errors. The main advantage of the latter approach (thereafter called PUI, for Parameter Uncertainty Inflation) is its transferability to the prediction of other quantities of interest based on the same parameters. A critical review of implementations of PUI in several areas of computational chemistry shows that it is biased, in the sense that it does not produce prediction uncertainty bands conforming to model inadequacy errors.
Photovoltaic module parameters acquisition model
NASA Astrophysics Data System (ADS)
Cibira, Gabriel; Koščová, Marcela
2014-09-01
This paper presents basic procedures for photovoltaic (PV) module parameters acquisition using MATLAB and Simulink modelling. In first step, MATLAB and Simulink theoretical model are set to calculate I-V and P-V characteristics for PV module based on equivalent electrical circuit. Then, limited I-V data string is obtained from examined PV module using standard measurement equipment at standard irradiation and temperature conditions and stated into MATLAB data matrix as a reference model. Next, the theoretical model is optimized to keep-up with the reference model and to learn its basic parameters relations, over sparse data matrix. Finally, PV module parameters are deliverable for acquisition at different realistic irradiation, temperature conditions as well as series resistance. Besides of output power characteristics and efficiency calculation for PV module or system, proposed model validates computing statistical deviation compared to reference model.
Parameters of care for craniosynostosis.
McCarthy, Joseph G; Warren, Stephen M; Bernstein, Joseph; Burnett, Whitney; Cunningham, Michael L; Edmond, Jane C; Figueroa, Alvaro A; Kapp-Simon, Kathleen A; Labow, Brian I; Peterson-Falzone, Sally J; Proctor, Mark R; Rubin, Marcie S; Sze, Raymond W; Yemen, Terrance A
2012-01-01
A multidisciplinary meeting was held from March 4 to 6, 2010, in Atlanta, Georgia, entitled "Craniosynostosis: Developing Parameters for Diagnosis, Treatment, and Management." The goal of this meeting was to create parameters of care for individuals with craniosynostosis. Fifty-two conference attendees represented a broad range of expertise, including anesthesiology, craniofacial surgery, dentistry, genetics, hand surgery, neurosurgery, nursing, ophthalmology, oral and maxillofacial surgery, orthodontics, otolaryngology, pediatrics, psychology, public health, radiology, and speech-language pathology. These attendees also represented 16 professional societies and peer-reviewed journals. The current state of knowledge related to each discipline was reviewed. Based on areas of expertise, four breakout groups were created to reach a consensus and draft specialty-specific parameters of care based on the literature or, in the absence of literature, broad clinical experience. In an iterative manner, the specialty-specific draft recommendations were presented to all conference attendees. Participants discussed the recommendations in multidisciplinary groups to facilitate exchange and consensus across disciplines. After the conference, a pediatric intensivist and social worker reviewed the recommendations. Consensus was reached among the 52 conference attendees and two post hoc reviewers. Longitudinal parameters of care were developed for the diagnosis, treatment, and management of craniosynostosis in each of the 18 specialty areas of care from prenatal evaluation to adulthood. To our knowledge, this is the first multidisciplinary effort to develop parameters of care for craniosynostosis. These parameters were designed to help facilitate the development of educational programs for the patient, families, and health-care professionals; stimulate the creation of a national database and registry to promote research, especially in the area of outcome studies; improve
Statistical parameters for gloss evaluation
Peiponen, Kai-Erik; Juuti, Mikko
2006-02-13
The measurement of minute changes in local gloss has not been presented in international standards due to a lack of suitable glossmeters. The development of a diffractive-element-based glossmeter (DOG) made it possible to detect local variation of gloss from planar and complex-shaped surfaces. Hence, a demand for proper statistical gloss parameters for classifying surface quality by gloss, similar to the standardized surface roughness classification, has become necessary. In this letter, we define statistical gloss parameters and utilize them as an example in the characterization of gloss from metal surface roughness standards by the DOG.
Beyond two dark energy parameters.
Sarkar, Devdeep; Sullivan, Scott; Joudaki, Shahab; Amblard, Alexandre; Holz, Daniel E; Cooray, Asantha
2008-06-20
Our ignorance of dark energy is generally described by a two-parameter equation of state. In these approaches, a particular ad hoc functional form is assumed, and only two independent parameters are incorporated. We propose a model-independent, multiparameter approach to fitting dark energy and show that next-generation surveys will constrain the equation of state in three or more independent redshift bins to better than 10%. Future knowledge of dark energy will surpass two numbers (e.g., [w{0},w{1}] or [w{0},w{a}]), and we propose a more flexible approach to the analysis of present and future data.
Reconstruction of fundamental SUSY parameters
P. M. Zerwas et al.
2003-09-25
We summarize methods and expected accuracies in determining the basic low-energy SUSY parameters from experiments at future e{sup +}e{sup -} linear colliders in the TeV energy range, combined with results from LHC. In a second step we demonstrate how, based on this set of parameters, the fundamental supersymmetric theory can be reconstructed at high scales near the grand unification or Planck scale. These analyses have been carried out for minimal supergravity [confronted with GMSB for comparison], and for a string effective theory.
Hubbard parameters for metallic Ce
Boring, A.M.; Albers, R.C.; Eriksson, O. ); Koelling, D.D. )
1992-04-27
We have obtained a phase diagram of the {alpha}{r arrow}{gamma} transition (moment formation) as a function of the {ital U} and {ital J} Kanamori Hubbard parameters. Overlap and hybridization terms are obtained by a tight-binding fit to first-principles band calculations. At the one-electron level we obtain no fundamental change in the interaction energies in going through the {alpha}{r arrow}{gamma} transition region. This is the first model to obtain self-consistent values for the Hubbard parameters in the solid state and they are in reasonable agreement with the experimentally derived values.
Parameter extraction and transistor models
NASA Technical Reports Server (NTRS)
Rykken, Charles; Meiser, Verena; Turner, Greg; Wang, QI
1985-01-01
Using specified mathematical models of the MOSFET device, the optimal values of the model-dependent parameters were extracted from data provided by the Jet Propulsion Laboratory (JPL). Three MOSFET models, all one-dimensional were used. One of the models took into account diffusion (as well as convection) currents. The sensitivity of the models was assessed for variations of the parameters from their optimal values. Lines of future inquiry are suggested on the basis of the behavior of the devices, of the limitations of the proposed models, and of the complexity of the required numerical investigations.
Evaluation of the Chromium Resonance Parameters Including Resonance Parameter Covariance
Leal, Luiz C; Derrien, Herve; Guber, Klaus H; Arbanas, Goran; Wiarda, Dorothea
2011-01-01
The intent of this work is to report the results and describe the procedures utilized to evaluate the chromium isotopes' cross sections, i.e., (50)Cr, (52)Cr, (53)Cr, and (54)Cr, for criticality safety applications. The evaluations were done in the resolved resonance region using the reduced Reich-Moore R-matrix formalism. The novel aspect of this evaluation is the inclusion of new transmission and capture cross-section measurements performed at the Oak Ridge Electron Linear Accelerator (ORELA) for energies below 100 keV and the extension of the (53)Cr energy region. The resonance analysis was performed with the multilevel R-matrix code, SAMMY, which utilizes the generalized least-squares technique based on the Bayes' theory. Complete sets of resonance parameters and resonance parameter covariance matrices (RPCMs) were obtained for each of the chromium isotopes from the SAMMY analysis of the experimental database.
GALAPAGOS: from pixels to parameters
NASA Astrophysics Data System (ADS)
Barden, Marco; Häußler, Boris; Peng, Chien Y.; McIntosh, Daniel H.; Guo, Yicheng
2012-05-01
To automate source detection, two-dimensional light profile Sérsic modelling and catalogue compilation in large survey applications, we introduce a new code Galaxy Analysis over Large Areas: Parameter Assessment by GALFITting Objects from SEXTRACTOR (GALAPAGOS). Based on a single set-up, GALAPAGOS can process a complete set of survey images. It detects sources in the data, estimates a local sky background, cuts postage stamp images for all sources, prepares object masks, performs Sérsic fitting including neighbours and compiles all objects in a final output catalogue. For the initial source detection, GALAPAGOS applies SEXTRACTOR, while GALFIT is incorporated for modelling Sérsic profiles. It measures the background sky involved in the Sérsic fitting by means of a flux growth curve. GALAPAGOS determines postage stamp sizes based on SEXTRACTOR shape parameters. In order to obtain precise model parameters, GALAPAGOS incorporates a complex sorting mechanism and makes use of modern CPU's multiplexing capabilities. It combines SEXTRACTOR and GALFIT data in a single output table. When incorporating information from overlapping tiles, GALAPAGOS automatically removes multiple entries from identical sources. GALAPAGOS is programmed in the Interactive Data Language (IDL). We test the stability and the ability to properly recover structural parameters extensively with artificial image simulations. Moreover, we apply GALAPAGOS successfully to the STAGES data set. For one-orbit Hubble Space Telescope data, a single 2.2-GHz CPU processes about 1000 primary sources per 24 h. Note that GALAPAGOS results depend critically on the user-defined parameter set-up. This paper provides useful guidelines to help the user make sensible choices.
Estimating random signal parameters from noisy images with nuisance parameters
Whitaker, Meredith Kathryn; Clarkson, Eric; Barrett, Harrison H.
2008-01-01
In a pure estimation task, an object of interest is known to be present, and we wish to determine numerical values for parameters that describe the object. This paper compares the theoretical framework, implementation method, and performance of two estimation procedures. We examined the performance of these estimators for tasks such as estimating signal location, signal volume, signal amplitude, or any combination of these parameters. The signal is embedded in a random background to simulate the effect of nuisance parameters. First, we explore the classical Wiener estimator, which operates linearly on the data and minimizes the ensemble mean-squared error. The results of our performance tests indicate that the Wiener estimator can estimate amplitude and shape once a signal has been located, but is fundamentally unable to locate a signal regardless of the quality of the image. Given these new results on the fundamental limitations of Wiener estimation, we extend our methods to include more complex data processing. We introduce and evaluate a scanning-linear estimator that performs impressively for location estimation. The scanning action of the estimator refers to seeking a solution that maximizes a linear metric, thereby requiring a global-extremum search. The linear metric to be optimized can be derived as a special case of maximum a posteriori (MAP) estimation when the likelihood is Gaussian and a slowly varying covariance approximation is made. PMID:18545527
Demographic parameters and natural selection.
Demetrius, L
1974-12-01
This paper introduces two new demographic parameters, the entropy and the reproductive potential of a population. The entropy of a population measures the variability of the contribution of the different age classes to the stationary age distribution. The reproductive potential measures the mean of the contribution of the different age classes to the growth rate. Using a relation between these measures and the Malthusian parameter, it is shown that in a random mating population in Hardy-Weinberg equilibrium, and under slow selection, the rate of change of entropy is equal to the genetic variance in entropy minus the genetic covariance of entropy and reproductive potential. This result is an analogue of Fisher's fundamental theorem of natural selection.
Identification of driver model parameters.
Reński, A
2001-01-01
The paper presents a driver model, which can be used in a computer simulation of a curved ride of a car. The identification of the driver parameters consisted in a comparison of the results of computer calculations obtained for the driver-vehicle-environment model with different driver data sets with test results of the double lane-change manoeuvre (Standard No. ISO/TR 3888:1975, International Organization for Standardization [ISO], 1975) and the wind gust manoeuvre. The optimisation method allows to choose for each real driver a set of driver model parameters for which the differences between test and calculation results are smallest. The presented driver model can be used in investigating the driver-vehicle control system, which allows to adapt the car construction to the psychophysical characteristics of a driver.
XPI: The Xanadu Parameter Interface
NASA Technical Reports Server (NTRS)
White, N.; Barrett, P.; Oneel, B.; Jacobs, P.
1992-01-01
XPI is a table driven parameter interface which greatly simplifies both command driven programs such as BROWSE and XIMAGE as well as stand alone single-task programs. It moves all of the syntax and semantic parsing of commands and parameters out of the users code into common code and externally defined tables. This allows the programmer to concentrate on writing the code unique to the application rather than reinventing the user interface and for external graphical interfaces to interface with no changes to the command driven program. XPI also includes a compatibility library which allows programs written using the IRAF host interface (Mandel and Roll) to use XPI in place of the IRAF host interface.
Parameter-exploring policy gradients.
Sehnke, Frank; Osendorfer, Christian; Rückstiess, Thomas; Graves, Alex; Peters, Jan; Schmidhuber, Jürgen
2010-05-01
We present a model-free reinforcement learning method for partially observable Markov decision problems. Our method estimates a likelihood gradient by sampling directly in parameter space, which leads to lower variance gradient estimates than obtained by regular policy gradient methods. We show that for several complex control tasks, including robust standing with a humanoid robot, this method outperforms well-known algorithms from the fields of standard policy gradients, finite difference methods and population based heuristics. We also show that the improvement is largest when the parameter samples are drawn symmetrically. Lastly we analyse the importance of the individual components of our method by incrementally incorporating them into the other algorithms, and measuring the gain in performance after each step.
Failure probability under parameter uncertainty.
Gerrard, R; Tsanakas, A
2011-05-01
In many problems of risk analysis, failure is equivalent to the event of a random risk factor exceeding a given threshold. Failure probabilities can be controlled if a decisionmaker is able to set the threshold at an appropriate level. This abstract situation applies, for example, to environmental risks with infrastructure controls; to supply chain risks with inventory controls; and to insurance solvency risks with capital controls. However, uncertainty around the distribution of the risk factor implies that parameter error will be present and the measures taken to control failure probabilities may not be effective. We show that parameter uncertainty increases the probability (understood as expected frequency) of failures. For a large class of loss distributions, arising from increasing transformations of location-scale families (including the log-normal, Weibull, and Pareto distributions), the article shows that failure probabilities can be exactly calculated, as they are independent of the true (but unknown) parameters. Hence it is possible to obtain an explicit measure of the effect of parameter uncertainty on failure probability. Failure probability can be controlled in two different ways: (1) by reducing the nominal required failure probability, depending on the size of the available data set, and (2) by modifying of the distribution itself that is used to calculate the risk control. Approach (1) corresponds to a frequentist/regulatory view of probability, while approach (2) is consistent with a Bayesian/personalistic view. We furthermore show that the two approaches are consistent in achieving the required failure probability. Finally, we briefly discuss the effects of data pooling and its systemic risk implications.
A parameter estimation subroutine package
NASA Technical Reports Server (NTRS)
Bierman, G. J.; Nead, W. M.
1977-01-01
Linear least squares estimation and regression analyses continue to play a major role in orbit determination and related areas. FORTRAN subroutines have been developed to facilitate analyses of a variety of parameter estimation problems. Easy to use multipurpose sets of algorithms are reported that are reasonably efficient and which use a minimal amount of computer storage. Subroutine inputs, outputs, usage and listings are given, along with examples of how these routines can be used.
Comment on Modified Stokes Parameters
NASA Technical Reports Server (NTRS)
Le Vine, D.M.; Utku, C.
2009-01-01
It is common practice in passive microwave remote sensing (microwave radiometry) to express observables as temperatures and in the case of polarimetric radiometry to use what are called "Modified Stokes Parameters in Brightness Temperature" to describe the scene. However, definitions with slightly different normalization (with and without division by bandwidth) have appeared in the literature. The purpose of this manuscript is to present an analysis to clarify the meaning of terms in the definition and resolve the question of the proper normalization.
IMPULSIVITY PARAMETER FOR SOLAR FLARES
Fajardo-Mendieta, W. G.; Alvarado-Gómez, J. D.; Calvo-Mozo, B.; Martinez-Oliveros, J. C. E-mail: bcalvom@unal.edu.co E-mail: jalvarad@eso.org
2016-02-10
Three phases are typically observed during solar flares: the preflare, impulsive, and decay phases. During the impulsive phase, it is believed that the electrons and other particles are accelerated after the stored energy in the magnetic field is released by reconnection. The impulsivity of a solar flare is a quantifiable property that shows how quickly this initial energy release occurs. It is measured via the impulsivity parameter, which we define as the inverse of the overall duration of the impulsive phase. We take the latter as the raw width of the most prominent nonthermal emission of the flare. We computed this observable over a work sample of 48 M-class events that occurred during the current Solar Cycle 24 by using three different methods. The first method takes into account all of the nonthermal flare emission and gives very accurate results, while the other two just cover fixed energy intervals (30–40 keV and 25–50 keV) and are useful for fast calculations. We propose an alternative way to classify solar flares according to their impulsivity parameter values, defining three different types of impulsivity, namely, high, medium, and low. This system of classification is independent of the manner used to calculated the impulsivity parameter. Lastly, we show the relevance of this tool as a discriminator of different HXR generation processes.
Delayed recombination and cosmic parameters
Galli, Silvia; Melchiorri, Alessandro; Bean, Rachel; Silk, Joseph
2008-09-15
Current cosmological constraints from cosmic microwave background anisotropies are typically derived assuming a standard recombination scheme, however additional resonance and ionizing radiation sources can delay recombination, altering the cosmic ionization history and the cosmological inferences drawn from the cosmic microwave background data. We show that for recent observations of the cosmic microwave background anisotropy, from the Wilkinson microwave anisotropy probe satellite mission (WMAP) 5-year survey and from the arcminute cosmology bolometer array receiver experiment, additional resonance radiation is nearly degenerate with variations in the spectral index, n{sub s}, and has a marked effect on uncertainties in constraints on the Hubble constant, age of the universe, curvature and the upper bound on the neutrino mass. When a modified recombination scheme is considered, the redshift of recombination is constrained to z{sub *}=1078{+-}11, with uncertainties in the measurement weaker by 1 order of magnitude than those obtained under the assumption of standard recombination while constraints on the shift parameter are shifted by 1{sigma} to R=1.734{+-}0.028. From the WMAP5 data we obtain the following constraints on the resonance and ionization sources parameters: {epsilon}{sub {alpha}}<0.39 and {epsilon}{sub i}<0.058 at 95% c.l.. Although delayed recombination limits the precision of parameter estimation from the WMAP satellite, we demonstrate that this should not be the case for future, smaller angular scales measurements, such as those by the Planck satellite mission.
GRCop-84 Rolling Parameter Study
NASA Technical Reports Server (NTRS)
Loewenthal, William S.; Ellis, David L.
2008-01-01
This report is a section of the final report on the GRCop-84 task of the Constellation Program and incorporates the results obtained between October 2000 and September 2005, when the program ended. NASA Glenn Research Center (GRC) has developed a new copper alloy, GRCop-84 (Cu-8 at.% Cr-4 at.% Nb), for rocket engine main combustion chamber components that will improve rocket engine life and performance. This work examines the sensitivity of GRCop-84 mechanical properties to rolling parameters as a means to better define rolling parameters for commercial warm rolling. Experiment variables studied were total reduction, rolling temperature, rolling speed, and post rolling annealing heat treatment. The responses were tensile properties measured at 23 and 500 C, hardness, and creep at three stress-temperature combinations. Understanding these relationships will better define boundaries for a robust commercial warm rolling process. The four processing parameters were varied within limits consistent with typical commercial production processes. Testing revealed that the rolling-related variables selected have a minimal influence on tensile, hardness, and creep properties over the range of values tested. Annealing had the expected result of lowering room temperature hardness and strength while increasing room temperature elongations with 600 C (1112 F) having the most effect. These results indicate that the process conditions to warm roll plate and sheet for these variables can range over wide levels without negatively impacting mechanical properties. Incorporating broader process ranges in future rolling campaigns should lower commercial rolling costs through increased productivity.
Mashouf, S; Ravi, A; Morton, G; Song, W
2015-06-15
Purpose: There is a strong evidence relating post-implant dosimetry for permanent seed prostate brachytherpy to local control rates. The delineation of the prostate on CT images, however, represents a challenge as it is difficult to confidently identify the prostate borders from soft tissue surrounding it. This study aims at quantifying the sensitivity of clinically relevant dosimetric parameters to prostate contouring uncertainty. Methods: The post-implant CT images and plans for a cohort of 43 patients, who have received I–125 permanent prostate seed implant in our centre, were exported to MIM Symphony LDR brachytherapy treatment planning system (MIM Software Inc., Cleveland, OH). The prostate contours in post-implant CT images were expanded/contracted uniformly for margins of ±1.00mm, ±2.00mm, ±3.00mm, ±4.00mm and ±5.00mm (±0.01mm). The values for V100 and D90 were extracted from Dose Volume Histograms for each contour and compared. Results: The mean value of V100 and D90 was obtained as 92.3±8.4% and 108.4±12.3% respectively (Rx=145Gy). V100 was reduced by −3.2±1.5%, −7.2±3.0%, −12.8±4.0%, −19.0±4.8%, − 25.5±5.4% for expanded contours of prostate with margins of +1mm, +2mm, +3mm, +4mm, and +5mm, respectively, while it was increased by 1.6±1.2%, 2.4±2.4%, 2.7±3.2%, 2.9±4.2%, 2.9±5.1% for the contracted contours. D90 was reduced by −6.9±3.5%, −14.5±6.1%, −23.8±7.1%, − 33.6±8.5%, −40.6±8.7% and increased by 4.1±2.6%, 6.1±5.0%, 7.2±5.7%, 8.1±7.3% and 8.1±7.3% for the same set of contours. Conclusion: Systematic expansion errors of more than 1mm may likely render a plan sub-optimal. Conversely contraction errors may Result in labeling a plan likely as optimal. The use of MRI images to contour the prostate should results in better delineation of prostate organ which increases the predictive value of post-op plans. Since observers tend to overestimate the prostate volume on CT, compared with MRI, the impact of the
Parameter estimation for transformer modeling
NASA Astrophysics Data System (ADS)
Cho, Sung Don
Large Power transformers, an aging and vulnerable part of our energy infrastructure, are at choke points in the grid and are key to reliability and security. Damage or destruction due to vandalism, misoperation, or other unexpected events is of great concern, given replacement costs upward of $2M and lead time of 12 months. Transient overvoltages can cause great damage and there is much interest in improving computer simulation models to correctly predict and avoid the consequences. EMTP (the Electromagnetic Transients Program) has been developed for computer simulation of power system transients. Component models for most equipment have been developed and benchmarked. Power transformers would appear to be simple. However, due to their nonlinear and frequency-dependent behaviors, they can be one of the most complex system components to model. It is imperative that the applied models be appropriate for the range of frequencies and excitation levels that the system experiences. Thus, transformer modeling is not a mature field and newer improved models must be made available. In this work, improved topologically-correct duality-based models are developed for three-phase autotransformers having five-legged, three-legged, and shell-form cores. The main problem in the implementation of detailed models is the lack of complete and reliable data, as no international standard suggests how to measure and calculate parameters. Therefore, parameter estimation methods are developed here to determine the parameters of a given model in cases where available information is incomplete. The transformer nameplate data is required and relative physical dimensions of the core are estimated. The models include a separate representation of each segment of the core, including hysteresis of the core, lambda-i saturation characteristic, capacitive effects, and frequency dependency of winding resistance and core loss. Steady-state excitation, and de-energization and re-energization transients
Balloon Thermal Model Design Parameters and Sensitivities
NASA Technical Reports Server (NTRS)
Ferguson, Douglas
2017-01-01
This presentation describes the thought process for determining balloon thermal model design parameters, including environmental parameters taken form NASA's top-of-atmosphere (TOA) database, and shows the sensitivity of an example model's key temperature results to those input parameters.
[Climatologic parameters and myocardial infarction].
Larcan, A; Gilgenkrantz, J M; Stoltz, J F; Lambert, H; Laprevote-Heully, M C; Evrard, D; Kempf, J B; Lambert, J
1983-01-01
535 patients admitted to hospital with myocardium infarct which was confirmed in a determined period and within a 80 kilometers radius from a city of the East of France were compared to the meteorological parameters of the day when the infarct occurred and of the day preceding its occurrence. On one hand, climatic parameters were selected: atmospheric pressure, temperature of the air under shelter, relative humidity, wind speed and wind direction, hydrometeors and electrometeors; on the other hand, parameters of solar and planetary activity: daily flare index, AA index, Ap index or daily planetary index, phases of the moon. The analytic study concerning all acute vascular accidents (infarcts and cerebral accidents all together) enabled to us to notice a higher frequency of vascular accidents in various meteorological circumstances: atmospheric pressure lower than 990 mb, temperature lower than 12 degrees, wind of sector North to South-South West, hoar-frost with fog, rain, snow, first quarter of the moon, daily flare index lower than 530, magnetic activity lower than 6. A factorial analysis of correspondence enabled to us to understand the problem better and to determine "an infarct area" in which main meteorological factors appeared: low or decreasing atmospheric pressure, relative or increasing humidity, clear or increasing solar activity, steady magnetic activity; other factors could play an apparently less important role: low temperature, snow, decrease of wind speed, full moon, wind of sector East to North-East, South-South West. Consequently it appeared in that study that the occurrence of myocardium infarct corresponded to a climatic tendency corresponding to cold, bad or deteriorating weather.
The Sequential Parameter Optimization Toolbox
NASA Astrophysics Data System (ADS)
Bartz-Beielstein, Thomas; Lasarczyk, Christian; Preuss, Mike
The sequential parameter optimization toolbox (SPOT) is one possible implementation of the SPO framework introduced in Chap. 2. It has been successfully applied to numerous heuristics for practical and theoretical optimization problems. We describe the mechanics and interfaces employed by SPOT to enable users to plug in their own algorithms. Furthermore, two case studies are presented to demonstrate how SPOT can be applied in practice, followed by a discussion of alternative metamodels to be plugged into it.We conclude with some general guidelines.
DP: Parameter Display Page Program
Anderson, M.
1994-02-19
The Parameter Display Page program (DP) is a Motif/X11-based program to allow easily configured, dynamic device and process variable monitoring and manipulation in the EPICS environment. DP provides a tabular data format for interactive viewing and manipulation of device and process variable statistics, as well as formatted PostScript output to files and printers. DP understands and operates in two (unfortunately disjoint at this time) namespaces in the EPICS environment ``devices`` and ``process variables``. The higher level namespace of devices includes Composite and Atomic Devices registered via the Device Access server; the lower level (flat) namespace is that of normal Process Variables accessible via Channel Access.
BRST symmetry and fictitious parameters
NASA Astrophysics Data System (ADS)
Nogueira, A. A.; Pimentel, B. M.
2017-03-01
Our goal in this work is to present the variational method of fictitious parameters and its connection with the Bechi-Rouet-Stora-Tyutin (BRST) symmetry. First, we implement the method in QED at zero temperature and then we extend the analysis to generalized QED at finite temperature. As we see the core of the study is the general statement in gauge theories at finite temperature, assigned by Tyutin work, that the physical degrees of freedom do not depend on the gauge choices, covariant or not, due to BRST symmetry.
Resonance parameter analysis with SAMMY
Larson, N.M.; Perey, F.G.
1988-01-01
The multilevel R-matrix computer code SAMMY has evolved over the past decade to become an important analysis tool for neutron data. SAMMY uses the Reich-Moore approximation to the multilevel R-matrix and includes an optional logarithmic parameterization of the external R-function. Doppler broadening is simulated either by numerical integration using the Gaussian approximation to the free gas model or by a more rigorous solution of the partial differential equation equivalent to the exact free gas model. Resolution broadening of cross sections and derivatives also has new options that more accurately represent the experimental situation. SAMMY treats constant normalization and some types of backgrounds directly and treats other normalizations and/or backgrounds with the introduction of user-generated partial derivatives. The code uses Bayes' method as an efficient alternative to least squares for fitting experimental data. SAMMY allows virtually any parameter to be varied and outputs values, uncertainties, and covariance matrix for all varied parameters. Versions of SAMMY exist for VAX, FPS, and IBM computers.
Pathway parameter and thermonuclear functions
NASA Astrophysics Data System (ADS)
Mathai, A. M.; Haubold, H. J.
2008-04-01
In the theory of thermonuclear reaction rates, analytical evaluation of thermonuclear functions for non-resonant reactions, including cases with cut-off and depletion of the tail of the Maxwell-Boltzmann distribution function were considered in a series of papers by Mathai and Haubold [A.M. Mathai, H.J. Haubold, Modern Problems in Nuclear and Neutrino Astrophysics, Akademie-Verlag, Berlin, 1988]. In the present paper we study more general classes of thermonuclear functions by introducing a pathway parameter α, so that when α→1 the thermonuclear functions in the Maxwell-Boltzmannian case are recovered. We will also give interpretations for the pathway parameter α in the case of cut-off and in terms of moments. Non-extensive statistical mechanics, as developed by Tsallis [C. Tsallis, What should a statistical mechanics satisfy to reflect nature? Physica D 193 (2004) 3-34], provides the physical basis for the generalized thermonuclear functions considered in this paper.
Kinetic parameters from thermogravimetric analysis
NASA Technical Reports Server (NTRS)
Kiefer, Richard L.
1993-01-01
High performance polymeric materials are finding increased use in aerospace applications. Proposed high speed aircraft will require materials to withstand high temperatures in an oxidative atmosphere for long periods of time. It is essential that accurate estimates be made of the performance of these materials at the given conditions of temperature and time. Temperatures of 350 F (177 C) and times of 60,000 to 100,000 hours are anticipated. In order to survey a large number of high performance polymeric materials on a reasonable time scale, some form of accelerated testing must be performed. A knowledge of the rate of a process can be used to predict the lifetime of that process. Thermogravimetric analysis (TGA) has frequently been used to determine kinetic information for degradation reactions in polymeric materials. Flynn and Wall studied a number of methods for using TGA experiments to determine kinetic information in polymer reactions. Kinetic parameters, such as the apparent activation energy and the frequency factor, can be determined in such experiments. Recently, researchers at the McDonnell Douglas Research Laboratory suggested that a graph of the logarithm of the frequency factor against the apparent activation energy can be used to predict long-term thermo-oxidative stability for polymeric materials. Such a graph has been called a kinetic map. In this study, thermogravimetric analyses were performed in air to study the thermo-oxidative degradation of several high performance polymers and to plot their kinetic parameters on a kinetic map.
Parameter learning for alpha integration.
Choi, Heeyoul; Choi, Seungjin; Choe, Yoonsuck
2013-06-01
In pattern recognition, data integration is an important issue, and when properly done, it can lead to improved performance. Also, data integration can be used to help model and understand multimodal processing in the brain. Amari proposed α-integration as a principled way of blending multiple positive measures (e.g., stochastic models in the form of probability distributions), enabling an optimal integration in the sense of minimizing the α-divergence. It also encompasses existing integration methods as its special case, for example, a weighted average and an exponential mixture. The parameter α determines integration characteristics, and the weight vector w assigns the degree of importance to each measure. In most work, however, α and w are given in advance rather than learned. In this letter, we present a parameter learning algorithm for learning α and ω from data when multiple integrated target values are available. Numerical experiments on synthetic as well as real-world data demonstrate the effectiveness of the proposed method.
Schizophrenia--a parameters' game?
Radulescu, Anca
2008-09-07
Schizophrenia is a severe, currently incurable, relatively common mental condition. Its symptoms are complex and widespread. It structurally and functionally affects cortical and subcortical regions involved in cognitive, emotional and motivational aspects of behavior. Its diagnosis is based on statistical behavior rather than on its actual cause and its treatment is elusive. We elaborate a theoretical paradigm that accounts for some of the most important features of this illness. Our nonlinear mathematical model, built upon recent hypotheses of neural vulnerability and limbic dysregulation, addresses the amygdala-hippocampus-prefrontal interactions and their evolution under perturbation. The dependence of the dynamics on the system's parameters offers an analytical context for the "normality/disease" dichotomy. The concept of bifurcation could be the key to understanding the threshold between these two states. The nonlinearity parameter (Lyapunov number) is responsible in our setup for tuning the limbic vulnerability characteristic to schizophrenia. Studying its effect on the dynamics helps us understand how stressful events and medication can switch the system from a regime of safety to one of instability, and conversely. The approach has potential for pre-symptomatic risk assessments and for long-term predictions.
NASA Astrophysics Data System (ADS)
Last, T.; de Winter, L.; Finders, J.
2015-10-01
EUV reticles need to be considered as complex optical elements in the beam path with considerable impact on lithography. Here we present a work flow for absorber optimization by applying a complementary approach of investigating lithographic metrics and mask-topography induced phase aberrations. In the first part this complementary approach is applied to find an optimum thickness of a typical Ta-based absorber for imaging horizontal spaces through pitch. And although an absorber thickness of around 70 nm is found to be preferable for this particular application, the thickness choice leads to conflicting results for the general printability of 10 nm technology node features. Hence we show that a moderate reduction of the absorber thickness can be allowed when the mask bias of these features is optimized appropriately. The moderate thickness reduction already allows for the mitigation of some of the conflicting imaging aspects. In the second part we expand the workflow by analyzing phase aberrations in n & k material space. This phase-based optical property screening shows that an alternative absorber based on materials such as Ni with k higher than Ta show superior best focus and contrast metrics. These alternative absorber embodiments would allow the overall reduction of M3D effects and adverse application dependencies of current Ta-based absorbers due to a combination of thickness reduction and enhancement of absorption.
Measuring neutrino oscillation parameters using $\
Backhouse, Christopher James
2011-01-01
MINOS is a long-baseline neutrino oscillation experiment. It consists of two large steel-scintillator tracking calorimeters. The near detector is situated at Fermilab, close to the production point of the NuMI muon-neutrino beam. The far detector is 735 km away, 716m underground in the Soudan mine, Northern Minnesota. The primary purpose of the MINOS experiment is to make precise measurements of the 'atmospheric' neutrino oscillation parameters (Δm_{atm}^{2} and sin^{2} 2θ_{atm}). The oscillation signal consists of an energy-dependent deficit of v_{μ} interactions in the far detector. The near detector is used to characterize the properties of the beam before oscillations develop. The two-detector design allows many potential sources of systematic error in the far detector to be mitigated by the near detector observations. This thesis describes the details of the v_{μ}-disappearance analysis, and presents a new technique to estimate the hadronic energy of neutrino interactions. This estimator achieves a significant improvement in the energy resolution of the neutrino spectrum, and in the sensitivity of the neutrino oscillation fit. The systematic uncertainty on the hadronic energy scale was re-evaluated and found to be comparable to that of the energy estimator previously in use. The best-fit oscillation parameters of the v_{μ}-disappearance analysis, incorporating this new estimator were: Δm^{2} = 2.32_{-0.08}^{+0.12} x 10^{-3} eV^{2}, sin ^{2} 2θ > 0.90 (90% C.L.). A similar analysis, using data from a period of running where the NuMI beam was operated in a configuration producing a predominantly $\\bar{v}$_{μ} beam, yielded somewhat different best-fit parameters Δ$\\bar{m}${sup 2} = (3.36_{-0.40}^{+0.46}(stat.) ± 0.06(syst.)) x 10^{-3}eV^{2}, sin^{2} 2$\\bar{θ}$ = 0.86_{-0.12}^{_0.11 }
Wearable vital parameters monitoring system
NASA Astrophysics Data System (ADS)
Caramaliu, Radu Vadim; Vasile, Alexandru; Bacis, Irina
2015-02-01
The system we propose monitors body temperature, heart rate and beside this, it tracks if the person who wears it suffers a faint. It uses a digital temperature sensor, a pulse sensor and a gravitational acceleration sensor to monitor the eventual faint or small heights free falls. The system continuously tracks the GPS position when available and stores the last valid data. So, when measuring abnormal vital parameters the module will send an SMS, using the GSM cellular network , with the person's social security number, the last valid GPS position for that person, the heart rate, the body temperature and, where applicable, a valid fall alert or non-valid fall alert. Even though such systems exist, they contain only faint detection or heart rate detection. Usually there is a strong correlation between low/high heart rate and an eventual faint. Combining both features into one system results in a more reliable detection device.
Noncommutativity Parameter and Composite Fermions
NASA Astrophysics Data System (ADS)
Jellal, Ahmed
We determine some particular values of the noncommutativity parameter θ and show that the Murthy Shankar approach is in fact a particular case of a more general one. Indeed, using the fractional quantum Hall effect (FQHE) experimental data, we give a measurement of θ. This measurement can be obtained by considering some values of the filling factor ν and other ingredients, magnetic field B and electron density ρ. Moreover, it is found that θ can be quantized either fractionally or integrally in terms of the magnetic length l0 and the quantization is exactly what Murthy and Shankar formulated recently for the FQHE. On the other hand, we show that the mapping of the FQHE in terms of the composite fermion basis has a noncommutative geometry nature and therefore there is a more general way than the Murthy Shankar method to do this mapping.
NASA Astrophysics Data System (ADS)
Khorashadi Zadeh, Farkhondeh; Nossent, Jiri; van Griensven, Ann; Bauwens, Willy
2017-04-01
Parameter estimation is a major concern in hydrological modeling, which may limit the use of complex simulators with a large number of parameters. To support the selection of parameters to include in or exclude from the calibration process, Global Sensitivity Analysis (GSA) is widely applied in modeling practices. Based on the results of GSA, the influential and the non-influential parameters are identified (i.e. parameters screening). Nevertheless, the choice of the screening threshold below which parameters are considered non-influential is a critical issue, which has recently received more attention in GSA literature. In theory, the sensitivity index of a non-influential parameter has a value of zero. However, since numerical approximations, rather than analytical solutions, are utilized in GSA methods to calculate the sensitivity indices, small but non-zero indices may be obtained for the indices of non-influential parameters. In order to assess the threshold that identifies non-influential parameters in GSA methods, we propose to calculate the sensitivity index of a "dummy parameter". This dummy parameter has no influence on the model output, but will have a non-zero sensitivity index, representing the error due to the numerical approximation. Hence, the parameters whose indices are above the sensitivity index of the dummy parameter can be classified as influential, whereas the parameters whose indices are below this index are within the range of the numerical error and should be considered as non-influential. To demonstrated the effectiveness of the proposed "dummy parameter approach", 26 parameters of a Soil and Water Assessment Tool (SWAT) model are selected to be analyzed and screened, using the variance-based Sobol' and moment-independent PAWN methods. The sensitivity index of the dummy parameter is calculated from sampled data, without changing the model equations. Moreover, the calculation does not even require additional model evaluations for the Sobol
Stokes' Parameters Compared to Astrophysical Magnetic Turbulence Parameters
NASA Astrophysics Data System (ADS)
Forman, Miriam; Wicks, Robert; Oughton, Sean; Horbury, Timothy
2015-04-01
Since the divergence of a magnetic field is zero, the Fourier transform of fluctuations δB(k) must be perpendicular to k, so δB(k) has components only in the plane perpendicular to k. When there is also a mean field B, the obvious choice of coordinates to describe δB(k) are the unit vectors tin the directionB x k and p in the direction (Bxk) x k, called the ``toroidal'' and ``poloidal'' directions, respectively. Oughton, et al. (1997) as elucidated by Wicks et al. (2012) showed that the power spectral tensor Pij(k) of magnetic fluctuations is described by four scalar functions of k, multiplying the tensors t:t, p:p, t:p +p:t, and t:p-p:t so that the Hermitian Pij(k) = Tor(k) t:t + Pol(k) p:p + C(k) [t:p +p:t] + i kH(k) [t:p-p:t]. Since the electromagnetic fluctuations δB(k) and δE(k) in a beam of light are also perpendicular to their k, the four scalar functions of magnetic turbulence in astrophysics which scatters cosmic rays and allows their acceleration, are analogs of the Stokes' parameters. Using Chandrasekhar's (1960) notation [I,Q,U,V]: I = Tor + Pol = Tr(Pij(k); Q = Tor-Pol; U = C; we speculate that V corresponds to magnetic helicity kH in turbulence. We are studying projections of Pij(k) observed by spacecraft in the solar wind.
System and method for motor parameter estimation
Luhrs, Bin; Yan, Ting
2014-03-18
A system and method for determining unknown values of certain motor parameters includes a motor input device connectable to an electric motor having associated therewith values for known motor parameters and an unknown value of at least one motor parameter. The motor input device includes a processing unit that receives a first input from the electric motor comprising values for the known motor parameters for the electric motor and receive a second input comprising motor data on a plurality of reference motors, including values for motor parameters corresponding to the known motor parameters of the electric motor and values for motor parameters corresponding to the at least one unknown motor parameter value of the electric motor. The processor determines the unknown value of the at least one motor parameter from the first input and the second input and determines a motor management strategy for the electric motor based thereon.
Coagulation Parameters in Wilson Disease.
Schaefer, Mark; Weber, Laura; Gotthardt, Daniel; Seessle, Jessica; Stremmel, Wolfgang; Pfeiffenberger, Jan; Weiss, Karl Heinz
2015-06-01
Wilson disease (WD) is an autosomal recessive disorder of copper metabolism. Alterations of copper metabolism have been associated with changes in coagulation factors. The aim of the present study was the analysis of coagulation factors in WD patients. 100 patients attending a tertiary WD outpatient clinic were analyzed in a prospective cross sectional cohort study. Out of peripheral venous blood samples coagulation factors were assessed including: full blood count, INR, partial thromboplastin time (PTT), clotting factors II, V, VII, VIII, IX, X, XI, XII, XIII, von Willebrand factor/-antigen, fibrinogen, antithrombin III, protein S, protein C, activated protein C (APC) resistance. Subgroup analyses of the blood tests were performed for sex, initial clinical presentation, WD treatment and liver function. Subgroup analysis by liver function showed decreased levels of factors II, V, VII and X. Subgroup analysis by gender or clinical course of the disease did not reveal significant coagulation changes. In patients treated with trientine significantly decreased levels of factors II, VII and antithrombin III and increased von Willebrand factor/-antigen levels were detected. Factor VIII levels were significantly reduced in patients receiving zinc. Although significant differences of some coagulation parameters in subgroup analysis were found, no clinically relevant alterations of the coagulation system in WD patients could be detected.
Deformation parameters influencing prepreg tack
Ahn, K.J.; Seferis, J.C. ); Pelton, T.; Wilhelm, M. )
1992-01-01
A compression to tension apparatus and a methodology capable of measuring prepreg tack have been analyzed in detail in order to establish fundamental material and operating characteristics. Both intrinsic and extrinsic parameters influencing prepreg tack were identified and analyzed using commercially available carbon fiber/epoxy prepregs and mechanical testing equipment. Two different factors, (1) contact (or wetting) area of adjacent prepreg plies and (2) viscoelastic properties of the prepreg, were found to control prepreg tack. At low temperatures, contact area was the main deformation controlling step, while at high temperatures, the viscoelastic property of the prepreg was found to be dominant. Both interlaminar and intralaminar deformations were observed depending on the prepreg systems examined as well as the operating conditions of the test. In addition, hold time, hold pressure, loading rate, resin content, and out-time were also found to affect prepreg tack. Energy of separation, which may be viewed as a descriptor of prepreg tack, was observed to increase with increasing hold time, hold pressure, and loading rate. Energy of separation also showed a maximum value at a specific resin content for a specific prepreg system, while it decreased with increasing prepreg out-time due to prepreg surface characteristic change rather than bulk physical aging. Conclusively, it was observed that prepreg tack must be viewed as an extrinsic, bulk, but surface-sensitive, viscoelastic property which depends on material as well as operating conditions.
Multispectral vegetative canopy parameter retrieval
NASA Astrophysics Data System (ADS)
Borel, Christoph C.; Bunker, David J.
2011-11-01
Precision agriculture, forestry and environmental remote sensing are applications uniquely suited to the 8 bands that DigitalGlobe's WorldView-2 provides. At the fine spatial resolution of 0.5 m (panchromatic) and 2 m (multispectral) individual trees can be readily resolved. Recent research [1] has shown that it is possible for hyper-spectral data to invert plant reflectance spectra and estimate nitrogen content, leaf water content, leaf structure, canopy leaf area index and, for sparse canopies, also soil reflectance. The retrieval is based on inverting the SAIL (Scattering by Arbitrary Inclined Leaves) vegetation radiative transfer model for the canopy structure and the reflectance model PROSPECT4/5 for the leaf reflectance. Working on the paper [1] confirmed that a limited number of adjacent bands covering just the visible and near infrared can retrieve the parameters as well, opening up the possibility that this method can be used to analyze multi-spectral WV-2 data. Thus it seems possible to create WV-2 specific inversions using 8 bands and apply them to imagery of various vegetation covered surfaces of agricultural and environmental interest. The capability of retrieving leaf water content and nitrogen content has important applications in determining the health of vegetation, e.g. plant growth status, disease mapping, quantitative drought assessment, nitrogen deficiency, plant vigor, yield, etc.
Acoustic metamaterial with negative parameter
NASA Astrophysics Data System (ADS)
Sun, Hongwei; Yan, Fei; Gu, Hao; Li, Ying
2014-03-01
In this paper we present theoretical results on an acoustic metamaterial beam and a bar that exhibit negative effective mass and negative effective stiffness. A one-dimensional acoustic metamaterial with an array of spring-mass subsystems was fabricated. The frequency of the acoustic one dimensional metamaterial structure has the same form as that of the permittivity in metals due to the plasma oscillation. We also provide a theory to explain the simulation results. And we use the concept of conventional mechanical vibration absorbers to reveal the actual working mechanism of the acoustic metamaterials. We explain the two vibrate modes which are optical mode and acoustic mode in detail. When the incoming elastic wave in the acoustic metamaterials to resonate the integrated spring-mass-damper absorbers to vibrate in their optical mode at frequencies close to but above their local resonance frequencies to create shear forces and bending moments to straighten the beam and stop the wave propagation. Moreover, we explain the negative parameter in acoustic metamaterials.
Rainfall-Runoff Parameters Uncertainity
NASA Astrophysics Data System (ADS)
Heidari, A.; Saghafian, B.; Maknoon, R.
2003-04-01
Karkheh river basin, located in southwest of Iran, drains an area of over 40000 km2 and is considered a flood active basin. A flood forecasting system is under development for the basin, which consists of a rainfall-runoff model, a river routing model, a reservior simulation model, and a real time data gathering and processing module. SCS, Clark synthetic unit hydrograph, and Modclark methods are the main subbasin rainfall-runoff transformation options included in the rainfall-runoff model. Infiltration schemes, such as exponentioal and SCS-CN methods, account for infiltration losses. Simulation of snow melt is based on degree day approach. River flood routing is performed by FLDWAV model based on one-dimensional full dynamic equation. Calibration and validation of the rainfall-runoff model on Karkheh subbasins are ongoing while the river routing model awaits cross section surveys.Real time hydrometeological data are collected by a telemetry network. The telemetry network is equipped with automatic sensors and INMARSAT-C comunication system. A geographic information system (GIS) stores and manages the spatial data while a database holds the hydroclimatological historical and updated time series. Rainfall runoff parameters uncertainty is analyzed by Monte Carlo and GLUE approaches.
Structural Design Parameters for Germanium
NASA Technical Reports Server (NTRS)
Salem, Jon; Rogers, Richard; Baker, Eric
2017-01-01
The fracture toughness and slow crack growth parameters of germanium supplied as single crystal beams and coarse grain disks were measured. Although germanium is anisotropic (A* 1.7), it is not as anisotropic as SiC, NiAl, or Cu. Thus the fracture toughness was similar on the 100, 110, and 111 planes, however, measurements associated with randomly oriented grinding cracks were 6 to 30 higher. Crack extension in ring loaded disks occurred on the 111 planes due to both the lower fracture energy and the higher stresses on stiff 111 planes. Germanium exhibits a Weibull scale effect, but does not exhibit significant slow crack growth in distilled water. (n 100), implying that design for quasi static loading can be performed with scaled strength statistics. Practical values for engineering design are a fracture toughness of 0.69 0.02 MPam (megapascals per square root meter) and a Weibull modulus of m 6 2. For well ground and reasonable handled coupons, average fracture strength should be greater than 40 megapascals. Aggregate, polycrystalline elastic constants are Epoly 131 gigapascals, vpoly 0.22.
On Markov parameters in system identification
NASA Technical Reports Server (NTRS)
Phan, Minh; Juang, Jer-Nan; Longman, Richard W.
1991-01-01
A detailed discussion of Markov parameters in system identification is given. Different forms of input-output representation of linear discrete-time systems are reviewed and discussed. Interpretation of sampled response data as Markov parameters is presented. Relations between the state-space model and particular linear difference models via the Markov parameters are formulated. A generalization of Markov parameters to observer and Kalman filter Markov parameters for system identification is explained. These extended Markov parameters play an important role in providing not only a state-space realization, but also an observer/Kalman filter for the system of interest.
Renormalizable two-parameter piecewise isometries.
Lowenstein, J H; Vivaldi, F
2016-06-01
We exhibit two distinct renormalization scenarios for two-parameter piecewise isometries, based on 2π/5 rotations of a rhombus and parameter-dependent translations. Both scenarios rely on the recently established renormalizability of a one-parameter triangle map, which takes place if and only if the parameter belongs to the algebraic number field K=Q(5) associated with the rotation matrix. With two parameters, features emerge which have no counterpart in the single-parameter model. In the first scenario, we show that renormalizability is no longer rigid: whereas one of the two parameters is restricted to K, the second parameter can vary continuously over a real interval without destroying self-similarity. The mechanism involves neighbouring atoms which recombine after traversing distinct return paths. We show that this phenomenon also occurs in the simpler context of Rauzy-Veech renormalization of interval exchange transformations, here regarded as parametric piecewise isometries on a real interval. We explore this analogy in some detail. In the second scenario, which involves two-parameter deformations of a three-parameter rhombus map, we exhibit a weak form of rigidity. The phase space splits into several (non-convex) invariant components, on each of which the renormalization still has a free parameter. However, the foliations of the different components are transversal in parameter space; as a result, simultaneous self-similarity of the component maps requires that both of the original parameters belong to the field K.
[Dalbavancin: pharmacokinetic and pharmacodynamic parameters].
Azanza, José Ramón; Sádaba, Belén; Reis, Joana
2017-01-01
Dalbavancin is a new lipoglycopeptide antibiotic whose structure influences its pharmacokinetic profile. It is not absorbed after oral administration and is therefore administered intravenously. It is distributed through intracellular fluid, reaching adequate concentrations in the skin, bone, blister fluid and synovial fluid. Plasma protein binding is very high. Concentrations in brain tissue and cerebrospinal fluid (CSF) are inadequate. Excretion is through non-microsomal metabolism with inactive metabolites and through the kidneys by glomerular filtration. Dalbavancin is eliminated slowly, as shown by its clearance value and its terminal elimination half-life, which exceeds 300 hours. This means that adequate concentrations of the drug remain in plasma and tissues for a prolonged period and explains the dosing regimen: a first dose of 1g followed 7 days later by a 500mg dose. The pharmacokinetics are linear and show little intra- and interindividual variability. There are no pharmacokinetic interactions. Dose adjustment is not required for patients with mild or moderate renal insufficiency (creatinine clearance ≥ 30 to 79ml/min). Dosage adjustment is not required in patients regularly receiving elective haemodialysis (3 times/week) and the drug can be administered without consideration of haemodialysis times. In patients with chronic renal insufficiency, whose creatinine clearance is < 30ml/min and who are not regularly receiving elective haemodialysis, the recommended dose should be reduced to 750mg per week, followed 1 week later by 375mg. Dosage adjustment does not seem necessary in patients with liver failure or in older patients. There is no information on the most appropriate dosage in children. The pharmacokinetic/pharmacodynamics parameter that best describes the effectiveness of dalbavancin is the ratio between the area under the curve and the minimum inhibitory concentration. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.
D'Alessandro, A G; Vizzarri, F; Palazzo, M; Martemucci, G
2017-03-07
Various uses of donkeys' milk have been recently proposed for human consumption on the basis of its nutritional characteristics. Improvements in milk fatty acid profile and animal oxidative status can be induced through dietary supplementation of phenolic compounds. The study aimed to evaluate in donkeys the effects of dietary supplementation with verbascoside (VB) on: (i) the fatty acid profile and vitamins A and E contents of milk during a whole lactation, and (ii) blood biochemical parameters and markers of oxidative status of the animals. At foaling, 12 lactating jennies were subdivided into two groups (n 6): control, without VB supplement; VB, receiving a lipid-encapsulated VB supplement. Gross composition, fatty acid profile and vitamins A and E contents in milk were assessed monthly over the 6 months of lactation. Serum total cholesterol, high-density lipoproteins cholesterol and low-density lipoproteins cholesterol, tryglicerides, non-esterified fatty acid, bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase, reactive oxygen metabolites, thiobarbituric acid reactive substances (TBARs), vitamin A and vitamin E were evaluated at 8 days after foaling (D0) and then at D90, D105 and D120 of lactation. In milk, the VB supplementation decreased the saturated fatty acids (P<0.05) and increased the monounsaturated fatty acids (P<0.05), and vitamins A and E (P<0.01) values. On the serum parameters, the VB supplementation decreased total cholesterol (P<0.01), tryglicerides, bilirubin, ALT and TBARs, and increased (P<0.01) vitamin E. In conclusion, the VB dietary supplementation affects the nutritional quality of donkey's milk with a benefit on the oxidative status and serum lipidic profile of the animals.
Parameter Estimation using Numerical Merger Waveforms
NASA Technical Reports Server (NTRS)
Thorpe, J. I.; McWilliams, S.; Kelly, B.; Fahey, R.; Arnaud, K.; Baker, J.
2008-01-01
Results: Developed parameter estimation model integrating complete waveforms and improved instrumental models. Initial results for equal-mass non-spinning systems indicate moderate improvement in most parameters, significant improvement in some Near-term improvement: a) Improved statistics; b) T-channel; c) Larger parameter space coverage. Combination with other results: a) Higher harmonics; b) Spin precession; c) Instrumental effects.
Extraction of SUSY Parameters from Collider Data
Zerwas, Dirk
2008-11-23
The extraction of the parameters of the supersymmetric Lagrangian is discussed. Particular emphasis is put on the rigorous treatment of experimental and theoretical errors. While the LHC can provide a valuable first estimate of the parameters, the combination of LHC and ILC will be necessary to determine with high precision the parameters of the MSSM.
Historical Analysis of Aircraft Flight Parameters
NASA Technical Reports Server (NTRS)
Lynch, Robert E. (Inventor); Lawrence, Robert E. (Inventor); Chidester, Thomas R. (Inventor); Amidan, Brett G. (Inventor); Prothero, Gary L. (Inventor); Romanowski, Timothy P. (Inventor)
2007-01-01
Method and system for analyzing and displaying one or more present flight parameter values (FP(t) of an aircraft in motion at a measurement time t(sub n), and for comparing the present flight parameter value with a selected percentage band, containing historical flight parameter data for similar conditions.
Optimal Linking Design for Response Model Parameters
ERIC Educational Resources Information Center
Barrett, Michelle D.; van der Linden, Wim J.
2017-01-01
Linking functions adjust for differences between identifiability restrictions used in different instances of the estimation of item response model parameters. These adjustments are necessary when results from those instances are to be compared. As linking functions are derived from estimated item response model parameters, parameter estimation…
Recovering Parameters of Johnson's SB Distribution
Bernard R. Parresol
2003-01-01
A new parameter recovery model for Johnson's SB distribution is developed. This latest alternative approach permits recovery of the range and both shape parameters. Previous models recovered only the two shape parameters. Also, a simple procedure for estimating the distribution minimum from sample values is presented. The new methodology...
Understanding Parameter Invariance in Unidimensional IRT Models
ERIC Educational Resources Information Center
Rupp, Andre A.; Zumbo, Bruno D.
2006-01-01
One theoretical feature that makes item response theory (IRT) models those of choice for many psychometric data analysts is parameter invariance, the equality of item and examinee parameters from different examinee populations or measurement conditions. In this article, using the well-known fact that item and examinee parameters are identical only…
Cosmological parameter estimation using Particle Swarm Optimization
NASA Astrophysics Data System (ADS)
Prasad, J.; Souradeep, T.
2014-03-01
Constraining parameters of a theoretical model from observational data is an important exercise in cosmology. There are many theoretically motivated models, which demand greater number of cosmological parameters than the standard model of cosmology uses, and make the problem of parameter estimation challenging. It is a common practice to employ Bayesian formalism for parameter estimation for which, in general, likelihood surface is probed. For the standard cosmological model with six parameters, likelihood surface is quite smooth and does not have local maxima, and sampling based methods like Markov Chain Monte Carlo (MCMC) method are quite successful. However, when there are a large number of parameters or the likelihood surface is not smooth, other methods may be more effective. In this paper, we have demonstrated application of another method inspired from artificial intelligence, called Particle Swarm Optimization (PSO) for estimating cosmological parameters from Cosmic Microwave Background (CMB) data taken from the WMAP satellite.
Parameter Identifiability of Fundamental Pharmacodynamic Models
Janzén, David L. I.; Bergenholm, Linnéa; Jirstrand, Mats; Parkinson, Joanna; Yates, James; Evans, Neil D.; Chappell, Michael J.
2016-01-01
Issues of parameter identifiability of routinely used pharmacodynamics models are considered in this paper. The structural identifiability of 16 commonly applied pharmacodynamic model structures was analyzed analytically, using the input-output approach. Both fixed-effects versions (non-population, no between-subject variability) and mixed-effects versions (population, including between-subject variability) of each model structure were analyzed. All models were found to be structurally globally identifiable under conditions of fixing either one of two particular parameters. Furthermore, an example was constructed to illustrate the importance of sufficient data quality and show that structural identifiability is a prerequisite, but not a guarantee, for successful parameter estimation and practical parameter identifiability. This analysis was performed by generating artificial data of varying quality to a structurally identifiable model with known true parameter values, followed by re-estimation of the parameter values. In addition, to show the benefit of including structural identifiability as part of model development, a case study was performed applying an unidentifiable model to real experimental data. This case study shows how performing such an analysis prior to parameter estimation can improve the parameter estimation process and model performance. Finally, an unidentifiable model was fitted to simulated data using multiple initial parameter values, resulting in highly different estimated uncertainties. This example shows that although the standard errors of the parameter estimates often indicate a structural identifiability issue, reasonably “good” standard errors may sometimes mask unidentifiability issues. PMID:27994553
On Interpreting the Model Parameters for the Three Parameter Logistic Model
ERIC Educational Resources Information Center
Maris, Gunter; Bechger, Timo
2009-01-01
This paper addresses two problems relating to the interpretability of the model parameters in the three parameter logistic model. First, it is shown that if the values of the discrimination parameters are all the same, the remaining parameters are nonidentifiable in a nontrivial way that involves not only ability and item difficulty, but also the…
On Interpreting the Model Parameters for the Three Parameter Logistic Model
ERIC Educational Resources Information Center
Maris, Gunter; Bechger, Timo
2009-01-01
This paper addresses two problems relating to the interpretability of the model parameters in the three parameter logistic model. First, it is shown that if the values of the discrimination parameters are all the same, the remaining parameters are nonidentifiable in a nontrivial way that involves not only ability and item difficulty, but also the…
Star Tracker/Mapper: System Design Parameters
1974-09-01
AD-A008 554 STAR TRACKER/MAPPER: SYSTEM’DESIGN PARAMETERS F. W. Schenkel Johns Hopkins University Prepared for: Naval Plant Representative Office...APLIJHU TG 1256 4. TITLE (andSubritle) 5. TYPE OF REPORT & PERIOD COVERED Star Tracker/Mapper: System Design Parameters 6. PERFORMING ORG. REPORT...identify by block number) Design parameters Star tracker/mapper Optical sensors Optical trackers Spectral characteristics 20. ABSTRACT (Continue on
The Solubility Parameters of Ionic Liquids
Marciniak, Andrzej
2010-01-01
The Hildebrand’s solubility parameters have been calculated for 18 ionic liquids from the inverse gas chromatography measurements of the activity coefficients at infinite dilution. Retention data were used for the calculation. The solubility parameters are helpful for the prediction of the solubility in the binary solvent mixtures. From the solubility parameters, the standard enthalpies of vaporization of ionic liquids were estimated. PMID:20559495
Roughness parameter selection for novel manufacturing processes.
Ham, M; Powers, B M
2014-01-01
This work proposes a method of roughness parameter (RP) selection for novel manufacturing processes or processes where little knowledge exists about which RPs are important. The method selects a single parameter to represent a group of highly correlated parameters. Single point incremental forming (SPIF) is used as the case study for the manufacturing process. This methodology was successful in reducing the number of RPs investigated from 18 to 8 in the case study. © Wiley Periodicals, Inc.
Constitutive Parameter Measurement Using Double Ridge Waveguide
2013-03-01
CONSTITUTIVE PARAMETER MEASUREMENT USING DOUBLE RIDGE WAVEGUIDE THESIS Nathan J. Lehman, Captain, USAF AFIT-ENG-13-M-30 DEPARTMENT OF THE AIR FORCE...copyright protection in the United States. AFIT-ENG-13-M-30 CONSTITUTIVE PARAMETER MEASUREMENT USING DOUBLE RIDGE WAVEGUIDE THESIS Presented to the Faculty...PARAMETER MEASUREMENT USING DOUBLE RIDGE WAVEGUIDE Nathan J. Lehman, B.S.E.E. Captain, USAF Approved: Michael Havrilla, PhD (Chairman) Maj Milo Hyde, PhD
Screening parameters for the relativistic hydrogenic model
NASA Astrophysics Data System (ADS)
Lanzini, Fernando; Di Rocco, Héctor O.
2015-12-01
We present a Relativistic Screened Hydrogenic Model (RSHM) where the screening parameters depend on the variables (n , l , j) and the parameters (Z , N) . These screening parameters were derived theoretically in a neat form with no use of experimental values nor numerical values from self-consistent codes. The results of the model compare favorably with those obtained by using more sophisticated approaches. For the interested reader, a copy of our code can be requested from the corresponding author.
Parameter Biases Introduced by Approximate Gravitational Waveforms
NASA Astrophysics Data System (ADS)
Farr, Benjamin; Coughlin, Scott; Le, John; Skeehan, Connor; Kalogera, Vicky
2013-04-01
The production of the most accurate gravitational waveforms from compact binary mergers require Einstein's equations to be solved numerically, a process far too expensive to produce the ˜10^7 waveforms necessary to estimate the parameters of a measured gravitational wave signal. Instead, parameter estimation depends on approximate or phenomenological waveforms to characterize measured signals. As part of the Ninja collaboration, we study the biases introduced by these methods when estimating the parameters of numerically produced waveforms.
Useful Scaling Parameters for the Pulse Tube
NASA Technical Reports Server (NTRS)
Lee, J. M.; Kittel, P.; Timmerhaus, K. D.; Radebaugh, R.; Cheng, Pearl L. (Technical Monitor)
1995-01-01
A set of eight non-dimensional scaling parameters for use in evaluating the performance of Pulse Tube Refrigerators is presented. The parameters result after scaling the mass, momentum and energy conservation equations for an axisymmetric, two-dimensional system. The physical interpretation of the parameters are described, and their usefulness is outlined for the enthalpy flow tube (open tube of the pulse tube). The scaling parameters allow the experimentalist to characterize three types of transport: enthalpy flow, mass streaming and heat transfer between the gas and the tube. Also reported are the results from a flow visualization experiment in which steady mass streaming in compressible oscillating flow is observed.
Change of coagulation parameters after double plateletpheresis.
Yilmaz, Mustafa; Dikmen, Tamer; Sonmez, Mehmet; Akdogan, Elif; Durmus, Ahmet; Omay, Serdar Bedii; Ovali, Ercument
2007-10-01
In the previous studies, some authors reported that automated apheresis leads to a hypercoagulable state. We tried to find out changes in coagulation parameters after double plateletpheresis in this study. Forty-five donors were recruited to the study, and coagulation parameters were assessed before and after double plateletpheresis. After double plateletpheresis, fibrinogen, factor V, factor VIII and factor IX were decreased compared with the values before apheresis. Although serum levels of this coagulation parameters are decreasing, they are still in the normal limits. Therefore, we suggest that double plateletpheresis is a safe procedure for healthy volunteers taking into account these coagulation parameters.
Parameter Estimation of Partial Differential Equation Models.
Xun, Xiaolei; Cao, Jiguo; Mallick, Bani; Carroll, Raymond J; Maity, Arnab
2013-01-01
Partial differential equation (PDE) models are commonly used to model complex dynamic systems in applied sciences such as biology and finance. The forms of these PDE models are usually proposed by experts based on their prior knowledge and understanding of the dynamic system. Parameters in PDE models often have interesting scientific interpretations, but their values are often unknown, and need to be estimated from the measurements of the dynamic system in the present of measurement errors. Most PDEs used in practice have no analytic solutions, and can only be solved with numerical methods. Currently, methods for estimating PDE parameters require repeatedly solving PDEs numerically under thousands of candidate parameter values, and thus the computational load is high. In this article, we propose two methods to estimate parameters in PDE models: a parameter cascading method and a Bayesian approach. In both methods, the underlying dynamic process modeled with the PDE model is represented via basis function expansion. For the parameter cascading method, we develop two nested levels of optimization to estimate the PDE parameters. For the Bayesian method, we develop a joint model for data and the PDE, and develop a novel hierarchical model allowing us to employ Markov chain Monte Carlo (MCMC) techniques to make posterior inference. Simulation studies show that the Bayesian method and parameter cascading method are comparable, and both outperform other available methods in terms of estimation accuracy. The two methods are demonstrated by estimating parameters in a PDE model from LIDAR data.
On the Interpretation of Scattering Parameters
NASA Technical Reports Server (NTRS)
Freeman, Jon C.
1999-01-01
This short paper is in response to one that appeared in this journal a few years ago [2]. The article was a comment on a previous paper [1], which presented the transformation equations between the standard two-port parameters. The equations were stated to be valid for complex terminations; which are useful when S-parameters are treated. The authors in [2] made some incorrect conclusions concerning the concept of "generalized scattering parameters", and this paper seeks to clarify the somewhat confusing area of generalized scattering parameters.
Quantifying uncertainty in state and parameter estimation.
Parlitz, Ulrich; Schumann-Bischoff, Jan; Luther, Stefan
2014-05-01
Observability of state variables and parameters of a dynamical system from an observed time series is analyzed and quantified by means of the Jacobian matrix of the delay coordinates map. For each state variable and each parameter to be estimated, a measure of uncertainty is introduced depending on the current state and parameter values, which allows us to identify regions in state and parameter space where the specific unknown quantity can(not) be estimated from a given time series. The method is demonstrated using the Ikeda map and the Hindmarsh-Rose model.
Multivariate distributions of soil hydraulic parameters
NASA Astrophysics Data System (ADS)
Qu, Wei; Pachepsky, Yakov; Huisman, Johan Alexander; Martinez, Gonzalo; Bogena, Heye; Vereecken, Harry
2014-05-01
Statistical distributions of soil hydraulic parameters have to be known when synthetic fields of soil hydraulic properties need to be generated in ensemble modeling of soil water dynamics and soil water content data assimilation. Pedotransfer functions that provide statistical distributions of water retention and hydraulic conductivity parameters for textural classes are most often used in the parameter field generation. Presence of strong correlations can substantially influence the parameter generation results. The objective of this work was to review and evaluate available data on correlations between van Genuchten-Mualem (VGM) model parameters. So far, two different approaches were developed to estimate these correlations. The first approach uses pedotransfer functions to generate VGM parameters for a large number of soil compositions within a textural class, and then computes parameter correlations for each of the textural classes. The second approach computes the VGM parameter correlations directly from parameter values obtained by fitting VGM model to measured water retention and hydraulic conductivity data for soil samples belonging to a textural class. Carsel and Parish (1988) used the Rawls et al. (1982) pedotransfer functions, and Meyer et al. (1997) used the Rosetta pedotransfer algorithms (Schaap, 2002) to develop correlations according to the first approach. We used the UNSODA database (Nemes et al. 2001), the US Southern Plains database (Timlin et al., 1999), and the Belgian database (Vereecken et al., 1989, 1990) to apply the second approach. A substantial number of considerable (>0.7) correlation coefficients were found. Large differences were encountered between parameter correlations obtained with different approaches and different databases for the same textural classes. The first of the two approaches resulted in generally higher values of correlation coefficients between VGM parameters. However, results of the first approach application depend
New fundamental parameters for attitude representation
NASA Astrophysics Data System (ADS)
Patera, Russell P.
2017-08-01
A new attitude parameter set is developed to clarify the geometry of combining finite rotations in a rotational sequence and in combining infinitesimal angular increments generated by angular rate. The resulting parameter set of six Pivot Parameters represents a rotation as a great circle arc on a unit sphere that can be located at any clocking location in the rotation plane. Two rotations are combined by linking their arcs at either of the two intersection points of the respective rotation planes. In a similar fashion, linking rotational increments produced by angular rate is used to derive the associated kinematical equations, which are linear and have no singularities. Included in this paper is the derivation of twelve Pivot Parameter elements that represent all twelve Euler Angle sequences, which enables efficient conversions between Pivot Parameters and any Euler Angle sequence. Applications of this new parameter set include the derivation of quaternions and the quaternion composition rule, as well as, the derivation of the analytical solution to time dependent coning motion. The relationships between Pivot Parameters and traditional parameter sets are included in this work. Pivot Parameters are well suited for a variety of aerospace applications due to their effective composition rule, singularity free kinematic equations, efficient conversion to and from Euler Angle sequences and clarity of their geometrical foundation.
Singh, Sachin Kumar; Srinivasan, K K; Gowthamarajan, K; Singare, Dhananjay S; Prakash, Dev; Gaikwad, Narayan Babulal
2011-08-01
The objective of this study was to identify and optimize formulation and process variables affecting characteristic and scale-up of nanosuspension manufacturing process on bead mill considering industrial perspective. Formulation factors evaluated were ratio of polymer to drug and ratio of surfactant to drug, whereas process parameters were milling time and milling speed. Responses measured in this study include zeta potential and mean particle size d(90). The test revealed that ratio of polymer to drug and milling speed have significant effect on zeta potential whereas milling time and milling speed have significant effect on the particle size distribution of nanosuspension. The X-ray powder diffraction pattern of drug milled at high and low speed reveals no form conversion when compared with unmilled drug. The formulated nanosuspension has shown a faster dissolution profile (98.97% in 10 min), relative to that of raw glyburide (18.17% in 10 min), mainly due to the formation of nanosized particles. The ANOVA test revealed that there was no significant difference in the dissolution profiles of fresh and aged nanosuspension. These results indicate the suitability of formulation procedure for preparation of nanosized poorly water-soluble drug with significantly improved in vitro dissolution rate and thus possibly enhance fast onset of therapeutic drug effect.
Two Interpretations of the Discrimination Parameter
ERIC Educational Resources Information Center
Tuerlinckx, Francis; De Boeck, Paul
2005-01-01
In this paper we propose two interpretations for the discrimination parameter in the two-parameter logistic model (2PLM). The interpretations are based on the relation between the 2PLM and two stochastic models. In the first interpretation, the 2PLM is linked to a diffusion model so that the probability of absorption equals the 2PLM. The…
Psychometric Consequences of Subpopulation Item Parameter Drift
ERIC Educational Resources Information Center
Huggins-Manley, Anne Corinne
2017-01-01
This study defines subpopulation item parameter drift (SIPD) as a change in item parameters over time that is dependent on subpopulations of examinees, and hypothesizes that the presence of SIPD in anchor items is associated with bias and/or lack of invariance in three psychometric outcomes. Results show that SIPD in anchor items is associated…
Psychometric Consequences of Subpopulation Item Parameter Drift
ERIC Educational Resources Information Center
Huggins-Manley, Anne Corinne
2017-01-01
This study defines subpopulation item parameter drift (SIPD) as a change in item parameters over time that is dependent on subpopulations of examinees, and hypothesizes that the presence of SIPD in anchor items is associated with bias and/or lack of invariance in three psychometric outcomes. Results show that SIPD in anchor items is associated…
Estimating nuisance parameters in inverse problems
NASA Astrophysics Data System (ADS)
Aravkin, Aleksandr Y.; van Leeuwen, Tristan
2012-11-01
Many inverse problems include nuisance parameters which, while not of direct interest, are required to recover primary parameters. The structure of these problems allows efficient optimization strategies—a well-known example is variable projection, where nonlinear least-squares problems which are linear in some parameters can be very efficiently optimized. In this paper, we extend the idea of projecting out a subset over the variables to a broad class of maximum likelihood and maximum a posteriori likelihood problems with nuisance parameters, such as variance or degrees of freedom (d.o.f.). As a result, we are able to incorporate nuisance parameter estimation into large-scale constrained and unconstrained inverse problem formulations. We apply the approach to a variety of problems, including estimation of unknown variance parameters in the Gaussian model, d.o.f. parameter estimation in the context of robust inverse problems, and automatic calibration. Using numerical examples, we demonstrate improvement in recovery of primary parameters for several large-scale inverse problems. The proposed approach is compatible with a wide variety of algorithms and formulations, and its implementation requires only minor modifications to existing algorithms.
Visualization of parameter space for image analysis.
Pretorius, A Johannes; Bray, Mark-Anthony P; Carpenter, Anne E; Ruddle, Roy A
2011-12-01
Image analysis algorithms are often highly parameterized and much human input is needed to optimize parameter settings. This incurs a time cost of up to several days. We analyze and characterize the conventional parameter optimization process for image analysis and formulate user requirements. With this as input, we propose a change in paradigm by optimizing parameters based on parameter sampling and interactive visual exploration. To save time and reduce memory load, users are only involved in the first step--initialization of sampling--and the last step--visual analysis of output. This helps users to more thoroughly explore the parameter space and produce higher quality results. We describe a custom sampling plug-in we developed for CellProfiler--a popular biomedical image analysis framework. Our main focus is the development of an interactive visualization technique that enables users to analyze the relationships between sampled input parameters and corresponding output. We implemented this in a prototype called Paramorama. It provides users with a visual overview of parameters and their sampled values. User-defined areas of interest are presented in a structured way that includes image-based output and a novel layout algorithm. To find optimal parameter settings, users can tag high- and low-quality results to refine their search. We include two case studies to illustrate the utility of this approach.
Influence parameters of impact grinding mills
NASA Technical Reports Server (NTRS)
Hoeffl, K.; Husemann, K.; Goldacker, H.
1984-01-01
Significant parameters for impact grinding mills were investigated. Final particle size was used to evaluate grinding results. Adjustment of the parameters toward increased charge load results in improved efficiency; however, it was not possible to define a single, unified set to optimum grinding conditions.
Visualization of Parameter Space for Image Analysis
Pretorius, A. Johannes; Bray, Mark-Anthony P.; Carpenter, Anne E.; Ruddle, Roy A.
2013-01-01
Image analysis algorithms are often highly parameterized and much human input is needed to optimize parameter settings. This incurs a time cost of up to several days. We analyze and characterize the conventional parameter optimization process for image analysis and formulate user requirements. With this as input, we propose a change in paradigm by optimizing parameters based on parameter sampling and interactive visual exploration. To save time and reduce memory load, users are only involved in the first step - initialization of sampling - and the last step - visual analysis of output. This helps users to more thoroughly explore the parameter space and produce higher quality results. We describe a custom sampling plug-in we developed for CellProfiler - a popular biomedical image analysis framework. Our main focus is the development of an interactive visualization technique that enables users to analyze the relationships between sampled input parameters and corresponding output. We implemented this in a prototype called Paramorama. It provides users with a visual overview of parameters and their sampled values. User-defined areas of interest are presented in a structured way that includes image-based output and a novel layout algorithm. To find optimal parameter settings, users can tag high- and low-quality results to refine their search. We include two case studies to illustrate the utility of this approach. PMID:22034361
Control technology development. [distributed parameter systems
NASA Technical Reports Server (NTRS)
Rodriguez, G.
1981-01-01
Static and dynamic control design approaches were developed for distributed parameter systems. A hardware flexible beam facility was constructed to demonstrate and verify the theoretical control concepts. Efforts were made in the area of model order estimation for control systems with uncertain or time varying parameters.
Ecophysiological parameters for Pacific Northwest trees.
Amy E. Hessl; Cristina Milesi; Michael A. White; David L. Peterson; Robert E. Keane
2004-01-01
We developed a species- and location-specific database of published ecophysiological variables typically used as input parameters for biogeochemical models of coniferous and deciduous forested ecosystems in the Western United States. Parameters are based on the requirements of Biome-BGC, a widely used biogeochemical model that was originally parameterized for the...
Neutron Resonance Parameters for Cm-242 (Curium)
NASA Astrophysics Data System (ADS)
Sukhoruchkin, S. I.; Soroko, Z. N.
This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Cm-242 (Curium).
Neutron Resonance Parameters for Np-237 (Neptunium)
NASA Astrophysics Data System (ADS)
Sukhoruchkin, S. I.; Soroko, Z. N.
This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Np-237 (Neptunium).
Linking Item Parameters to a Base Scale
ERIC Educational Resources Information Center
Kang, Taehoon; Petersen, Nancy S.
2012-01-01
This paper compares three methods of item calibration--concurrent calibration, separate calibration with linking, and fixed item parameter calibration--that are frequently used for linking item parameters to a base scale. Concurrent and separate calibrations were implemented using BILOG-MG. The Stocking and Lord in "Appl Psychol Measure"…
Parameters and controlling of plasma chemistry
NASA Technical Reports Server (NTRS)
Tsuji, O.
1981-01-01
The parameters involved in plasma polymerization reactions are examined and the use of these parameters in the control of plasma reactions is dicussed. The variables associated with the reaction chamber, electrical discharge form, frequency and electrical source for the development of plasma, and monitoring techniques are addressed.
Qualitative Parameters of Practice during University Studies
ERIC Educational Resources Information Center
Stasiunaitiene, Egle; Norkute, Odeta
2011-01-01
In this article, relevance of practice during university studies is highlighted, as well as the main stages of its organisation, qualitative parameters, as well as criteria and indicators that validate them are defined. Discussion on the idea that taking into consideration qualitative parameters of organising practice as a component of studies…
Two Interpretations of the Discrimination Parameter
ERIC Educational Resources Information Center
Tuerlinckx, Francis; De Boeck, Paul
2005-01-01
In this paper we propose two interpretations for the discrimination parameter in the two-parameter logistic model (2PLM). The interpretations are based on the relation between the 2PLM and two stochastic models. In the first interpretation, the 2PLM is linked to a diffusion model so that the probability of absorption equals the 2PLM. The…
RESEARCH NOTE : Inversion for multiple parameter classes
NASA Astrophysics Data System (ADS)
Kennett, B. L. N.; Sambridge, M.
1998-10-01
Many geophysical data, such as the frequencies of the free oscillations of the Earth, depend on more than one type of model parameter. For inverse problems depending on multiple parameter classes, an iterative solution procedure is introduced in which each parameter class can be treated in the same way. This approach has considerable advantages where a large number of parameters are employed, but can still be useful for smaller systems. The iteration by parameter class commences by solving for the direct dependence on a particular parameter class, and at subsequent iterations the cross-dependences between classes are introduced. The update affects only the right-hand side of the equations, and, because the same sets of equations have to be solved at each iteration, an efficient computational implementation can be made. The largest set of equations that has to be solved at a time corresponds to the number of variables in an individual parameter class rather than the full set of parameters, which confers substantial computational benefits for very large problems.
Linking Item Parameters to a Base Scale
ERIC Educational Resources Information Center
Kang, Taehoon; Petersen, Nancy S.
2012-01-01
This paper compares three methods of item calibration--concurrent calibration, separate calibration with linking, and fixed item parameter calibration--that are frequently used for linking item parameters to a base scale. Concurrent and separate calibrations were implemented using BILOG-MG. The Stocking and Lord in "Appl Psychol Measure"…
Component reliability parameters estimation considering weather factors
NASA Astrophysics Data System (ADS)
Wang, Yuan
2017-08-01
In order to study influence of power system reliability parameters under the complex weather, this paper presents a component reliability parameter estimation method based on the one directional S-rough law and F-decomposition law. The S-rough rule handles the failure rate and the uncertain weather conditions. According to this, it establishes reliable parameter estimation model. Then the power system reliability evaluation adds the F-decomposition law analysis to form the interfere metrics and analyzes influence of component reliability parameters under different weather combinations. In the numerical example verification, the results show that the proposed model can predict the transmission line failure rate, and reveals the influence regularity of component reliability parameter. Based on the objective data (climate in many years), the proposed method can eliminate the influence of subjective factor. Evaluation results are more objective, and provide important information for the power system reliability evaluation.
Coordinate transformation by minimizing correlations between parameters
NASA Technical Reports Server (NTRS)
Kumar, M.
1972-01-01
This investigation was to determine the transformation parameters (three rotations, three translations and a scale factor) between two Cartesian coordinate systems from sets of coordinates given in both systems. The objective was the determination of well separated transformation parameters with reduced correlations between each other, a problem especially relevant when the sets of coordinates are not well distributed. The above objective is achieved by preliminarily determining the three rotational parameters and the scale factor from the respective direction cosines and chord distances (these being independent of the translation parameters) between the common points, and then computing all the seven parameters from a solution in which the rotations and the scale factor are entered as weighted constraints according to their variances and covariances obtained in the preliminary solutions. Numerical tests involving two geodetic reference systems were performed to evaluate the effectiveness of this approach.
Variable deceleration parameter and dark energy models
NASA Astrophysics Data System (ADS)
Bishi, Binaya K.
2016-03-01
This paper deals with the Bianchi type-III dark energy model and equation of state parameter in a first class of f(R,T) gravity. Here, R and T represents the Ricci scalar and trace of the energy momentum tensor, respectively. The exact solutions of the modified field equations are obtained by using (i) linear relation between expansion scalar and shear scalar, (ii) linear relation between state parameter and skewness parameter and (iii) variable deceleration parameter. To obtain the physically plausible cosmological models, the variable deceleration parameter with the suitable substitution leads to the scale factor of the form a(t) = [sinh(αt)] 1 n, where α and n > 0 are arbitrary constants. It is observed that our models are accelerating for 0 < n < 1 and for n > 1, transition phase from deceleration to acceleration. Further, we have discussed physical properties of the models.
Analysis of sagittal spinopelvic parameters in achondroplasia.
Hong, Jae-Young; Suh, Seung-Woo; Modi, Hitesh N; Park, Jong-Woong; Park, Jung-Ho
2011-08-15
Prospective radiological analysis of patients with achondroplasia. To analyze sagittal spinal alignment and pelvic orientation in achondroplasia patients. Knowledge of sagittal spinopelvic parameters is important for the treatment of achondroplasia, because they differ from those of the normal population and can induce pain. The study and control groups were composed of 32 achondroplasia patients and 24 healthy volunteers, respectively. All underwent lateral radiography of the whole spine including hip joints. The radiographic parameters examined were sacral slope (SS), pelvic tilt, pelvic incidence (PI), S1 overhang, thoracic kyphosis, T10-L2 kyphosis, lumbar lordosis (LL1, LL2), and sagittal balance. Statistical analysis was performed to identify significant differences between the two groups. In addition, correlations between parameters and symptoms were sought. Sagittal spinopelvic parameters, namely, pelvic tilt, pelvic incidence, S1 overhang, thoracic kyphosis, T10-L2 kyphosis, lumbar lordosis 1 and sagittal balance were found to be significantly different in the patient and control groups (P < 0.05). In addition, sagittal parameters were found to be related to each other in the patient group (P < 0.05), that is, PI was related to SS and pelvic tilt, and LL was related to thoracic kyphosis. Furthermore, in terms of relations between spinal and pelvic parameters, LL was related to SS and PI, and sagittal balance was related to SS and PI. Furthermore, LL and T10-L2 kyphosis were found to be related to pain (P < 0.05), whereas no other parameter was found to be related to VAS scores. Sagittal parameters and possible relationships between sagittal parameters and symptoms were found to be significantly different in achondroplasia patients and normal healthy controls. The present study shows that sagittal spinal and pelvic parameters can assist the treatment of spinal disorders in achondroplasia patients.
MFV reductions of MSSM parameter space
NASA Astrophysics Data System (ADS)
AbdusSalam, S. S.; Burgess, C. P.; Quevedo, F.
2015-02-01
The 100+ free parameters of the minimal supersymmetric standard model (MSSM) make it computationally difficult to compare systematically with data, motivating the study of specific parameter reductions such as the cMSSM and pMSSM. Here we instead study the reductions of parameter space implied by using minimal flavour violation (MFV) to organise the R-parity conserving MSSM, with a view towards systematically building in constraints on flavour-violating physics. Within this framework the space of parameters is reduced by expanding soft supersymmetry-breaking terms in powers of the Cabibbo angle, leading to a 24-, 30- or 42-parameter framework (which we call MSSM-24, MSSM-30, and MSSM-42 respectively), depending on the order kept in the expansion. We provide a Bayesian global fit to data of the MSSM-30 parameter set to show that this is manageable with current tools. We compare the MFV reductions to the 19-parameter pMSSM choice and show that the pMSSM is not contained as a subset. The MSSM-30 analysis favours a relatively lighter TeV-scale pseudoscalar Higgs boson and tan β ˜ 10 with multi-TeV sparticles.
Exploiting intrinsic fluctuations to identify model parameters.
Zimmer, Christoph; Sahle, Sven; Pahle, Jürgen
2015-04-01
Parameterisation of kinetic models plays a central role in computational systems biology. Besides the lack of experimental data of high enough quality, some of the biggest challenges here are identification issues. Model parameters can be structurally non-identifiable because of functional relationships. Noise in measured data is usually considered to be a nuisance for parameter estimation. However, it turns out that intrinsic fluctuations in particle numbers can make parameters identifiable that were previously non-identifiable. The authors present a method to identify model parameters that are structurally non-identifiable in a deterministic framework. The method takes time course recordings of biochemical systems in steady state or transient state as input. Often a functional relationship between parameters presents itself by a one-dimensional manifold in parameter space containing parameter sets of optimal goodness. Although the system's behaviour cannot be distinguished on this manifold in a deterministic framework it might be distinguishable in a stochastic modelling framework. Their method exploits this by using an objective function that includes a measure for fluctuations in particle numbers. They show on three example models, immigration-death, gene expression and Epo-EpoReceptor interaction, that this resolves the non-identifiability even in the case of measurement noise with known amplitude. The method is applied to partially observed recordings of biochemical systems with measurement noise. It is simple to implement and it is usually very fast to compute. This optimisation can be realised in a classical or Bayesian fashion.
Hyperspectral signature analysis of skin parameters
NASA Astrophysics Data System (ADS)
Vyas, Saurabh; Banerjee, Amit; Garza, Luis; Kang, Sewon; Burlina, Philippe
2013-02-01
The temporal analysis of changes in biological skin parameters, including melanosome concentration, collagen concentration and blood oxygenation, may serve as a valuable tool in diagnosing the progression of malignant skin cancers and in understanding the pathophysiology of cancerous tumors. Quantitative knowledge of these parameters can also be useful in applications such as wound assessment, and point-of-care diagnostics, amongst others. We propose an approach to estimate in vivo skin parameters using a forward computational model based on Kubelka-Munk theory and the Fresnel Equations. We use this model to map the skin parameters to their corresponding hyperspectral signature. We then use machine learning based regression to develop an inverse map from hyperspectral signatures to skin parameters. In particular, we employ support vector machine based regression to estimate the in vivo skin parameters given their corresponding hyperspectral signature. We build on our work from SPIE 2012, and validate our methodology on an in vivo dataset. This dataset consists of 241 signatures collected from in vivo hyperspectral imaging of patients of both genders and Caucasian, Asian and African American ethnicities. In addition, we also extend our methodology past the visible region and through the short-wave infrared region of the electromagnetic spectrum. We find promising results when comparing the estimated skin parameters to the ground truth, demonstrating good agreement with well-established physiological precepts. This methodology can have potential use in non-invasive skin anomaly detection and for developing minimally invasive pre-screening tools.
A parametric reconstruction of the deceleration parameter
NASA Astrophysics Data System (ADS)
Mamon, Abdulla Al; Das, Sudipta
2017-07-01
The present work is based on a parametric reconstruction of the deceleration parameter q( z) in a model for the spatially flat FRW universe filled with dark energy and non-relativistic matter. In cosmology, the parametric reconstruction technique deals with an attempt to build up a model by choosing some specific evolution scenario for a cosmological parameter and then estimate the values of the parameters with the help of different observational datasets. In this paper, we have proposed a logarithmic parametrization of q( z) to probe the evolution history of the universe. Using the type Ia supernova, baryon acoustic oscillation and the cosmic microwave background datasets, the constraints on the arbitrary model parameters q0 and q1 are obtained (within 1σ and 2σ confidence limits) by χ 2-minimization technique. We have then reconstructed the deceleration parameter, the total EoS parameter ω _tot, the jerk parameter and have compared the reconstructed results of q( z) with other well-known parametrizations of q( z). We have also shown that two model selection criteria (namely, the Akaike information criterion and Bayesian information criterion) provide a clear indication that our reconstructed model is well consistent with other popular models.
Parameter estimation methods for chaotic intercellular networks.
Mariño, Inés P; Ullner, Ekkehard; Zaikin, Alexey
2013-01-01
We have investigated simulation-based techniques for parameter estimation in chaotic intercellular networks. The proposed methodology combines a synchronization-based framework for parameter estimation in coupled chaotic systems with some state-of-the-art computational inference methods borrowed from the field of computational statistics. The first method is a stochastic optimization algorithm, known as accelerated random search method, and the other two techniques are based on approximate Bayesian computation. The latter is a general methodology for non-parametric inference that can be applied to practically any system of interest. The first method based on approximate Bayesian computation is a Markov Chain Monte Carlo scheme that generates a series of random parameter realizations for which a low synchronization error is guaranteed. We show that accurate parameter estimates can be obtained by averaging over these realizations. The second ABC-based technique is a Sequential Monte Carlo scheme. The algorithm generates a sequence of "populations", i.e., sets of randomly generated parameter values, where the members of a certain population attain a synchronization error that is lesser than the error attained by members of the previous population. Again, we show that accurate estimates can be obtained by averaging over the parameter values in the last population of the sequence. We have analysed how effective these methods are from a computational perspective. For the numerical simulations we have considered a network that consists of two modified repressilators with identical parameters, coupled by the fast diffusion of the autoinducer across the cell membranes.
Guideline for Deciding Physical Parameters for Acrobot
NASA Astrophysics Data System (ADS)
Baba, Atsushi; Watanabe, Ryo
This paper presents a guideline for deciding physical parameters for the Acrobot, a typical example of two-link underactuated robots. A set of physical parameters for the Acrobot is determined using an evaluation function, which is derived by analyzing the robustness of an existing swing-up controller for the Acrobot. A typical set of physical parameters used in many papers are then evaluated using our evaluation function, and the validity and performance of our proposed guideline are studied with a series of simulations.
Transmission Electron Microscope Measures Lattice Parameters
NASA Technical Reports Server (NTRS)
Pike, William T.
1996-01-01
Convergent-beam microdiffraction (CBM) in thermionic-emission transmission electron microscope (TEM) is technique for measuring lattice parameters of nanometer-sized specimens of crystalline materials. Lattice parameters determined by use of CBM accurate to within few parts in thousand. Technique developed especially for use in quantifying lattice parameters, and thus strains, in epitaxial mismatched-crystal-lattice multilayer structures in multiple-quantum-well and other advanced semiconductor electronic devices. Ability to determine strains in indivdual layers contributes to understanding of novel electronic behaviors of devices.
Material parameter determination from scattering measurements
NASA Technical Reports Server (NTRS)
Dominek, A.; Park, A.; Peters, L., Jr.
1988-01-01
The electrical, macroscopic performance of isotropic material can generally be described through their constitutive scalar parameters, permittivity and permeability which are symbolically represented by epsilon and mu, respectively. These parameters relate the electric and magnetic flux densities to the electric and magnetic fields through the following relationships: (1) D=epsilonE; and (2) B=muH. It is through these parameters that the interaction of electromagnetic waves with material can be quantized in terms of reflection and transmission coefficients, and propagation and attenuation factors.
Constitutive parameter measurements of lossy materials
NASA Technical Reports Server (NTRS)
Dominek, A.; Park, A.
1989-01-01
The electrical constitutive parameters of lossy materials are considered. A discussion of the NRL arch for lossy coatings is presented involving analytical analyses of the reflected field using the geometrical theory of diffraction (GTD) and physical optics (PO). The actual values for these parameters can be obtained through a traditional transmission technique which is examined from an error analysis standpoint. Alternate sample geometries are suggested for this technique to reduce sample tolerance requirements for accurate parameter determination. The performance for one alternate geometry is given.
ZASPE: Zonal Atmospheric Stellar Parameters Estimator
NASA Astrophysics Data System (ADS)
Brahm, Rafael; Jordan, Andres; Hartman, Joel; Bakos, Gaspar
2016-07-01
ZASPE (Zonal Atmospheric Stellar Parameters Estimator) computes the atmospheric stellar parameters (Teff, log(g), [Fe/H] and vsin(i)) from echelle spectra via least squares minimization with a pre-computed library of synthetic spectra. The minimization is performed only in the most sensitive spectral zones to changes in the atmospheric parameters. The uncertainities and covariances computed by ZASPE assume that the principal source of error is the systematic missmatch between the observed spectrum and the sythetic one that produces the best fit. ZASPE requires a grid of synthetic spectra and can use any pre-computed library minor modifications.
Transmission Electron Microscope Measures Lattice Parameters
NASA Technical Reports Server (NTRS)
Pike, William T.
1996-01-01
Convergent-beam microdiffraction (CBM) in thermionic-emission transmission electron microscope (TEM) is technique for measuring lattice parameters of nanometer-sized specimens of crystalline materials. Lattice parameters determined by use of CBM accurate to within few parts in thousand. Technique developed especially for use in quantifying lattice parameters, and thus strains, in epitaxial mismatched-crystal-lattice multilayer structures in multiple-quantum-well and other advanced semiconductor electronic devices. Ability to determine strains in indivdual layers contributes to understanding of novel electronic behaviors of devices.
Manifold parameter space and its applications
NASA Astrophysics Data System (ADS)
Sato, Atsushi
2004-11-01
We review the several features of the new parameter space which we presented in the previous paper, and show the differentiable manifold properties of this parameter space coordinate. Using this parameter coordinate we calculate three Feynman amplitudes of the vacuum polarization with a gluon loop, a quark loop and a ghost loop in QCD and show that the results are perfectly equal to those of the usual calculations by the Feynman parametrization technique in the scheme of the dimensional regularization. Then we try to calculate the anomalous magnetic moment of an on-shell quark in QCD by using the dimensional regularization, our new parametrization and integral method.
Dual Operating Parameter Relationship with Engine Performance
NASA Astrophysics Data System (ADS)
Devi. I, Aparna; Ramesh, R.; Kumar, N. Ravi; Charan, G. Shiva
2016-11-01
In order to reduce emissions and maximize performance of internal combustion engines, it is important to understand the relationship between operating parameters and performance. Estimation of engine performance under simultaneous variation of operating parameters is not well addressed in literature. In the present work an attempt has been made to develop a relationship between engine performance (brake thermal efficiency) and operating parameters such as load and compression ratio. Experiments were conducted varying load and compression ratio and Brake Thermal Effiency obtained was recorded. The results of the model were validated with the experimental results.
Parameter identification of civil engineering structures
NASA Technical Reports Server (NTRS)
Juang, J. N.; Sun, C. T.
1980-01-01
This paper concerns the development of an identification method required in determining structural parameter variations for systems subjected to an extended exposure to the environment. The concept of structural identifiability of a large scale structural system in the absence of damping is presented. Three criteria are established indicating that a large number of system parameters (the coefficient parameters of the differential equations) can be identified by a few actuators and sensors. An eight-bay-fifteen-story frame structure is used as example. A simple model is employed for analyzing the dynamic response of the frame structure.
Extended tradeoff parameters for composite correlation filters
NASA Astrophysics Data System (ADS)
Carlson, Daniel W.
2005-03-01
Composite correlation filters have been demonstrated in many automatic target recognition (ATR) applications because of their ability for class recognition and distortion-tolerance with shift invariance. Both the optimal tradeoff synthetic discriminant function (OTSDF) filters and optimal tradeoff distance classifier correlation filter (OTDCCF) approaches use parameters to combine multiple characteristics. Usually a set of filters is grouped into a bank for recognizing multiple targets across multiple geometric distortions. We extend these approaches to use independent tradeoff parameters in the filter synthesis for each class and grouping bin to improve classification. A method for determining the extended parameters is presented. Test results using the public SAR imagery MSTAR database are shown.
Parameters Describing Earth Observing Remote Sensing Systems
NASA Technical Reports Server (NTRS)
Zanoni, Vicki; Ryan, Robert E.; Pagnutti, Mary; Davis, Bruce; Markham, Brian; Storey, Jim
2003-01-01
The Earth science community needs to generate consistent and standard definitions for spatial, spectral, radiometric, and geometric properties describing passive electro-optical Earth observing sensors and their products. The parameters used to describe sensors and to describe their products are often confused. In some cases, parameters for a sensor and for its products are identical; in other cases, these parameters vary widely. Sensor parameters are bound by the fundamental performance of a system, while product parameters describe what is available to the end user. Products are often resampled, edge sharpened, pan-sharpened, or compressed, and can differ drastically from the intrinsic data acquired by the sensor. Because detailed sensor performance information may not be readily available to an international science community, standardization of product parameters is of primary performance. Spatial product parameters described include Modulation Transfer Function (MTF), point spread function, line spread function, edge response, stray light, edge sharpening, aliasing, ringing, and compression effects. Spectral product parameters discussed include full width half maximum, ripple, slope edge, and out-of-band rejection. Radiometric product properties discussed include relative and absolute radiometry, noise equivalent spectral radiance, noise equivalent temperature diffenence, and signal-to-noise ratio. Geometric product properties discussed include geopositional accuracy expressed as CE90, LE90, and root mean square error. Correlated properties discussed include such parameters as band-to-band registration, which is both a spectral and a spatial property. In addition, the proliferation of staring and pushbroom sensor architectures requires new parameters to describe artifacts that are different from traditional cross-track system artifacts. A better understanding of how various system parameters affect product performance is also needed to better ascertain the
Deductive multiscale simulation using order parameters
Ortoleva, Peter J.
2017-05-16
Illustrative embodiments of systems and methods for the deductive multiscale simulation of macromolecules are disclosed. In one illustrative embodiment, a deductive multiscale simulation method may include (i) constructing a set of order parameters that model one or more structural characteristics of a macromolecule, (ii) simulating an ensemble of atomistic configurations for the macromolecule using instantaneous values of the set of order parameters, (iii) simulating thermal-average forces and diffusivities for the ensemble of atomistic configurations, and (iv) evolving the set of order parameters via Langevin dynamics using the thermal-average forces and diffusivities.
NASA Astrophysics Data System (ADS)
Ren, Huiying; Hou, Zhangshuan; Huang, Maoyi; Bao, Jie; Sun, Yu; Tesfa, Teklu; Ruby Leung, L.
2016-05-01
The Community Land Model (CLM) represents physical, chemical, and biological processes of the terrestrial ecosystems that interact with climate across a range of spatial and temporal scales. As CLM includes numerous sub-models and associated parameters, the high-dimensional parameter space presents a formidable challenge for quantifying uncertainty and improving Earth system predictions needed to assess environmental changes and risks. This study aims to evaluate the potential of transferring hydrologic model parameters in CLM through sensitivity analyses and classification across watersheds from the Model Parameter Estimation Experiment (MOPEX) in the United States. The sensitivity of CLM-simulated water and energy fluxes to hydrological parameters across 431 MOPEX basins are first examined using an efficient stochastic sampling-based sensitivity analysis approach. Linear, interaction, and high-order nonlinear impacts are all identified via statistical tests and stepwise backward removal parameter screening. The basins are then classified according to their parameter sensitivity patterns (internal attributes), as well as their hydrologic indices/attributes (external hydrologic factors) separately, using Principal component analysis (PCA) and expectation-maximization (EM) - based clustering approach. Similarities and differences among the parameter sensitivity-based classification system (S-Class), the hydrologic indices-based classification (H-Class), and the Koppen climate classification systems (K-Class) are discussed. Within each parameter sensitivity-based classification system (S-Class) with similar parameter sensitivity characteristics, similar inversion modeling setups can be used for parameter calibration, and the parameters and their contribution or significance to water and energy cycling may also be more transferrable. This classification study provides guidance on identifiable parameters, and on parameterization and inverse model design for CLM but the
Fixing the c Parameter in the Three-Parameter Logistic Model
ERIC Educational Resources Information Center
Han, Kyung T.
2012-01-01
For several decades, the "three-parameter logistic model" (3PLM) has been the dominant choice for practitioners in the field of educational measurement for modeling examinees' response data from multiple-choice (MC) items. Past studies, however, have pointed out that the c-parameter of 3PLM should not be interpreted as a guessing parameter. This…
The Influence of the AGS Beam Parameters on the Beam Parameters at the RHIC Injection Point
Xu, Jianming
1988-01-03
The change of the AGS ejected beam parameter will influence the injection efficiency of RHIC, cause phase space dilution and decrease the luminosity of RHIC. The changes of the beam parameters at the RHIC injection point caused by the changes of the AGS ejected beam parameters have been calculated and summarized in this note.
Fixing the c Parameter in the Three-Parameter Logistic Model
ERIC Educational Resources Information Center
Han, Kyung T.
2012-01-01
For several decades, the "three-parameter logistic model" (3PLM) has been the dominant choice for practitioners in the field of educational measurement for modeling examinees' response data from multiple-choice (MC) items. Past studies, however, have pointed out that the c-parameter of 3PLM should not be interpreted as a guessing parameter. This…
Sample Size and Item Parameter Estimation Precision When Utilizing the One-Parameter "Rasch" Model
ERIC Educational Resources Information Center
Custer, Michael
2015-01-01
This study examines the relationship between sample size and item parameter estimation precision when utilizing the one-parameter model. Item parameter estimates are examined relative to "true" values by evaluating the decline in root mean squared deviation (RMSD) and the number of outliers as sample size increases. This occurs across…
Parameter identification for nonlinear aerodynamic systems
NASA Technical Reports Server (NTRS)
Pearson, Allan E.
1990-01-01
Parameter identification for nonlinear aerodynamic systems is examined. It is presumed that the underlying model can be arranged into an input/output (I/O) differential operator equation of a generic form. The algorithm estimation is especially efficient since the equation error can be integrated exactly given any I/O pair to obtain an algebraic function of the parameters. The algorithm for parameter identification was extended to the order determination problem for linear differential system. The degeneracy in a least squares estimate caused by feedback was addressed. A method of frequency analysis for determining the transfer function G(j omega) from transient I/O data was formulated using complex valued Fourier based modulating functions in contrast with the trigonometric modulating functions for the parameter estimation problem. A simulation result of applying the algorithm is given under noise-free conditions for a system with a low pass transfer function.
Organogel formation rationalized by Hansen solubility parameters.
Raynal, Matthieu; Bouteiller, Laurent
2011-08-07
Some organic compounds gelate particular solvents by forming a network of anisotropic fibres. We show that Hansen solubility parameters can be used to predict the range of solvents that are likely to be gelled by any given gelator.
Thermophysical parameters of the LBO crystal
Grechin, Sergei G; Zuev, A V; Fokin, A S; Kokh, Aleksandr E; Moiseev, N V; Popov, Petr A; Sidorov, Aleksei A
2010-08-27
The thermophysical parameters (linear thermal expansion coefficients, thermal conductivities, and heat capacity) of the lithium triborate (LBO) crystal are measured and compared with previously published data. (nonlinear-optics phenomena)
Efficient computation of parameter confidence intervals
NASA Technical Reports Server (NTRS)
Murphy, Patrick C.
1987-01-01
An important step in system identification of aircraft is the estimation of stability and control derivatives from flight data along with an assessment of parameter accuracy. When the maximum likelihood estimation technique is used, parameter accuracy is commonly assessed by the Cramer-Rao lower bound. It is known, however, that in some cases the lower bound can be substantially different from the parameter variance. Under these circumstances the Cramer-Rao bounds may be misleading as an accuracy measure. This paper discusses the confidence interval estimation problem based on likelihood ratios, which offers a more general estimate of the error bounds. Four approaches are considered for computing confidence intervals of maximum likelihood parameter estimates. Each approach is applied to real flight data and compared.
Thermodynamic consistency of the interaction parameter formalism
NASA Astrophysics Data System (ADS)
Srikanth, S.; Jacob, K. T.
1988-04-01
The apparent contradiction between the exact nature of the interaction parameter formalism as presented by Lupis and Elliott and the inconsistencies discussed recently by Pelton and Bale arise from the truncation of the Maclaurin series in the latter treatment. The truncation removes the exactness of the expression for the logarithm of the activity coefficient of a solute in a multi-component system. The integrals are therefore path dependent. Formulae for integration along paths of constant Xi, or X i/Xj are presented. The expression for In γsolvent given by Pelton and Bale is valid only in the limit that the mole fraction of solvent tends to one. The truncation also destroys the general relations between interaction parameters derived by Lupis and Elliott. For each specific choice of parameters special relationships are obtained between interaction parameters.
Reionization history and CMB parameter estimation
Dizgah, Azadeh Moradinezhad; Kinney, William H.; Gnedin, Nickolay Y. E-mail: gnedin@fnal.edu
2013-05-01
We study how uncertainty in the reionization history of the universe affects estimates of other cosmological parameters from the Cosmic Microwave Background. We analyze WMAP7 data and synthetic Planck-quality data generated using a realistic scenario for the reionization history of the universe obtained from high-resolution numerical simulation. We perform parameter estimation using a simple sudden reionization approximation, and using the Principal Component Analysis (PCA) technique proposed by Mortonson and Hu. We reach two main conclusions: (1) Adopting a simple sudden reionization model does not introduce measurable bias into values for other parameters, indicating that detailed modeling of reionization is not necessary for the purpose of parameter estimation from future CMB data sets such as Planck. (2) PCA analysis does not allow accurate reconstruction of the actual reionization history of the universe in a realistic case.
Earth Rotation Parameters from DSN VLBI: 1994
NASA Technical Reports Server (NTRS)
Steppe, J. A.; Oliveau, S. H.; Sovers, O. J.
1994-01-01
In this report, Earth Rotation Parameter (ERP) estimates ahve been obtained from an analysis of Deep Space Network (DSN) VLBI data that directly aligns its celestial and terrestrial reference frames with those of the International Earth Rotation Service (IERS).
Design parameters for rotary extrusion macerators
Nelson, F.W.; Barrington, G.P.; Straub, R.J.; Bruhn, H.D.
1981-01-01
Design parameters for an extrusion macerator for plant juice protein extraction are discussed. Forces developed can be predicted for various machine configurations, throughputs, speeds, and extrusion pressures from a simple nomogram. 5 refs.
Integral data analysis for resonance parameters determination
Larson, N.M.; Leal, L.C.; Derrien, H.
1997-09-01
Neutron time-of-flight experiments have long been used to determine resonance parameters. Those resonance parameters have then been used in calculations of integral quantities such as Maxwellian averages or resonance integrals, and results of those calculations in turn have been used as a criterion for acceptability of the resonance analysis. However, the calculations were inadequate because covariances on the parameter values were not included in the calculations. In this report an effort to correct for that deficiency is documented: (1) the R-matrix analysis code SAMMY has been modified to include integral quantities of importance, (2) directly within the resonance parameter analysis, and (3) to determine the best fit to both differential (microscopic) and integral (macroscopic) data simultaneously. This modification was implemented because it is expected to have an impact on the intermediate-energy range that is important for criticality safety applications.
Bayesian inference to identify parameters in viscoelasticity
NASA Astrophysics Data System (ADS)
Rappel, Hussein; Beex, Lars A. A.; Bordas, Stéphane P. A.
2017-08-01
This contribution discusses Bayesian inference (BI) as an approach to identify parameters in viscoelasticity. The aims are: (i) to show that the prior has a substantial influence for viscoelasticity, (ii) to show that this influence decreases for an increasing number of measurements and (iii) to show how different types of experiments influence the identified parameters and their uncertainties. The standard linear solid model is the material description of interest and a relaxation test, a constant strain-rate test and a creep test are the tensile experiments focused on. The experimental data are artificially created, allowing us to make a one-to-one comparison between the input parameters and the identified parameter values. Besides dealing with the aforementioned issues, we believe that this contribution forms a comprehensible start for those interested in applying BI in viscoelasticity.
Efficient computation of parameter confidence intervals
NASA Technical Reports Server (NTRS)
Murphy, Patrick C.
1987-01-01
An important step in system identification of aircraft is the estimation of stability and control derivatives from flight data along with an assessment of parameter accuracy. When the maximum likelihood estimation technique is used, parameter accuracy is commonly assessed by the Cramer-Rao lower bound. It is known, however, that in some cases the lower bound can be substantially different from the parameter variance. Under these circumstances the Cramer-Rao bounds may be misleading as an accuracy measure. This paper discusses the confidence interval estimation problem based on likelihood ratios, which offers a more general estimate of the error bounds. Four approaches are considered for computing confidence intervals of maximum likelihood parameter estimates. Each approach is applied to real flight data and compared.
Component temperature versus laser-welding parameters
Jones, W.H.
1983-01-01
Applications have arisen in which the component temperature near a laser weld is critical because of possible damage to the explosive powder adjacent to the member being welded. To evaluate the thermal excursion experienced at the powder cavity wall, a study was conducted using assemblies that had been equipped with 0.05 mm diameter thermocouple wires. The main goal of the study was to determine how changes in the laser welding parameters owuld affect the powder cavity wall temperature. The objective lens-to-work distance, pulse rate, and beam power parameters were varied. The peak temperature varied from 117/sup 0/C to 311/sup 0/C in response to welding parameter changes. The study concluded that by utilizing a selected set of welding parameters, the design requirement of a 160/sup 0/C maximum powder cavity wall temperature could easily be satisfied.
Information Conversion, Effective Samples, and Parameter Size
Lin, Xiaodong; Pittman, Jennifer; Clarke, Bertrand
2008-01-01
Consider the relative entropy between a posterior density for a parameter given a sample and a second posterior density for the same parameter, based on a different model and a different data set. Then the relative entropy can be minimized over the second sample to get a virtual sample that would make the second posterior as close as possible to the first in an informational sense. If the first posterior is based on a dependent dataset and the second posterior uses an independence model, the effective inferential power of the dependent sample is transferred into the independent sample by the optimization. Examples of this optimization are presented for models with nuisance parameters, finite mixture models, and models for correlated data. Our approach is also used to choose the effective parameter size in a Bayesian hierarchical model. PMID:19079764
Atmospheric Science Data Center
2013-02-18
... Parameters: IR Aerosol Scattering Ratio (1064 nm) Composite Tropospheric Ozone Cross-Sections Tropopause heights ... Scattering Ratio (587 nm) Visible Aerosol Depolarization (1064 nm) SCAR-B Block: SCAR-B Products ...
Earth Rotation Parameters from DSN VLBI: 1994
NASA Technical Reports Server (NTRS)
Steppe, J. A.; Oliveau, S. H.; Sovers, O. J.
1994-01-01
In this report, Earth Rotation Parameter (ERP) estimates ahve been obtained from an analysis of Deep Space Network (DSN) VLBI data that directly aligns its celestial and terrestrial reference frames with those of the International Earth Rotation Service (IERS).
Optical components damage parameters database system
NASA Astrophysics Data System (ADS)
Tao, Yizheng; Li, Xinglan; Jin, Yuquan; Xie, Dongmei; Tang, Dingyong
2012-10-01
Optical component is the key to large-scale laser device developed by one of its load capacity is directly related to the device output capacity indicators, load capacity depends on many factors. Through the optical components will damage parameters database load capacity factors of various digital, information technology, for the load capacity of optical components to provide a scientific basis for data support; use of business processes and model-driven approach, the establishment of component damage parameter information model and database systems, system application results that meet the injury test optical components business processes and data management requirements of damage parameters, component parameters of flexible, configurable system is simple, easy to use, improve the efficiency of the optical component damage test.
Tropospheric range error parameters: Further studies
NASA Technical Reports Server (NTRS)
Hopfield, H. S.
1972-01-01
Improved parameters are presented for predicting the tropospheric effect on electromagnetic range measurements from surface meteorological data. More geographic locations have been added to the earlier list. Parameters are given for computing the dry component of the zenith radio range effect from surface pressure alone with an rms error of 1 to 2 mm, or the total range effect from the dry and wet components of the surface refractivity and a two-part quartic profile model. The new parameters are obtained, as before, from meteorological balloon data but with improved procedures, including the conversion of the geopotential heights of the balloon data to actual or geometric heights before using the data. The revised values of the parameter k (dry component of vertical radio range effect per unit pressure at the surface) show more latitude variation than is accounted for by the variation of g, the acceleration of gravity.
Tropospheric range error parameters: Further studies
NASA Technical Reports Server (NTRS)
Hopfield, H. S.
1972-01-01
Improved parameters are presented for predicting the tropospheric effect on electromagnetic range measurements from surface meteorological data. Parameters are given for computing the dry component of the zenith radio range effect from surface pressure alone with an rms error of 1 to 2 mm, or the total range effect from the dry and wet components of the surface refractivity, N, and a two-part quartic profile model. The parameters were obtained from meteorological balloon data with improved procedures, including the conversion of the geopotential heights of the balloon data to actual or geometric heights before using the data. The revised values of the parameter k show more latitude variation than is accounted for by the variation of g. This excess variation of k indicates a small latitude variation in the mean molecular weight of air and yields information about the latitude-varying water vapor content of air.
LISA Parameter Estimation using Numerical Merger Waveforms
NASA Technical Reports Server (NTRS)
Thorpe, J. I.; McWilliams, S.; Baker, J.
2008-01-01
Coalescing supermassive black holes are expected to provide the strongest sources for gravitational radiation detected by LISA. Recent advances in numerical relativity provide a detailed description of the waveforms of such signals. We present a preliminary study of LISA's sensitivity to waveform parameters using a hybrid numerical/analytic waveform describing the coalescence of two equal-mass, nonspinning black holes. The Synthetic LISA software package is used to simulate the instrument response and the Fisher information matrix method is used to estimate errors in the waveform parameters. Initial results indicate that inclusion of the merger signal can significantly improve the precision of some parameter estimates. For example, the median parameter errors for an ensemble of systems with total redshifted mass of 10(exp 6) deg M solar mass at a redshift of z is approximately 1 were found to decrease by a factor of slightly more than two when the merger was included.
Vertical Axis Wind Turbine Foundation parameter study
Lodde, P.F.
1980-07-01
The dynamic failure criterion governing the dimensions of prototype Vertical Axis Wind Turbine Foundations is treated as a variable parameter. The resulting change in foundation dimensions and costs is examined.
Project Integration Architecture: Formulation of Semantic Parameters
NASA Technical Reports Server (NTRS)
Jones, William Henry
2005-01-01
One of several key elements of the Project Integration Architecture (PIA) is the intention to formulate parameter objects which convey meaningful semantic information. In so doing, it is expected that a level of automation can be achieved in the consumption of information content by PIA-consuming clients outside the programmatic boundary of a presenting PIA-wrapped application. This paper discusses the steps that have been recently taken in formulating such semantically-meaningful parameters.
Theoretical temperature dependence of solar cell parameters
NASA Technical Reports Server (NTRS)
Fan, John C. C.
1986-01-01
A simple formulation has been derived for the temperature dependence of cell parameters for any solar cell material. Detailed calculations have been performed for high-quality monocrystalline GaAs, Si and Ge cells. Preliminary experimental data for GaAs and Si cells are close to the calculated values. In general, the higher the energy gap of a material, the small is the temperature dependence of its solar cell parameters.
empiriciSN: Supernova parameter generator
NASA Astrophysics Data System (ADS)
Holoien, Thomas W.-S.; Marshall, Philip J.; Wechsler, Risa H.
2017-08-01
empiriciSN generates realistic supernova parameters given photometric observations of a potential host galaxy, based entirely on empirical correlations measured from supernova datasets. It is intended to be used to improve supernova simulation for DES and LSST. It is extendable such that additional datasets may be added in the future to improve the fitting algorithm or so that additional light curve parameters or supernova types may be fit.
Material parameter measurements at high temperatures
NASA Technical Reports Server (NTRS)
Dominek, A.; Park, A.; Peters, L., Jr.
1988-01-01
Alternate fixtures of techniques for the measurement of the constitutive material parameters at elevated temperatures are presented. The technique utilizes scattered field data from material coated cylinders between parallel plates or material coated hemispheres over a finite size groundplane. The data acquisition is centered around the HP 8510B Network Analyzer. The parameters are then found from a numerical search algorithm using the Newton-Ralphson technique with the measured and calculated fields from these canonical scatters. Numerical and experimental results are shown.
Design Parameters in Multimodal Games for Rehabilitation
Basteris, Angelo; Amirabdollahian, Farshid
2014-01-01
Abstract Objectives: The repetitive and sometimes mundane nature of conventional rehabilitation therapy provides an ideal opportunity for development of interactive and challenging therapeutic games that have the potential to engage and motivate the players. Certain game design parameters that may encourage patients to actively participate by making the games more enjoyable have been identified. In this article, we describe a formative study in which we designed and evaluated some of these parameters with healthy subjects. Materials and Methods: The “operant conditioning” and “scoring” design parameters were incorporated in a remake of a classic labyrinth game, “Marble Maze.” A group of participants (n=37) played the game twice: Once in the control condition without both modalities and then with either one of the parameters or with both. Measures of game duration and number of fails in the game were recorded along with survey questionnaires to measure player perceptions of intrinsic motivation on the game. Results: Longer playtimes, higher levels of interest/enjoyment, and effort to play the game were recorded with the introduction of these parameters. Conclusions: This study provides an understanding on how game design parameters can be used to motivate and encourage people to play longer. With these positive results, future aims are to test the parameters with stroke patients, providing much clearer insight as to what influences these parameters have on patients undergoing therapy. The ultimate goal is to utilize game design in order to maintain longer therapeutic interaction between a patient and his or her therapy medium. PMID:24761328
Statistical Inference for Data Adaptive Target Parameters.
Hubbard, Alan E; Kherad-Pajouh, Sara; van der Laan, Mark J
2016-05-01
Consider one observes n i.i.d. copies of a random variable with a probability distribution that is known to be an element of a particular statistical model. In order to define our statistical target we partition the sample in V equal size sub-samples, and use this partitioning to define V splits in an estimation sample (one of the V subsamples) and corresponding complementary parameter-generating sample. For each of the V parameter-generating samples, we apply an algorithm that maps the sample to a statistical target parameter. We define our sample-split data adaptive statistical target parameter as the average of these V-sample specific target parameters. We present an estimator (and corresponding central limit theorem) of this type of data adaptive target parameter. This general methodology for generating data adaptive target parameters is demonstrated with a number of practical examples that highlight new opportunities for statistical learning from data. This new framework provides a rigorous statistical methodology for both exploratory and confirmatory analysis within the same data. Given that more research is becoming "data-driven", the theory developed within this paper provides a new impetus for a greater involvement of statistical inference into problems that are being increasingly addressed by clever, yet ad hoc pattern finding methods. To suggest such potential, and to verify the predictions of the theory, extensive simulation studies, along with a data analysis based on adaptively determined intervention rules are shown and give insight into how to structure such an approach. The results show that the data adaptive target parameter approach provides a general framework and resulting methodology for data-driven science.
Meteor light curves: the relevant parameters
NASA Astrophysics Data System (ADS)
Brosch, N.; Helled, Ravit; Polishook, D.; Almoznino, E.; David, N.
2004-11-01
We investigate a uniform sample of 113 light curves of meteors collected at the Wise Observatory in 2002 November during a campaign to observe the Leonid meteor shower. We use previously defined descriptors, such as the classical skewness parameter F and a recently defined pointedness variable P, along with a number of other measurable or derived quantities, in order to explore the parameter space in search of meaningful light curve descriptors. In comparison with previous publications, we make extensive use of statistical techniques to reveal links among the various parameters and to understand their relative importance. In particular, we show that meteors with long-duration trails rise slowly to their maximal brightness and also decay slowly from the peak, while showing milder flaring than other meteors. Early skewed meteors, with their peak brightness in the first half of the light curve, show a fast rise to the peak. We show that the duration of the luminous phase of the meteor is the most important variable differentiating among the 2002 meteor trails. The skewness parameter F, which is widely used in meteor light curve analyses, appears only as the second or third in order of importance in explaining the variance among the observed light curves, with the most important parameter being related to the duration of the meteor light-producing phase. We suggest that the pointedness parameter P could possibly be useful in describing differences among meteor showers, perhaps by being related to the different compositions of meteoroids, and also in comparing observations to model light curves. We compare the derived characteristics of the 2002 meteors with model predictions and conclude that more work is required to define a consistent set of measurable and derived light-curve parameters that would characterize the light production from meteors. We suggest that meteor observers should consider publishing more characterizing parameters from the light curves they
Distillation tray structural parameter study: Phase 1
NASA Technical Reports Server (NTRS)
Winter, J. Ronald
1991-01-01
The purpose here is to identify the structural parameters (plate thickness, liquid level, beam size, number of beams, tray diameter, etc.) that affect the structural integrity of distillation trays in distillation columns. Once the sensitivity of the trays' dynamic response to these parameters has been established, the designer will be able to use this information to prepare more accurate specifications for the construction of new trays. Information is given on both static and dynamic analysis, modal response, and tray failure details.
Measurements of thermal parameters of solar modules
NASA Astrophysics Data System (ADS)
Górecki, K.; Krac, E.
2016-04-01
In the paper the methods of measuring thermal parameters of photovoltaic panels - transient thermal impedance and the absorption factor of light-radiation are presented. The manner of realising these methods is described and the results of measurements of the considered thermal parameters of selected photovoltaic panels are presented. The influence of such selected factors as a type of the investigated panel and its mounting manner on transient thermal impedance of the considered panels is also discussed.
Correlation of Catalytic Rates With Solubility Parameters
NASA Technical Reports Server (NTRS)
Lawson, Daniel D.; England, Christopher
1987-01-01
Catalyst maximizes activity when its solubility parameter equals that of reactive species. Catalytic activities of some binary metal alloys at maximum when alloy compositions correspond to Hildebrand solubility parameters equal to those of reactive atomic species on catalyst. If this suggestive correlation proves to be general, applied to formulation of other mixed-metal catalysts. Also used to identify reactive species in certain catalytic reactions.
Graphitic carbon-water nonbonded interaction parameters.
Wu, Yanbin; Aluru, N R
2013-07-25
In this study, we develop graphitic carbon-water nonbonded interaction parameters entirely from ab initio calculation data of interaction energies between graphene and a single water molecule. First, we employ the Møller-Plesset perturbation theory of the second order (MP2) method to compute the polycyclic aromatic hydrocarbon (PAH)-water interaction energies, with proper size of basis sets and energy component analysis to extrapolate to infinite-sized graphene limit. Then, we develop graphitic carbon-water interaction parameters based on the MP2 data from this work and the ab initio data available in the literature from other methods such as random-phase approximation (RPA), density functional theory-symmetry-adapted perturbation theory (DFT-SAPT), and coupled cluster treatment with single and double excitations and perturbative triples (CCSD(T)). The accuracy of the interaction parameters is evaluated by predicting water contact angle on graphite and carbon nanotube (CNT) radial breathing mode (RBM) frequency shift and comparing them with experimental data. The interaction parameters obtained from MP2 data predict the CNT RBM frequency shift that is in good agreement with experiments. The interaction parameters obtained from RPA and DFT-SAPT data predict the contact angles and the CNT RBM frequency shift that agree well with experiments. The interaction parameters obtained from CCSD(T) data underestimate the contact angles and overestimate the CNT RBM frequency shift probably due to the use of small basis sets in CCSD(T) calculations.
[Nonischemic dilated cardiomyopathy. Parameters of autonomic tone].
Demming, Thomas; Sandrock, Sarah; Bonnemeier, Hendrik
2015-03-01
Nonischemic dilated cardiomyopathies (DCM) are the most common reason for heart failure in developed countries after ischemic disease. They often lead to device therapy. Left ventricular ejection fraction as a single parameter to identify patients at risk for sudden cardiac death revealed inconclusive data in patients with DCM. Autonomic tone, measured by classical and innovative parameters of heart rate variability (HRV), heart rate turbulence or baroreceptor reflex, was demonstrated to give valuable prognostic information especially in patients with ischemic disease and after acute myocardial infarction. In patients with DCM, classical parameters of HRV showed inhomogeneous data in a heterogeneous patient collective caused by unsystematic measurement of single parameters in various patient collectives. Innovative parameters of HRV are promising in patients with DCM and showed prognostic relevance although patient numbers are limited and prospective data are missing. Further studies are needed in this field. Despite the in part convincing evidence for the relevance of autonomic tone as a prognostic marker in patients with DCM, their evaluation is still not part of clinical routine. Additional parameters to estimate the risk of sudden cardiac death are urgently needed.
Parameter Estimation of a Spiking Silicon Neuron
Russell, Alexander; Mazurek, Kevin; Mihalaş, Stefan; Niebur, Ernst; Etienne-Cummings, Ralph
2012-01-01
Spiking neuron models are used in a multitude of tasks ranging from understanding neural behavior at its most basic level to neuroprosthetics. Parameter estimation of a single neuron model, such that the model’s output matches that of a biological neuron is an extremely important task. Hand tuning of parameters to obtain such behaviors is a difficult and time consuming process. This is further complicated when the neuron is instantiated in silicon (an attractive medium in which to implement these models) as fabrication imperfections make the task of parameter configuration more complex. In this paper we show two methods to automate the configuration of a silicon (hardware) neuron’s parameters. First, we show how a Maximum Likelihood method can be applied to a leaky integrate and fire silicon neuron with spike induced currents to fit the neuron’s output to desired spike times. We then show how a distance based method which approximates the negative log likelihood of the lognormal distribution can also be used to tune the neuron’s parameters. We conclude that the distance based method is better suited for parameter configuration of silicon neurons due to its superior optimization speed. PMID:23852978
Computational approaches for RNA energy parameter estimation
Andronescu, Mirela; Condon, Anne; Hoos, Holger H.; Mathews, David H.; Murphy, Kevin P.
2010-01-01
Methods for efficient and accurate prediction of RNA structure are increasingly valuable, given the current rapid advances in understanding the diverse functions of RNA molecules in the cell. To enhance the accuracy of secondary structure predictions, we developed and refined optimization techniques for the estimation of energy parameters. We build on two previous approaches to RNA free-energy parameter estimation: (1) the Constraint Generation (CG) method, which iteratively generates constraints that enforce known structures to have energies lower than other structures for the same molecule; and (2) the Boltzmann Likelihood (BL) method, which infers a set of RNA free-energy parameters that maximize the conditional likelihood of a set of reference RNA structures. Here, we extend these approaches in two main ways: We propose (1) a max-margin extension of CG, and (2) a novel linear Gaussian Bayesian network that models feature relationships, which effectively makes use of sparse data by sharing statistical strength between parameters. We obtain significant improvements in the accuracy of RNA minimum free-energy pseudoknot-free secondary structure prediction when measured on a comprehensive set of 2518 RNA molecules with reference structures. Our parameters can be used in conjunction with software that predicts RNA secondary structures, RNA hybridization, or ensembles of structures. Our data, software, results, and parameter sets in various formats are freely available at http://www.cs.ubc.ca/labs/beta/Projects/RNA-Params. PMID:20940338
Modeling pattern in collections of parameters
Link, W.A.
1999-01-01
Wildlife management is increasingly guided by analyses of large and complex datasets. The description of such datasets often requires a large number of parameters, among which certain patterns might be discernible. For example, one may consider a long-term study producing estimates of annual survival rates; of interest is the question whether these rates have declined through time. Several statistical methods exist for examining pattern in collections of parameters. Here, I argue for the superiority of 'random effects models' in which parameters are regarded as random variables, with distributions governed by 'hyperparameters' describing the patterns of interest. Unfortunately, implementation of random effects models is sometimes difficult. Ultrastructural models, in which the postulated pattern is built into the parameter structure of the original data analysis, are approximations to random effects models. However, this approximation is not completely satisfactory: failure to account for natural variation among parameters can lead to overstatement of the evidence for pattern among parameters. I describe quasi-likelihood methods that can be used to improve the approximation of random effects models by ultrastructural models.
Food allergy: a practice parameter update-2014.
Sampson, Hugh A; Aceves, Seema; Bock, S Allan; James, John; Jones, Stacie; Lang, David; Nadeau, Kari; Nowak-Wegrzyn, Anna; Oppenheimer, John; Perry, Tamara T; Randolph, Christopher; Sicherer, Scott H; Simon, Ronald A; Vickery, Brian P; Wood, Robert; Bernstein, David; Blessing-Moore, Joann; Khan, David; Lang, David; Nicklas, Richard; Oppenheimer, John; Portnoy, Jay; Randolph, Christopher; Schuller, Diane; Spector, Sheldon; Tilles, Stephen A; Wallace, Dana; Sampson, Hugh A; Aceves, Seema; Bock, S Allan; James, John; Jones, Stacie; Lang, David; Nadeau, Kari; Nowak-Wegrzyn, Anna; Oppenheimer, John; Perry, Tamara T; Randolph, Christopher; Sicherer, Scott H; Simon, Ronald A; Vickery, Brian P; Wood, Robert
2014-11-01
This parameter was developed by the Joint Task Force on Practice Parameters, representing the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma & Immunology (JCAAI). The AAAAI and the ACAAI have jointly accepted responsibility for establishing "Food Allergy: A practice parameter update-2014." This is a complete and comprehensive document at the current time. The medical environment is a changing one, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, ACAAI, and JCAAI. These parameters are not designed for use by pharmaceutical companies in drug promotion. Copyright © 2014. Published by Elsevier Inc.
Lee, Kang Il
2013-11-01
In the present study, correlations of linear and nonlinear ultrasound parameters (speed of sound, normalized broadband ultrasound attenuation, and nonlinear parameter B/A) with bone mineral density and microarchitectural parameters were investigated in 28 bovine femoral trabecular bone samples in vitro. All three ultrasound parameters exhibited relatively high correlation coefficients with the indexes of bone quantity (bone mineral density and bone volume fraction) and lower correlation coefficients with the remaining microarchitectural parameters. These results suggest that B/A, in addition to speed of sound and attenuation, may have potential as an index for the assessment of bone status and osteoporosis.
A new fifth parameter for transverse isotropy
NASA Astrophysics Data System (ADS)
Kawakatsu, Hitoshi
2016-04-01
Kawakatsu et al. (2015) recently proposed a new parameter, ηκ that properly characterizes the incidence angle dependence (relative to the symmetry axis) of seismic bodywaves in a transverse isotropy (TI) system. While the commonly used fifth parameter in global seismology to describe TI system, η = F/(A - 2L), has no simple physical meaning, the newly defined parameter, ηκ = (F + L)/[(A - L)1/2(C - L)1/2] where A, C, F and L denote the Love's elastic constants for TI, measures the departure from the "elliptic condition" when ηκ not equal to unity, and characterizes nicely the incidence angle dependence of bodywaves. When existing models of upper mantle radial anisotropy are compared in terms of this new parameter, PREM shows a distinct property. Within the anisotropic layer of PREM (a depth range of 24.4-220km), ηκ < 1 in the top half and ηκ > 1 in the lower half. If ηκ > 1, anisotropy cannot be attributed to the layering of homogeneous layers, and thus requires the presence of intrinsic anisotropy (Kawakatsu, 2016). To further investigate significance of the new parameter for long-period seismology, partial derivatives of surface wave phase velocity and normal mode eigen-frequency for the new set of five parameters are examined. The partial derivative for ηκ is about twice as large as that for the conventional η, indicating that ηκ is more resolved than is usually considered. While partial derivatives for (anisotropic) S-velocities are not so changed, those for (anisotropic) P-velocities are significantly modified; the sensitivity for anisotropic P-velocities is greatly reduced. In contrary to Dziewonski and Anderson (1981)'s suggestion, there is not much control on the anisotropic P-velocities. The significance of ηκ for the long-period seismology has been shown. While how well the fifth parameter is constrained from data needs to be carefully examined, we now have, at least, a parameter that properly characterizes the TI system. This
Ren, Huiying; Hou, Zhangshuan; Huang, Maoyi; Bao, Jie; Sun, Yu; Tesfa, Teklu K.; Leung, Lai-Yung R.
2016-02-27
The Community Land Model (CLM) represents physical, chemical, and biological processes of the terrestrial ecosystems that interact with climate across a range of spatial and temporal scales. As CLM includes numerous sub-models and associated parameters, the high-dimensional parameter space presents a formidable challenge for quantifying uncertainty and improving Earth system predictions needed to assess environmental changes and risks. This study aims to evaluate the potential of transferring hydrologic model parameters in CLM through sensitivity analyses and classification across watersheds from the Model Parameter Estimation Experiment (MOPEX) in the United States. The sensitivity of CLM-simulated water and energy fluxes to hydrological parameters across 431 MOPEX basins are first examined using an efficient stochastic sampling-based sensitivity analysis approach. Linear, interaction, and high-order nonlinear impacts are all identified via statistical tests and stepwise backward removal parameter screening. The basins are then classified accordingly to their parameter sensitivity patterns (internal attributes), as well as their hydrologic indices/attributes (external hydrologic factors) separately, using a Principal component analyses (PCA) and expectation-maximization (EM) –based clustering approach. Similarities and differences among the parameter sensitivity-based classification system (S-Class), the hydrologic indices-based classification (H-Class), and the Koppen climate classification systems (K-Class) are discussed. Within each S-class with similar parameter sensitivity characteristics, similar inversion modeling setups can be used for parameter calibration, and the parameters and their contribution or significance to water and energy cycling may also be more transferrable. This classification study provides guidance on identifiable parameters, and on parameterization and inverse model design for CLM but the methodology is applicable to other models
Delineating parameter unidentifiabilities in complex models
NASA Astrophysics Data System (ADS)
Raman, Dhruva V.; Anderson, James; Papachristodoulou, Antonis
2017-03-01
Scientists use mathematical modeling as a tool for understanding and predicting the properties of complex physical systems. In highly parametrized models there often exist relationships between parameters over which model predictions are identical, or nearly identical. These are known as structural or practical unidentifiabilities, respectively. They are hard to diagnose and make reliable parameter estimation from data impossible. They furthermore imply the existence of an underlying model simplification. We describe a scalable method for detecting unidentifiabilities, as well as the functional relations defining them, for generic models. This allows for model simplification, and appreciation of which parameters (or functions thereof) cannot be estimated from data. Our algorithm can identify features such as redundant mechanisms and fast time-scale subsystems, as well as the regimes in parameter space over which such approximations are valid. We base our algorithm on a quantification of regional parametric sensitivity that we call `multiscale sloppiness'. Traditionally, the link between parametric sensitivity and the conditioning of the parameter estimation problem is made locally, through the Fisher information matrix. This is valid in the regime of infinitesimal measurement uncertainty. We demonstrate the duality between multiscale sloppiness and the geometry of confidence regions surrounding parameter estimates made where measurement uncertainty is non-negligible. Further theoretical relationships are provided linking multiscale sloppiness to the likelihood-ratio test. From this, we show that a local sensitivity analysis (as typically done) is insufficient for determining the reliability of parameter estimation, even with simple (non)linear systems. Our algorithm can provide a tractable alternative. We finally apply our methods to a large-scale, benchmark systems biology model of necrosis factor (NF)-κ B , uncovering unidentifiabilities.
Halo Spin Parameter in Cosmological Simulations
NASA Astrophysics Data System (ADS)
Ahn, Jieun; Kim, Juhan; Shin, Jihye; Kim, Sungsoo S.; Choi, Yun-Young
2014-04-01
Using a cosmological ΛCDM simulation, we analyze the differences between the widely-used spin parameters suggested by Peebles and Bullock. The dimensionless spin parameter λ proposed by Peebles is theoretically well-justified but includes an annoying term, the potential energy, which cannot be directly obtained from observations and is computationally expensive to calculate in numerical simulations. The Bullock's spin parameter λ^' avoids this problem assuming the isothermal density profile of a virialized halo in the Newtonian potential model. However, we find that there exists a substantial discrepancy between λ and λ^' depending on the adopted potential model (Newtonian or Plummer) to calculate the halo total energy and that their redshift evolutions differ to each other significantly. Therefore, we introduce a new spin parameter, λ^{''}, which is simply designed to roughly recover the value of λ but to use the same halo quantities as used in λ^'. If the Plummer potential is adopted, the λ^{''} is related to the Bullock's definition as λ^{''} = 0.80× (1 + z)^{-1/12} λ^'. Hence, the new spin parameter λ^{''} distribution becomes consistent with a log-normal distribution frequently seen for the λ^' while its mean value is much closer to that of λ. On the other hand, in case of the Newtonian potential model, we obtain the relation of λ^{''}=(1+z)^{-1/8}λ^{'}; there is no significant difference at z = 0 as found by others but λ^{'} becomes more overestimated than λ or λ^{''} at higher redshifts. We also investigate the dependence of halo spin parameters on halo mass and redshift. We clearly show that although the λ^' for small-mass halos with M_h < 2× 10^{12} M_odot seems redshift independent after z=1, all the spin parameters explored, on the whole, show a stronger correlation with the increasing halo mass at higher redshifts.
Systematic parameter inference in stochastic mesoscopic modeling
NASA Astrophysics Data System (ADS)
Lei, Huan; Yang, Xiu; Li, Zhen; Karniadakis, George Em
2017-02-01
We propose a method to efficiently determine the optimal coarse-grained force field in mesoscopic stochastic simulations of Newtonian fluid and polymer melt systems modeled by dissipative particle dynamics (DPD) and energy conserving dissipative particle dynamics (eDPD). The response surfaces of various target properties (viscosity, diffusivity, pressure, etc.) with respect to model parameters are constructed based on the generalized polynomial chaos (gPC) expansion using simulation results on sampling points (e.g., individual parameter sets). To alleviate the computational cost to evaluate the target properties, we employ the compressive sensing method to compute the coefficients of the dominant gPC terms given the prior knowledge that the coefficients are "sparse". The proposed method shows comparable accuracy with the standard probabilistic collocation method (PCM) while it imposes a much weaker restriction on the number of the simulation samples especially for systems with high dimensional parametric space. Fully access to the response surfaces within the confidence range enables us to infer the optimal force parameters given the desirable values of target properties at the macroscopic scale. Moreover, it enables us to investigate the intrinsic relationship between the model parameters, identify possible degeneracies in the parameter space, and optimize the model by eliminating model redundancies. The proposed method provides an efficient alternative approach for constructing mesoscopic models by inferring model parameters to recover target properties of the physics systems (e.g., from experimental measurements), where those force field parameters and formulation cannot be derived from the microscopic level in a straight forward way.
Parameter Estimation Methods for Chaotic Intercellular Networks
Mariño, Inés P.; Ullner, Ekkehard; Zaikin, Alexey
2013-01-01
We have investigated simulation-based techniques for parameter estimation in chaotic intercellular networks. The proposed methodology combines a synchronization–based framework for parameter estimation in coupled chaotic systems with some state–of–the–art computational inference methods borrowed from the field of computational statistics. The first method is a stochastic optimization algorithm, known as accelerated random search method, and the other two techniques are based on approximate Bayesian computation. The latter is a general methodology for non–parametric inference that can be applied to practically any system of interest. The first method based on approximate Bayesian computation is a Markov Chain Monte Carlo scheme that generates a series of random parameter realizations for which a low synchronization error is guaranteed. We show that accurate parameter estimates can be obtained by averaging over these realizations. The second ABC–based technique is a Sequential Monte Carlo scheme. The algorithm generates a sequence of “populations”, i.e., sets of randomly generated parameter values, where the members of a certain population attain a synchronization error that is lesser than the error attained by members of the previous population. Again, we show that accurate estimates can be obtained by averaging over the parameter values in the last population of the sequence. We have analysed how effective these methods are from a computational perspective. For the numerical simulations we have considered a network that consists of two modified repressilators with identical parameters, coupled by the fast diffusion of the autoinducer across the cell membranes. PMID:24282513
Parameter estimation uncertainty: Comparing apples and apples?
NASA Astrophysics Data System (ADS)
Hart, D.; Yoon, H.; McKenna, S. A.
2012-12-01
Given a highly parameterized ground water model in which the conceptual model of the heterogeneity is stochastic, an ensemble of inverse calibrations from multiple starting points (MSP) provides an ensemble of calibrated parameters and follow-on transport predictions. However, the multiple calibrations are computationally expensive. Parameter estimation uncertainty can also be modeled by decomposing the parameterization into a solution space and a null space. From a single calibration (single starting point) a single set of parameters defining the solution space can be extracted. The solution space is held constant while Monte Carlo sampling of the parameter set covering the null space creates an ensemble of the null space parameter set. A recently developed null-space Monte Carlo (NSMC) method combines the calibration solution space parameters with the ensemble of null space parameters, creating sets of calibration-constrained parameters for input to the follow-on transport predictions. Here, we examine the consistency between probabilistic ensembles of parameter estimates and predictions using the MSP calibration and the NSMC approaches. A highly parameterized model of the Culebra dolomite previously developed for the WIPP project in New Mexico is used as the test case. A total of 100 estimated fields are retained from the MSP approach and the ensemble of results defining the model fit to the data, the reproduction of the variogram model and prediction of an advective travel time are compared to the same results obtained using NSMC. We demonstrate that the NSMC fields based on a single calibration model can be significantly constrained by the calibrated solution space and the resulting distribution of advective travel times is biased toward the travel time from the single calibrated field. To overcome this, newly proposed strategies to employ a multiple calibration-constrained NSMC approach (M-NSMC) are evaluated. Comparison of the M-NSMC and MSP methods suggests
Cosmological parameter estimation: impact of CMB aberration
Catena, Riccardo; Notari, Alessio E-mail: notari@ffn.ub.es
2013-04-01
The peculiar motion of an observer with respect to the CMB rest frame induces an apparent deflection of the observed CMB photons, i.e. aberration, and a shift in their frequency, i.e. Doppler effect. Both effects distort the temperature multipoles a{sub lm}'s via a mixing matrix at any l. The common lore when performing a CMB based cosmological parameter estimation is to consider that Doppler affects only the l = 1 multipole, and neglect any other corrections. In this paper we reconsider the validity of this assumption, showing that it is actually not robust when sky cuts are included to model CMB foreground contaminations. Assuming a simple fiducial cosmological model with five parameters, we simulated CMB temperature maps of the sky in a WMAP-like and in a Planck-like experiment and added aberration and Doppler effects to the maps. We then analyzed with a MCMC in a Bayesian framework the maps with and without aberration and Doppler effects in order to assess the ability of reconstructing the parameters of the fiducial model. We find that, depending on the specific realization of the simulated data, the parameters can be biased up to one standard deviation for WMAP and almost two standard deviations for Planck. Therefore we conclude that in general it is not a solid assumption to neglect aberration in a CMB based cosmological parameter estimation.
Pumping test evaluation of stream depletion parameters.
Lough, Hilary K; Hunt, Bruce
2006-01-01
Descriptions are given of a pumping test and a corresponding analysis that permit calculation of all five hydrogeological parameters appearing in the Hunt (2003) solution for stream depletion caused by ground water abstraction from a well beside a stream. This solution assumes that flow in the pumped aquifer is horizontal, flow in the overlying aquitard or system of aquitards is vertical, and the free surface in the top aquitard is allowed to draw down. The definition of an aquitard in this paper is any layer with a vertical hydraulic conductivity much lower than the horizontal hydraulic conductivity of the pumped aquifer. These "aquitards" may be reasonably permeable layers but are distinguished from the pumped aquifer by their hydraulic conductivity contrast. The pumping test requires a complete set of drawdown measurements from at least one observation well. This well must be deep enough to penetrate the pumped aquifer, and pumping must continue for a sufficient time to ensure that depleted streamflow becomes a significant portion of the well abstraction rate. Furthermore, two of the five parameters characterize an aquitard that overlies the pumped aquifer, and values for these parameters are seen to be dependent upon the initial water table elevation in the aquitard. The field test analyzed herein used a total of eight observation wells screened in the pumped aquifer, and measurements from these wells gave eight sets of parameters that are used in a sensitivity analysis to determine the relative importance of each parameter in the stream depletion calculations.
Multiwavelength light curve parameters of Cepheid variables
NASA Astrophysics Data System (ADS)
Bhardwaj, Anupam; Kanbur, Shashi M.; Marconi, Marcella; Rejkuba, Marina; Singh, Harinder P.; Ngeow, Chow-Choong
2017-09-01
We present a comparative analysis of theoretical and observed light curves of Cepheid variables using Fourier decomposition. The theoretical light curves at multiple wavelengths are generated using stellar pulsation models for chemical compositions representative of Cepheids in the Galaxy and Magellanic Clouds. The observed light curves at optical (VI), near-infrared (JHKs) and mid-infrared (3.6 & 4.5-μm) bands are compiled from the literature. We discuss the variation of light curve parameters as a function of period, wavelength and metallicity. Theoretical and observed Fourier amplitude parameters decrease with increase in wavelength while the phase parameters increase with wavelength. We find that theoretical amplitude parameters obtained using canonical mass-luminosity levels exhibit a greater offset with respect to observations when compared to non-canonical relations. We also discuss the impact of variation in convective efficiency on the light curve structure of Cepheid variables. The increase in mixing length parameter results in a zero-point offset in bolometric mean magnitudes and reduces the systematic large difference in theoretical amplitudes with respect to observations.
Supersymmetry Parameter Analysis: SPA Convention and Project
Hinchliffe, I.; et al.
2005-05-05
High-precision analyses of supersymmetry parameters aim atreconstructing the fundamental supersymmetric theory and its breakingmechanism. A well defined theoretical framework is needed whenhigher-order corrections are included. We propose such a scheme,Supersymmetry Parameter Analysis SPA, based on a consistent set ofconventions and input parameters. A repository for computer programs isprovided which connect parameters in different schemes and relate theLagrangian parameters to physical observables at LHC and high energy e+e-linear collider experiments, i.e., masses, mixings, decay widths andproduction cross sections for supersymmetric particles. In addition,programs for calculating high-precision low energy observables, thedensity of cold dark matter (CDM) in the universe as well as the crosssections for CDM search experiments are included. The SPA scheme stillrequires extended efforts on both the theoretical and experimental sidebefore data can be evaluated in the future at the level of the desiredprecision. We take here an initial step of testing the SPA scheme byapplying the techniques involved to a specific supersymmetry referencepoint.
A Tool for Parameter-space Explorations
NASA Astrophysics Data System (ADS)
Murase, Yohsuke; Uchitane, Takeshi; Ito, Nobuyasu
A software for managing simulation jobs and results, named "OACIS", is presented. It controls a large number of simulation jobs executed in various remote servers, keeps these results in an organized way, and manages the analyses on these results. The software has a web browser front end, and users can submit various jobs to appropriate remote hosts from a web browser easily. After these jobs are finished, all the result files are automatically downloaded from the computational hosts and stored in a traceable way together with the logs of the date, host, and elapsed time of the jobs. Some visualization functions are also provided so that users can easily grasp the overview of the results distributed in a high-dimensional parameter space. Thus, OACIS is especially beneficial for the complex simulation models having many parameters for which a lot of parameter searches are required. By using API of OACIS, it is easy to write a code that automates parameter selection depending on the previous simulation results. A few examples of the automated parameter selection are also demonstrated.
Quality Assurance in Endoscopy: Which Parameters?
Denzer, Ulrike W.
2016-01-01
Background The verbalisation of quality standards and parameters by medical societies are relevant for qualitative improvement but may also be an instrument to demand more resources for health care or be a unique characteristic. Within the health care system 3 different quality levels can be defined: structure, process and result quality. Methods The current S2k guideline of the German Society for Gastroenterology (quality requirements for gastrointestinal endoscopy) AWMF registry no. 021-022 provides recommendations based on the available evidence for the structure quality (requirements for equipment, human resources) as well as for the process quality (patient preparation, conduct, documentation) and result quality (follow-up of specific endoscopic procedures). Results Based on these recommendations, measurable quality indicators/parameters for the endoscopy have been selected and formulated. General quality parameters for endoscopic examinations are given as well as quality parameters for specific procedures for the preparation, conduct, and follow-up of specific endoscopic interventions. Conclusion Only the regular review of processes and courses by means of defined measurement parameters builds up the basis for corrections based on facts. In addition, the implementation of recommended standards may be an instrument in demanding more resources from the health care system and, therefore, should be embedded as routine. PMID:27588295
Estimating Respiratory Mechanical Parameters during Mechanical Ventilation
Barbini, Paolo
1982-01-01
We propose an algorithm for the estimation of the parameters of the mechanical respiratory system. The algorithm is based on non linear regression analysis with a two-compartment respiratory system model. The model used allows us to take account of the non homogeneous properties of the lungs which may cause uneven distribution of ventilation and thus affect the gas exchange in the lungs. The estimation of the parameters of such a model permits the optimization of the type of ventilation to be used in patients undergoing respiratory treatment. This can be done bearing in mind the effects of the mechanical ventilation on venous return as well as the quality of gas exchange. We have valued the performances of the estimation algorithm which is proposed on the basis of the agreement between the data and the model response, of the stability of the parameter estimates and of the standard deviations of the parameters. The parameter estimation algorithm described does not have recourse to the examination of the impedance spectra and is completely independent of the type of ventilator employed.
Determining wave direction using curvature parameters.
de Queiroz, Eduardo Vitarelli; de Carvalho, João Luiz Baptista
2016-01-01
The curvature of the sea wave was tested as a parameter for estimating wave direction in the search for better results in estimates of wave direction in shallow waters, where waves of different sizes, frequencies and directions intersect and it is difficult to characterize. We used numerical simulations of the sea surface to determine wave direction calculated from the curvature of the waves. Using 1000 numerical simulations, the statistical variability of the wave direction was determined. The results showed good performance by the curvature parameter for estimating wave direction. Accuracy in the estimates was improved by including wave slope parameters in addition to curvature. The results indicate that the curvature is a promising technique to estimate wave directions.•In this study, the accuracy and precision of curvature parameters to measure wave direction are analyzed using a model simulation that generates 1000 wave records with directional resolution.•The model allows the simultaneous simulation of time-series wave properties such as sea surface elevation, slope and curvature and they were used to analyze the variability of estimated directions.•The simultaneous acquisition of slope and curvature parameters can contribute to estimates wave direction, thus increasing accuracy and precision of results.
[Incidental finding of pathological coagulation parameters].
Luxembourg, B; Lindhoff-Last, E
2014-10-01
Pathological coagulation parameters may reflect life-threatening hemorrhagic or thromboembolic diseases but may also be a laboratory result without any clinical significance, result from in vitro phenomena or preanalytical errors. This article gives an overview of potential pitfalls in coagulation diagnostics, lists the differential diagnoses of pathological coagulation parameters and describes further steps in the diagnostic approach to clarify pathological results. The focus lies on coagulation parameters that are frequently determined in routine clinical investigations, e.g. platelet count, prothrombin time, activated partial thromboplastin time (aPTT) and fibrinogen. Besides heparin, fondaparinux, danaparoid, and vitamin K antagonists, direct factor Xa inhibitors and direct thrombin inhibitors are nowadays available for therapeutic anticoagulation. This article gives an overview of the influence of anticoagulants on coagulation parameters which depends on the dose, the time of the last administration, as well as the method used for the determination of coagulation parameters. Moreover, common reasons for elevation of the fibrin degradation product D-dimer are presented. The clinical utility of D-dimer assays is limited by their poor specificity. Elevated D-dimer concentrations can be found in various diseases and also under normal physiological circumstances (e.g. in the elderly). Thus, the most useful clinical application of D-dimer is evidence of normal values to essentially rule out venous thromboembolism.
ERIC Educational Resources Information Center
Karkee, Thakur B.; Wright, Karen R.
2004-01-01
Different item response theory (IRT) models may be employed for item calibration. Change of testing vendors, for example, may result in the adoption of a different model than that previously used with a testing program. To provide scale continuity and preserve cut score integrity, item parameter estimates from the new model must be linked to the…
Determining Spacecraft Reaction Wheel Friction Parameters
NASA Technical Reports Server (NTRS)
Sarani, Siamak
2009-01-01
Software was developed to characterize the drag in each of the Cassini spacecraft's Reaction Wheel Assemblies (RWAs) to determine the RWA friction parameters. This tool measures the drag torque of RWAs for not only the high spin rates (greater than 250 RPM), but also the low spin rates (less than 250 RPM) where there is a lack of an elastohydrodynamic boundary layer in the bearings. RWA rate and drag torque profiles as functions of time are collected via telemetry once every 4 seconds and once every 8 seconds, respectively. Intermediate processing steps single-out the coast-down regions. A nonlinear model for the drag torque as a function of RWA spin rate is incorporated in order to characterize the low spin rate regime. The tool then uses a nonlinear parameter optimization algorithm based on the Nelder-Mead simplex method to determine the viscous coefficient, the Dahl friction, and the two parameters that account for the low spin-rate behavior.
Band-structure parameters by genetic algorithm
Starrost, F.; Bornholdt, S.; Solterbeck, C.; Schattke, W.
1996-05-01
A genetic algorithm has been used to solve a complex multidimensional parameter-fitting problem. We will focus on the parameters of an empirical tight-binding Hamiltonian. The method is used to approximate the electronic energy band structure if energy values are known for a few wave vectors of high symmetry. Compared to the usual manual procedure this method is more accurate and automatic. This approach, based on the extended H{umlt u}ckel theory (EHT), has provided a list of EHT parameters for IV-IV and III-V semiconductors with zinc-blende structure and helped us to find a symmetry in the EHT. {copyright} {ital 1996 The American Physical Society.}
Effect of Burnishing Parameters on Surface Finish
NASA Astrophysics Data System (ADS)
Shirsat, Uddhav; Ahuja, Basant; Dhuttargaon, Mukund
2017-08-01
Burnishing is cold working process in which hard balls are pressed against the surface, resulting in improved surface finish. The surface gets compressed and then plasticized. This is a highly finishing process which is becoming more popular. Surface quality of the product improves its aesthetic appearance. The product made up of aluminum material is subjected to burnishing process during which kerosene is used as a lubricant. In this study factors affecting burnishing process such as burnishing force, speed, feed, work piece diameter and ball diameter are considered as input parameters while surface finish is considered as an output parameter In this study, experiments are designed using 25 factorial design in order to analyze the relationship between input and output parameters. The ANOVA technique and F-test are used for further analysis.
Technical parameters for specifying imagery requirements
NASA Technical Reports Server (NTRS)
Coan, Paul P.; Dunnette, Sheri J.
1994-01-01
Providing visual information acquired from remote events to various operators, researchers, and practitioners has become progressively more important as the application of special skills in alien or hazardous situations increases. To provide an understanding of the technical parameters required to specify imagery, we have identified, defined, and discussed seven salient characteristics of images: spatial resolution, linearity, luminance resolution, spectral discrimination, temporal discrimination, edge definition, and signal-to-noise ratio. We then describe a generalizing imaging system and identified how various parts of the system affect the image data. To emphasize the different applications of imagery, we have constrasted the common television system with the significant parameters of a televisual imaging system for technical applications. Finally, we have established a method by which the required visual information can be specified by describing certain technical parameters which are directly related to the information content of the imagery. This method requires the user to complete a form listing all pertinent data requirements for the imagery.
Technical parameters for specifying imagery requirements
NASA Technical Reports Server (NTRS)
Coan, Paul P.; Dunnette, Sheri J.
1994-01-01
Providing visual information acquired from remote events to various operators, researchers, and practitioners has become progressively more important as the application of special skills in alien or hazardous situations increases. To provide an understanding of the technical parameters required to specify imagery, we have identified, defined, and discussed seven salient characteristics of images: spatial resolution, linearity, luminance resolution, spectral discrimination, temporal discrimination, edge definition, and signal-to-noise ratio. We then describe a generalizing imaging system and identified how various parts of the system affect the image data. To emphasize the different applications of imagery, we have constrasted the common television system with the significant parameters of a televisual imaging system for technical applications. Finally, we have established a method by which the required visual information can be specified by describing certain technical parameters which are directly related to the information content of the imagery. This method requires the user to complete a form listing all pertinent data requirements for the imagery.
Proline puckering parameters for collagen structure simulations
NASA Astrophysics Data System (ADS)
Wu, Di
2015-03-01
Collagen is made of triple helices rich in proline residues, and hence is influenced by the conformational motions of prolines. Because the backbone motions of prolines are restricted by the helical structures, the only side chain motion—proline puckering—becomes an influential factor that may affect the stability of collagen structures. In molecular simulations, a proper proline puckering population is desired so to yield valid results of the collagen properties. Here we design the proline puckering parameters in order to yield suitable proline puckering populations as demonstrated in the experimental results. We test these parameters in collagen and the proline dipeptide simulations. Compared with the results of the PDB and the quantum calculations, we propose the proline puckering parameters for the selected collagen model simulations.
Scaling parameters in film-cooling
NASA Astrophysics Data System (ADS)
Forth, C. J. P.; Jones, T. V.
Scaling parameters which govern the performance of film-cooling systems were determined experimentally and analytically for three film-cooling geometries and over a range of injection-to-mainstream temperature ratios and injection rates. Experiments were performed in an isentropic light piston tunnel. The results suggest that, for the conditions studied, the momentum flux ratio is the correct scaling parameter for injection flows classified as 'weak injections', where no gross separation of the injection flow occurs from the surface. For the 'strong injections', were the injection jets penetrate into the freestream, the velocity ratio is more useful. Using the experimental results, parameters are proposed which scale heat transfer data for all injection rates and downstream distances, allowing data obtained at conditions unrepresentative of a gas turbine engine to be correctly interpreted in order to predict heat transfer loads in the engine.
Determination of kinetic parameters for biomass combustion.
Álvarez, A; Pizarro, C; García, R; Bueno, J L; Lavín, A G
2016-09-01
The aim of this work is to provide a wide database of kinetic data for the most common biomass by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG). Due to the characteristic parameters of DTG curves, a two-stage reaction model is proposed and the kinetic parameters obtained from model-based methods with energy activation values for first and second stages in the range 1.75·10(4)-1.55·10(5)J/mol and 1.62·10(4)-2.37·10(5)J/mol, respectively. However, it has been found that Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose model-free methods are not suitable to determine the kinetic parameters of biomass combustion since the assumptions of these two methods were not accomplished in the full range of the combustion process.
Asteroid absolute magnitudes and slope parameters
NASA Technical Reports Server (NTRS)
Tedesco, Edward F.
1991-01-01
A new listing of absolute magnitudes (H) and slope parameters (G) has been created and published in the Minor Planet Circulars; this same listing will appear in the 1992 Ephemerides of Minor Planets. Unlike previous listings, the values of the current list were derived from fits of data at the V band. All observations were reduced in the same fashion using, where appropriate, a single basis default value of 0.15 for the slope parameter. Distances and phase angles were computed for each observation. The data for 113 asteroids was of sufficiently high quality to permit derivation of their H and G. These improved absolute magnitudes and slope parameters will be used to deduce the most reliable bias-corrected asteroid size-frequency distribution yet made.
Estimating physiological skin parameters from hyperspectral signatures
NASA Astrophysics Data System (ADS)
Vyas, Saurabh; Banerjee, Amit; Burlina, Philippe
2013-05-01
We describe an approach for estimating human skin parameters, such as melanosome concentration, collagen concentration, oxygen saturation, and blood volume, using hyperspectral radiometric measurements (signatures) obtained from in vivo skin. We use a computational model based on Kubelka-Munk theory and the Fresnel equations. This model forward maps the skin parameters to a corresponding multiband reflectance spectra. Machine-learning-based regression is used to generate the inverse map, and hence estimate skin parameters from hyperspectral signatures. We test our methods using synthetic and in vivo skin signatures obtained in the visible through the short wave infrared domains from 24 patients of both genders and Caucasian, Asian, and African American ethnicities. Performance validation shows promising results: good agreement with the ground truth and well-established physiological precepts. These methods have potential use in the characterization of skin abnormalities and in minimally-invasive prescreening of malignant skin cancers.
Estimating physiological skin parameters from hyperspectral signatures.
Vyas, Saurabh; Banerjee, Amit; Burlina, Philippe
2013-05-01
We describe an approach for estimating human skin parameters, such as melanosome concentration, collagen concentration, oxygen saturation, and blood volume, using hyperspectral radiometric measurements (signatures) obtained from in vivo skin. We use a computational model based on Kubelka-Munk theory and the Fresnel equations. This model forward maps the skin parameters to a corresponding multiband reflectance spectra. Machine-learning-based regression is used to generate the inverse map, and hence estimate skin parameters from hyperspectral signatures. We test our methods using synthetic and in vivo skin signatures obtained in the visible through the short wave infrared domains from 24 patients of both genders and Caucasian, Asian, and African American ethnicities. Performance validation shows promising results: good agreement with the ground truth and well-established physiological precepts. These methods have potential use in the characterization of skin abnormalities and in minimally-invasive prescreening of malignant skin cancers.
On entanglement of light and Stokes parameters
NASA Astrophysics Data System (ADS)
Żukowski, Marek; Laskowski, Wiesław; Wieśniak, Marcin
2016-08-01
We present a new approach to Stokes parameters, which enables one to see better non-classical properties of bright quantum light, and of undefined overall photon numbers. The crucial difference is as follows. The standard quantum optical Stokes parameters are averages of differences of intensities of light registered at the two exits of polarization analyzers, and one gets their normalized version by dividing them by the average total intensity. The new ones are averages of the registered normalized Stokes parameters, for the duration of the experiment. That is, we redefine each Stokes observable as the difference of photon number operators at the two exits of a polarizing beam splitter multiplied by the inverse of their sum. The vacuum eigenvalue of the operator is defined a zero. We show that with such an approach one can obtain more sensitive entanglement indicators based on polarization measurements.
Effect of Burnishing Parameters on Surface Finish
NASA Astrophysics Data System (ADS)
Shirsat, Uddhav; Ahuja, Basant; Dhuttargaon, Mukund
2016-06-01
Burnishing is cold working process in which hard balls are pressed against the surface, resulting in improved surface finish. The surface gets compressed and then plasticized. This is a highly finishing process which is becoming more popular. Surface quality of the product improves its aesthetic appearance. The product made up of aluminum material is subjected to burnishing process during which kerosene is used as a lubricant. In this study factors affecting burnishing process such as burnishing force, speed, feed, work piece diameter and ball diameter are considered as input parameters while surface finish is considered as an output parameter In this study, experiments are designed using 25 factorial design in order to analyze the relationship between input and output parameters. The ANOVA technique and F-test are used for further analysis.
Parameter adaptive estimation of random processes
NASA Technical Reports Server (NTRS)
Caglayan, A. K.; Vanlandingham, H. F.
1975-01-01
This paper is concerned with the parameter adaptive least squares estimation of random processes. The main result is a general representation theorem for the conditional expectation of a random variable on a product probability space. Using this theorem along with the general likelihood ratio expression, the least squares estimate of the process is found in terms of the parameter conditioned estimates. The stochastic differential for the a posteriori probability and the stochastic differential equation for the a posteriori density are found by using simple stochastic calculus on the representations obtained. The results are specialized to the case when the parameter has a discrete distribution. The results can be used to construct an implementable recursive estimator for certain types of nonlinear filtering problems. This is illustrated by some simple examples.
Proline puckering parameters for collagen structure simulations
Wu, Di
2015-03-15
Collagen is made of triple helices rich in proline residues, and hence is influenced by the conformational motions of prolines. Because the backbone motions of prolines are restricted by the helical structures, the only side chain motion—proline puckering—becomes an influential factor that may affect the stability of collagen structures. In molecular simulations, a proper proline puckering population is desired so to yield valid results of the collagen properties. Here we design the proline puckering parameters in order to yield suitable proline puckering populations as demonstrated in the experimental results. We test these parameters in collagen and the proline dipeptide simulations. Compared with the results of the PDB and the quantum calculations, we propose the proline puckering parameters for the selected collagen model simulations.
Discriminative parameter estimation for random walks segmentation.
Baudin, Pierre-Yves; Goodman, Danny; Kumrnar, Puneet; Azzabou, Noura; Carlier, Pierre G; Paragios, Nikos; Kumar, M Pawan
2013-01-01
The Random Walks (RW) algorithm is one of the most efficient and easy-to-use probabilistic segmentation methods. By combining contrast terms with prior terms, it provides accurate segmentations of medical images in a fully automated manner. However, one of the main drawbacks of using the RW algorithm is that its parameters have to be hand-tuned. we propose a novel discriminative learning framework that estimates the parameters using a training dataset. The main challenge we face is that the training samples are not fully supervised. Specifically, they provide a hard segmentation of the images, instead of a probabilistic segmentation. We overcome this challenge by treating the optimal probabilistic segmentation that is compatible with the given hard segmentation as a latent variable. This allows us to employ the latent support vector machine formulation for parameter estimation. We show that our approach significantly outperforms the baseline methods on a challenging dataset consisting of real clinical 3D MRI volumes of skeletal muscles.
Simulating performance sensitivity of supercomputer job parameters.
Clearwater, Scott Harvey; Kleban, Stephen David
2003-03-01
We report on the use of a supercomputer simulation to study the performance sensitivity to systematic changes in the job parameters of run time, number of CPUs, and interarrival time. We also examine the effect of changes in share allocation and service ratio for job prioritization under a Fair Share queuing Algorithm to see the effect on facility figures of merit. We used log data from the ASCI supercomputer Blue Mountain and the ASCI simulator BIRMinator to perform this study. The key finding is that the performance of the supercomputer is quite sensitive to all the job parameters with the interarrival rate of the jobs being most sensitive at the highest rates and increasing run times the least sensitive job parameter with respect to utilization and rapid turnaround. We also find that this facility is running near its maximum practical utilization. Finally, we show the importance of the use of simulation in understanding the performance sensitivity of a supercomputer.
[Parameters adaptation in the populations models].
Il'ichev, V G
2005-01-01
Ecology-evolutionary models of low dimensions were developed on the basis of competitive selection criteria. Dynamics of variables (number of individuals) and the search of evolutionary-stable values of parameters (biological characterictics of populations) were monitored in the suggested models. If the environmental temperature is changing periodically, the average (a) and width (d) of temperature tolerance range appears to be the important parameters. By model experiments it was established that stable values of temperature (a), favorable for development of highly specialized algae (d is low) were close to minimum and maximum of temperature curve. And for the low specialized algae (d is high) this values were close to the average temperature of environment. In a similar manner, a set of evolutionally stable parameters (a, d) was established for either of the two interacted populations (competitors and "predator-prey"). The hypotheses concerning it's geometric structure and the process of coevolution is formulated.
Aquifer parameter estimation from surface resistivity data.
Niwas, Sri; de Lima, Olivar A L
2003-01-01
This paper is devoted to the additional use, other than ground water exploration, of surface geoelectrical sounding data for aquifer hydraulic parameter estimation. In a mesoscopic framework, approximated analytical equations are developed separately for saline and for fresh water saturations. A few existing useful aquifer models, both for clean and shaley sandstones, are discussed in terms of their electrical and hydraulic effects, along with the linkage between the two. These equations are derived for insight and physical understanding of the phenomenon. In a macroscopic scale, a general aquifer model is proposed and analytical relations are derived for meaningful estimation, with a higher level of confidence, of hydraulic parameter from electrical parameters. The physical reasons for two different equations at the macroscopic level are explicitly explained to avoid confusion. Numerical examples from existing literature are reproduced to buttress our viewpoint.
Parameter estimate of signal transduction pathways
Arisi, Ivan; Cattaneo, Antonino; Rosato, Vittorio
2006-01-01
Background The "inverse" problem is related to the determination of unknown causes on the bases of the observation of their effects. This is the opposite of the corresponding "direct" problem, which relates to the prediction of the effects generated by a complete description of some agencies. The solution of an inverse problem entails the construction of a mathematical model and takes the moves from a number of experimental data. In this respect, inverse problems are often ill-conditioned as the amount of experimental conditions available are often insufficient to unambiguously solve the mathematical model. Several approaches to solving inverse problems are possible, both computational and experimental, some of which are mentioned in this article. In this work, we will describe in details the attempt to solve an inverse problem which arose in the study of an intracellular signaling pathway. Results Using the Genetic Algorithm to find the sub-optimal solution to the optimization problem, we have estimated a set of unknown parameters describing a kinetic model of a signaling pathway in the neuronal cell. The model is composed of mass action ordinary differential equations, where the kinetic parameters describe protein-protein interactions, protein synthesis and degradation. The algorithm has been implemented on a parallel platform. Several potential solutions of the problem have been computed, each solution being a set of model parameters. A sub-set of parameters has been selected on the basis on their small coefficient of variation across the ensemble of solutions. Conclusion Despite the lack of sufficiently reliable and homogeneous experimental data, the genetic algorithm approach has allowed to estimate the approximate value of a number of model parameters in a kinetic model of a signaling pathway: these parameters have been assessed to be relevant for the reproduction of the available experimental data. PMID:17118160
Application of Statistically Derived CPAS Parachute Parameters
NASA Technical Reports Server (NTRS)
Romero, Leah M.; Ray, Eric S.
2013-01-01
The Capsule Parachute Assembly System (CPAS) Analysis Team is responsible for determining parachute inflation parameters and dispersions that are ultimately used in verifying system requirements. A model memo is internally released semi-annually documenting parachute inflation and other key parameters reconstructed from flight test data. Dispersion probability distributions published in previous versions of the model memo were uniform because insufficient data were available for determination of statistical based distributions. Uniform distributions do not accurately represent the expected distributions since extreme parameter values are just as likely to occur as the nominal value. CPAS has taken incremental steps to move away from uniform distributions. Model Memo version 9 (MMv9) made the first use of non-uniform dispersions, but only for the reefing cutter timing, for which a large number of sample was available. In order to maximize the utility of the available flight test data, clusters of parachutes were reconstructed individually starting with Model Memo version 10. This allowed for statistical assessment for steady-state drag area (CDS) and parachute inflation parameters such as the canopy fill distance (n), profile shape exponent (expopen), over-inflation factor (C(sub k)), and ramp-down time (t(sub k)) distributions. Built-in MATLAB distributions were applied to the histograms, and parameters such as scale (sigma) and location (mu) were output. Engineering judgment was used to determine the "best fit" distribution based on the test data. Results include normal, log normal, and uniform (where available data remains insufficient) fits of nominal and failure (loss of parachute and skipped stage) cases for all CPAS parachutes. This paper discusses the uniform methodology that was previously used, the process and result of the statistical assessment, how the dispersions were incorporated into Monte Carlo analyses, and the application of the distributions in
Order parameter fluctuations in the holographic superconductor
NASA Astrophysics Data System (ADS)
Plantz, N. W. M.; Stoof, H. T. C.; Vandoren, S.
2017-03-01
We investigate the effect of order parameter fluctuations in the holographic superconductor. In particular, following an introduction to the concept of intrinsic dynamics and its implementation within holographic models, we compute the intrinsic spectral functions of the order parameter in both the normal and the superconducting phase, using a fully backreacted bulk geometry. We also present a vector-like large-N version of the Ginzburg–Landau model that accurately describes our long-wavelength results in both phases. Our results indicate that the holographic superconductor describes a relativistic multi-component superfluid in the universal regime of the BEC–BCS crossover.
Generalized Stokes parameters in phase space.
Sahin, Serkan
2010-05-15
The generalized Stokes parameters (GSP) are studied under the theory of phase space. It is noted that phase-space Stokes parameters can be a useful tool for Wigner distribution function measurements. Electromagnetic Wigner functions are introduced by use of the two-point statistics of GSP. The advantage in the GSP is that they can be measured in terms of the electric correlation matrix (which is a measurable quantity) or they can be measured independently. Hence, the GSP help in finding the polarization and coherence properties of electromagnetic beams. Within this framework, by using the GSP in phase space, the intensity feature of electromagnetic beams in phase space is given, as well.
Reducibility of Matrix Equations Containing Several Parameters.
1981-12-01
AD-AI15 568 AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOO;-ETC EF G 12 1ADA1551 REDUCIBILITY OF MATRIX EQUATIONS CONTAINING SEVERAL...PARAMETERS.E U)CA E UNCLASSIFIED AFIT/GE/RA/81D-1 N P11111111II soonhh Eu;o I. ’Trm * a, ~t- NMI 4 i’- 00Nt. met r~ REDUCIBILITY OF MATRIX EQUATIONS CONTAINING...1 REDUCIBILITY OF MATRIX EQUATIONS CONTAINING SEVERAL PARAMETERS THESIS Presented to the Faculty of the School of Engineering of the Air Force
On identifiability of flexible structure parameters
NASA Technical Reports Server (NTRS)
Joshi, S. M.; Goglia, G. L.
1983-01-01
This report investigates the identifiability of modal parameters of flexible structures. Expressions are derived for Cramer-Rao lower bounds for the modal parameters, that is, frequencies, damping ratios and mode shapes or slopes. The optimal initial state, which maximizes the trace of the Fisher information matrix in the absence of persistent input, is obtained. The concepts discussed are applied to a finite-element model of the 122 meter hoop/column antenna. The numerical results show that the identifiability of the structural frequencies is excellent, followed by that of the damping ratios and the mode-slopes.
Optimization for minimum sensitivity to uncertain parameters
NASA Technical Reports Server (NTRS)
Pritchard, Jocelyn I.; Adelman, Howard M.; Sobieszczanski-Sobieski, Jaroslaw
1994-01-01
A procedure to design a structure for minimum sensitivity to uncertainties in problem parameters is described. The approach is to minimize directly the sensitivity derivatives of the optimum design with respect to fixed design parameters using a nested optimization procedure. The procedure is demonstrated for the design of a bimetallic beam for minimum weight with insensitivity to uncertainties in structural properties. The beam is modeled with finite elements based on two dimensional beam analysis. A sequential quadratic programming procedure used as the optimizer supplies the Lagrange multipliers that are used to calculate the optimum sensitivity derivatives. The method was perceived to be successful from comparisons of the optimization results with parametric studies.
Estimating RASATI scores using acoustical parameters
NASA Astrophysics Data System (ADS)
Agüero, P. D.; Tulli, J. C.; Moscardi, G.; Gonzalez, E. L.; Uriz, A. J.
2011-12-01
Acoustical analysis of speech using computers has reached an important development in the latest years. The subjective evaluation of a clinician is complemented with an objective measure of relevant parameters of voice. Praat, MDVP (Multi Dimensional Voice Program) and SAV (Software for Voice Analysis) are some examples of software for speech analysis. This paper describes an approach to estimate the subjective characteristics of RASATI scale given objective acoustical parameters. Two approaches were used: linear regression with non-negativity constraints, and neural networks. The experiments show that such approach gives correct evaluations with ±1 error in 80% of the cases.
Linear Parameter Varying Control for Actuator Failure
NASA Technical Reports Server (NTRS)
Shin, Jong-Yeob; Wu, N. Eva; Belcastro, Christine; Bushnell, Dennis M. (Technical Monitor)
2002-01-01
A robust linear parameter varying (LPV) control synthesis is carried out for an HiMAT vehicle subject to loss of control effectiveness. The scheduling parameter is selected to be a function of the estimates of the control effectiveness factors. The estimates are provided on-line by a two-stage Kalman estimator. The inherent conservatism of the LPV design is reducing through the use of a scaling factor on the uncertainty block that represents the estimation errors of the effectiveness factors. Simulations of the controlled system with the on-line estimator show that a superior fault-tolerance can be achieved.
On parameter estimation in population models.
Ross, J V; Taimre, T; Pollett, P K
2006-12-01
We describe methods for estimating the parameters of Markovian population processes in continuous time, thus increasing their utility in modelling real biological systems. A general approach, applicable to any finite-state continuous-time Markovian model, is presented, and this is specialised to a computationally more efficient method applicable to a class of models called density-dependent Markov population processes. We illustrate the versatility of both approaches by estimating the parameters of the stochastic SIS logistic model from simulated data. This model is also fitted to data from a population of Bay checkerspot butterfly (Euphydryas editha bayensis), allowing us to assess the viability of this population.
Design parameters of toroidal and bobbin magnetics
NASA Technical Reports Server (NTRS)
Mclyman, W. T.
1973-01-01
The adoption by NASA of the metric system for dimensioning to replace the long-used English units imposes a requirement on the U.S. transformer designer to convert from the familiar units to the less familiar metric equivalents. Material is presented to assist in that transition in the field of transformer design and fabrication. The conversion data makes it possible for the designer to obtain a fast and close approximation of significant parameters such as size, weight, and temperature rise. Nomographs are included to provide a close approximation for breadboarding purposes. For greater convenience, derivations of some of the parameters are also presented.
Quantum Fluctuations of a Superconductor Order Parameter
NASA Astrophysics Data System (ADS)
Arutyunov, K. Yu; Lehtinen, J. S.
2016-08-01
Tunneling I-V characteristics between very narrow titanium nanowires and "massive" superconducting aluminum were measured. The clear trend was observed: the thinner the titanium electrode, the broader the singularity at eV = Δ1(Al) + Δ2(Ti). The phenomenon can be explained by broadening of the gap edge of the quasi-one-dimensional titanium channels due to quantum fluctuations of the order parameter modulus |Δ2|. The range of the nanowire diameters, where the effect is pronounced, correlates with dimensions where the phase fluctuations of the complex superconducting order parameter Δ = |Δ|eiφ, the quantum phase slips, broadening the R(T) dependencies, have been observed.
A three-parameter asteroid taxonomy
NASA Technical Reports Server (NTRS)
Tedesco, Edward F.; Williams, James G.; Matson, Dennis L.; Veeder, Glenn J.; Gradie, Jonathan C.
1989-01-01
Broadband U, V, and x photometry together with IRAS asteroid albedos have been used to construct an asteroid classification system. The system is based on three parameters (U-V and v-x color indices and visual geometric albedo), and it is able to place 96 percent of the present sample of 357 asteroids into 11 taxonomic classes. It is noted that all but one of these classes are analogous to those previously found using other classification schemes. The algorithm is shown to account for the observational uncertainties in each of the classification parameters.
Rescaling the nonadditivity parameter in Tsallis thermostatistics
NASA Astrophysics Data System (ADS)
Korbel, Jan
2017-08-01
The paper introduces nonadditivity parameter transformation group induced by Tsallis entropy. We discuss simple physical applications such as systems in the contact with finite heat bath or systems with temperature fluctuations. With help of the transformation, it is possible to introduce generalized distributive rule in q-deformed algebra. We focus on MaxEnt distributions of Tsallis entropy with rescaled nonadditivity parameter under escort energy constraints. We show that each group element corresponds to one class of q-deformed distributions. Finally, we briefly discuss the application of the transformation to Jizba-Arimitsu hybrid entropy and its connection to Average Hybrid entropy.
Fractional Action Cosmology with Variable Order Parameter
NASA Astrophysics Data System (ADS)
El-Nabulsi, Rami Ahmad
2017-01-01
Fractional action cosmology with variable order parameter was constructed in this paper. Starting from a fractional weighted action which generalizes the fractional actionlike variational approach, a large number of cosmological dynamical equations are obtained depending on the mathematical type of the fractional order parameter. Through this paper, we selected two independent types which result on a number of cosmological scenarios and we discussed their dynamical consequences. It was observed that the present fractional cosmological formalism holds a large family of solutions and offers new features not found in the standard formalism and in many fundamental research papers.
A measuring system for surface roughness parameters
NASA Astrophysics Data System (ADS)
Han, Jinhong; Wang, Yunkai; Zhang, Xianfeng
2006-11-01
We designed a measurement and control system which can measure the surface roughness parameters with a Single Chip Micyoco (SCM) as its kernel. It uses an inductive transducer to pick up the data. The instrumental structure and the working principle are also introduced in this paper. The integrated hardware and software systems have been designed and improved. The prototype model was calibrated and the instrumental precision was analysed according to the measured data. In this system the surface roughness parameters can automatically be measured and controlled, such as data processing, determination of the reference line, disposal of the surface profile informations, display and print of the results etc.
Asymmetry in the reconstructed deceleration parameter
NASA Astrophysics Data System (ADS)
Bernal, Carla; Cárdenas, Víctor H.; Motta, Veronica
2017-02-01
We study the orientation dependence of the reconstructed deceleration parameter as a function of redshift. We use the Union 2 and Loss datasets, and the well known preferred axis discussed in the literature, and find the best fit reconstructed deceleration parameter. Our results show that a low redshift transition of the reconstructed q (z) is clearly absent in one direction and amazingly sharp in the opposite one. We discuss the possibility that such behavior can be associated to large scale structures affecting the data.
Fractional Action Cosmology with Variable Order Parameter
NASA Astrophysics Data System (ADS)
El-Nabulsi, Rami Ahmad
2017-04-01
Fractional action cosmology with variable order parameter was constructed in this paper. Starting from a fractional weighted action which generalizes the fractional actionlike variational approach, a large number of cosmological dynamical equations are obtained depending on the mathematical type of the fractional order parameter. Through this paper, we selected two independent types which result on a number of cosmological scenarios and we discussed their dynamical consequences. It was observed that the present fractional cosmological formalism holds a large family of solutions and offers new features not found in the standard formalism and in many fundamental research papers.
Noniterative estimation of a nonlinear parameter
NASA Technical Reports Server (NTRS)
Bergstroem, A.
1973-01-01
An algorithm is described which solves the parameters X = (x1,x2,...,xm) and p in an approximation problem Ax nearly equal to y(p), where the parameter p occurs nonlinearly in y. Instead of linearization methods, which require an approximate value of p to be supplied as a priori information, and which may lead to the finding of local minima, the proposed algorithm finds the global minimum by permitting the use of series expansions of arbitrary order, exploiting an a priori knowledge that the addition of a particular function, corresponding to a new column in A, will not improve the goodness of the approximation.
A three-parameter asteroid taxonomy
NASA Technical Reports Server (NTRS)
Tedesco, Edward F.; Williams, James G.; Matson, Dennis L.; Veeder, Glenn J.; Gradie, Jonathan C.
1989-01-01
Broadband U, V, and x photometry together with IRAS asteroid albedos have been used to construct an asteroid classification system. The system is based on three parameters (U-V and v-x color indices and visual geometric albedo), and it is able to place 96 percent of the present sample of 357 asteroids into 11 taxonomic classes. It is noted that all but one of these classes are analogous to those previously found using other classification schemes. The algorithm is shown to account for the observational uncertainties in each of the classification parameters.
Hail parameter relations - A comprehensive digest
NASA Technical Reports Server (NTRS)
Ulbrich, C. W.; Atlas, D.
1982-01-01
Diagrams of hail size parameters are presented and attempts are made to correlate size and mass/volume as indicators of integral quantities of hailstone fall. Radar cross-sections are presented, along with related radar parameters such as the equivalent radar reflectivity factor, the mean Doppler fallspeed, the variance of the Doppler spectrum, and the ratio of the reflectivity factors for the 3.21 and 10.0 cm radar wavelengths used. An analysis of the possible effects of natural or artificial modification of the hail size distribution are discussed.
Pellet impact drilling operational parameters: experimental research
NASA Astrophysics Data System (ADS)
Kovalyov, A. V.; Ryabchikov, S. Ya; Isaev, Ye D.; Aliev, F. R.; Gorbenko, M. V.; Baranova, A. V.
2015-02-01
The article deals with the study of particle-impact drilling that is designed to enhance the rate-of-penetration function in hard and tough drilling environments. It contains the experimental results on relation between drilling parameters and drilling efficiency, the experiments being conducted by means of a specially designed laboratory model. To interpret the results properly a high-speed camera was used to capture the pellet motion. These results can be used to choose optimal parameters, as well as to develop enhanced design of ejector pellet impact drill bits.
Estimation of Parameters in Latent Class Models with Constraints on the Parameters.
1986-06-01
parameter. This rules out models which characterize each Pkj in terms of conjoint effects of item and state parameters, as the Rasch model does, for... example . It also rules out models that impose ordering constraints on the Pkj’S. Thus, while many interesting models can be cast in terms of equality...ONR86-1 m 4 4. TITLE (mnd Subtitle) S. TYPE OF REPORT & PERIOD COVERED Estimation of Parameters in Latent Class Models with Constraints on the
Estimation of Weibull parameters from parameters of initial distribution of flaw size
NASA Astrophysics Data System (ADS)
Wakabayashi, C.; Yasuda, K.; Shiota, T.
2009-11-01
The distribution of the largest flaw size is derived from the initial distribution of flaw size based on extreme value statistics, and also the distribution of fracture origin size is given by transforming Weibull distribution by fracture mechanical relation. These two distributions are equivalent under uniaxial loading. By using this relation, their parameters are related each other and Weibull parameters are estimated from the parameters of the initial distribution of flaw size and the number of links.
GEODYN- ORBITAL AND GEODETIC PARAMETER ESTIMATION
NASA Technical Reports Server (NTRS)
Putney, B.
1994-01-01
The Orbital and Geodetic Parameter Estimation program, GEODYN, possesses the capability to estimate that set of orbital elements, station positions, measurement biases, and a set of force model parameters such that the orbital tracking data from multiple arcs of multiple satellites best fits the entire set of estimation parameters. The estimation problem can be divided into two parts: the orbit prediction problem, and the parameter estimation problem. GEODYN solves these two problems by employing Cowell's method for integrating the orbit and a Bayesian least squares statistical estimation procedure for parameter estimation. GEODYN has found a wide range of applications including determination of definitive orbits, tracking instrumentation calibration, satellite operational predictions, and geodetic parameter estimation, such as the estimations for global networks of tracking stations. The orbit prediction problem may be briefly described as calculating for some later epoch the new conditions of state for the satellite, given a set of initial conditions of state for some epoch, and the disturbing forces affecting the motion of the satellite. The user is required to supply only the initial conditions of state and GEODYN will provide the forcing function and integrate the equations of motion of the satellite. Additionally, GEODYN performs time and coordinate transformations to insure the continuity of operations. Cowell's method of numerical integration is used to solve the satellite equations of motion and the variational partials for force model parameters which are to be adjusted. This method uses predictor-corrector formulas for the equations of motion and corrector formulas only for the variational partials. The parameter estimation problem is divided into three separate parts: 1) instrument measurement modeling and partial derivative computation, 2) data error correction, and 3) statistical estimation of the parameters. Since all of the measurements modeled by
GEODYN- ORBITAL AND GEODETIC PARAMETER ESTIMATION
NASA Technical Reports Server (NTRS)
Putney, B.
1994-01-01
The Orbital and Geodetic Parameter Estimation program, GEODYN, possesses the capability to estimate that set of orbital elements, station positions, measurement biases, and a set of force model parameters such that the orbital tracking data from multiple arcs of multiple satellites best fits the entire set of estimation parameters. The estimation problem can be divided into two parts: the orbit prediction problem, and the parameter estimation problem. GEODYN solves these two problems by employing Cowell's method for integrating the orbit and a Bayesian least squares statistical estimation procedure for parameter estimation. GEODYN has found a wide range of applications including determination of definitive orbits, tracking instrumentation calibration, satellite operational predictions, and geodetic parameter estimation, such as the estimations for global networks of tracking stations. The orbit prediction problem may be briefly described as calculating for some later epoch the new conditions of state for the satellite, given a set of initial conditions of state for some epoch, and the disturbing forces affecting the motion of the satellite. The user is required to supply only the initial conditions of state and GEODYN will provide the forcing function and integrate the equations of motion of the satellite. Additionally, GEODYN performs time and coordinate transformations to insure the continuity of operations. Cowell's method of numerical integration is used to solve the satellite equations of motion and the variational partials for force model parameters which are to be adjusted. This method uses predictor-corrector formulas for the equations of motion and corrector formulas only for the variational partials. The parameter estimation problem is divided into three separate parts: 1) instrument measurement modeling and partial derivative computation, 2) data error correction, and 3) statistical estimation of the parameters. Since all of the measurements modeled by
Putting Parameters in Their Proper Place
ERIC Educational Resources Information Center
Montrul, Silvina; Yoon, James
2009-01-01
Seeing the logical problem of second language acquisition as that of primarily selecting and re-assembling bundles of features anew, Lardiere proposes to dispense with the deductive learning approach and its broad range of consequences subsumed under the concept of parameters. While we agree that feature assembly captures more precisely the…
Averaged controllability of parameter dependent conservative semigroups
NASA Astrophysics Data System (ADS)
Lohéac, Jérôme; Zuazua, Enrique
2017-02-01
We consider the problem of averaged controllability for parameter depending (either in a discrete or continuous fashion) control systems, the aim being to find a control, independent of the unknown parameters, so that the average of the states is controlled. We do it in the context of conservative models, both in an abstract setting and also analysing the specific examples of the wave and Schrödinger equations. Our first result is of perturbative nature. Assuming the averaging probability measure to be a small parameter-dependent perturbation (in a sense that we make precise) of an atomic measure given by a Dirac mass corresponding to a specific realisation of the system, we show that the averaged controllability property is achieved whenever the system corresponding to the support of the Dirac is controllable. Similar tools can be employed to obtain averaged versions of the so-called Ingham inequalities. Particular attention is devoted to the 1d wave equation in which the time-periodicity of solutions can be exploited to obtain more precise results, provided the parameters involved satisfy Diophantine conditions ensuring the lack of resonances.
A Handbook of Sound and Vibration Parameters
1978-09-18
fixed in space. (Reference 1.) no motion atay node Static Divergence: (See Divergence.) Statistical Energy Analysis (SEA): Statistical energy analysis is...parameters of the circuits come from statistics of the vibrational characteristics of the structure. Statistical energy analysis is uniquely successful
Resonance Parameter Adjustment Based on Integral Experiments
Sobes, Vladimir; Leal, Luiz; Arbanas, Goran; Forget, Benoit
2016-06-02
Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, such as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.
Resonance Parameter Adjustment Based on Integral Experiments
Sobes, Vladimir; Leal, Luiz; Arbanas, Goran; ...
2016-06-02
Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, suchmore » as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.« less
Calibration in temperature of photometric parameters
NASA Astrophysics Data System (ADS)
Hauck, B.
In calibrating photometric parameters in temperature, it is very easy to use a Planck distribution to show that a color index is a temperature parameter, but it is more difficult to calibrate such a color index in terms of temperature because only a few effective temperature values are determined. A pioneering work is that of Kuiper (1938), who derived a temperature scale according to spectral type (from A0 to M2 for dwarfs and from G0 to M8 for giants) and a Becker index. The first study giving a relation between effective temperature and a photoelectric color index is that of Popper (1959) in which Popper derives a relation between effective temperature and B-V for the A and F stars and for G8 to K5 (dwarf and giant) stars. Popper has shown the relation between temperature parameters of two photometric systems, R-I from the six-color system of Stebbins and Whitford, and B-V. The intent of the present work is to define a set of stars which can be used to determine a calibration of a photometric parameter in terms of effective temperature.
Relations between some photometric temperature parameters
NASA Astrophysics Data System (ADS)
Meylan, G.; Hauck, B.
1981-11-01
The relations between temperature parameters of various photometric systems are given. The photometries concerned are the following: UBVB1B2V1G (Geneva), UBV (Johnson), uvby-beta (Stromgren), UPXYZVS (Vilnius), UBVRIJKLMNH (Johnson), UVBGRI (Stebbins and Whitford). The effects due to the different luminosity classes and to blanketing (Am, Ap and population II dwarf stars) are taken into account.
Local tsunamis and earthquake source parameters
Geist, Eric L.; Dmowska, Renata; Saltzman, Barry
1999-01-01
This chapter establishes the relationship among earthquake source parameters and the generation, propagation, and run-up of local tsunamis. In general terms, displacement of the seafloor during the earthquake rupture is modeled using the elastic dislocation theory for which the displacement field is dependent on the slip distribution, fault geometry, and the elastic response and properties of the medium. Specifically, nonlinear long-wave theory governs the propagation and run-up of tsunamis. A parametric study is devised to examine the relative importance of individual earthquake source parameters on local tsunamis, because the physics that describes tsunamis from generation through run-up is complex. Analysis of the source parameters of various tsunamigenic earthquakes have indicated that the details of the earthquake source, namely, nonuniform distribution of slip along the fault plane, have a significant effect on the local tsunami run-up. Numerical methods have been developed to address the realistic bathymetric and shoreline conditions. The accuracy of determining the run-up on shore is directly dependent on the source parameters of the earthquake, which provide the initial conditions used for the hydrodynamic models.
Design parameters for rotating cylindrical filtration
NASA Technical Reports Server (NTRS)
Schwille, John A.; Mitra, Deepanjan; Lueptow, Richard M.
2002-01-01
Rotating cylindrical filtration displays significantly reduced plugging of filter pores and build-up of a cake layer, but the number and range of parameters that can be adjusted complicates the design of these devices. Twelve individual parameters were investigated experimentally by measuring the build-up of particles on the rotating cylindrical filter after a fixed time of operation. The build-up of particles on the filter depends on the rotational speed, the radial filtrate flow, the particle size and the gap width. Other parameters, such as suspension concentration and total flow rate are less important. Of the four mechanisms present in rotating filters to reduce pore plugging and cake build-up, axial shear, rotational shear, centrifugal sedimentation and vortical motion, the evidence suggests rotational shear is the dominant mechanism, although the other mechanisms still play minor roles. The ratio of the shear force acting parallel to the filter surface on a particle to the Stokes drag acting normal to the filter surface on the particle due to the difference between particle motion and filtrate flow can be used as a non-dimensional parameter that predicts the degree of particle build-up on the filter surface for a wide variety of filtration conditions. c2002 Elsevier Science B.V. All rights reserved.
Five-Parameter Bivariate Probability Distribution
NASA Technical Reports Server (NTRS)
Tubbs, J.; Brewer, D.; Smith, O. W.
1986-01-01
NASA technical memorandum presents four papers about five-parameter bivariate gamma class of probability distributions. With some overlap of subject matter, papers address different aspects of theories of these distributions and use in forming statistical models of such phenomena as wind gusts. Provides acceptable results for defining constraints in problems designing aircraft and spacecraft to withstand large wind-gust loads.
Dimensionless parameters for lidar performance characterization
NASA Astrophysics Data System (ADS)
Comerón, Adolfo; Agishev, Ravil R.
2014-10-01
A set of three dimensionless parameters is proposed to characterize lidar systems. Two of them are based on an asymptotic approximation of the output signal-to-noise ratio as a function of the input optical power reaching the photoreceiver when there is no background radiation. Of these, one is defined as the ratio between the input signal power level coming from a reference range in a reference atmosphere (reference power level) and the input power level that would produce a reference output signal-to-noise ratio if the photoreceiver operated always in signal-shot noise limited regime. The other is defined as the ratio between the reference power level and the input power level for which the signal-induced shot noise power equals the receiver noise power. A third parameter, defined as the ratio between the background optical power at the photoreceiver input and the reference power level, quantifies the effect of background radiation. With these three parameters a good approximation to the output signal-to-noise ratio of the lidar can be calculated as a function of the power reduction with respect to the power reaching the photodetector in the reference situation. These parameters can also be used to compare and rank the performance of different systems.
Practice Parameter for Psychodynamic Psychotherapy with Children
ERIC Educational Resources Information Center
Medicus, Jennifer
2012-01-01
This Practice Parameter describes the principles of psychodynamic psychotherapy with children and is based on clinical consensus and available research evidence. It presents guidelines for the practice of child psychodynamic psychotherapy, including indications and contraindications, the setting, verbal and interactive (play) techniques, work with…
Surface grid generation in a parameter space
NASA Astrophysics Data System (ADS)
Samareh-Abolhassani, Jamshid; Stewart, John E.
1994-07-01
A robust and efficient technique is discussed for surface-grid generation on a general curvilinear surface. This technique is based on a nonuniform parameter space and allows for the generation of surface grids on highly skewed and nonuniform spaced background surface-grids. This method has been successfully integrated into the GRIDGEN software system.
Surface Grid Generation in a Parameter Space
NASA Astrophysics Data System (ADS)
Samareh-Abolhassani, Jamshid; Stewart, John E.
1994-07-01
A robust and efficient technique is discussed for surface-grid generation on a general curvilinear surface. This technique is based on a non-uniform parameter space and allows for the generation of surface grids on highly skewed and nonuniform spaced background surface-grids. This method has been successfully integrated into the GRIDGEN software system.
Surface grid generation in a parameter space
Samareh-Abolhassani, J.; Stewart, J.E. )
1994-07-01
A robust and efficient technique is discussed for surface-grid generation on a general curvilinear surface. This technique is based on a nonuniform parameter space and allows for the generation of surface grids on highly skewed and nonuniform spaced background surface-grids. This method has been successfully integrated into the GRIDGEN software system. 8 refs., 6 figs.
Surface grid generation in a parameter space
NASA Technical Reports Server (NTRS)
Samareh-Abolhassani, Jamshid; Stewart, John E.
1994-01-01
A robust and efficient technique is discussed for surface-grid generation on a general curvilinear surface. This technique is based on a nonuniform parameter space and allows for the generation of surface grids on highly skewed and nonuniform spaced background surface-grids. This method has been successfully integrated into the GRIDGEN software system.
Resonance Parameter Adjustment Based on Integral Experiments
Sobes, Vladimir; Leal, Luiz; Arbanas, Goran; Forget, Benoit
2016-06-02
Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, such as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.
Evolution of Pedostructure Parameters Under Tillage Practices
USDA-ARS?s Scientific Manuscript database
The pedostructure (PS) concept is a physically-based method of soil characterization that defines a soil based on its structure and the relationship between structure and soil water behavior. There are 15 unique pedostructure parameters that define the macropore and micropore soil water behavior fo...
Changing Throwing Pattern: Instruction and Control Parameter
ERIC Educational Resources Information Center
Southard, Dan
2006-01-01
The purpose of this study was to determine the effects of instruction and scaling up a control parameter (velocity of throw) on changes in throwing pattern. Sixty adult female throwers (ages 20-26 years) were randomly placed into one of four practice conditions: (a) scale up on velocity with no instruction, (b) maintain constant velocity with no…
Order Parameters for Two-Dimensional Networks
NASA Astrophysics Data System (ADS)
Kaatz, Forrest; Bultheel, Adhemar; Egami, Takeshi
2007-10-01
We derive methods that explain how to quantify the amount of order in ``ordered'' and ``highly ordered'' porous arrays. Ordered arrays from bee honeycomb and several from the general field of nanoscience are compared. Accurate measures of the order in porous arrays are made using the discrete pair distribution function (PDF) and the Debye-Waller Factor (DWF) from 2-D discrete Fourier transforms calculated from the real-space data using MATLAB routines. An order parameter, OP3, is defined from the PDF to evaluate the total order in a given array such that an ideal network has the value of 1. When we compare PDFs of man-made arrays with that of our honeycomb we find OP3=0.399 for the honeycomb and OP3=0.572 for man's best hexagonal array. The DWF also scales with this order parameter with the least disorder from a computer-generated hexagonal array and the most disorder from a random array. An ideal hexagonal array normalizes a two-dimensional Fourier transform from which a Debye-Waller parameter is derived which describes the disorder in the arrays. An order parameter S, defined by the DWF, takes values from [0, 1] and for the analyzed man-made array is 0.90, while for the honeycomb it is 0.65. This presentation describes methods to quantify the order found in these arrays.
Online Dynamic Parameter Estimation of Synchronous Machines
NASA Astrophysics Data System (ADS)
West, Michael R.
Traditionally, synchronous machine parameters are determined through an offline characterization procedure. The IEEE 115 standard suggests a variety of mechanical and electrical tests to capture the fundamental characteristics and behaviors of a given machine. These characteristics and behaviors can be used to develop and understand machine models that accurately reflect the machine's performance. To perform such tests, the machine is required to be removed from service. Characterizing a machine offline can result in economic losses due to down time, labor expenses, etc. Such losses may be mitigated by implementing online characterization procedures. Historically, different approaches have been taken to develop methods of calculating a machine's electrical characteristics, without removing the machine from service. Using a machine's input and response data combined with a numerical algorithm, a machine's characteristics can be determined. This thesis explores such characterization methods and strives to compare the IEEE 115 standard for offline characterization with the least squares approximation iterative approach implemented on a 20 h.p. synchronous machine. This least squares estimation method of online parameter estimation shows encouraging results for steady-state parameters, in comparison with steady-state parameters obtained through the IEEE 115 standard.
Design parameters for rotating cylindrical filtration
NASA Technical Reports Server (NTRS)
Schwille, John A.; Mitra, Deepanjan; Lueptow, Richard M.
2002-01-01
Rotating cylindrical filtration displays significantly reduced plugging of filter pores and build-up of a cake layer, but the number and range of parameters that can be adjusted complicates the design of these devices. Twelve individual parameters were investigated experimentally by measuring the build-up of particles on the rotating cylindrical filter after a fixed time of operation. The build-up of particles on the filter depends on the rotational speed, the radial filtrate flow, the particle size and the gap width. Other parameters, such as suspension concentration and total flow rate are less important. Of the four mechanisms present in rotating filters to reduce pore plugging and cake build-up, axial shear, rotational shear, centrifugal sedimentation and vortical motion, the evidence suggests rotational shear is the dominant mechanism, although the other mechanisms still play minor roles. The ratio of the shear force acting parallel to the filter surface on a particle to the Stokes drag acting normal to the filter surface on the particle due to the difference between particle motion and filtrate flow can be used as a non-dimensional parameter that predicts the degree of particle build-up on the filter surface for a wide variety of filtration conditions. c2002 Elsevier Science B.V. All rights reserved.
Maximum Likelihood Estimation of Population Parameters
Fu, Y. X.; Li, W. H.
1993-01-01
One of the most important parameters in population genetics is θ = 4N(e)μ where N(e) is the effective population size and μ is the rate of mutation per gene per generation. We study two related problems, using the maximum likelihood method and the theory of coalescence. One problem is the potential improvement of accuracy in estimating the parameter θ over existing methods and the other is the estimation of parameter λ which is the ratio of two θ's. The minimum variances of estimates of the parameter θ are derived under two idealized situations. These minimum variances serve as the lower bounds of the variances of all possible estimates of θ in practice. We then show that Watterson's estimate of θ based on the number of segregating sites is asymptotically an optimal estimate of θ. However, for a finite sample of sequences, substantial improvement over Watterson's estimate is possible when θ is large. The maximum likelihood estimate of λ = θ(1)/θ(2) is obtained and the properties of the estimate are discussed. PMID:8375660
Recursive parameter estimation of hydrologic models
NASA Astrophysics Data System (ADS)
Rajaram, Harihar; Georgakakos, Konstantine P.
1989-02-01
Proposed is a nonlinear filtering approach to recursive parameter estimation of conceptual watershed response models in state-space form. The conceptual model state is augmented by the vector of free parameters which are to be estimated from input-output data, and the extended Kaiman filter is used to recursively estimate and predict the augmented state. The augmented model noise covariance is parameterized as the sum of two components: one due to errors in the augmented model input and another due to errors in the specification of augmented model constants that were estimated from other than input-output data (e.g., topographic and rating curve constants). These components depend on the sensitivity of the augmented model to input and uncertain constants. Such a novel parameterization allows for nonstationary model noise statistics that are consistent with the dynamics of watershed response as they are described by the conceptual watershed response model. Prior information regarding uncertainty in input and uncertain constants in the form of degree-of-belief estimates of hydrologists can be used directly within the proposed formulation. Even though model structure errors are not explicitly parameterized in the present formulation, such errors can be identified through the examination of the one-step ahead predicted normalized residuals and the parameter traces during convergence. The formulation is exemplified by the estimation of the parameters of a conceptual hydrologic model with data from the 2.1-km2 watershed of Woods Lake located in the Adirondack Mountains of New York.
Models and parameters for environmental radiological assessments
Miller, C W
1984-01-01
This book presents a unified compilation of models and parameters appropriate for assessing the impact of radioactive discharges to the environment. Models examined include those developed for the prediction of atmospheric and hydrologic transport and deposition, for terrestrial and aquatic food-chain bioaccumulation, and for internal and external dosimetry. Chapters have been entered separately into the data base. (ACR)
Estimation of Model Parameters for Steerable Needles
Park, Wooram; Reed, Kyle B.; Okamura, Allison M.; Chirikjian, Gregory S.
2010-01-01
Flexible needles with bevel tips are being developed as useful tools for minimally invasive surgery and percutaneous therapy. When such a needle is inserted into soft tissue, it bends due to the asymmetric geometry of the bevel tip. This insertion with bending is not completely repeatable. We characterize the deviations in needle tip pose (position and orientation) by performing repeated needle insertions into artificial tissue. The base of the needle is pushed at a constant speed without rotating, and the covariance of the distribution of the needle tip pose is computed from experimental data. We develop the closed-form equations to describe how the covariance varies with different model parameters. We estimate the model parameters by matching the closed-form covariance and the experimentally obtained covariance. In this work, we use a needle model modified from a previously developed model with two noise parameters. The modified needle model uses three noise parameters to better capture the stochastic behavior of the needle insertion. The modified needle model provides an improvement of the covariance error from 26.1% to 6.55%. PMID:21643451
A variable parameter parametric snake method
NASA Astrophysics Data System (ADS)
Marouf, A.; Houacine, A.
2015-12-01
In this paper, we introduce a new approach to parametric snake method by using variable snake parameters. Adopting fixed parameter values for all points of the snake, as usual, constitutes by itself a limitation that leads to poor performances in terms of convergence and tracking properties. A more adapted choice should be the one that allows selection depending on the image region properties as on the contour shape and position. However, such variability is not an easy task in general and a precise method need to be defined to assure contour point dependent tuning at iterations. We were particularly interested in applying this idea to the recently presented parametric method [1]. In the work mentioned, an attraction term is used to improve the convergence of the standard parametric snake without a significant increase in computational load. We show here, that improved performances can ensue from applying variable parameter concepts. For this purpose, the method is first analyzed and then a procedure is developed to assure an automatic variable parameter tuning. The interest of our approach is illustrated through object segmentation results.
Seasonal variations of haematological parameters in athletes.
Banfi, Giuseppe; Lundby, Carsten; Robach, Paul; Lippi, Giuseppe
2011-01-01
The influence of training and competition workloads is crucial for evaluation of longitudinal haematological data in athletes. There are only a few papers on the variation of haematological parameters during long-lasting periods and, especially, during an entire competitive season. We summarized that some haematological parameters can be influenced by long-term training and competition periods. Haemoglobin (Hb) and haematocrit (Ht) are decreased during the more intense periods of training, throughout the season. In different sport disciplines, the decline of Hb ranges from 3 to 8% during the competition season, while the range of reticulocytes (Ret%) varies from 5 to 21%. Reticulocytes are also decreased after long periods of training and competitions, but their variation is not necessarily associated with that of Hb. The qualitative variations (trend of modifications) of haematological parameters are roughly independent of the sport discipline, but quantitatively (amount of modifications) dependent on sport discipline. The modifications are more evident in cycling, running, swimming than they are in football and rugby. The variations of haematological parameters within the same sport discipline are qualitatively concordant and quantitatively different among separate but consecutive competitive seasons. These findings are described in aerobic and team sports sportsmen. The definition of reliable reference ranges in sportsmen would only be possible by following the best laboratory practices. For antidoping purposes more studies investigating haematological modifications during the season are advisable.
Quality control parameters for Tamra (copper) Bhasma
Jagtap, Chandrashekhar Yuvaraj; Prajapati, Pradeepkumar; Patgiri, Biswajyoti; Shukla, Vinay J.
2012-01-01
Background: Metallic Bhasmas are highly valued and have their own importance in Ayurvedic formulations. To testify the Bhasmas various parameters have been told in Rasashastra classics. Tamra Bhasma (TB) with its different properties is used in the treatment of various diseases is quiet famous among the Ayurvedic physicians (Vaidyas). Objectives: The present study was carried out to set up the quality control parameters for the TB by making the use of classical tests along with advanced analytical tools. Settings and Design: Copper wire taken for the preparation of Bhasma was first analyzed for its copper content and then subjected to Shodhana, Marana and Amrutikarana procedures as per the classical references. Final product complied with all the classical parameters like Rekhapurnatwa, Varitaratwa etc. Materials and Methods: After complying with these tests TB was analyzed by advanced analytical techniques like particle size distribution (PSD) analysis, scanning electron microscopy (SEM), and inductive coupled plasma spectrometry (ICP). Results: PSD analysis of TB showed volumetric mean diameter of 28.70 μm, 50% of the material was below 18.40 μm size. Particle size less than 2μm were seen in SEM. 56.24 wt % of copper and 23.06 wt % of sulphur was found in ICP-AES. Heavy metals like cadmium, selenium were not detected while others like arsenic, lead and mercury were present in traces. Conclusions: These observations could be specified as the quality control parameters conforming to all the classical tests under the Bhasma Pariksha. PMID:23661863
Quality control parameters for Tamra (copper) Bhasma.
Jagtap, Chandrashekhar Yuvaraj; Prajapati, Pradeepkumar; Patgiri, Biswajyoti; Shukla, Vinay J
2012-04-01
Metallic Bhasmas are highly valued and have their own importance in Ayurvedic formulations. To testify the Bhasmas various parameters have been told in Rasashastra classics. Tamra Bhasma (TB) with its different properties is used in the treatment of various diseases is quiet famous among the Ayurvedic physicians (Vaidyas). The present study was carried out to set up the quality control parameters for the TB by making the use of classical tests along with advanced analytical tools. Copper wire taken for the preparation of Bhasma was first analyzed for its copper content and then subjected to Shodhana, Marana and Amrutikarana procedures as per the classical references. Final product complied with all the classical parameters like Rekhapurnatwa, Varitaratwa etc. After complying with these tests TB was analyzed by advanced analytical techniques like particle size distribution (PSD) analysis, scanning electron microscopy (SEM), and inductive coupled plasma spectrometry (ICP). PSD analysis of TB showed volumetric mean diameter of 28.70 μm, 50% of the material was below 18.40 μm size. Particle size less than 2μm were seen in SEM. 56.24 wt % of copper and 23.06 wt % of sulphur was found in ICP-AES. Heavy metals like cadmium, selenium were not detected while others like arsenic, lead and mercury were present in traces. These observations could be specified as the quality control parameters conforming to all the classical tests under the Bhasma Pariksha.
Experimental determination of terahertz atmospheric absorption parameters
NASA Astrophysics Data System (ADS)
Slocum, David M.; Goyette, Thomas M.; Giles, Robert H.; Nixon, William E.
2015-05-01
The terahertz frequency regime is often used as the `chemical fingerprint' region of the electromagnetic spectrum since many molecules exhibit a dense selection of rotational and vibrational transitions. Water is a major component of the atmosphere and since it has a large dipole moment the propagation of terahertz radiation will be dominated by atmospheric effects. This study will present the results of high--resolution broadband measurements of the terahertz atmospheric absorption and detail the technique for directly measuring the pressure broadening coefficients, absolute absorption coefficients, line positions, and continuum effects. Differences between these measured parameters and those tabulated in HITRAN will be discussed. Once the water vapor absorption was characterized, the same technique was used to measure the line parameters for methanol, a trace gas of interest within Earth's atmosphere. Methanol has a dense absorption spectrum in the terahertz frequency region and is an important molecule in fields such as environmental monitoring, security, and astrophysics. The data obtained in the present study will be of immediate use for the remote sensing community, as it is uncommon to measure this many independent parameters as well as to measure the absolute absorption of the transitions. Current models rely on tabulated databases of calculated values for the line parameters measured in this study. Differences between the measured data and those in the databases will be highlighted and discussed.
Putting Parameters in Their Proper Place
ERIC Educational Resources Information Center
Montrul, Silvina; Yoon, James
2009-01-01
Seeing the logical problem of second language acquisition as that of primarily selecting and re-assembling bundles of features anew, Lardiere proposes to dispense with the deductive learning approach and its broad range of consequences subsumed under the concept of parameters. While we agree that feature assembly captures more precisely the…
Multi-Parameter Scattering Sensor and Methods
NASA Technical Reports Server (NTRS)
Greenberg, Paul S. (Inventor); Fischer, David G. (Inventor)
2016-01-01
Methods, detectors and systems detect particles and/or measure particle properties. According to one embodiment, a detector for detecting particles comprises: a sensor for receiving radiation scattered by an ensemble of particles; and a processor for determining a physical parameter for the detector, or an optimal detection angle or a bound for an optimal detection angle, for measuring at least one moment or integrated moment of the ensemble of particles, the physical parameter, or detection angle, or detection angle bound being determined based on one or more of properties (a) and/or (b) and/or (c) and/or (d) or ranges for one or more of properties (a) and/or (b) and/or (c) and/or (d), wherein (a)-(d) are the following: (a) is a wavelength of light incident on the particles, (b) is a count median diameter or other characteristic size parameter of the particle size distribution, (c) is a standard deviation or other characteristic width parameter of the particle size distribution, and (d) is a refractive index of particles.
Perturbative quantum gravity with the Immirzi parameter
NASA Astrophysics Data System (ADS)
Benedetti, Dario; Speziale, Simone
2011-06-01
We study perturbative quantum gravity in the first-order tetrad formalism. The lowest order action corresponds to Einstein-Cartan plus a parity-odd term, and is known in the literature as the Holst action. The coupling constant of the parity-odd term can be identified with the Immirzi parameter γ of loop quantum gravity. We compute the quantum effective action in the one-loop expansion. As in the metric second-order formulation, we find that in the case of pure gravity the theory is on-shell finite, and the running of Newton's constant and the Immirzi parameter is inessential. In the presence of fermions, the situation changes in two fundamental aspects. First, non-renormalizable logarithmic divergences appear, as usual. Second, the Immirzi parameter becomes a priori observable, and we find that it is renormalized by a four-fermion interaction generated by radiative corrections. We compute its beta function and discuss possible implications. The sign of the beta function depends on whether the Immirzi parameter is larger or smaller than one in absolute value, and γ2 = 1 is a UV fixed-point (we work in Euclidean signature). Finally, we find that the Holst action is stable with respect to radiative corrections in the case of minimal coupling, up to higher order non-renormalizable interactions.
Practice Parameter for Psychodynamic Psychotherapy with Children
ERIC Educational Resources Information Center
Medicus, Jennifer
2012-01-01
This Practice Parameter describes the principles of psychodynamic psychotherapy with children and is based on clinical consensus and available research evidence. It presents guidelines for the practice of child psychodynamic psychotherapy, including indications and contraindications, the setting, verbal and interactive (play) techniques, work with…
Stokes parameters modulator for birefringent filters
NASA Technical Reports Server (NTRS)
Dollfus, A.
1985-01-01
The Solar Birefringent Filter (Filter Polarisiant Solaire Selectif FPSS) of Meudon Observatory is presently located at the focus of a solar refractor with a 28 cm lens directly pointed at the Sun. It produces a diffraction limited image without instrumental polarization and with a spectral resolution of 46,000 in a field of 6 arc min. diameter. The instrument is calibrated for absolute Doppler velocity measurements and is presently used for quantitative imagery of the radial velocity motions in the photosphere. The short period oscillations are recorded. Work of adapting the instrument for the imagery of the solar surface in the Stokes parameters is discussed. The first polarizer of the birefringent filter, with a reference position angle 0 deg, is associated with a fixed quarter wave plate at +45 deg. A rotating quarter wave plate is set at 0 deg and can be turned by incremented steps of exactly +45 deg. Another quarter wave plate also initially set at 0 deg is simultaneously incremented by -45 deg but only on each even step of the first plate. A complete cycle of increments produces images for each of the 6 parameters I + or - Q, I + or - U and I + or - V. These images are then subtracted by pairs to produce a full image in the three Stokes parameters Q, U and V. With proper retardation tolerance and positioning accuracy of the quarter wave plates, the cross talk between the Stokes parameters was calculated and checked to be minimal.
Practice Parameter for Psychiatric Consultation to Schools
ERIC Educational Resources Information Center
Journal of the American Academy of Child and Adolescent Psychiatry, 2005
2005-01-01
This practice parameter reviews the topic of psychiatric consultation to schools. The review covers the history of school consultation and current consultative models; the process of developing a consultative relationship; school administrative procedures, personnel, and milieu; legal protections for students with mental disabilities; and issues…
Changing Throwing Pattern: Instruction and Control Parameter
ERIC Educational Resources Information Center
Southard, Dan
2006-01-01
The purpose of this study was to determine the effects of instruction and scaling up a control parameter (velocity of throw) on changes in throwing pattern. Sixty adult female throwers (ages 20-26 years) were randomly placed into one of four practice conditions: (a) scale up on velocity with no instruction, (b) maintain constant velocity with no…
Vital parameters related low level laser radiation
NASA Astrophysics Data System (ADS)
Palmieri, Beniamino; Capone, Stefania
2011-08-01
The first work hypotesis is that biosensors on the patient detecting heart, breath rate and skin parameters, modulate laser radiation to enhance the therapeutic outcome; in the second work hypotesis: biofeedback could be effective, when integrated in the low level laser energy release.
Solar Eruption and Local Magnetic Parameters
NASA Astrophysics Data System (ADS)
Lee, Jeongwoo; Liu, Chang; Jing, Ju; Chae, Jongchul
2016-11-01
It is now a common practice to use local magnetic parameters such as magnetic decay index for explaining solar eruptions from active regions, but there can be an alternative view that the global properties of the source region should be counted as a more important factor. We discuss this issue based on Solar Dynamics Observatory observations of the three successive eruptions within 1.5 hr from the NOAA active region 11444 and the magnetic parameters calculated using the nonlinear force-free field model. Two violent eruptions occurred in the regions with relatively high magnetic twist number (0.5-1.5) and high decay index (0.9-1.1) at the nominal height of the filament (12″) and otherwise a mild eruption occurred, which supports the local-parameter paradigm. Our main point is that the time sequence of the eruptions did not go with these parameters. It is argued that an additional factor, in the form of stabilizing force, should operate to determine the onset of the first eruption and temporal behaviors of subsequent eruptions. As supporting evidence, we report that the heating and fast plasma flow continuing for a timescale of an hour was the direct cause for the first eruption and that the unidirectional propagation of the disturbance determined the timing of subsequent eruptions. Both of these factors are associated with the overall magnetic structure rather than local magnetic properties of the active region.
Missing Data and IRT Item Parameter Estimation.
ERIC Educational Resources Information Center
DeMars, Christine
The situation of nonrandomly missing data has theoretically different implications for item parameter estimation depending on whether joint maximum likelihood or marginal maximum likelihood methods are used in the estimation. The objective of this paper is to illustrate what potentially can happen, under these estimation procedures, when there is…
Structural health monitoring using parameter identification methods
NASA Astrophysics Data System (ADS)
Liu, Pengxiang; Rao, Vittal S.
2000-06-01
A structural health monitoring method for determination of damages in structural system is developed using state variable model. A time-domain identification method, the subspace system identification algorithm, is first applied to get a state-space model of the structure. The identified state-space model is then transformed to two special realization forms, for determination of the equation of motion of multiple- degrees-freedom of the structure. The parameters of equation of motion, mass and stiffness matrices or damage indices are used to determine the location and extent of the damage. This method is also extended for the health monitoring of substructural system. Unlike the health monitoring of the whole structure, the health monitoring of substructure uses localized parameter identification which only involves the measurement of substructure parameters. Using this method, the number of unknown parameters and the computational requirement for each identification can be significantly reduced, hence the accuracy of estimation can be improved. Illustrative cases studies using both numerical and experimental structures are presented.
Water quality parameter measurement using spectral signatures
NASA Technical Reports Server (NTRS)
White, P. E.
1973-01-01
Regression analysis is applied to the problem of measuring water quality parameters from remote sensing spectral signature data. The equations necessary to perform regression analysis are presented and methods of testing the strength and reliability of a regression are described. An efficient algorithm for selecting an optimal subset of the independent variables available for a regression is also presented.
Ion beam parameters of a plasma accelerator
Nazarov, V.G.; Vinogradov, A.M.; Veselovzorov, A.N.; Efremov, V.K.
1987-08-01
The aim of this investigation was to determine the dependences of the current density, the energy, and the divergence of the ion beams of an UZDP-type source (a plasma accelerator with closed electron drift in the accelerator channel and an extended zone of ion acceleration) on the parameters which determine its performance, and to establish qualitative relationships between these values.
Educational Parameters Revealed from VLE Logging Data
ERIC Educational Resources Information Center
van der Zanden, A. H. W. (Piet); Veen, W. (Wim)
2007-01-01
Educational management wants to comprehend the uses of ICT in Education to get a grip on its effects due to the multiple annual investments in the Virtual Learning Environment. In the search to define educational parameters a vast amount of datasets is examined from 289 institutes using Blackboard. The focus is on the three dimensions growth,…
Empirical and analytical determination of eruptive parameters
NASA Astrophysics Data System (ADS)
Bonadonna, C.; Costa, A.; Connor, C.; Volentik, A.; Connor, L.
2009-04-01
The determination of eruptive parameters (e.g. plume height, erupted volume, mass discharge rate, duration, grainsize distribution) is crucial to the interpretation of the activity and therefore the hazard assessment of any given volcano. Characterization of tephra deposits allows for most eruptive parameters to be constrained, even though some parameters of recent eruptions can be more accurately derived from direct observations and satellite retrievals (e.g. plume height). In particular, the distribution of tephra thickness and mass per unit area around the volcano (isopach and isomass maps) is necessary for the estimate of erupted volume, whereas the distribution of the largest clasts (isopleth maps) is typically used for the estimate of column height and wind speed at the time of the eruption. Both isopach/isomass maps and isopleth maps can also be used for the determination of the eruptive vent location and the classification of the eruptive style. The mass eruption rate and the duration of the sustained phase can be calculated from a combination of these parameters. Indications on fragmentation mechanisms can also be inferred from the study of particle size. Eruptive parameters can be inferred by applying empirical, analytical and numerical models and through the inversion solutions of analytical models. These empirical and analytical models need to be thoroughly analyzed and the associated assumptions and limitations need to be investigated in order to assess the variability of resulting eruptive parameters. This is crucial not only because these eruptive parameters are used to characterize volcanic eruptions but also because they are used as input to numerical models and to construct potential activity scenarios for hazard assessment. In addition, tephra deposits cannot be uniquely characterized especially when associated with old eruptions and were affected by erosion and reworking. Here we apply different models to different eruptions, both recent and
Mixed integer evolution strategies for parameter optimization.
Li, Rui; Emmerich, Michael T M; Eggermont, Jeroen; Bäck, Thomas; Schütz, M; Dijkstra, J; Reiber, J H C
2013-01-01
Evolution strategies (ESs) are powerful probabilistic search and optimization algorithms gleaned from biological evolution theory. They have been successfully applied to a wide range of real world applications. The modern ESs are mainly designed for solving continuous parameter optimization problems. Their ability to adapt the parameters of the multivariate normal distribution used for mutation during the optimization run makes them well suited for this domain. In this article we describe and study mixed integer evolution strategies (MIES), which are natural extensions of ES for mixed integer optimization problems. MIES can deal with parameter vectors consisting not only of continuous variables but also with nominal discrete and integer variables. Following the design principles of the canonical evolution strategies, they use specialized mutation operators tailored for the aforementioned mixed parameter classes. For each type of variable, the choice of mutation operators is governed by a natural metric for this variable type, maximal entropy, and symmetry considerations. All distributions used for mutation can be controlled in their shape by means of scaling parameters, allowing self-adaptation to be implemented. After introducing and motivating the conceptual design of the MIES, we study the optimality of the self-adaptation of step sizes and mutation rates on a generalized (weighted) sphere model. Moreover, we prove global convergence of the MIES on a very general class of problems. The remainder of the article is devoted to performance studies on artificial landscapes (barrier functions and mixed integer NK landscapes), and a case study in the optimization of medical image analysis systems. In addition, we show that with proper constraint handling techniques, MIES can also be applied to classical mixed integer nonlinear programming problems.
Estimated hydrogeological parameters by artificial neurons network
NASA Astrophysics Data System (ADS)
Lin, H.; Chen, C.; Tan, Y.; Ke, K.
2009-12-01
In recent years, many approaches had been developed using artificial neurons network (ANN) model cooperated with Theis analytical solution to estimate the effective hydrological parameters for the homogenous and isotropic porous media, such as Lin and Chen approach [Lin and Chen, 2006] (or called the ANN approach hereafter), PC-ANN approach [Samani et al., 2008]. The above methods assumed a full superimposition of the type curve and the observed drawdown, and tried to use the first time-drawdown data as a match point to make a fine approximation of the effective parameters. However, using the first time-drawdown data or the early time-drawdown data is not always correct for the estimation of the hydrological parameters, especially for heterogeneous and anisotropic aquifers. Therefore, this paper mainly corrected the concept of superimposed plot by modifying the ANN approach and PC-ANN approach, as well as cooperating with Papadopoulos analytical solution, to estimate the transmissivities and storage coefficient for anisotropic, heterogeneous aquifers. The ANN model is trained with 4000 training sets of the well function, and tested with 1000 sets and 300 sets of synthetic time-drawdown generated from homogonous and heterogonous parameters, respectively. In-situ observation data, the time-drawdown at station Shi-Chou of the Chihuahua River alluvial fan, Taiwan, is further adopted to test the applicability and reliability of proposed methods, as well as comparing with Straight-line method and Type-curve method. Results suggested that both of the modified methods had better performance than the original ones. Using late time drawdown to optimize the effective parameters is shown better than using early-time drawdown. Additionally, results indicated that the modified ANN approach is better than the modified PC-ANN approach in terms of precision, while the efficiency of the modified PC-ANN approach is approximately three times better than the modified ANN approach.
NASA Astrophysics Data System (ADS)
Xu, Wei; Mueller, Klaus
2010-02-01
Previous work indicated that using ordered subsets (OS-SIRT) for iterative CT can optimize the reconstruction performance once optimal settings for parameters such as number of subsets and relaxation factor have been identified. However, recent work also indicated that the optimal settings have dependent relations with regards to the quality of the projection data (such as SNR-level), which are hard to obtain a-priori. In addition, users may also have preferences in trading off between the dependent parameters, such as reconstruction speed and quality, which makes these (independent) parameters even more difficult to determine in an automated manner. Therefore, we devise an effective parameter space navigation interface allowing users to interactively assist parameter selection for iterative CT reconstruction algorithms (here for OS-SIRT). It is based on a 2D scatter plot with six display modes to show different features of the reconstruction results based on the user preferences. It also enables a dynamic visualization by gradual parameter alteration for illustrating the rate of impact of a given parameter constellation. Finally, we note the generality of our approach, which could be applied to assist any parameter selection related systems.
Effect of the cutter parameters and machining parameters on the interference in gear slicing
NASA Astrophysics Data System (ADS)
Chen, Xinchun; Li, Jia; Lou, Benchao; Shi, Jiang; Yang, Qijun
2013-11-01
Current researches have not yet found the effect law of the cutter parameters and machining parameters on the interference in gear slicing, the interference between the cutter and machined gear often happens because the appropriate cutter parameters and machining parameters cannot be set, which reduces the gear machining accuracy. The relative position between the major flank face and edge-sweeping surface, distribution law of the interference area in forming process of edge-sweeping surface, and effect law of relative positions among edge-sweeping surfaces on the interference are studied by graphical analysis. The effect law of the cutter parameters and machining parameters on the interference is found. The effect law shows that the interference in gear slicing can be controlled when the relief angle measured on the top edge and feed of every rotation are chosen respectively larger than 9° and smaller than 0.15 mm/r. An internal helical gear is sliced with the spur slice cutter and the cutter parameters and machining parameters are set based on above the effect law. The machined gear is measured in Gear Measuring Center and the detection result shows that the comprehensive accuracy reaches GB/T Class 7, where some reach GB/T Class 6. The result can meet the gear machining accuracy requirement and shows that the effect law found is valid. The problem of the interference in gear slicing is solved and the gear machining accuracy can be improved.
Accuracy of Parameter Estimation in Gibbs Sampling under the Two-Parameter Logistic Model.
ERIC Educational Resources Information Center
Kim, Seock-Ho; Cohen, Allan S.
The accuracy of Gibbs sampling, a Markov chain Monte Carlo procedure, was considered for estimation of item and ability parameters under the two-parameter logistic model. Memory test data were analyzed to illustrate the Gibbs sampling procedure. Simulated data sets were analyzed using Gibbs sampling and the marginal Bayesian method. The marginal…
Which image parameter(s) for the automation of the electron microscope?
Bonnet, N; Zinzindohoue, P
1989-03-01
Experiments on automating the transmission electron microscope rely on the search for minimum variance. This image parameter gives satisfactory results for automatic focusing, astigmatism correction, and beam alignment. We investigate here the different image descriptors that might also be used; we conclude that texture parameters, which are directional, would be better candidates correcting astigmatism and beam tilt.
NASA Astrophysics Data System (ADS)
Zhu, Zhiliang; Meng, Zhiqiang; Cao, Tingting; Zhang, Zhengjiang; Dai, Yuxing
2017-06-01
State and parameter estimation (SPE) plays an important role in process monitoring, online optimization, and process control. The estimation of states and parameters is generally solved simultaneously in the SPE problem, where the parameters to be estimated are specified as augmented states. When state and/or measurement equations are highly nonlinear and the posterior probability of the state is non-Gaussian, particle filter (PF) is commonly used for SPE. However, when the parameters switch with the operating conditions, the change of parameters cannot be detected and tracked by the conventional SPE method. This paper proposes a PF-based robust SPE method for a nonlinear process system with variable parameters. The measurement test criterion based on observation error is introduced to indirectly identify whether the parameters are changed. Based on the result of identification, the variances of the particles are modified adaptively for the tracking of the changed parameters. Finally, reliable SPE can be derived through iterative particles. The proposed PF-based robust SPE method is applied to two nonlinear process systems. The results demonstrate the effectiveness and robustness of the proposed method.
Sensitivity of adjustment to parameter correlations and to response-parameter correlations
Wagschal, J.J.
2011-07-01
The adjusted parameters and response, and their respective posterior uncertainties and correlations, are presented explicitly as functions of all relevant prior correlations for the two parameters, one response case. The dependence of these adjusted entities on the various prior correlations is analyzed and portrayed graphically for various valid correlation combinations on a simple criticality problem. (authors)
Zhao, Bo; Lam, Fan; Liang, Zhi-Pei
2014-01-01
MR parameter mapping (e.g., T1 mapping, T2 mapping, T2∗ mapping) is a valuable tool for tissue characterization. However, its practical utility has been limited due to long data acquisition times. This paper addresses this problem with a new model-based parameter mapping method. The proposed method utilizes a formulation that integrates the explicit signal model with sparsity constraints on the model parameters, enabling direct estimation of the parameters of interest from highly undersampled, noisy k-space data. An efficient greedy-pursuit algorithm is described to solve the resulting constrained parameter estimation problem. Estimation-theoretic bounds are also derived to analyze the benefits of incorporating sparsity constraints and benchmark the performance of the proposed method. The theoretical properties and empirical performance of the proposed method are illustrated in a T2 mapping application example using computer simulations. PMID:24833520
Parameter estimation for lithium ion batteries
NASA Astrophysics Data System (ADS)
Santhanagopalan, Shriram
With an increase in the demand for lithium based batteries at the rate of about 7% per year, the amount of effort put into improving the performance of these batteries from both experimental and theoretical perspectives is increasing. There exist a number of mathematical models ranging from simple empirical models to complicated physics-based models to describe the processes leading to failure of these cells. The literature is also rife with experimental studies that characterize the various properties of the system in an attempt to improve the performance of lithium ion cells. However, very little has been done to quantify the experimental observations and relate these results to the existing mathematical models. In fact, the best of the physics based models in the literature show as much as 20% discrepancy when compared to experimental data. The reasons for such a big difference include, but are not limited to, numerical complexities involved in extracting parameters from experimental data and inconsistencies in interpreting directly measured values for the parameters. In this work, an attempt has been made to implement simplified models to extract parameter values that accurately characterize the performance of lithium ion cells. The validity of these models under a variety of experimental conditions is verified using a model discrimination procedure. Transport and kinetic properties are estimated using a non-linear estimation procedure. The initial state of charge inside each electrode is also maintained as an unknown parameter, since this value plays a significant role in accurately matching experimental charge/discharge curves with model predictions and is not readily known from experimental data. The second part of the dissertation focuses on parameters that change rapidly with time. For example, in the case of lithium ion batteries used in Hybrid Electric Vehicle (HEV) applications, the prediction of the State of Charge (SOC) of the cell under a variety of
CASIM input parameters for various materials
Malensek, A.J.; Elwyn, A.J.
1994-07-14
During the past year, the computer program CASIM has been placed in a common area from which copies can be obtained by a wide array of users. The impetus for this arrangement was the need to have a standard code that could be maintained and transported to other platforms. In addition, an historical record would be kept of each version as the program evolved. CASIM requires a series of parameters (input by the user) that describe the medium in which the cascade develops. Presently a total of 9 materials can be defined. Occasions arise when one needs to know the properties of materials (elements, compounds, and mixtures) that have not been defined. Because it is desirable to have a uniform set of values for all CASIM users, this note presents a methodology for obtaining the input parameters for an arbitrary material. They are read in by the Subroutine CASIM{underscore}PROG from the user supplied file CASIM.DAT.
Renal parameter estimates in unrestrained dogs
NASA Technical Reports Server (NTRS)
Rader, R. D.; Stevens, C. M.
1974-01-01
A mathematical formulation has been developed to describe the hemodynamic parameters of a conceptualized kidney model. The model was developed by considering regional pressure drops and regional storage capacities within the renal vasculature. Estimation of renal artery compliance, pre- and postglomerular resistance, and glomerular filtration pressure is feasible by considering mean levels and time derivatives of abdominal aortic pressure and renal artery flow. Changes in the smooth muscle tone of the renal vessels induced by exogenous angiotensin amide, acetylcholine, and by the anaesthetic agent halothane were estimated by use of the model. By employing totally implanted telemetry, the technique was applied on unrestrained dogs to measure renal resistive and compliant parameters while the dogs were being subjected to obedience training, to avoidance reaction, and to unrestrained caging.
Hexagonal boron nitride and water interaction parameters.
Wu, Yanbin; Wagner, Lucas K; Aluru, Narayana R
2016-04-28
The study of hexagonal boron nitride (hBN) in microfluidic and nanofluidic applications at the atomic level requires accurate force field parameters to describe the water-hBN interaction. In this work, we begin with benchmark quality first principles quantum Monte Carlo calculations on the interaction energy between water and hBN, which are used to validate random phase approximation (RPA) calculations. We then proceed with RPA to derive force field parameters, which are used to simulate water contact angle on bulk hBN, attaining a value within the experimental uncertainties. This paper demonstrates that end-to-end multiscale modeling, starting at detailed many-body quantum mechanics and ending with macroscopic properties, with the approximations controlled along the way, is feasible for these systems.
Dynamic compensation, parameter identifiability, and equivariances
2017-01-01
A recent paper by Karin et al. introduced a mathematical notion called dynamical compensation (DC) of biological circuits. DC was shown to play an important role in glucose homeostasis as well as other key physiological regulatory mechanisms. Karin et al. went on to provide a sufficient condition to test whether a given system has the DC property. Here, we show how DC can be formulated in terms of a well-known concept in systems biology, statistics, and control theory—that of parameter structural non-identifiability. Viewing DC as a parameter identification problem enables one to take advantage of powerful theoretical and computational tools to test a system for DC. We obtain as a special case the sufficient criterion discussed by Karin et al. We also draw connections to system equivalence and to the fold-change detection property. PMID:28384175
Parameter Estimation for Viscoplastic Material Modeling
NASA Technical Reports Server (NTRS)
Saleeb, Atef F.; Gendy, Atef S.; Wilt, Thomas E.
1997-01-01
A key ingredient in the design of engineering components and structures under general thermomechanical loading is the use of mathematical constitutive models (e.g. in finite element analysis) capable of accurate representation of short and long term stress/deformation responses. In addition to the ever-increasing complexity of recent viscoplastic models of this type, they often also require a large number of material constants to describe a host of (anticipated) physical phenomena and complicated deformation mechanisms. In turn, the experimental characterization of these material parameters constitutes the major factor in the successful and effective utilization of any given constitutive model; i.e., the problem of constitutive parameter estimation from experimental measurements.
Rapid Compact Binary Coalescence Parameter Estimation
NASA Astrophysics Data System (ADS)
Pankow, Chris; Brady, Patrick; O'Shaughnessy, Richard; Ochsner, Evan; Qi, Hong
2016-03-01
The first observation run with second generation gravitational-wave observatories will conclude at the beginning of 2016. Given their unprecedented and growing sensitivity, the benefit of prompt and accurate estimation of the orientation and physical parameters of binary coalescences is obvious in its coupling to electromagnetic astrophysics and observations. Popular Bayesian schemes to measure properties of compact object binaries use Markovian sampling to compute the posterior. While very successful, in some cases, convergence is delayed until well after the electromagnetic fluence has subsided thus diminishing the potential science return. With this in mind, we have developed a scheme which is also Bayesian and simply parallelizable across all available computing resources, drastically decreasing convergence time to a few tens of minutes. In this talk, I will emphasize the complementary use of results from low latency gravitational-wave searches to improve computational efficiency and demonstrate the capabilities of our parameter estimation framework with a simulated set of binary compact object coalescences.
Habitable zone dependence on stellar parameter uncertainties
Kane, Stephen R.
2014-02-20
An important property of exoplanetary systems is the extent of the Habitable Zone (HZ), defined as that region where water can exist in a liquid state on the surface of a planet with sufficient atmospheric pressure. Both ground- and space-based observations have revealed a plethora of confirmed exoplanets and exoplanetary candidates, most notably from the Kepler mission using the transit detection technique. Many of these detected planets lie within the predicted HZ of their host star. However, as is the case with the derived properties of the planets themselves, the HZ boundaries depend on how well we understand the host star. Here we quantify the uncertainties of HZ boundaries on the parameter uncertainties of the host star. We examine the distribution of stellar parameter uncertainties from confirmed exoplanet hosts and Kepler candidate hosts and translate these into HZ boundary uncertainties. We apply this to several known systems with an HZ planet to determine the uncertainty in their HZ status.
Study of Nightitme enhancement of ionospheric parameters
NASA Astrophysics Data System (ADS)
Sardar, Nuzhat
2012-07-01
In the present work ionospheric electron content (IEC) as well as critical frequency of F2-layer (foF2) data from three locations (low, mid and high) latitudes have been used to study the anomalous nighttime F-region during low to moderate solar activity period i.e. from January 2006 to December 2010. Our results show that at high and mid latitude locations percentage of enhancement with IEC and foF2 is maximum during winter, whereas at low latitude location maximum percentage of enhancement with both the parameters is maximum during equinox. Out of 1176 number of enhancements for IEC, 661 enhancements occurred during pre-midnight hours and 515 occurred during post-midnight hours. Although for foF2 parameter out of 948 enhancements, 457 enhancements occurred during pre-midnight hours and 491 enhancements occurred during post-midnight hours.
Parameter identification and modeling of longitudinal aerodynamics
NASA Technical Reports Server (NTRS)
Aksteter, J. W.; Parks, E. K.; Bach, R. E., Jr.
1995-01-01
Using a comprehensive flight test database and a parameter identification software program produced at NASA Ames Research Center, a math model of the longitudinal aerodynamics of the Harrier aircraft was formulated. The identification program employed the equation error method using multiple linear regression to estimate the nonlinear parameters. The formulated math model structure adhered closely to aerodynamic and stability/control theory, particularly with regard to compressibility and dynamic manoeuvring. Validation was accomplished by using a three degree-of-freedom nonlinear flight simulator with pilot inputs from flight test data. The simulation models agreed quite well with the measured states. It is important to note that the flight test data used for the validation of the model was not used in the model identification.
Calibrated Hydrothermal Parameters, Barrow, Alaska, 2013
Atchley, Adam; Painter, Scott; Harp, Dylan; Coon, Ethan; Wilson, Cathy; Liljedahl, Anna; Romanovsky, Vladimir
2015-01-29
A model-observation-experiment process (ModEx) is used to generate three 1D models of characteristic micro-topographical land-formations, which are capable of simulating present active thaw layer (ALT) from current climate conditions. Each column was used in a coupled calibration to identify moss, peat and mineral soil hydrothermal properties to be used in up-scaled simulations. Observational soil temperature data from a tundra site located near Barrow, AK (Area C) is used to calibrate thermal properties of moss, peat, and sandy loam soil to be used in the multiphysics Advanced Terrestrial Simulator (ATS) models. Simulation results are a list of calibrated hydrothermal parameters for moss, peat, and mineral soil hydrothermal parameters.
A Full 24-Parameter MSSM Exploration
AbdusSalam, Shehu S.
2008-11-23
Up until now a complete scan in all phenomenologically relevant directions of the MSSM at the TeV scale for performing global fit has not been done. Given the imminent start of operation of the LHC, this is a major gap on our quest to discovering and understanding the physical implications of low energy supersymmetry. The main reason for this is the large number of parameters involved that makes it computationally extremely expensive using the traditional methods. In this talk I demonstrate that with advanced Bayesian sampling techniques the problem is solvable. The results from the explored 24-parameter TeV scale MSSM (phenoMSSM) are remarkably distinct from previous studies and are independent of models for supersymmetry breaking and mediation mechanisms. Hence they are a more robust guide to searches for supersymmetry.
UPRE method for total variation parameter selection
Wohlberg, Brendt; Lin, Youzuo
2008-01-01
Total Variation (TV) Regularization is an important method for solving a wide variety of inverse problems in image processing. In order to optimize the reconstructed image, it is important to choose the optimal regularization parameter. The Unbiased Predictive Risk Estimator (UPRE) has been shown to give a very good estimate of this parameter for Tikhonov Regularization. In this paper we propose an approach to extend UPRE method to the TV problem. However, applying the extended UPRE is impractical in the case of inverse problems such as de blurring, due to the large scale of the associated linear problem. We also propose an approach to reducing the large scale problem to a small problem, significantly reducing computational requirements while providing a good approximation to the original problem.
Analysis of Modeling Parameters on Threaded Screws.
Vigil, Miquela S.; Brake, Matthew Robert; Vangoethem, Douglas
2015-06-01
Assembled mechanical systems often contain a large number of bolted connections. These bolted connections (joints) are integral aspects of the load path for structural dynamics, and, consequently, are paramount for calculating a structure's stiffness and energy dissipation prop- erties. However, analysts have not found the optimal method to model appropriately these bolted joints. The complexity of the screw geometry cause issues when generating a mesh of the model. This paper will explore different approaches to model a screw-substrate connec- tion. Model parameters such as mesh continuity, node alignment, wedge angles, and thread to body element size ratios are examined. The results of this study will give analysts a better understanding of the influences of these parameters and will aide in finding the optimal method to model bolted connections.
Hexagonal boron nitride and water interaction parameters
NASA Astrophysics Data System (ADS)
Wu, Yanbin; Wagner, Lucas K.; Aluru, Narayana R.
2016-04-01
The study of hexagonal boron nitride (hBN) in microfluidic and nanofluidic applications at the atomic level requires accurate force field parameters to describe the water-hBN interaction. In this work, we begin with benchmark quality first principles quantum Monte Carlo calculations on the interaction energy between water and hBN, which are used to validate random phase approximation (RPA) calculations. We then proceed with RPA to derive force field parameters, which are used to simulate water contact angle on bulk hBN, attaining a value within the experimental uncertainties. This paper demonstrates that end-to-end multiscale modeling, starting at detailed many-body quantum mechanics and ending with macroscopic properties, with the approximations controlled along the way, is feasible for these systems.
Determination and analysis of synchronous motor's parameters
NASA Astrophysics Data System (ADS)
Mesņajevs, Aleksandrs; Zviedris, Andrejs
2009-01-01
In this work the parameters of synchronous machines are analyzed- direct-axis reaction Xad and quadrature-axis reaction Xaq. Methods of calculation in view of magnetic system's and its element's saturation are presented. It is shown that definition of these reactances, using as a basis a two-reaction method, is not correct and connected with work demanding chart analyzing calculations. The new approach to the qualitative and quantitative analysis of synchronous machine's operating modes which is based on consecutive use of the magnetic field's theory is offered, without it with two-reaction parameters Xad and Xaq. This approach is realized by means of a magnetic field's modeling using numerical methods with help of modern computers.
NMR parameters in gapped graphene systems
NASA Astrophysics Data System (ADS)
Crisan, Mircea; Grosu, Ioan; Ţifrea, Ionel
2016-06-01
We calculate the nuclear spin-lattice relaxation time and the Knight shift for the case of gapped graphene systems. Our calculations consider both the massive and massless gap scenarios. Both the spin-lattice relaxation time and the Knight shift depend on temperature, chemical potential, and the value of the electronic energy gap. In particular, at the Dirac point, the electronic energy gap has stronger effects on the system nuclear magnetic resonance parameters in the case of the massless gap scenario. Differently, at large values of the chemical potential, both gap scenarios behave in a similar way and the gapped graphene system approaches a Fermi gas from the nuclear magnetic resonance parameters point of view. Our results are important for nuclear magnetic resonance measurements that target the 13C active nuclei in graphene samples.
CosmoSIS: Modular cosmological parameter estimation
Zuntz, J.; Paterno, M.; Jennings, E.; ...
2015-06-09
Cosmological parameter estimation is entering a new era. Large collaborations need to coordinate high-stakes analyses using multiple methods; furthermore such analyses have grown in complexity due to sophisticated models of cosmology and systematic uncertainties. In this paper we argue that modularity is the key to addressing these challenges: calculations should be broken up into interchangeable modular units with inputs and outputs clearly defined. Here we present a new framework for cosmological parameter estimation, CosmoSIS, designed to connect together, share, and advance development of inference tools across the community. We describe the modules already available in CosmoSIS, including CAMB, Planck, cosmicmore » shear calculations, and a suite of samplers. Lastly, we illustrate it using demonstration code that you can run out-of-the-box with the installer available at http://bitbucket.org/joezuntz/cosmosis« less
CosmoSIS: Modular cosmological parameter estimation
Zuntz, J.; Paterno, M.; Jennings, E.; Rudd, D.; Manzotti, A.; Dodelson, S.; Bridle, S.; Sehrish, S.; Kowalkowski, J.
2015-06-09
Cosmological parameter estimation is entering a new era. Large collaborations need to coordinate high-stakes analyses using multiple methods; furthermore such analyses have grown in complexity due to sophisticated models of cosmology and systematic uncertainties. In this paper we argue that modularity is the key to addressing these challenges: calculations should be broken up into interchangeable modular units with inputs and outputs clearly defined. Here we present a new framework for cosmological parameter estimation, CosmoSIS, designed to connect together, share, and advance development of inference tools across the community. We describe the modules already available in CosmoSIS, including CAMB, Planck, cosmic shear calculations, and a suite of samplers. Lastly, we illustrate it using demonstration code that you can run out-of-the-box with the installer available at http://bitbucket.org/joezuntz/cosmosis
Molybdenum disulfide and water interaction parameters.
Heiranian, Mohammad; Wu, Yanbin; Aluru, Narayana R
2017-09-14
Understanding the interaction between water and molybdenum disulfide (MoS2) is of crucial importance to investigate the physics of various applications involving MoS2 and water interfaces. An accurate force field is required to describe water and MoS2 interactions. In this work, water-MoS2 force field parameters are derived using the high-accuracy random phase approximation (RPA) method and validated by comparing to experiments. The parameters obtained from the RPA method result in water-MoS2 interface properties (solid-liquid work of adhesion) in good comparison to the experimental measurements. An accurate description of MoS2-water interaction will facilitate the study of MoS2 in applications such as DNA sequencing, sea water desalination, and power generation.
Molybdenum disulfide and water interaction parameters
NASA Astrophysics Data System (ADS)
Heiranian, Mohammad; Wu, Yanbin; Aluru, Narayana R.
2017-09-01
Understanding the interaction between water and molybdenum disulfide (MoS2) is of crucial importance to investigate the physics of various applications involving MoS2 and water interfaces. An accurate force field is required to describe water and MoS2 interactions. In this work, water-MoS2 force field parameters are derived using the high-accuracy random phase approximation (RPA) method and validated by comparing to experiments. The parameters obtained from the RPA method result in water-MoS2 interface properties (solid-liquid work of adhesion) in good comparison to the experimental measurements. An accurate description of MoS2-water interaction will facilitate the study of MoS2 in applications such as DNA sequencing, sea water desalination, and power generation.
Testing Saliency Parameters for Automatic Target Recognition
NASA Technical Reports Server (NTRS)
Pandya, Sagar
2012-01-01
A bottom-up visual attention model (the saliency model) is tested to enhance the performance of Automated Target Recognition (ATR). JPL has developed an ATR system that identifies regions of interest (ROI) using a trained OT-MACH filter, and then classifies potential targets as true- or false-positives using machine-learning techniques. In this project, saliency is used as a pre-processing step to reduce the space for performing OT-MACH filtering. Saliency parameters, such as output level and orientation weight, are tuned to detect known target features. Preliminary results are promising and future work entails a rigrous and parameter-based search to gain maximum insight about this method.
Supersymmetric parameter space of family symmetries
Velasco-Sevilla, L.
2008-11-23
In this talk I have emphasized the effects of considering departures from the minimal flavour violation conditions, in the context of CMSSM-like theories, introduced by boundary conditions at GUT scale from Family Symmetries. In [1] we have shown the results of running these conditions down to EW, where constraints from fermion masses and CKM matrix elements have been used. Only when the expansion parameter in the sdown-squark sector is relatively large it is possible to relax the lower limit from b{yields}s{gamma} on the universal gaugino mass. The expansion parameter associated with the slepton sector needs to be smaller than the analogous in the sdown-squark sector in order to satisfy the bound imposed by the decay of {tau}{yields}{mu}{mu}.
Renal parameter estimates in unrestrained dogs
NASA Technical Reports Server (NTRS)
Rader, R. D.; Stevens, C. M.
1974-01-01
A mathematical formulation has been developed to describe the hemodynamic parameters of a conceptualized kidney model. The model was developed by considering regional pressure drops and regional storage capacities within the renal vasculature. Estimation of renal artery compliance, pre- and postglomerular resistance, and glomerular filtration pressure is feasible by considering mean levels and time derivatives of abdominal aortic pressure and renal artery flow. Changes in the smooth muscle tone of the renal vessels induced by exogenous angiotensin amide, acetylcholine, and by the anaesthetic agent halothane were estimated by use of the model. By employing totally implanted telemetry, the technique was applied on unrestrained dogs to measure renal resistive and compliant parameters while the dogs were being subjected to obedience training, to avoidance reaction, and to unrestrained caging.
"Cosmological Parameters from Large Scale Structure"
NASA Technical Reports Server (NTRS)
Hamilton, A. J. S.
2005-01-01
This grant has provided primary support for graduate student Mark Neyrinck, and some support for the PI and for colleague Nick Gnedin, who helped co-supervise Neyrinck. This award had two major goals. First, to continue to develop and apply methods for measuring galaxy power spectra on large, linear scales, with a view to constraining cosmological parameters. And second, to begin try to understand galaxy clustering at smaller. nonlinear scales well enough to constrain cosmology from those scales also. Under this grant, the PI and collaborators, notably Max Tegmark. continued to improve their technology for measuring power spectra from galaxy surveys at large, linear scales. and to apply the technology to surveys as the data become available. We believe that our methods are best in the world. These measurements become the foundation from which we and other groups measure cosmological parameters.
Compressing measurements in quantum dynamic parameter estimation
NASA Astrophysics Data System (ADS)
Magesan, Easwar; Cooper, Alexandre; Cappellaro, Paola
2013-12-01
We present methods that can provide an exponential savings in the resources required to perform dynamic parameter estimation using quantum systems. The key idea is to merge classical compressive sensing techniques with quantum control methods to significantly reduce the number of signal coefficients that are required for reconstruction of time-varying parameters with high fidelity. We show that incoherent measurement bases and, more generally, suitable random measurement matrices can be created by performing simple control sequences on the quantum system. Random measurement matrices satisfying the restricted isometry property can be used efficiently to reconstruct signals that are sparse in any basis. Because many physical processes are approximately sparse in some basis, these methods can benefit a variety of applications such as quantum sensing and magnetometry with nitrogen-vacancy centers.
Perturbing Misiurewicz Parameters in the Exponential Family
NASA Astrophysics Data System (ADS)
Dobbs, Neil
2015-04-01
In one-dimensional real and complex dynamics, a map whose post-singular (or post-critical) set is bounded and uniformly repelling is often called a Misiurewicz map. In results hitherto, perturbing a Misiurewicz map is likely to give a non-hyperbolic map, as per Jakobson's Theorem for unimodal interval maps. This is despite genericity of hyperbolic parameters (at least in the interval setting). We show the contrary holds in the complex exponential family Misiurewicz maps are Lebesgue density points for hyperbolic parameters. As a by-product, we also show that Lyapunov exponents almost never exist for exponential Misiurewicz maps. The lower Lyapunov exponent is -∞ almost everywhere. The upper Lyapunov exponent is non-negative and depends on the choice of metric.
Bayesian parameter estimation for effective field theories
NASA Astrophysics Data System (ADS)
Wesolowski, S.; Klco, N.; Furnstahl, R. J.; Phillips, D. R.; Thapaliya, A.
2016-07-01
We present procedures based on Bayesian statistics for estimating, from data, the parameters of effective field theories (EFTs). The extraction of low-energy constants (LECs) is guided by theoretical expectations in a quantifiable way through the specification of Bayesian priors. A prior for natural-sized LECs reduces the possibility of overfitting, and leads to a consistent accounting of different sources of uncertainty. A set of diagnostic tools is developed that analyzes the fit and ensures that the priors do not bias the EFT parameter estimation. The procedures are illustrated using representative model problems, including the extraction of LECs for the nucleon-mass expansion in SU(2) chiral perturbation theory from synthetic lattice data.
Parameter studies for traveling wave coaxial launchers
Wu, A.Y. . Center for Electromechanics)
1991-01-01
The traveling wave coaxial launcher is a complex machine that requires very extensive parameter studies to optimize. Most of previous attempts to realize hypervelocity using coaxial launchers have failed partly due to inadequate analyses. This paper reports the results of very extensive air-core coaxial launcher parameter studies performed using computers. These results and the methodology introduced should help future researchers on this topic. In the course of studying the feasibility of accelerating a 1-kg projectile to 10 km/s with an 18 m air-core multiphase coaxial launcher powered by a rising frequency generator (RFGs), a complete simulation code based on the current filament method was developed. Results from the simulation code indicate rather chaotic behavior of an arbitrary coaxial launcher design. More fundamental studies were then conducted using various computer codes based on the current filament method.
Nonlinear, lumped parameter transformer model reduction technique
Degeneff, R.C.; Gutierrez, M.R.; Vakilian, M.
1995-04-01
Utility engineers often need nonlinear transformer models in order to investigate power system transient events. Methods exist to create accurate wideband reduced order linear transformer models, however, to date a method of creating a reduced order wideband nonlinear transformer model has not been presented. This paper describes a technique that starts with a detailed nonlinear transformer model used for insulation design studies and reduces its order so that it can be used conveniently in EMTP. The method is based on linearization of the core`s saturable characteristic during each solution time intervals. The technique uses Kron`s reduction approach in each solution time interval. It can be applied to any nonlinear lumped parameter network which uses electric parameter analogies (i.e., FEM networks). This paper outlines the nonlinear reduction technique. An illustrative example is given using the transient voltage response during saturation for a 785/345/34.5kV, YYD 500 MVA single phase auto transformer.
Functional diagnostic parameters for arteriovenous fistula.
Rajabi-Jagahrgh, Ehsan; Banerjee, Rupak K
2015-06-01
The inability to detect the arteriovenous fistula (AVF) dysfunction in a timely manner under the current surveillance programs, which are based on either diameter (d), flow rate (Q), or pressure (p) measurements, is one of the major challenges of dialysis treatment. Thus, our aim is to introduce new functional diagnostic parameters that can better predict AVF functionality status. Six AVFs were created between the femoral arteries and veins of three pigs, each pig having two AVFs on either limb. Flow fields and pressure drop (Δp) in AVFs were obtained via numerical analysis utilizing the CT scan and Doppler ultrasound data at 2D (D: days), 7D, and 28D postsurgery. The dataset included 16 (two pigs [four AVFs] for three time points, and one pig [two AVFs] for two time points) repeated measurements over time, and the statistical analysis was done using a mixed model. To evaluate the nature of pressure drop-flow relationships in AVFs, the Δp was correlated with the average velocity at proximal artery (v) and also the corresponding scaled velocity (v*) by the curvature ratio of anastomotic segment. Based on these relationships, two new functional diagnostic parameters, including the nonlinear pressure drop coefficient (Cp ; pressure drop divided by dynamic pressure at proximal artery) and the linear resistance index (R; pressure drop divided by velocity at proximal artery), were introduced. The diagnostic parameters that were calculated based on scaled velocity are represented as R* and Cp *. A marginal (P = 0.1) increase in d from 2D (5.4 ± 0.7 mm) to 7D (6.8 ± 0.7 mm), along with a significant increase in Q (2D: 967 ± 273 mL/min; 7D: 1943 ± 273 mL/min), was accompanied by an almost unchanged Δp over this time period (2D: 16.42 ± 4.6 mm Hg; 7D: 16.40 ± 4.6 mm Hg). However, the insignificant increase in d and Q from 7D to 28D (d = 7.8 ± 0.8 mm; Q = 2181 ± 378 mL/min) was accompanied by the elevation in Δp (24.6 ± 6.5 mm Hg). The functional diagnostic
Quantum parameter estimation with optimal control
NASA Astrophysics Data System (ADS)
Liu, Jing; Yuan, Haidong
2017-07-01
A pivotal task in quantum metrology, and quantum parameter estimation in general, is to design schemes that achieve the highest precision with the given resources. Standard models of quantum metrology usually assume that the dynamics is fixed and that the highest precision is achieved by preparing the optimal probe states and performing optimal measurements. However, in many practical experimental settings, additional controls are usually available to alter the dynamics. Here we propose to use optimal control methods for further improvement of the precision limit of quantum parameter estimation. We show that, by exploring the additional degree of freedom offered by the controls, a higher-precision limit can be achieved. In particular, we show that the precision limit under the controlled schemes can go beyond the constraints put by the coherent time, which is in contrast with the standard scheme where the precision limit is always bounded by the coherent time.
Quantum Fluctuations of a Superconductor Order Parameter.
Arutyunov, K Yu; Lehtinen, J S
2016-12-01
Tunneling I-V characteristics between very narrow titanium nanowires and "massive" superconducting aluminum were measured. The clear trend was observed: the thinner the titanium electrode, the broader the singularity at eV = Δ1(Al) + Δ2(Ti). The phenomenon can be explained by broadening of the gap edge of the quasi-one-dimensional titanium channels due to quantum fluctuations of the order parameter modulus |Δ2|. The range of the nanowire diameters, where the effect is pronounced, correlates with dimensions where the phase fluctuations of the complex superconducting order parameter Δ = |Δ|e(iφ), the quantum phase slips, broadening the R(T) dependencies, have been observed.
Fracture mechanics parameters for small fatigue cracks
NASA Technical Reports Server (NTRS)
Newman, J. C., Jr.
1992-01-01
This paper presents a review of some common small-crack test specimens, the underlying causes of the small-crack effect, and the fracture-mechanics parameters that have been used to correlate or predict their growth behavior. This review concentrates on continuum mechanics concepts and on the nonlinear behavior of small cracks. The paper reviews some stress-intensity factor solutions for small-crack test specimens and develops some simple elastic-plastic J integral and cyclic J integral expressions that include the influence of crack-closure. These parameters were applied to small-crack growth data on two aluminum alloys, and a fatigue life prediction methodology is demonstrated. For these materials, the crack-closure transient from the plastic wake was found to be the major factor in causing the small-crack effect.
Evaluation of the IRT Parameter Invariance Property for the MCAT.
ERIC Educational Resources Information Center
Kelkar, Vinaya; Wightman, Linda F.; Luecht, Richard M.
The purpose of this study was to investigate the viability of the property of parameter invariance for the one-parameter (1P), two-parameter (2P), and three-parameter (3P) item response theory (IRT) models for the Medical College Admissions Tests (MCAT). Invariance of item parameters across different gender, ethnic, and language groups and the…
Extraction of the Susy and Higgs parameters
Adam-Bourdarios, Claire
2010-02-10
If supersymmetry is discovered by the next generation of collider experiments, it will be crucial to determine its fundamental high-scale parameters. Three scenarios have been recently investigated by the SFitter collaboration : the case where the LHC 'only' measures a light Higgs like signal, the case where SUSY signal are discovered at the LHC, and the dream scenario, where LHC and ILC measurements can be combined.
Determination of inertial parameters using a dynamometer.
Son, Jongsang; Ryu, Jeseong; Kim, Jungyoon; Kim, Youngho
2014-01-01
In this study, a simple method based on the dynamic equation of motion was introduced to determine the moment of inertia using a commercial dynamometer, and an optimization technique was utilized to estimate inertial parameters with the determined moment of inertia. To evaluate the feasibility of the developed method, three different passive speeds (i.e. 240, 270 and 300°/s) were chosen to confirm whether the moment of inertia values are the same irrespective of angular speeds. Moreover, the estimated inertial parameters (i.e., the mass, center of mass and moment of inertia) of the elbow attachment and the disk-like 3 kg-weight were compared with solutions of uniform square cube and solid disk, respectively. As a result, the values of moments of inertia of the elbow attachment were 0.216 ± 0.017, 0.215 ± 0.016 and 0.216 ± 0.017 kg · m(2) at angular speeds of 240, 270 and 300°/s, respectively. The values of the moment of inertia of both the attachment and weight were 0.821 ± 0.054, 0.823 ± 0.058 and 0.824 ± 0.053 kg · m(2) at angular speeds of 240, 270 and 300°/s, respectively. There were no significant differences among the speeds. The estimated inertial parameters of the attachment or the weight were very similar to the theoretical values. Therefore, it is expected that the developed method has the potential to estimate inertial parameters of a human body segment and to improve the accuracy and reliability of the studies on human dynamics.
Surveillance of industrial processes with correlated parameters
White, Andrew M.; Gross, Kenny C.; Kubic, William L.; Wigeland, Roald A.
1996-01-01
A system and method for surveillance of an industrial process. The system and method includes a plurality of sensors monitoring industrial process parameters, devices to convert the sensed data to computer compatible information and a computer which executes computer software directed to analyzing the sensor data to discern statistically reliable alarm conditions. The computer software is executed to remove serial correlation information and then calculate Mahalanobis distribution data to carry out a probability ratio test to determine alarm conditions.
Surveillance of industrial processes with correlated parameters
White, A.M.; Gross, K.C.; Kubic, W.L.; Wigeland, R.A.
1996-12-17
A system and method for surveillance of an industrial process are disclosed. The system and method includes a plurality of sensors monitoring industrial process parameters, devices to convert the sensed data to computer compatible information and a computer which executes computer software directed to analyzing the sensor data to discern statistically reliable alarm conditions. The computer software is executed to remove serial correlation information and then calculate Mahalanobis distribution data to carry out a probability ratio test to determine alarm conditions. 10 figs.
Hansen Solubility Parameters for Octahedral Oligomeric Silsesquioxanes
2012-08-28
Sci. 2005, 97, 939-945. 40. Cataldo, F. On the Solubility Parameter of C60 and Higher Fullerenes. Fuller. Nanotub . Carbon Nanostruct. 2009, 17, 79-84...First, the cohesive energy for the naphthyl group is calculated by scaling the values for phenyl groups 17 by the number of carbons (10 for...mass of the peripheral carbon atom nearest to each silicon atom actually falls within the cube, so each corner of the cube contains a region that is
Beyond six parameters: Extending Λ CDM
NASA Astrophysics Data System (ADS)
Di Valentino, Eleonora; Melchiorri, Alessandro; Silk, Joseph
2015-12-01
Cosmological constraints are usually derived under the assumption of a six-parameter Λ CDM theoretical framework or simple one-parameter extensions. In this paper we present, for the first time, cosmological constraints in a significantly extended scenario, varying up to 12 cosmological parameters simultaneously, including the sum of neutrino masses, the neutrino effective number, the dark energy equation of state, the gravitational wave background and the running of the spectral index of primordial perturbations. Using the latest Planck 2015 data release (with polarization), we found no significant indication for extensions to the standard Λ CDM scenario, with the notable exception of the angular power spectrum lensing amplitude, Alens , which is larger than the expected value at more than 2 standard deviations, even when combining the Planck data with BAO and supernovae type Ia external data sets. In our extended cosmological framework, we find that a combined Planck+BAO analysis constrains the value of the rms density fluctuation parameter to σ8=0.781-0.063+0.065 at 95 % C.L., helping to relieve the possible tensions with the CFHTlenS cosmic shear survey. We also find a lower value for the reionization optical depth τ =0.058-0.043+0.040 at 95 % C.L. with respect to the one derived under the assumption of Λ CDM . The scalar spectral index nS is now compatible with a Harrison-Zeldovich spectrum to within 2.5 standard deviations. Combining the Planck data set with the Hubble Space Telescope prior on the Hubble constant provides a value for the equation of state w <-1 at more than 2 standard deviations, while the neutrino effective number is fully compatible with the expectations of the standard three neutrino framework.
Telemetry methods for monitoring physiological parameters
NASA Technical Reports Server (NTRS)
Fryer, T. B.; Sandler, H.
1982-01-01
The use of telemetry to monitor various physiological functions is discussed. The advantages of the technique and the parameters that it can monitor are assessed, and the main telemetry systems, including pressure telemetry, flow telemetry, and multichannel telemetry, are detailed. Human applications of implanted flow transducers, total implant versus backpack telemetry, the use of power sources and integrated circuits in telemetry, and the future prospects of the technique in hypertension treatment and research are discussed.
Parameter Uncertainty for Repository Thermal Analysis
Hardin, Ernest; Hadgu, Teklu; Greenberg, Harris; Dupont, Mark
2015-10-01
This report is one follow-on to a study of reference geologic disposal design concepts (Hardin et al. 2011a). Based on an analysis of maximum temperatures, that study concluded that certain disposal concepts would require extended decay storage prior to emplacement, or the use of small waste packages, or both. The study used nominal values for thermal properties of host geologic media and engineered materials, demonstrating the need for uncertainty analysis to support the conclusions. This report is a first step that identifies the input parameters of the maximum temperature calculation, surveys published data on measured values, uses an analytical approach to determine which parameters are most important, and performs an example sensitivity analysis. Using results from this first step, temperature calculations planned for FY12 can focus on only the important parameters, and can use the uncertainty ranges reported here. The survey of published information on thermal properties of geologic media and engineered materials, is intended to be sufficient for use in generic calculations to evaluate the feasibility of reference disposal concepts. A full compendium of literature data is beyond the scope of this report. The term “uncertainty” is used here to represent both measurement uncertainty and spatial variability, or variability across host geologic units. For the most important parameters (e.g., buffer thermal conductivity) the extent of literature data surveyed samples these different forms of uncertainty and variability. Finally, this report is intended to be one chapter or section of a larger FY12 deliverable summarizing all the work on design concepts and thermal load management for geologic disposal (M3FT-12SN0804032, due 15Aug2012).
CHAMP: Changepoint Detection Using Approximate Model Parameters
2014-06-01
detecting changes in the parameters and mod- els that generate observed data. Commonly cited examples include detecting changes in stock market behavior [4...experimentally verified using artifi- cially generated data and are compared to those of Fearnhead and Liu [5]. 2 Related work Hidden Markov Models ( HMMs ) are...largely the de facto tool of choice when analyzing time series data, but the standard HMM formulation has several undesirable properties. The number of
Structure parameters in molecular tunneling ionization theory
NASA Astrophysics Data System (ADS)
Wang, Jun-Ping; Li, Wei; Zhao, Song-Feng
2014-04-01
We extracted the accurate structure parameters in molecular tunneling ionization theory (so called MO-ADK theory) for 22 selected linear molecules including some inner orbitals. The molecular wave functions with the correct asymptotic behavior are obtained by solving the time-independent Schrödinger equation with B-spline functions and molecular potentials numerically constructed using the modified Leeuwen-Baerends (LBα) model.
Operational parameters for the superconducting cavity maser
NASA Astrophysics Data System (ADS)
Wang, R. T.; Dick, G. J.; Strayer, D. M.
1989-05-01
Tests of the superconducting cavity maser (SCM) ultra-stable frequency source have been made for the first time using a hydrogen maser for a frequency reference. In addition to characterizing the frequency stability, the sensitivity of the output frequency to several crucial parameters was determined for various operating conditions. Based on this determination, the refrigeration and thermal control systems of the SCM were modified. Subsequent tests showed substantially improved performance, especially at the longest averaging times.
Estimating Grammar Parameters using Bounded Memory
2002-01-01
algorithm, called HOLA , for estimating the parameters of SCFGs that computes summary statis- tics for each string as it is observed and then discards...the string. The memory used by HOLA is bounded by the size of the grammar, not by the amount of training data. Empirical results show that HOLA ...of the grammar improves monotonically as more computation is allocated to learning. This paper introduces an algorithm called HOLA that satisfies
Aerodynamics as a subway design parameter
NASA Technical Reports Server (NTRS)
Kurtz, D. W.
1976-01-01
A parametric sensitivity study has been performed on the system operational energy requirement in order to guide subway design strategy. Aerodynamics can play a dominant or trivial role, depending upon the system characteristics. Optimization of the aerodynamic parameters may not minimize the total operational energy. Isolation of the station box from the tunnel and reduction of the inertial power requirements pay the largest dividends in terms of the operational energy requirement.
Updated MDRIZTAB Parameters for ACS/WFC
NASA Astrophysics Data System (ADS)
Hoffman, S. L.; Avila, R. J.
2017-03-01
The Mikulski Archive for Space Telescopes (MAST) pipeline performs geometric distortion corrections, associated image combinations, and cosmic ray rejections with AstroDrizzle. The MDRIZTAB reference table contains a list of relevant parameters that controls this program. This document details our photometric analysis of Advanced Camera for Surveys Wide Field Channel (ACS/WFC) data processed by AstroDrizzle. Based on this analysis, we update the MDRIZTAB table to improve the quality of the drizzled products delivered by MAST.
Parameter estimation techniques for LTP system identification
NASA Astrophysics Data System (ADS)
Nofrarias Serra, Miquel
LISA Pathfinder (LPF) is the precursor mission of LISA (Laser Interferometer Space Antenna) and the first step towards gravitational waves detection in space. The main instrument onboard the mission is the LTP (LISA Technology Package) whose scientific goal is to test LISA's drag-free control loop by reaching a differential acceleration noise level between two masses in √ geodesic motion of 3 × 10-14 ms-2 / Hz in the milliHertz band. The mission is not only challenging in terms of technology readiness but also in terms of data analysis. As with any gravitational wave detector, attaining the instrument performance goals will require an extensive noise hunting campaign to measure all contributions with high accuracy. But, opposite to on-ground experiments, LTP characterisation will be only possible by setting parameters via telecommands and getting a selected amount of information through the available telemetry downlink. These two conditions, high accuracy and high reliability, are the main restrictions that the LTP data analysis must overcome. A dedicated object oriented Matlab Toolbox (LTPDA) has been set up by the LTP analysis team for this purpose. Among the different toolbox methods, an essential part for the mission are the parameter estimation tools that will be used for system identification during operations: Linear Least Squares, Non-linear Least Squares and Monte Carlo Markov Chain methods have been implemented as LTPDA methods. The data analysis team has been testing those methods with a series of mock data exercises with the following objectives: to cross-check parameter estimation methods and compare the achievable accuracy for each of them, and to develop the best strategies to describe the physics underlying a complex controlled experiment as the LTP. In this contribution we describe how these methods were tested with simulated LTP-like data to recover the parameters of the model and we report on the latest results of these mock data exercises.
146 Kepler-Lamost targets fundamental parameters
NASA Astrophysics Data System (ADS)
Wu, Yaqian
2015-08-01
Accurate stellar fundamental parameters with high precision are important for distinguishing stellar populationand star study.Turn-off stars are in the relatively vital stellar evolution state. Studying turn-off stars can help us to have a more comprehensive understand of the stellar physics.With the help of observation provided by Lamost project, we obtain atmospheric parameters of 146 turn-off stars from LSP3 pipeline. Combined with stellar pulsation data from Kepler, we can get asteroseismic characteristic of stars,such as Δν and νmax.In this paper,we constructed a grid of evolutionary models, with the mass range from 0.8 to 2.5 M⊙ and metallicities Zini = 0.0085, 0.0105, 0.0130, 0.0165, 0.0200, 0.0250, 0.0300, 0.0400 (i.e.[Fe/H] from -0.3 to 0.4dex).All evolutionary tracks were started in the pre-main sequence birth line and ended at the base of Red Giant Branch.Based on the stellar model grid we constructed,as well as Kepler-Lamost observations, we obtained fundamental parameters of 146 around turn-off stars, and found that 112 targets lied in turn-off state or in the Main Sequence,15 targets are subgiant stars and 7 targets have evolved to the red giants stage.Then we use pulsation code(JIG) of Guenther to extract theorical individual frequencies and calculate theorical Δν.Meanwhile we obtained more precise fundamental parameters of these stars.
Identifying Crucial Parameter Correlations Maintaining Bursting Activity
Doloc-Mihu, Anca; Calabrese, Ronald L.
2014-01-01
Recent experimental and computational studies suggest that linearly correlated sets of parameters (intrinsic and synaptic properties of neurons) allow central pattern-generating networks to produce and maintain their rhythmic activity regardless of changing internal and external conditions. To determine the role of correlated conductances in the robust maintenance of functional bursting activity, we used our existing database of half-center oscillator (HCO) model instances of the leech heartbeat CPG. From the database, we identified functional activity groups of burster (isolated neuron) and half-center oscillator model instances and realistic subgroups of each that showed burst characteristics (principally period and spike frequency) similar to the animal. To find linear correlations among the conductance parameters maintaining functional leech bursting activity, we applied Principal Component Analysis (PCA) to each of these four groups. PCA identified a set of three maximal conductances (leak current, Leak; a persistent K current, K2; and of a persistent Na+ current, P) that correlate linearly for the two groups of burster instances but not for the HCO groups. Visualizations of HCO instances in a reduced space suggested that there might be non-linear relationships between these parameters for these instances. Experimental studies have shown that period is a key attribute influenced by modulatory inputs and temperature variations in heart interneurons. Thus, we explored the sensitivity of period to changes in maximal conductances of Leak, K2, and P, and we found that for our realistic bursters the effect of these parameters on period could not be assessed because when varied individually bursting activity was not maintained. PMID:24945358
Identifying tectonic parameters that influence tsunamigenesis
NASA Astrophysics Data System (ADS)
van Zelst, Iris; Brizzi, Silvia; van Dinther, Ylona; Heuret, Arnauld; Funiciello, Francesca
2017-04-01
The role of tectonics in tsunami generation is at present poorly understood. However, the fact that some regions produce more tsunamis than others indicates that tectonics could influence tsunamigenesis. Here, we complement a global earthquake database that contains geometrical, mechanical, and seismicity parameters of subduction zones with tsunami data. We statistically analyse the database to identify the tectonic parameters that affect tsunamigenesis. The Pearson's product-moment correlation coefficients reveal high positive correlations of 0.65 between, amongst others, the maximum water height of tsunamis and the seismic coupling in a subduction zone. However, these correlations are mainly caused by outliers. The Spearman's rank correlation coefficient results in more robust correlations of 0.60 between the number of tsunamis in a subduction zone and subduction velocity (positive correlation) and the sediment thickness at the trench (negative correlation). Interestingly, there is a positive correlation between the latter and tsunami magnitude. In an effort towards multivariate statistics, a binary decision tree analysis is conducted with one variable. However, this shows that the amount of data is too scarce. To complement this limited amount of data and to assess physical causality of the tectonic parameters with regard to tsunamigenesis, we conduct a numerical study of the most promising parameters using a geodynamic seismic cycle model. We show that an increase in sediment thickness on the subducting plate results in a shift in seismic activity from outerrise normal faults to splay faults. We also show that the splay fault is the preferred rupture path for a strongly velocity strengthening friction regime in the shallow part of the subduction zone, which increases the tsunamigenic potential. A larger updip limit of the seismogenic zone results in larger vertical surface displacement.
Nonlocal Parameters for Multiparticle Density Matrices
NASA Astrophysics Data System (ADS)
Linden, N.; Popescu, S.; Sudbery, A.
1999-07-01
As far as entanglement is concerned, two density matrices of n particles are completely equivalent if one can be transformed into the other by local unitary transformations. We present two methods to find whether or not two generic density matrices of arbitrary numbers of spin-1/2 particles are equivalent. Both methods describe density matrices in terms of a finite number of invariant parameters.
Target parameter and error estimation using magnetometry
NASA Astrophysics Data System (ADS)
Norton, S. J.; Witten, A. J.; Won, I. J.; Taylor, D.
The problem of locating and identifying buried unexploded ordnance from magnetometry measurements is addressed within the context of maximum likelihood estimation. In this approach, the magnetostatic theory is used to develop data templates, which represent the modeled magnetic response of a buried ferrous object of arbitrary location, iron content, size, shape, and orientation. It is assumed that these objects are characterized both by a magnetic susceptibility representing their passive response to the earth's magnetic field and by a three-dimensional magnetization vector representing a permanent dipole magnetization. Analytical models were derived for four types of targets: spheres, spherical shells, ellipsoids, and ellipsoidal shells. The models can be used to quantify the Cramer-Rao (error) bounds on the parameter estimates. These bounds give the minimum variance in the estimated parameters as a function of measurement signal-to-noise ratio, spatial sampling, and target characteristics. For cases where analytic expressions for the Cramer-Rao bounds can be derived, these expressions prove quite useful in establishing optimal sampling strategies. Analytic expressions for various Cramer-Rao bounds have been developed for spherical- and spherical shell-type objects. An maximum likelihood estimation algorithm has been developed and tested on data acquired at the Magnetic Test Range at the Naval Explosive Ordnance Disposal Tech Center in Indian Head, Maryland. This algorithm estimates seven target parameters. These parameters are the three Cartesian coordinates (x, y, z) identifying the buried ordnance's location, the three Cartesian components of the permanent dipole magnetization vector, and the equivalent radius of the ordnance assuming it is a passive solid iron sphere.
Parameters of a runaway electron avalanche
NASA Astrophysics Data System (ADS)
Oreshkin, E. V.; Barengolts, S. A.; Oreshkin, V. I.; Mesyats, G. A.
2017-10-01
The features of runaway electron avalanches developing in air at different pressures are investigated using a three-dimensional numerical simulation. The simulation results indicate that an avalanche of this type can be characterized, besides the time and length of its exponential growth, by the propagation velocity and by the average kinetic energy of the runaway electrons. It is shown that these parameters obey the similarity laws applied to gas discharges.
Comparison of Dam Breach Parameter Estimators
2008-01-01
from a large storm in 1975 (CEATI). The dam was constructed of a clay core containing shale. The upstream and downstream fill was homogeneous earth ...Comparison of Dam Breach Parameter Estimators D. Michael Gee1 1 Senior Hydraulic Engineer, Corps of Engineers Hydrologic Engineering...Center, 609 2nd St., Davis, CA 95616; email: michael.gee@usace.army.mil. ABSTRACT Analytical techniques for the estimation of dam breach
Equations For Selected Fracture-Mechanics Parameters
NASA Technical Reports Server (NTRS)
Bubsey, Raymond T.; Orange, Thomas W.; Pierce, William S.; Shannon, John L., Jr.
1994-01-01
Equations describing crack-mouth-opening displacements, stress-intensity factors, and related fracture-mechanics parameters of chevron-notched short bar and rod specimens presented in report. Equations in forms suitable for determining fracture toughnesses from maximum loads, for determining crack-extension-resistance curves, and for setting sensitivities of testing instruments. Useful in facilitating testing and interpretation of data from tests of brittle metals, ceramics, and glasses, formed into chevron-notched specimens for fracture testing according to concepts.
Mechanical Four-Pole Parameters: Transmission Matrices
1976-04-19
theory a. an effective means of analyzing four-terminal networksl•; more recently, with mchanical notetion, they have been used to solve vibra- tion...they are driven and terminated ao that only symmetrical vibrations about their mid- points are excited. Four-pole parameter theory is actually a simple... theory of transmission miatzices. When more complicated situations are encountered than those mentioned hitherto, four-pole theory becomes inadequate
Operational parameters for the superconducting cavity maser
NASA Technical Reports Server (NTRS)
Wang, R. T.; Dick, G. J.; Strayer, D. M.
1989-01-01
Tests of the superconducting cavity maser (SCM) ultra-stable frequency source have been made for the first time using a hydrogen maser for a frequency reference. In addition to characterizing the frequency stability, the sensitivity of the output frequency to several crucial parameters was determined for various operating conditions. Based on this determination, the refrigeration and thermal control systems of the SCM were modified. Subsequent tests showed substantially improved performance, especially at the longest averaging times.
Differential interferometric measurement of mirror shape parameters
NASA Astrophysics Data System (ADS)
Robinson, Brian
This project was inspired by the need for a remote method to accurately measure radius of curvature of mirrors tested under the NASA Advanced Mirror System Demonstrator program. Under this program, off axis parabolas (subscale candidates for James Webb Space Telescope optical elements) were tested under cryo-vac conditions. A remote, differential interferometric method is presented for measuring the shape parameters of general aspheric mirrors. The result of measurement is the assignment of best-fit values to a set of parameters that characterize the shape of the surface. If the mirror is nominally a conic of rotation, for example, the measurement yields the radius of curvature and conic constant. The method involves testing the optic in an interferometric center-of-curvature null configuration but can easily be extended to include conjugate null tests. During the measurement, known translational misalignments are introduced and the effects on the optical path length function are measured using a phase-shifting interferometer. Based on the nominal mirror shape, a model function is defined, up to a set of free shape parameters. The mirror shape parameters are regressed, based on the interferometric data, from this model. This differential measurement method works for on- and off-axis mirrors of all shapes and can be applied remotely as long as the mirror is mounted on an actuated stage. Hence, this measurement method would work well in a cryogenic testing situation. We have successfully applied the method to the case of an off-axis parabola with a nominal radius of curvature of 304.8 mm, a diameter of 76.17 mm, and a pupil offset of -89.40 mm.
Regularization Parameter Selections via Generalized Information Criterion
Zhang, Yiyun; Li, Runze; Tsai, Chih-Ling
2009-01-01
We apply the nonconcave penalized likelihood approach to obtain variable selections as well as shrinkage estimators. This approach relies heavily on the choice of regularization parameter, which controls the model complexity. In this paper, we propose employing the generalized information criterion (GIC), encompassing the commonly used Akaike information criterion (AIC) and Bayesian information criterion (BIC), for selecting the regularization parameter. Our proposal makes a connection between the classical variable selection criteria and the regularization parameter selections for the nonconcave penalized likelihood approaches. We show that the BIC-type selector enables identification of the true model consistently, and the resulting estimator possesses the oracle property in the terminology of Fan and Li (2001). In contrast, however, the AIC-type selector tends to overfit with positive probability. We further show that the AIC-type selector is asymptotically loss efficient, while the BIC-type selector is not. Our simulation results confirm these theoretical findings, and an empirical example is presented. Some technical proofs are given in the online supplementary material. PMID:20676354
Software Computes Tape-Casting Parameters
NASA Technical Reports Server (NTRS)
deGroh, Henry C., III
2003-01-01
Tcast2 is a FORTRAN computer program that accelerates the setup of a process in which a slurry containing metal particles and a polymeric binder is cast, to a thickness regulated by a doctor blade, onto fibers wound on a rotating drum to make a green precursor of a metal-matrix/fiber composite tape. Before Tcast2, setup parameters were determined by trial and error in time-consuming multiple iterations of the process. In Tcast2, the fiber architecture in the final composite is expressed in terms of the lateral distance between fibers and the thickness-wise distance between fibers in adjacent plies. The lateral distance is controlled via the manner of winding. The interply spacing is controlled via the characteristics of the slurry and the doctor-blade height. When a new combination of fibers and slurry is first cast and dried to a green tape, the shrinkage from the wet to the green condition and a few other key parameters of the green tape are measured. These parameters are provided as input to Tcast2, which uses them to compute the doctor-blade height and fiber spacings needed to obtain the desired fiber architecture and fiber volume fraction in the final composite.
Line Parameters for the Oxygen a Band
NASA Astrophysics Data System (ADS)
Benner, D. Chris; Devi, V. Malathy; Hoo, Jiajun; Sung, Keeyoon; Hodges, Joseph T.; Long, David A.; Bui, Thinh; Rupasinghe, Priyanka Milinda; Okumura, Mitchio
2013-06-01
Simulation of the oxygen A band to a level that is sufficient for accurate studies of the Earth's atmosphere is complex in that not only are Doppler and Lorentz broadening important, but also Dicke narrowing, pressure shifts, line mixing and speed dependence. In addition all of these parameters except the speed dependence require temperature dependence parameters as well. To measure all of the required line parameters with the multispectrum nonlinear least squares fitting technique, spectra were acquired by the Bruker IFS125-HR Fourier Transform Spectrometer at the Jet Propulsion Laboratory in combination with various multpass cells, a cavity ring down spectrometer at NIST and a photoacoustic spectrometer at the California Institute of Technology. The combination of the data from these three very different types of spectrometers in a single simultaneous fit of the entire band enables the measurement of all of these quantities. The results to this point will be summarized. D. Chris Benner, C. P. Rinsland, V. M. Devi, M. A. H. Smith, and D. Atkins, JQSRT 1995;53:705-21. Support for the work at William and Mary was provided by JPL and the NIST Greenhouse Gas Measurements and Climate Research Program. Part of the research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology under contracts with National Aeronautics and Space Administration. Support for the work at NIST was provided by at the NIST Greenhouse Gas Measurements and Climate Research Program and an Innovations in Measurement Sciences (IMS) award.
Associations between sleep parameters and food reward.
McNeil, Jessica; Cadieux, Sébastien; Finlayson, Graham; Blundell, John E; Doucet, Éric
2015-06-01
This study examined the effects of acute, isocaloric aerobic and resistance exercise on different sleep parameters, and whether changes in these sleep parameters between sessions were related to next morning food reward. Fourteen men and women (age: 21.9 ± 2.7 years; body mass index: 22.7 ± 1.9 kg m(-) ²) participated in three randomized crossover sessions: aerobic exercise; resistance exercise; and sedentary control. Target exercise energy expenditure was matched at 4 kcal kg(-1) of body weight, and performed at 70% of VO2peak or 70% of 1 repetition-maximal. Sleep was measured (accelerometry) for 22 h following each session. The 'wanting' for visual food cues (validated computer task) was assessed the next morning. There were no differences in sleep parameters and food 'wanting' between conditions. Decreases in sleep duration and earlier wake-times were significantly associated with increased food 'wanting' between sessions (P = 0.001). However, these associations were no longer significant after controlling for elapsed time between wake-time and the food reward task. These findings suggest that shorter sleep durations and earlier wake-times are associated with increased food reward, but these associations are driven by elapsed time between awakening and completion of the food reward task.
Electromagnetic radiation--parameters for risk assessment.
Israel, M S
1994-01-01
The assessment of human exposure to electromagnetic radiation (EMR) under occupational and environmental conditions is one of the most complicated problems of public health science and practice. The problems arise from the very essence of EMR, the conflicting requirements of the measuring instruments, the complexity of electromagnetic waves in the working environment, and the still unknown mechanisms of their biological effects. One of the best ways to develop methods and criteria for exposure assessment of EMR is to determine the electromagnetic field parameters as well as those related to the quantity of energy absorbed by the organism. Definitions have been given mainly regarding tissues' electric and magnetic characteristics, and regarding the energetic parameters of EMR, without description of concrete methods of exposure assessment in different complicated cases of wide-ranging impulsive, non-homogeneous radiation. The best parameters for exposure assessment are the Specific Absorption Rate (SAR), the energetic loading of the human body (the electromagnetic dose W), the time-weighted average (TWA), using time-dependent hygienic norms and standards.
Order Parameter Theory for Anderson Localization
NASA Astrophysics Data System (ADS)
Dobrosavljevic, Vladimir; Pastor, Andrei
2001-03-01
The Anderson metal-insulator transition is well known to display many similarities to standard critical phenomena, yet an obvious order parameter has remained difficult to find. In this work, we demonstrate that a relevant local order parameter can be defined and self-consistently determined, providing a simple and physically transparent picture of the Anderson transition. Our formulation proceeds in close analogy with the well-known coherent potential approximation (CPA), with a small but crucial difference. Our theory self-consistently calculates not the average but instead the typical local density of states, which serves as the order parameter, and is found to vanish at the Anderson transition. As a result, we show that both the escape rate of an electron from a given site, and the conductivity vanish in the insulating phase, which emerges for disorder strengths comparable to the electronic bandwidth. Due to the local character of our theory, it can easily be combined with standard dynamical mean-field approaches for strong electronic correlations, thus opening an attractive avenue for the study of the interplay (A. A. Pastor and V. Dobrosavljevic, Phys. Rev. Lett. 83), 4642 (1999) ( V. Dobrosavljevic and G. Kotliar, Phys. Rev. Lett. 78), 3943 (1997) of interaction and disorder.
Visual parameter optimisation for biomedical image processing.
Pretorius, A J; Zhou, Y; Ruddle, R A
2015-01-01
Biomedical image processing methods require users to optimise input parameters to ensure high-quality output. This presents two challenges. First, it is difficult to optimise multiple input parameters for multiple input images. Second, it is difficult to achieve an understanding of underlying algorithms, in particular, relationships between input and output. We present a visualisation method that transforms users' ability to understand algorithm behaviour by integrating input and output, and by supporting exploration of their relationships. We discuss its application to a colour deconvolution technique for stained histology images and show how it enabled a domain expert to identify suitable parameter values for the deconvolution of two types of images, and metrics to quantify deconvolution performance. It also enabled a breakthrough in understanding by invalidating an underlying assumption about the algorithm. The visualisation method presented here provides analysis capability for multiple inputs and outputs in biomedical image processing that is not supported by previous analysis software. The analysis supported by our method is not feasible with conventional trial-and-error approaches.
Maximum likelihood estimation of population parameters
Fu, Y.X.; Li, W.H. )
1993-08-01
One of the most important parameters in population genetics is [theta] = 4N[sub e][mu] where N[sub e] is the effective population size and [mu] is the rate of mutation per gene per generation. The authors study two related problems, using the maximum likelihood method and the theory of coalescence. One problem is the potential improvement of accuracy in estimating the parameter [theta] over existing methods and the other is the estimation of parameter [lambda] which is the ratio of two [theta]'s. The minimum variances serve as the lower bounds of the variances of all possible estimates of [theta] in practice. The authors then show that Watterson's estimate of [theta] based on the number of segregating sites is asymptotically an optimal estimate of [theta]. However, for a finite sample of sequences, substantial improvement over Watterson's estimate is possible when [theta] is large. The maximum likelihood estimate of [lambda] = [theta][sub 1]/[theta][sub 2] is obtained and the properties of the estimate are discussed. 9 refs., 3 figs., 3 tabs.
Neutrino mass implications for muon decay parameters
Erwin, Rebecca J.; Kile, Jennifer; Ramsey-Musolf, Michael J.; Wang Peng
2007-02-01
We use the scale of neutrino mass and naturalness considerations to obtain model-independent expectations for the magnitude of possible contributions to muon decay Michel parameters from new physics above the electroweak symmetry-breaking scale. Focusing on Dirac neutrinos, we obtain a complete basis of dimension four and dimension six effective operators that are invariant under the gauge symmetry of the standard model and that contribute to both muon decay and neutrino mass. We show that - in the absence of fine tuning - the most stringent neutrino-mass naturalness bounds on chirality-changing vector operators relevant to muon decay arise from one-loop operator mixing. The bounds we obtain on their contributions to the Michel parameters are 2 orders of magnitude stronger than bounds previously obtained in the literature. In addition, we analyze the implications of one-loop matching considerations and find that the expectations for the size of various scalar and tensor contributions to the Michel parameters are considerably smaller than derived from previous estimates of two-loop operator mixing. We also show, however, that there exist gauge-invariant operators that generate scalar and tensor contributions to muon decay but whose flavor structure allows them to evade neutrino-mass naturalness bounds. We discuss the implications of our analysis for the interpretation of muon-decay experiments.
Parameter Estimation of Spacecraft Fuel Slosh Model
NASA Technical Reports Server (NTRS)
Gangadharan, Sathya; Sudermann, James; Marlowe, Andrea; Njengam Charles
2004-01-01
Fuel slosh in the upper stages of a spinning spacecraft during launch has been a long standing concern for the success of a space mission. Energy loss through the movement of the liquid fuel in the fuel tank affects the gyroscopic stability of the spacecraft and leads to nutation (wobble) which can cause devastating control issues. The rate at which nutation develops (defined by Nutation Time Constant (NTC can be tedious to calculate and largely inaccurate if done during the early stages of spacecraft design. Pure analytical means of predicting the influence of onboard liquids have generally failed. A strong need exists to identify and model the conditions of resonance between nutation motion and liquid modes and to understand the general characteristics of the liquid motion that causes the problem in spinning spacecraft. A 3-D computerized model of the fuel slosh that accounts for any resonant modes found in the experimental testing will allow for increased accuracy in the overall modeling process. Development of a more accurate model of the fuel slosh currently lies in a more generalized 3-D computerized model incorporating masses, springs and dampers. Parameters describing the model include the inertia tensor of the fuel, spring constants, and damper coefficients. Refinement and understanding the effects of these parameters allow for a more accurate simulation of fuel slosh. The current research will focus on developing models of different complexity and estimating the model parameters that will ultimately provide a more realistic prediction of Nutation Time Constant obtained through simulation.
Bias in parameter estimation of form errors
NASA Astrophysics Data System (ADS)
Zhang, Xiangchao; Zhang, Hao; He, Xiaoying; Xu, Min
2014-09-01
The surface form qualities of precision components are critical to their functionalities. In precision instruments algebraic fitting is usually adopted and the form deviations are assessed in the z direction only, in which case the deviations at steep regions of curved surfaces will be over-weighted, making the fitted results biased and unstable. In this paper the orthogonal distance fitting is performed for curved surfaces and the form errors are measured along the normal vectors of the fitted ideal surfaces. The relative bias of the form error parameters between the vertical assessment and orthogonal assessment are analytically calculated and it is represented as functions of the surface slopes. The parameter bias caused by the non-uniformity of data points can be corrected by weighting, i.e. each data is weighted by the 3D area of the Voronoi cell around the projection point on the fitted surface. Finally numerical experiments are given to compare different fitting methods and definitions of the form error parameters. The proposed definition is demonstrated to show great superiority in terms of stability and unbiasedness.
Propellant Sloshing Parameter Extraction from CFD Analysis
NASA Technical Reports Server (NTRS)
Yang, H. Q.; Peugeot, John
2010-01-01
Propellant slosh is a potential source of disturbance critical to the stability of space vehicle. The sloshing dynamics is typically represented by a mechanical model of spring mass damper. This mechanical model is then included in the equation of motion of the entire vehicle for Guidance, Navigation and Control analysis. The typical parameters required by the mechanical model include natural frequency of the sloshing, sloshing mass, sloshing mass center coordinates, and critical damping coefficient. During the 1960 s US space program, these parameters were either computed from analytical solution for simple geometry or by experimental testing for the sub-scaled configurations. The purpose of this work is to demonstrate the soundness of a CFD approach in modeling the detailed fluid dynamics of tank sloshing and the excellent accuracy in extracting mechanical properties for different tank configurations and at different fill levels. The validation studies included straight cylinder against analytical solution, and sub-scaled Centaur LOX and LH2 tanks with and without baffles against experimental results. This effort shows that CFD technology can provide accurate mechanical parameters for any tank configuration, and is especially valuable to the future design of propellant tanks, as there is no previous experimental data available for the same size and configuration.
Reproductive Parameters of the Dogo Argentino Bitch
González, Griselda; Gorla, Nora; Guendulain, Corina
2013-01-01
The Dogo Argentino (DA) is the first and only breed from Argentina recognized worldwide. Although its morphologic features have been well established, its normal reproductive parameters are not clearly known. The aim of this study was to determine the main DA bitch reproductive parameters. One hundred and forty-nine surveys were obtained from breeders from Córdoba province, Argentina: one for each intact DA bitch from 1 to 14 years old. The DA bitch reached puberty at an average of 8.93 months. The mean duration of vulval bleeding found in this study was 11.11 days. The clinical signs characteristic for proestrous-estrous were vulval edema (89.93%), bleeding during the time of mating (32.21%), holding the tail to the side (95.30%), and docility during mating (85.91%). DA bitches had a whelping rate of 84%. Out of 299 pregnancies, 89.30% exhibited a normal parturition, 6.69% presented dystocia, 2.68% needed Cesarean section, and 1.34% aborted. In conclusion, the reproductive parameters of the DA bitch are similar to those identified for other large breeds. DA often showed a prolonged vulval bleeding longer than proestrus. Its high whelping rate, its low incidence of dystocia, and its good maternal ability define the DA as a good reproductive breed with normal reproductive functions. PMID:26464905
Transmission parameters of vector-borne infections.
Desenclos, J-C
2011-11-01
Vector-borne infections are those for which the agent (virus, bacteria, or parasite) is transmitted from an infected host (animal or human) to another by a hematophagous arthropod (mosquito, tick, lice, and flea). Two parameters quantify the dynamics of a vector-borne infection: (1) the basic reproductive number (R(0)) that is the mean number of secondary infections transmitted from an infectious host by the bite of the vector and (2) the generation interval that explores the speed of occurrence of secondary cases transmitted by the vector from an infectious case. In a population in which some individuals are immune, the parameter of interest is the net reproduction number (R) function of R(0) and the proportion of those immune. For vector-borne infectious agents, R(0) is determined by the number of vectors in contact with a given individual (m), the number of a given vector bites/day on individuals (a), the daily survival rate of the vector (p), the duration of the pathogenic agent's development cycle in the vector (n), the proportion of infected vectors that are really infectious (vector competence) (b), the probability of agent transmission from a viremic individual to the vector for one bite (c) and the host's infectiousness clearance rate (r) with R(0)=(m. a(2). p(n)/-lnp). b. c/r. These parameters are related to geographic and climatic conditions and cannot, therefore, be extrapolated from one situation to another.
Kinetic parameters for source driven systems
Dulla, S.; Ravetto, P.; Carta, M.; D'Angelo, A.
2006-07-01
The definition of the characteristic kinetic parameters of a subcritical source-driven system constitutes an interesting problem in reactor physics with important consequences for practical applications. Consistent and physically meaningful values of the parameters allow to obtain accurate results from kinetic simulation tools and to correctly interpret kinetic experiments. For subcritical systems a preliminary problem arises for the adoption of a suitable weighting function to be used in the projection procedure to derive a point model. The present work illustrates a consistent factorization-projection procedure which leads to the definition of the kinetic parameters in a straightforward manner. The reactivity term is introduced coherently with the generalized perturbation theory applied to the source multiplication factor ks, which is thus given a physical role in the kinetic model. The effective prompt lifetime is introduced on the assumption that a neutron generation can be initiated by both the fission process and the source emission. Results are presented for simplified configurations to fully comprehend the physical features and for a more complicated highly decoupled system treated in transport theory. (authors)
The Advanced Photon Source list of parameters
Bizek, H.M.
1996-07-01
The Advanced Photon Source (APS) is a third-generation synchrotron radiation source that stores positrons in a storage ring. The choice of positrons as accelerating particles was motivated by the usual reason: to eliminate the degradation of the beam caused by trapping of positively charged dust particles or ions. The third-generation synchrotron radiation sources are designed to have low beam emittance and many straight sections for insertion devices. The parameter list is comprised of three basic systems: the injection system, the storage ring system, and the experimental facilities system. The components of the injection system are listed according to the causal flow of positrons. Below we briefly list the individual components of the injection system, with the names of people responsible for managing these machines in parentheses: the linac system; electron linac-target-positron linac (Marion White); low energy transport line from linac to the PAR (Michael Borland); positron accumulator ring or PAR (Michael Borland); low energy transport line from PAR to injector synchrotron (Michael Borland); injector synchrotron (Stephen Milton); high energy transport line from injector synchrotron to storage ring (Stephen Milton). The storage ring system, managed by Glenn Decker, uses the Chasman-Green lattice. The APS storage ring, 1104 m in circumference, has 40 periodic sectors. Six are used to house hardware and 34 serve as insertion devices. Another 34 beamlines emit radiation from bending magnets. The experimental facilities system`s parameters include parameters for both an undulator and a wiggler.
On selecting satellite conjunction filter parameters
NASA Astrophysics Data System (ADS)
Alfano, Salvatore; Finkleman, David
2014-06-01
This paper extends concepts of signal detection theory to predict the performance of conjunction screening techniques and guiding the selection of keepout and screening thresholds. The most efficient way to identify satellites likely to collide is to employ filters to identify orbiting pairs that should not come close enough over a prescribed time period to be considered hazardous. Such pairings can then be eliminated from further computation to accelerate overall processing time. Approximations inherent in filtering techniques include screening using only unperturbed Newtonian two body astrodynamics and uncertainties in orbit elements. Therefore, every filtering process is vulnerable to including objects that are not threats and excluding some that are threats, Type I and Type II errors. The approach in this paper guides selection of the best operating point for the filters suited to a user's tolerance for false alarms and unwarned threats. We demonstrate the approach using three archetypal filters with an initial three-day span, select filter parameters based on performance, and then test those parameters using eight historical snapshots of the space catalog. This work provides a mechanism for selecting filter parameters but the choices depend on the circumstances.
Automated reticulocyte parameters for hereditary spherocytosis screening.
Lazarova, Elena; Pradier, Olivier; Cotton, Frédéric; Gulbis, Béatrice
2014-11-01
The laboratory diagnosis of hereditary spherocytosis (HS) is based on several screening and confirmatory tests; our algorithm includes clinical features, red blood cell morphology analysis and cryohaemolysis test, and, in case of positive screening, sodium dodecyl sulphate polyacrylamide gel electrophoresis as a diagnostic test. Using the UniCel DxH800 (Beckman Coulter) haematology analyser, we investigated automated reticulocyte parameters as HS screening tool, i.e. mean reticulocyte volume (MRV), immature reticulocyte fraction (IRF) and mean sphered cell volume (MSCV). A total of 410 samples were screened. Gel electrophoresis was applied to 159 samples that were positive for the screening tests. A total of 48 patients were diagnosed as HS, and seven were diagnosed as acquired autoimmune haemolytic anaemia (AIHA). Some other 31 anaemic conditions were also studied. From the receiver operating characteristic (ROC) curve analysis, both delta (mean cell volume (MCV)-MSCV) and MRV presented an area under the curve (AUC) of 0.98. At the diagnostic cut-off of 100 % sensitivity, MRV showed the best specificity of 88 % and a positive likelihood ratio of 8.7. The parameters IRF, MRV and MSCV discriminated HS not only from controls and other tested pathologies but also from AIHA contrary to the cryohaemolysis test. In conclusion, automated reticulocyte parameters might be helpful for haemolytic anaemia diagnostic orientation even for general laboratories. In combination with cryohaemolysis, they ensure an effective and time-saving screening for HS for more specialised laboratories.
Visual parameter optimisation for biomedical image processing
2015-01-01
Background Biomedical image processing methods require users to optimise input parameters to ensure high-quality output. This presents two challenges. First, it is difficult to optimise multiple input parameters for multiple input images. Second, it is difficult to achieve an understanding of underlying algorithms, in particular, relationships between input and output. Results We present a visualisation method that transforms users' ability to understand algorithm behaviour by integrating input and output, and by supporting exploration of their relationships. We discuss its application to a colour deconvolution technique for stained histology images and show how it enabled a domain expert to identify suitable parameter values for the deconvolution of two types of images, and metrics to quantify deconvolution performance. It also enabled a breakthrough in understanding by invalidating an underlying assumption about the algorithm. Conclusions The visualisation method presented here provides analysis capability for multiple inputs and outputs in biomedical image processing that is not supported by previous analysis software. The analysis supported by our method is not feasible with conventional trial-and-error approaches. PMID:26329538
Reproductive Parameters of the Dogo Argentino Bitch.
Caffaratti, Marina; González, Griselda; Gorla, Nora; Guendulain, Corina
2013-01-01
The Dogo Argentino (DA) is the first and only breed from Argentina recognized worldwide. Although its morphologic features have been well established, its normal reproductive parameters are not clearly known. The aim of this study was to determine the main DA bitch reproductive parameters. One hundred and forty-nine surveys were obtained from breeders from Córdoba province, Argentina: one for each intact DA bitch from 1 to 14 years old. The DA bitch reached puberty at an average of 8.93 months. The mean duration of vulval bleeding found in this study was 11.11 days. The clinical signs characteristic for proestrous-estrous were vulval edema (89.93%), bleeding during the time of mating (32.21%), holding the tail to the side (95.30%), and docility during mating (85.91%). DA bitches had a whelping rate of 84%. Out of 299 pregnancies, 89.30% exhibited a normal parturition, 6.69% presented dystocia, 2.68% needed Cesarean section, and 1.34% aborted. In conclusion, the reproductive parameters of the DA bitch are similar to those identified for other large breeds. DA often showed a prolonged vulval bleeding longer than proestrus. Its high whelping rate, its low incidence of dystocia, and its good maternal ability define the DA as a good reproductive breed with normal reproductive functions.
Regularization Parameter Selections via Generalized Information Criterion.
Zhang, Yiyun; Li, Runze; Tsai, Chih-Ling
2010-03-01
We apply the nonconcave penalized likelihood approach to obtain variable selections as well as shrinkage estimators. This approach relies heavily on the choice of regularization parameter, which controls the model complexity. In this paper, we propose employing the generalized information criterion (GIC), encompassing the commonly used Akaike information criterion (AIC) and Bayesian information criterion (BIC), for selecting the regularization parameter. Our proposal makes a connection between the classical variable selection criteria and the regularization parameter selections for the nonconcave penalized likelihood approaches. We show that the BIC-type selector enables identification of the true model consistently, and the resulting estimator possesses the oracle property in the terminology of Fan and Li (2001). In contrast, however, the AIC-type selector tends to overfit with positive probability. We further show that the AIC-type selector is asymptotically loss efficient, while the BIC-type selector is not. Our simulation results confirm these theoretical findings, and an empirical example is presented. Some technical proofs are given in the online supplementary material.
A New Parameter for Cardiac Efficiency Analysis
NASA Astrophysics Data System (ADS)
Borazjani, Iman; Rajan, Navaneetha Krishnan; Song, Zeying; Hoffmann, Kenneth; MacMahon, Eileen; Belohlavek, Marek
2014-11-01
Detecting and evaluating a heart with suboptimal pumping efficiency is a significant clinical goal. However, the routine parameters such as ejection fraction, quantified with current non-invasive techniques are not predictive of heart disease prognosis. Furthermore, they only represent left-ventricular (LV) ejection function and not the efficiency, which might be affected before apparent changes in the function. We propose a new parameter, called the hemodynamic efficiency (H-efficiency) and defined as the ratio of the useful to total power, for cardiac efficiency analysis. Our results indicate that the change in the shape/motion of the LV will change the pumping efficiency of the LV even if the ejection fraction is kept constant at 55% (normal value), i.e., H-efficiency can be used for suboptimal cardiac performance diagnosis. To apply H-efficiency on a patient-specific basis, we are developing a system that combines echocardiography (echo) and computational fluid dynamics (CFD) to provide the 3D pressure and velocity field to directly calculate the H-efficiency parameter. Because the method is based on clinically used 2D echo, which has faster acquisition time and lower cost relative to other imaging techniques, it can have a significant impact on a large number of patients. This work is partly supported by the American Heart Association.
What parameters characterize “life”?
Mitaku, Shigeki; Sawada, Ryusuke
2016-01-01
“Life” is a particular state of matter, and matter is composed of various molecules. The state corresponding to “life” is ultimately determined by the genome sequence, and this sequence determines the conditions necessary for survival of the organism. In order to elucidate one parameter characterizing the state of “life”, we analyzed the amino acid sequences encoded in the total genomes of 557 prokaryotes and 40 eukaryotes using a membrane protein prediction online tool called SOSUI. SOSUI uses only the physical parameters of the encoded amino acid sequences to make its predictions. The ratio of membrane proteins in a genome predicted by the SOSUI online tool was around 23% for all genomes, indicating that this parameter is controlled by some mechanism in cells. In order to identify the property of genome DNA sequences that is the possible cause of the constant ratio of membrane proteins, we analyzed the nucleotide compositions at codon positions and observed the existence of systematic biases distinct from those expected based on random distribution. We hypothesize that the constant ratio of membrane proteins is the result of random mutations restricted by the systematic biases inherent to nucleotide codon composition. A new approach to the biological sciences based on the holistic analysis of whole genomes is discussed in order to elucidate the principles underlying “life” at the biological system level. PMID:28409082
Unsaturated flow parameters of municipal solid waste.
Feng, Shi-Jin; Zheng, Qi-Teng; Chen, H X
2017-01-24
Leachate pollution/recirculation and landfill gas emission are the major environmental concerns in municipal solid waste (MSW) landfills. A good understanding and prediction of MSW unsaturated properties are critical for the design of piping systems and the control of these problems within landfills. This paper reviews the recent studies of unsaturated properties of MSW, including experimental methods, theoretical models and corresponding model parameters. For experimental methods, the sample size is a common and significant limitation and large test apparatuses (e.g., >80cm in diameter) are generally required and valuable. The theoretical models for MSW also have some limitations due to the changes in waste composition and particle size distribution caused by biodegradation. Thus, the available data of intrinsic permeabilities, water retention curves, relative permeabilities and anisotropy of MSW were summarized to investigate the influences of porosity, waste composition and particle size distribution. A series of estimation methods were subsequently proposed to determine the parameters of water retention curve like θLm, θLr, nv and α. The other parameters such as the pore connectivity term (l) and the degree of anisotropy (k) were significantly lacking data, thus only their relationships with porosity were proposed. The results show that it is possible to define the second order effects caused by variations in porosity, waste composition and particle size distribution. However, the estimation methods still need more experimental data for improvement, especially their dependence on waste composition and particle size distribution.
Prebiotic network evolution: six key parameters.
Nghe, Philippe; Hordijk, Wim; Kauffman, Stuart A; Walker, Sara I; Schmidt, Francis J; Kemble, Harry; Yeates, Jessica A M; Lehman, Niles
2015-12-01
The origins of life likely required the cooperation among a set of molecular species interacting in a network. If so, then the earliest modes of evolutionary change would have been governed by the manners and mechanisms by which networks change their compositions over time. For molecular events, especially those in a pre-biological setting, these mechanisms have rarely been considered. We are only recently learning to apply the results of mathematical analyses of network dynamics to prebiotic events. Here, we attempt to forge connections between such analyses and the current state of knowledge in prebiotic chemistry. Of the many possible influences that could direct primordial network, six parameters emerge as the most influential when one considers the molecular characteristics of the best candidates for the emergence of biological information: polypeptides, RNA-like polymers, and lipids. These parameters are viable cores, connectivity kinetics, information control, scalability, resource availability, and compartmentalization. These parameters, both individually and jointly, guide the aggregate evolution of collectively autocatalytic sets. We are now in a position to translate these conclusions into a laboratory setting and test empirically the dynamics of prebiotic network evolution.
Fast Harmonic Splines and Parameter Choice Methods
NASA Astrophysics Data System (ADS)
Gutting, Martin
2017-04-01
Solutions to boundary value problems in geoscience where the boundary is the Earth's surface are constructed in terms of harmonic splines. These are localizing trial functions that allow regional modeling or the improvement of a global model in a part of the Earth's surface. Some cases of the occurring kernels can be equipped with a fast matrix-vector multiplication using the fast multipole method (FMM). The main idea of the fast multipole algorithm consists of a hierarchical decomposition of the computational domain into cubes and a kernel approximation for the more distant points. The numerical effort of the matrix-vector multiplication becomes linear in reference to the number of points for a prescribed accuracy of the kernel approximation. This fast spline approximation which also allows the treatment of noisy data requires the choice of a smoothing parameter. We investigate several methods to (ideally automatically) choose this parameter with and without prior knowledge of the noise level. However, in order to keep a fast solution algorithm we do no longer have access to the whole matrix or e.g. its singular values whose computation requires a much larger numerical effort. This must be reflected by the parameter choice methods. Therefore, in some cases a further approximation is necessary. The performance of these methods is considered for different types of noise in a large simulation study with applications to gravitational field modeling as well as to boundary value problems.
Scheipers, U; Ermert, H; Sommerfeld, H J; Garcia-Schürmann, M; Kühne, K; Senge, T; Philippou, S
2003-05-01
An ultrasonic multi-feature tissue characterizing system for the detection of prostate cancer is presented. The system is based on the processing of radio frequency (RF) ultrasonic echo data. Data from 100 patients was acquired in a clinical study. Parameters are extracted from the RF echo data and classified using two adaptive network-based fuzzy inference systems (FIS) working in parallel as a nonlinear classifier. Next to spectral parameters, conventional texture parameters are calculated using demodulated and log-compressed echo data. In the first approach, the classifier is trained on both, spectral and texture parameters. In the second approach, the classifier is only trained on texture parameters. Classification results of both approaches are compared and it is demonstrated, that only the use of spectral parameters yields satisfying classification results. Results of a minimum distance classifier (MDC) are presented for comparison with the fuzzy inference system. For the final fuzzy inference systems used in this approach, the area under the ROC curve is between 84% and 86% for the combined approach and between 70% and 74% for the approach based on texture parameters only.
Sparsity regularization for parameter identification problems
NASA Astrophysics Data System (ADS)
Jin, Bangti; Maass, Peter
2012-12-01
The investigation of regularization schemes with sparsity promoting penalty terms has been one of the dominant topics in the field of inverse problems over the last years, and Tikhonov functionals with ℓp-penalty terms for 1 ⩽ p ⩽ 2 have been studied extensively. The first investigations focused on regularization properties of the minimizers of such functionals with linear operators and on iteration schemes for approximating the minimizers. These results were quickly transferred to nonlinear operator equations, including nonsmooth operators and more general function space settings. The latest results on regularization properties additionally assume a sparse representation of the true solution as well as generalized source conditions, which yield some surprising and optimal convergence rates. The regularization theory with ℓp sparsity constraints is relatively complete in this setting; see the first part of this review. In contrast, the development of efficient numerical schemes for approximating minimizers of Tikhonov functionals with sparsity constraints for nonlinear operators is still ongoing. The basic iterated soft shrinkage approach has been extended in several directions and semi-smooth Newton methods are becoming applicable in this field. In particular, the extension to more general non-convex, non-differentiable functionals by variational principles leads to a variety of generalized iteration schemes. We focus on such iteration schemes in the second part of this review. A major part of this survey is devoted to applying sparsity constrained regularization techniques to parameter identification problems for partial differential equations, which we regard as the prototypical setting for nonlinear inverse problems. Parameter identification problems exhibit different levels of complexity and we aim at characterizing a hierarchy of such problems. The operator defining these inverse problems is the parameter-to-state mapping. We first summarize some
Linear Parameter Varying Control Synthesis for Actuator Failure, Based on Estimated Parameter
NASA Technical Reports Server (NTRS)
Shin, Jong-Yeob; Wu, N. Eva; Belcastro, Christine
2002-01-01
The design of a linear parameter varying (LPV) controller for an aircraft at actuator failure cases is presented. The controller synthesis for actuator failure cases is formulated into linear matrix inequality (LMI) optimizations based on an estimated failure parameter with pre-defined estimation error bounds. The inherent conservatism of an LPV control synthesis methodology is reduced using a scaling factor on the uncertainty block which represents estimated parameter uncertainties. The fault parameter is estimated using the two-stage Kalman filter. The simulation results of the designed LPV controller for a HiMXT (Highly Maneuverable Aircraft Technology) vehicle with the on-line estimator show that the desired performance and robustness objectives are achieved for actuator failure cases.
NASA Astrophysics Data System (ADS)
Jakšić, Nikola
2015-03-01
The optimality of the procedure of parameter identification is scrutinized in this paper. It was shown, with the relations between the mathematical theory of function approximation, three parameter probability distributions, which can adjust their shape, and the maximum-likelihood method, that the optimal expression of the distance between measured data and model fitting it can be established by using the three parameter probability distributions on the basis of iteration procedure, where the noise contained in the measured signal is extracted as well. The iterative method for optimal system/model parameter identification is presented and tested by the numerical experimentation. Four types of noise added to the simple single-degree-of-freedom system response are considered: Gauss, Cauchy, Laplace and Uniform. The method performs well for the noise types at relatively high noise content in the signal.
Wagschal, J. J.
2012-07-01
The two parameters one response model of the generalized linear least squares parameter adjustment methodology was used in order to analyze the procedure of improving cross sections agreement with integral experimental results. Two extreme adjustment cases were considered. One case is using extremely accurate measured integral responses, such as k{sub eff} of Godiva or Jezebel for instance. The other one is modifying only one parameter, for instance the modification of {nu}-bar in ENDF/B-VII, in order to improve agreement of calculated responses with corresponding integral measurements results. In both cases new posterior parameters correlations are generated. The conclusion is that it is not advised to use integral measurements information in the evaluation process of a general purpose nuclear data file. (authors)
Deveci, Alper; Cankaya, Deniz; Yilmaz, Serdar; Celen, Ersin; Sakman, Bulent; Bozkurt, Murat
2017-01-01
When the evaluation of patellar instability is examined from the aspect of the conical-cylindrical anatomy of the tibia, metric measurement parameters such as the tuberositas tibia (TT)-trochlear groove (TG) and patellar tendon (PT) insertion-trochlear groove (TG) distances are not sufficient. We asked whether defined angular parameters reveal the rotational movement of the tuberositas tibia on the tibia shaft, additional to the metric parameters and there is a correlation between the metric and angular parameters. 19 patients with patellar instability and 22 patients without patellar instability were evaluated. For all patients, two angle and three length parameters were evaluated on the slices taken. Evaluations were made of the TT-TG, the midpoint of the PT insertion-TG distances, the anatomic midpoint of the dome of the TT-TG, the TG-PT angle, and the TG-dome angle (DA). The Pearson correlation test was used for the statistical analysis of correlations between groups. A statistically significant increase was determined in the patellar instability group in the TG-DA and TG-PT angle values compared to the group without patellar instability ( p < 0.05). In both groups, a positive and strong correlation was determined between the TT-TG and the TG-PT and dome of the TT-TG distances, but no statistically significant correlation was determined between the tuberositas TT-TG and TG-PT angle and TG-DA. Metric parameters may not be sufficient alone in the evaluation of patellar instability. Metric parameters should be supported by additional angular parameters which reveal the rotational movement of the TT on the tibia shaft.
1993-01-25
AD-A260 299 OFFICE OF NAVAL RESEARCH Contract N00014-91-J-1910 R & T Code 4131025 Technical Report #51 Correlations Between the Ligand ...COVERED January 25, 1993 Technical - June 1991 to July 1992 4 TITLE AND SUBTITLE S. FUNDING NUMBERS Correlations Between the Ligand Electrochemical...Ontario, Canada, M3J 1P3. Correlations Between the Ligand Electrochemical Parameter. ET (D and the Hammett Substituent Param~eter. a. By Hitoshi
[Morbidity parameters in mining industry workers of Southern Urals].
Askarova, Z F; Askarov, R A
2009-01-01
The authors presented parameters of transitory disablement morbidity, occupational morbidity for workers in two mining enterprises (Bashkortostan Republic), calculated integral parameter of disablement.
Ren, Huiying; Hou, Zhangshuan; Huang, Maoyi; Bao, Jie; Sun, Yu; Tesfa, Teklu; Ruby Leung, L.
2016-05-01
Effective uncertainty quantification approaches are needed to identify important parameters or factors that affect complex Earth system models that composed of multi-phase multi-component phenomena and multiple biogeophysical-biogeochemical processes. In this study, the impacts of 10 hydrologic parameters in Community Land Model (CLM) simulations of runoff and latent heat flux in a watershed are evaluated. Simple residual statistics, the Nash-Sutcliffe coefficient, and log mean square error are used as alternative measures of the deviations between the simulated and field observed values. The effects of the input parameters on the deviations are evaluated quantitatively using analysis of variance (ANOVA) based on the generalized linear model (GLM), and using generalized cross validation (GCV) based on the multivariate adaptive regression splines (MARS) model. These analyses 1) help identify how to adjust parameter values and therefore the calibration of the CLM parameters and to improve the model’s simulations, and 2) can approximately predict the model calibration performance. The convergence behavior of the sensitivity analysis with number of sampling points for both ANOVA and GCV is also examined relative to different combinations of input parameters and output response variables and their metrics.
NASA Astrophysics Data System (ADS)
Ozturk, Yusuf; Egemen Yilmaz, Asim; Ozbay, Ekmel
2016-04-01
In this study, we explain an approach including conversion from constitutive parameters to dispersive transmission line parameters using the double-band DNG (double-negative) properties of the circular type fishnet metamaterials. After designing the metamaterial structure, the numerical calculations and the composite right/left-handed (CRLH) modeling of circular-type metamaterials are realized in free space. Detailed dispersion characteristics give us the opportunity to explain the true behavior of the inclusions during the analysis stage. By combining the results coming from the standard retrieval procedure with the conventional CRLH theory, we calculate the actual values of the transmission line parameters for all frequency regimes. The constitutive parameters of an equivalent CRLH transmission line are derived and shown to be negative values. It is shown that the constitutive parameters present the same behavior for all negative refractive index regimes. The double-negative properties and the phase advance/lag behavior of metamaterials are observed based on the dispersive transmission line parameters.
Karr, Jonathan R.; Williams, Alex H.; Zucker, Jeremy D.; Raue, Andreas; Steiert, Bernhard; Timmer, Jens; Kreutz, Clemens; Wilkinson, Simon; Allgood, Brandon A.; Bot, Brian M.; Hoff, Bruce R.; Kellen, Michael R.; Covert, Markus W.; Stolovitzky, Gustavo A.; Meyer, Pablo
2015-01-01
Whole-cell models that explicitly represent all cellular components at the molecular level have the potential to predict phenotype from genotype. However, even for simple bacteria, whole-cell models will contain thousands of parameters, many of which are poorly characterized or unknown. New algorithms are needed to estimate these parameters and enable researchers to build increasingly comprehensive models. We organized the Dialogue for Reverse Engineering Assessments and Methods (DREAM) 8 Whole-Cell Parameter Estimation Challenge to develop new parameter estimation algorithms for whole-cell models. We asked participants to identify a subset of parameters of a whole-cell model given the model’s structure and in silico “experimental” data. Here we describe the challenge, the best performing methods, and new insights into the identifiability of whole-cell models. We also describe several valuable lessons we learned toward improving future challenges. Going forward, we believe that collaborative efforts supported by inexpensive cloud computing have the potential to solve whole-cell model parameter estimation. PMID:26020786
Optimal design criteria - prediction vs. parameter estimation
NASA Astrophysics Data System (ADS)
Waldl, Helmut
2014-05-01
G-optimality is a popular design criterion for optimal prediction, it tries to minimize the kriging variance over the whole design region. A G-optimal design minimizes the maximum variance of all predicted values. If we use kriging methods for prediction it is self-evident to use the kriging variance as a measure of uncertainty for the estimates. Though the computation of the kriging variance and even more the computation of the empirical kriging variance is computationally very costly and finding the maximum kriging variance in high-dimensional regions can be time demanding such that we cannot really find the G-optimal design with nowadays available computer equipment in practice. We cannot always avoid this problem by using space-filling designs because small designs that minimize the empirical kriging variance are often non-space-filling. D-optimality is the design criterion related to parameter estimation. A D-optimal design maximizes the determinant of the information matrix of the estimates. D-optimality in terms of trend parameter estimation and D-optimality in terms of covariance parameter estimation yield basically different designs. The Pareto frontier of these two competing determinant criteria corresponds with designs that perform well under both criteria. Under certain conditions searching the G-optimal design on the above Pareto frontier yields almost as good results as searching the G-optimal design in the whole design region. In doing so the maximum of the empirical kriging variance has to be computed only a few times though. The method is demonstrated by means of a computer simulation experiment based on data provided by the Belgian institute Management Unit of the North Sea Mathematical Models (MUMM) that describe the evolution of inorganic and organic carbon and nutrients, phytoplankton, bacteria and zooplankton in the Southern Bight of the North Sea.
Transition Parameter applied to boundaries at Venus
NASA Astrophysics Data System (ADS)
Guymer, Gemma; Grande, Manuel; Fraenz, Marcus; Barabash, Stas; Zhang, Tielong; Pinter, Balazs
2015-04-01
We have used a transition parameter to characterise magnetospheric boundaries at Venus. The technique allows sparsely sampled data to be related to a variable and rapidly moving structure, such as the Bow shock, Magnetic Pile-up boundary or Ion Composition boundary. The solar minimum in 2009 was one of the lowest on record, and by 2006 minimum conditions were already in place. Utilising the ASPERA-4 Ion Mass Analyzer data and the paired magnetometers on board Venus Express the relation between the ions and flux ropes are investigated, in order to determine whether they a part of the replenishment or loss of the Venusian atmosphere. First, by using the magnetometer to identify the flux rope in the ionosphere Wei H.Y. (2006 -personal communication) and then by using the IMA to observe coincident composition changes. The altitude of ropes is dependent on the time spent in the ionosphere, with older ropes increasing weight and dropping weight. However, the occurrence of flux ropes and a mixed populations of ionospheric and solar wind ions is coincidental. Venus boundaries are examined during 2007, and 2011 / 2012 going toward solar maximum. A new use of the transition parameter is put forward; to aid with boundary placement. The bow shock is located with an automatic algorithm and this is then compared with previous models, giving a sense of Venus reaction to solar activity. It is shown that the bow shock position is largely unchanged. The ion composition boundary and the magnetic pile-up boundary are also located. They coincide to within an ion sampling period, but transition parameter analysis reveals that they are not coincident, with the ion composition boundary inside the pileup boundary.
Measuring Structural Parameters Through Stacking Galaxy Images
NASA Astrophysics Data System (ADS)
Li, Yubin; Zheng, Xian Zhong; Gu, Qiu-Sheng; Wang, Yi-Peng; Wen, Zhang Zheng; Guo, Kexin; An, Fang Xia
2016-12-01
It remains challenging to detect the low surface brightness structures of faint high-z galaxies, which are key to understanding the structural evolution of galaxies. The technique of image stacking allows us to measure the averaged light profile beneath the detection limit and probe the extended structure of a group of galaxies. We carry out simulations to examine the recovery of the averaged surface brightness profile through stacking model Hubble Space Telescope/Advanced Camera for Surveys images of a set of galaxies as functions of the Sérsic index (n), effective radius (R e) and axis ratio (AR). The Sérsic profile best fitting the radial profile of the stacked image is taken as the recovered profile, in comparison with the intrinsic mean profile of the model galaxies. Our results show that, in general, the structural parameters of the mean profile can be properly determined through stacking, though systematic biases need to be corrected when spreads of R e and AR are counted. We find that the Sérsic index is slightly overestimated and R e is underestimated at {AR}\\lt 0.5 because the stacked image appears to be more compact due to the presence of inclined galaxies; the spread of R e biases the stacked profile to have a higher Sérsic index. We stress that the measurements of structural parameters through stacking should take these biases into account. We estimate the biases in the recovered structural parameters from stacks of galaxies when the samples have distributions of {R}{{e}}, AR and n seen in local galaxies.
TDR method for determine IC's parameters
NASA Astrophysics Data System (ADS)
Timoshenkov, V.; Rodionov, D.; Khlybov, A.
2016-12-01
Frequency domain simulation is a widely used approach for determine integrated circuits parameters. This approach can be found in most of software tools used in IC industry. Time domain simulation approach shows intensive usage last years due to some advantages. In particular it applicable for analysis of nonlinear and nonstationary systems where frequency domain is inapplicable. Resolution of time domain systems allow see heterogeneities on distance 1mm, determine it parameters and properties. Authors used approach based on detecting reflected signals from heterogeneities - time domain reflectometry (TDR). Field effect transistor technology scaling up to 30-60nm gate length and 10nm gate dielectric, heterojunction bi-polar transistors with 10-30nm base width allows fabricate digital IC's with 20GHz clock frequency and RF-IC's with tens GHz bandwidth. Such devices and operation speed suppose transit signal by use microwave lines. There are local heterogeneities can be found inside of the signal path due to connections between different parts of signal lines (stripe line-RF-connector pin, stripe line - IC package pin). These heterogeneities distort signals that cause bandwidth decrease for RF-devices. Time domain research methods of transmission and reflected signals give the opportunities to determine heterogeneities, it properties, parameters and built up equivalent circuits. Experimental results are provided and show possibility for inductance and capacitance measurement up to 25GHz. Measurements contains result of signal path research on IC and printed circuit board (PCB) used for 12GHz RF chips. Also dielectric constant versus frequency was measured up to 35GHz.
Reliability of parameter estimation in respirometric models.
Checchi, Nicola; Marsili-Libelli, Stefano
2005-09-01
When modelling a biochemical system, the fact that model parameters cannot be estimated exactly stimulates the definition of tests for checking unreliable estimates and design better experiments. The method applied in this paper is a further development from Marsili-Libelli et al. [2003. Confidence regions of estimated parameters for ecological systems. Ecol. Model. 165, 127-146.] and is based on the confidence regions computed with the Fisher or the Hessian matrix. It detects the influence of the curvature, representing the distortion of the model response due to its nonlinear structure. If the test is passed then the estimation can be considered reliable, in the sense that the optimisation search has reached a point on the error surface where the effect of nonlinearities is negligible. The test is used here for an assessment of respirometric model calibration, i.e. checking the experimental design and estimation reliability, with an application to real-life data in the ASM context. Only dissolved oxygen measurements have been considered, because this is a very popular experimental set-up in wastewater modelling. The estimation of a two-step nitrification model using batch respirometric data is considered, showing that the initial amount of ammonium-N and the number of data play a crucial role in obtaining reliable estimates. From this basic application other results are derived, such as the estimation of the combined yield factor and of the second step parameters, based on a modified kinetics and a specific nitrite experiment. Finally, guidelines for designing reliable experiments are provided.
Influence of meteorological parameters on air quality
NASA Astrophysics Data System (ADS)
Gioda, Adriana; Ventura, Luciana; Lima, Igor; Luna, Aderval
2013-04-01
The physical characterization representative of ambient air particle concentrations is becoming a topic of great interest for urban air quality monitoring and human exposure assessment. Human exposure to particulate matter of less than 2.5 µm in diameter (PM2.5) can result in a variety of adverse health impacts, including reduced lung function and premature mortality. Numerous studies have shown that fine airborne inhalable particulate matter particles (PM2.5) are more dangerous to human health than coarse particles, e.g. PM10. This study investigates meteorological parameter impacts on PM2.5 concentrations in the atmosphere of Rio de Janeiro, Brazil. Samples were collected during 24 h every six days using a high-volume sampler from six sites in the metropolitan area of Rio de Janeiro from January to December 2011. The particles mass was determined by Gravimetry. Meteorological parameters were obtained from automatic stations near the sampling sites. The average PM2.5 concentrations ranged from 9 to 32 µg/m3 for all sites, exceeding the suggested annual limit of WHO (10 µg/m3). The relationship between the effects of temperature, relative humidity, wind speed and direction and particle concentration was examined using a Principal Component Analysis (PCA) for the different sites and seasons. The results for each sampling point and season presented different principal component numbers, varying from 2 to 4, and extremely different relationships with the parameters. This clearly shows that changes in meteorological conditions exert a marked influence on air quality.
Microwave remote sensing of hydrologic parameters
NASA Technical Reports Server (NTRS)
Ulaby, F. T.
1977-01-01
A perspective on the implementation of microwave sensors in future airborne and spaceborne observations of hydrologic parameters is presented. The rationale is based on a review of the status and future trends of active (radar) and passive (radiometer) microwave research as applied to the remote sensing of soil moisture content, snowpack water equivalent, freeze/thaw boundaries, lake ice thickness, surface water area, and the specification of watershed runoff coefficients. Analyses and observations based on data acquired from ground based, airborne and spaceborne platforms, and an evaluation of advantages and limitations of microwave sensors are included.
Photon Interaction Parameters for Some Borate Glasses
Mann, Nisha; Kaur, Updesh; Singh, Tejbir; Sharma, J. K.; Singh, Parjit S.
2010-11-06
Some photon interaction parameters of dosimetric interest such as mass attenuation coefficients, effective atomic number, electron density and KERMA relative to air have been computed in the wide energy range from 1 keV to 100 GeV for some borate glasses viz. barium-lead borate, bismuth-borate, calcium-strontium borate, lead borate and zinc-borate glass. It has been observed that lead borate glass and barium-lead borate glass have maximum values of mass attenuation coefficient, effective atomic number and KERMA relative to air. Hence, these borate glasses are suitable as gamma ray shielding material, packing of radioactive sources etc.
Index of central obesity - A novel parameter.
Parikh, Rakesh M; Joshi, Shashank R; Menon, Padmavathy S; Shah, Nalini S
2007-01-01
Waist circumference (WC) is globally used as a parameter to quantify central obesity, the key culprit in insulin resistance and related disorders. Hitherto globally in various definitions of metabolic syndrome and risk scores, WC is used to quantify central obesity. For defining central obesity, which is a single entity numerous WC cutoffs have been suggested, separately for males and females and various races. We believe that this difference is amenable to differences in their average heights. To quantify proportion of visceral fat in the total body fat, WC alone is not sufficient. We hereby hypothesize that Index of central obesity (ICO) defined by us, as a ratio of WC and height is a better parameter of central obesity. If ICO is used in place of WC we may do away with various WC cutoffs and may have a single cutoff applicable to all races and both genders. Using average heights of various countries and their respective WC cutoffs suggested by IDF consensus definition for defining metabolic syndrome (MS) we derived their ICO cutoffs mathematically. The ICO cutoffs obtained ranged from 0.51 to 0.58 among males and 0.47 to 0.54 among females. The range has narrowed down compared to wide range of cutoffs for WC i.e. 90-102 cm for males and 80-88 cm for females. To test superiority of ICO over WC even among people of same race and same gender we conducted a pilot study in which, we compared two subjects with same WC and body mass index (BMI), though they differed in their stature. Body fat distribution was compared on DEXA and oral glucose tolerance was tested. Percentage of total body fat contributed by truncal fat was 36.11% in taller subject (Dr. P) and 46.31% in the shorter one (Mr. P). On investigation Dr P had normal glucose tolerance while Mr. P was diagnosed to be diabetic. These differences unexplained by identical WC and BMI could be explained by difference in their ICO (0.557 vs 0.645). ICO has a potential to be a better parameter of central obesity. It
Parameter-Free Spatial and Stream Mining
2005-09-01
2 ≈ 0.276 and the amplitude 10This parameter is also related to the Hurst exponent . 158 Chapter 12. Patterns on a single stream 0 50 100 150 200 − 50...to the exponent α. This fact and how to estimate Vl are what the reader needs to keep in mind. —- 12.3 Proposed method In this section we introduce...α̂ is the self-similarity exponent (−1 < α < 0, closer to zero the more bursty the series). A large value of |ρα|, at least across several scales
Optimal parameters uncoupling vibration modes of oscillators
NASA Astrophysics Data System (ADS)
Le, K. C.; Pieper, A.
2017-07-01
This paper proposes a novel optimization concept for an oscillator with two degrees of freedom. By using specially defined motion ratios, we control the action of springs to each degree of freedom of the oscillator. We aim at showing that, if the potential action of the springs in one period of vibration, used as the payoff function for the conservative oscillator, is maximized among all admissible parameters and motions satisfying Lagrange's equations, then the optimal motion ratios uncouple vibration modes. A similar result holds true for the dissipative oscillator having dampers. The application to optimal design of vehicle suspension is discussed.
Attitude Estimation Using Modified Rodrigues Parameters
NASA Technical Reports Server (NTRS)
Crassidis, John L.; Markley, F. Landis
1996-01-01
In this paper, a Kalman filter formulation for attitude estimation is derived using the Modified Rodrigues Parameters. The extended Kalman filter uses a gyro-based model for attitude propagation. Two solutions are developed for the sensitivity matrix in the Kalman filter. One is based upon an additive error approach, and the other is based upon a multiplicative error approach. It is shown that the two solutions are in fact equivalent. The Kalman filter is then used to estimate the attitude of a simulated spacecraft. Results indicate that then new algorithm produces accurate attitude estimates by determining actual gyro biases.
Measurement of rain parameters by optical scintillation.
Wang, T I; Lerfald, G; Lawrence, R S; Clifford, S F
1977-08-01
We describe a technique for measuring path-averaged rain parameters by analyzing the rainfall-induced scintillations of a laser beam. From the time-lagged covariance function of two vertically spaced line detectors, we determine the average rainfall rate and drop-size distribution along the optical path. This technique requires no prior assumption of the form of the drop-size distribution. Sample measurements on a 140-m path confirm that the path-averaged drop-size distribution of a steady rain follows a Marshall-Palmer distribution. The optically measured path-averaged rain rate also shows good agreement with conventional tipping-bucket rain-gauge data.
Multiple emitter location and signal parameter estimation
NASA Astrophysics Data System (ADS)
Schmidt, R. O.
1986-03-01
Multiple signal classification (MUSIC) techniques involved in determining the parameters of multiple wavefronts arriving at an antenna array are discussed. A MUSIC algorithm is described, which provides asymptotically unbiased estimates of (1) the number of signals, (2) directions of arrival (or emitter locations), (3) strengths and cross correlations among the incident waveforms, and (4) the strength of noise/interference. The example of the use of the algorithm as a multiple frequency estimator operating on time series is examined. Comparisons of this method with methods based on maximum likelihood and maximum entropy, as well as conventional beamforming, are presented.
Epizootiologic parameters for plague in Kazakhstan.
Begon, Michael
2006-02-01
Reliable estimates are lacking of key epizootiologic parameters for plague caused by Yersinia pestis infection in its natural reservoirs. We report results of a 3-year longitudinal study of plague dynamics in populations of a maintenance host, the great gerbil (Rhombomys opimus), in 2 populations in Kazakhstan. Serologic results suggest a mid-summer peak in the abundance of infectious hosts and possible transmission from the reservoir to humans. Decrease in antibody titer to an undetectable level showed no seasonal pattern. Our findings did not support the use of the nitroblue-tetrazolium test characterization of plague-infected hosts. Y. pestis infection reduced survival of otherwise asymptomatic hosts.
Epizootiologic Parameters for Plague in Kazakhstan
Klassovskiy, Nikolay; Ageyev, Vladimir; Suleimenov, Bakhtiar; Atshabar, Bakhyt; Bennett, Malcolm
2006-01-01
Reliable estimates are lacking of key epizootiologic parameters for plague caused by Yersinia pestis infection in its natural reservoirs. We report results of a 3-year longitudinal study of plague dynamics in populations of a maintenance host, the great gerbil (Rhombomys opimus), in 2 populations in Kazakhstan. Serologic results suggest a mid-summer peak in the abundance of infectious hosts and possible transmission from the reservoir to humans. Decrease in antibody titer to an undetectable level showed no seasonal pattern. Our findings did not support the use of the nitroblue-tetrazolium test characterization of plague-infected hosts. Y. pestis infection reduced survival of otherwise asymptomatic hosts. PMID:16494753
Mass loss parameters for typical Shuttle materials
NASA Technical Reports Server (NTRS)
Muscari, J. A.; Odonnell, T.
1982-01-01
The weight loss of twenty different typical Shuttle materials was measured with a thermogravimetric analyzer as the material temperature was increased from ambient to 300 C. An additional ten tests were performed where conditioning of the material varied. The materials were selected from each general grouping such as adhesives, coatings, lubricants, encapsulants, elastomers, and resins. Care was taken in the preparation, curing, and preconditioning of the materials to simulate flight use. Making the assumption that the weight loss follows first order rate theory, the source outgassing parameters for these thirty materials is presented.
Renormalization group running of neutrino parameters.
Ohlsson, Tommy; Zhou, Shun
2014-10-17
Neutrinos are the most elusive particles in our Universe. They have masses at least one million times smaller than the electron mass, carry no electric charge and very weakly interact with other particles, meaning that they are rarely captured in terrestrial detectors. Tremendous efforts in the past two decades have revealed that neutrinos can transform from one type to another as a consequence of neutrino oscillations--a quantum mechanical effect over macroscopic distances--yet the origin of neutrino masses remains puzzling. The physical evolution of neutrino parameters with respect to energy scale may help elucidate the mechanism for their mass generation.
Structural and electronic parameters of ferroelectric KWOF
NASA Astrophysics Data System (ADS)
Atuchin, V. V.; Gavrilova, T. A.; Kesler, V. G.; Molokeev, M. S.; Aleksandrov, K. S.
2010-11-01
The low-temperature ferroelectric G2 polymorph of K 3WO 3F 3 oxyfluoride is formed by chemical synthesis. The electronic parameters of G2-K 3WO 3F 3 have been measured by X-ray photoelectron spectroscopy under excitation with Al Kα radiation (1486.6 eV). Detailed spectra have been recorded for all element core levels and Auger lines. The chemical bonding effects in the WO 3F 3 and WO 6 octahedrons are considered by using the binding energy difference ΔBE(O-W)=BE(O 1s)-BE(W 4f).
[Modern approaches to periodontal microcirculatory parameters assessment].
Krechina, E K; Smirnova, T N
2017-01-01
The article presents comprehensive functional study of periodontal tissues in 62 patients aged 20-45 with periodontal disease by laser Doppler flowmetry, Doppler ultrasound and computer capillaroscopy. All patients were divided into 5 groups depending on the severity of inflammation in the periodontium (chronic gingivitis, light, moderate and severe chronic periodontal disease). The relationship between microcirculatory indexes was evaluated by Pearson Product Moment Correlation or PPMC. The study shows high correlation between blood flow velocity measurement, diameter of microvessels and oxygen saturation in periodontal tissues that establish a direct relationship between studied parameters.
Parameters influencing zeolite incorporation in PDMS membranes
Vankelecom, I.F.J.; Scheppers, E.; Heus, R.; Uytterhoeven, J.B. )
1994-11-24
The incorporation of several types of zeolite in PDMS membranes is studied, by measuring the tensile strength, xylene sorption, and density of the membranes. The zeolite is shown to be involved in the cross-linking of the membrane. The interaction between the PDMS matrix and the zeolites results in reinforced membranes in the case of zeolite Y. The parameters influencing the dispersion of the zeolite in the membrane are investigated, as well as several aspects of the preparation method. Finally, the idea of cross-linking is applied to explain the results of water/ethanol pervaporation. 25 refs., 9 figs., 4 tabs.
Design parameters for wearable optical imagers
NASA Astrophysics Data System (ADS)
Akin, Ata; Kim, Sanghyun; Pourrezaei, Kambiz; Chance, Britton; Nioka, Shoko
2001-06-01
This paper summarizes the design steps that are followed during the development of the portable optical imager for breast cancer screening. The design steps considered the parameters such as total power consumption versus battery weight and size, speed of data acquisition versus cost and complexity of the design (functionality), graphical display versus operating system choice. We have used a single board computer system that uses Windows CE as the real time operating system. This choice was preferred since our graphical display requirements can only be carried out with the CE environment's GUI kernels.