QoS support over ultrafast TDM optical networks

NASA Astrophysics Data System (ADS)

Narvaez, Paolo; Siu, Kai-Yeung; Finn, Steven G.

1999-08-01

HLAN is a promising architecture to realize Tb/s access networks based on ultra-fast optical TDM technologies. This paper presents new research results on efficient algorithms for the support of quality of service over the HLAN network architecture. In particular, we propose a new scheduling algorithm that emulates fair queuing in a distributed manner for bandwidth allocation purpose. The proposed scheduler collects information on the queue of each host on the network and then instructs each host how much data to send. Our new scheduling algorithm ensures full bandwidth utilization, while guaranteeing fairness among all hosts.

A novel dynamic wavelength bandwidth allocation scheme over OFDMA PONs

NASA Astrophysics Data System (ADS)

Yan, Bo; Guo, Wei; Jin, Yaohui; Hu, Weisheng

2011-12-01

With rapid growth of Internet applications, supporting differentiated service and enlarging system capacity have been new tasks for next generation access system. In recent years, research in OFDMA Passive Optical Networks (PON) has experienced extraordinary development as for its large capacity and flexibility in scheduling. Although much work has been done to solve hardware layer obstacles for OFDMA PON, scheduling algorithm on OFDMA PON system is still under primary discussion. In order to support QoS service on OFDMA PON system, a novel dynamic wavelength bandwidth allocation (DWBA) algorithm is proposed in this paper. Per-stream QoS service is supported in this algorithm. Through simulation, we proved our bandwidth allocation algorithm performs better in bandwidth utilization and differentiate service support.

Predictive Cache Modeling and Analysis

DTIC Science & Technology

2011-11-01

metaheuristic /bin-packing algorithm to optimize task placement based on task communication characterization. Our previous work on task allocation showed...Cache Miss Minimization Technology To efficiently explore combinations and discover nearly-optimal task-assignment algorithms , we extended to our...it was possible to use our algorithmic techniques to decrease network bandwidth consumption by ~25%. In this effort, we adapted these existing

Hybrid WDM/TDM PON Using the AWG FSR and Featuring Centralized Light Generation and Dynamic Bandwidth Allocation

NASA Astrophysics Data System (ADS)

Bock, Carlos; Prat, Josep; Walker, Stuart D.

2005-12-01

A novel time/space/wavelength division multiplexing (TDM/WDM) architecture using the free spectral range (FSR) periodicity of the arrayed waveguide grating (AWG) is presented. A shared tunable laser and a photoreceiver stack featuring dynamic bandwidth allocation (DBA) and remote modulation are used for transmission and reception. Transmission tests show correct operation at 2.5 Gb/s to a 30-km reach, and network performance calculations using queue modeling demonstrate that a high-bandwidth-demanding application could be deployed on this network.

Bandwidth-Efficient Communication through 225 MHz Ka-band Relay Satellite Channel

NASA Technical Reports Server (NTRS)

Downey, Joseph; Downey, James; Reinhart, Richard C.; Evans, Michael Alan; Mortensen, Dale John

2016-01-01

The communications and navigation space infrastructure of the National Aeronautics and Space Administration (NASA) consists of a constellation of relay satellites (called Tracking and Data Relay Satellites (TDRS)) and a global set of ground stations to receive and deliver data to researchers around the world from mission spacecraft throughout the solar system. Planning is underway to enhance and transform the infrastructure over the coming decade. Key to the upgrade will be the simultaneous and efficient use of relay transponders to minimize cost and operations while supporting science and exploration spacecraft. Efficient use of transponders necessitates bandwidth efficient communications to best use and maximize data throughput within the allocated spectrum. Experiments conducted with NASA's Space Communication and Navigation (SCaN) Testbed on the International Space Station provides a unique opportunity to evaluate advanced communication techniques, such as bandwidth-efficient modulations, in an operational flight system. Demonstrations of these new techniques in realistic flight conditions provides critical experience and reduces the risk of using these techniques in future missions. Efficient use of spectrum is enabled by using high-order modulations coupled with efficient forward error correction codes. This paper presents a high-rate, bandwidth-efficient waveform operating over the 225 MHz Ka-band service of the TDRS System (TDRSS). The testing explores the application of Gaussian Minimum Shift Keying (GMSK), 248-phase shift keying (PSK) and 1632- amplitude PSK (APSK) providing over three bits-per-second-per-Hertz (3 bsHz) modulation combined with various LDPC encoding rates to maximize throughput. With a symbol rate of 200 Mbaud, coded data rates of 1000 Mbps were tested in the laboratory and up to 800 Mbps over the TDRS 225 MHz channel. This paper will present on the high-rate waveform design, channel characteristics, performance results, compensation techniques for filtering and equalization, and architecture considerations going forward for efficient use of NASA's infrastructure.

Bandwidth-Efficient Communication through 225 MHz Ka-band Relay Satellite Channel

NASA Technical Reports Server (NTRS)

Downey, Joseph A.; Downey, James M.; Reinhart, Richard C.; Evans, Michael A.; Mortensen, Dale J.

2016-01-01

The communications and navigation space infrastructure of the National Aeronautics and Space Administration (NASA) consists of a constellation of relay satellites (called Tracking and Data Relay Satellites (TDRS)) and a global set of ground stations to receive and deliver data to researchers around the world from mission spacecraft throughout the solar system. Planning is underway to enhance and transform the infrastructure over the coming decade. Key to the upgrade will be the simultaneous and efficient use of relay transponders to minimize cost and operations while supporting science and exploration spacecraft. Efficient use of transponders necessitates bandwidth efficient communications to best use and maximize data throughput within the allocated spectrum. Experiments conducted with NASA's Space Communication and Navigation (SCaN) Testbed on the International Space Station provides a unique opportunity to evaluate advanced communication techniques, such as bandwidth-efficient modulations, in an operational flight system. Demonstrations of these new techniques in realistic flight conditions provides critical experience and reduces the risk of using these techniques in future missions. Efficient use of spectrum is enabled by using high-order modulations coupled with efficient forward error correction codes. This paper presents a high-rate, bandwidth-efficient waveform operating over the 225 MHz Ka-band service of the TDRS System (TDRSS). The testing explores the application of Gaussian Minimum Shift Keying (GMSK), 2/4/8-phase shift keying (PSK) and 16/32- amplitude PSK (APSK) providing over three bits-per-second-per-Hertz (3 b/s/Hz) modulation combined with various LDPC encoding rates to maximize through- put. With a symbol rate of 200 M-band, coded data rates of 1000 Mbps were tested in the laboratory and up to 800 Mbps over the TDRS 225 MHz channel. This paper will present on the high-rate waveform design, channel characteristics, performance results, compensation techniques for filtering and equalization, and architecture considerations going forward for efficient use of NASA's infrastructure.

Terabit bandwidth-adaptive transmission using low-complexity format-transparent digital signal processing.

PubMed

Zhuge, Qunbi; Morsy-Osman, Mohamed; Chagnon, Mathieu; Xu, Xian; Qiu, Meng; Plant, David V

2014-02-10

In this paper, we propose a low-complexity format-transparent digital signal processing (DSP) scheme for next generation flexible and energy-efficient transceiver. It employs QPSK symbols as the training and pilot symbols for the initialization and tracking stage of the receiver-side DSP, respectively, for various modulation formats. The performance is numerically and experimentally evaluated in a dual polarization (DP) 11 Gbaud 64QAM system. Employing the proposed DSP scheme, we conduct a system-level study of Tb/s bandwidth-adaptive superchannel transmissions with flexible modulation formats including QPSK, 8QAM and 16QAM. The spectrum bandwidth allocation is realized in the digital domain instead of turning on/off sub-channels, which improves the performance of higher order QAM. Various transmission distances ranging from 240 km to 6240 km are demonstrated with a colorless detection for hardware complexity reduction.

Final Report on DOE Project entitled Dynamic Optimized Advanced Scheduling of Bandwidth Demands for Large-Scale Science Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramamurthy, Byravamurthy

2014-05-05

In this project, developed scheduling frameworks for dynamic bandwidth demands for large-scale science applications. In particular, we developed scheduling algorithms for dynamic bandwidth demands in this project. Apart from theoretical approaches such as Integer Linear Programming, Tabu Search and Genetic Algorithm heuristics, we have utilized practical data from ESnet OSCARS project (from our DOE lab partners) to conduct realistic simulations of our approaches. We have disseminated our work through conference paper presentations and journal papers and a book chapter. In this project we addressed the problem of scheduling of lightpaths over optical wavelength division multiplexed (WDM) networks. We published severalmore » conference papers and journal papers on this topic. We also addressed the problems of joint allocation of computing, storage and networking resources in Grid/Cloud networks and proposed energy-efficient mechanisms for operatin optical WDM networks.« less

Dynamic Resource Allocation for IEEE802.16e

NASA Astrophysics Data System (ADS)

Nascimento, Alberto; Rodriguez, Jonathan

Mobile communications has witnessed an exponential increase in the amount of users, services and applications. New high bandwidth consuming applications are targeted for B3G networks raising more stringent requirements for Dynamic Resource Allocation (DRA) architectures and packet schedulers that must be spectrum efficient and deliver QoS for heterogeneous applications and services. In this paper we propose a new cross layer-based architecture framework embedded in a newly designed DRA architecture for the Mobile WiMAX standard. System level simulation results show that the proposed architecture can be considered a viable candidate solution for supporting mixed services in a cost-effective manner in contrast to existing approaches.

Performance Evaluation and Control of Distributed Computer Communication Networks.

DTIC Science & Technology

1985-09-01

Zukerman, S. Katz, P. Rodriguez, R. Pazos , S. Resheff, Z. Tsai, Z. Zhang, L. Jong, V. Minh. Other participants are the following visiting... Pazos -Rangel "Bandwidth Allocation and Routing in ISDN’s," IEEE Communications Magazine, February 1984. Abstract The goal of communications network design...location and routing for integrated networks - is formulated, and efficient methods for its solution are presented. (2) R.A. Pazos -Rangel "Evaluation

Design and implementation of the next generation Landsat satellite communications system

USGS Publications Warehouse

Mah, Grant R.; O'Brien, Michael; Garon, Howard; Mott, Claire; Ames, Alan; Dearth, Ken

2012-01-01

The next generation Landsat satellite, Landsat 8 (L8), also known as the Landsat Data Continuity Mission (LDCM), uses a highly spectrally efficient modulation and data formatting approach to provide large amounts of downlink (D/L) bandwidth in a limited X-Band spectrum allocation. In addition to purely data throughput and bandwidth considerations, there were a number of additional constraints based on operational considerations for prevention of interference with the NASA Deep-Space Network (DSN) band just above the L8 D/L band, minimization of jitter contributions to prevent impacts to instrument performance, and the need to provide an interface to the Landsat International Cooperator (IC) community. A series of trade studies were conducted to consider either X- or Ka-Band, modulation type, and antenna coverage type, prior to the release of the request for proposal (RFP) for the spacecraft. Through use of the spectrally efficient rate-7/8 Low-Density Parity-Check error-correction coding and novel filtering, an XBand frequency plan was developed that balances all the constraints and considerations, while providing world-class link performance, fitting 384 Mbits/sec of data into the 375 MHz X-Band allocation with bit-error rates better than 10-12 using an earth-coverage antenna.

47 CFR 2.1049 - Measurements required: Occupied bandwidth.

Code of Federal Regulations, 2010 CFR

2010-10-01

... established for the characteristic baseband frequency. (Modulation reference level is defined as the average....1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS... Certification § 2.1049 Measurements required: Occupied bandwidth. The occupied bandwidth, that is the frequency...

Orchestrating Bulk Data Movement in Grid Environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vazhkudai, SS

2005-01-25

Data Grids provide a convenient environment for researchers to manage and access massively distributed bulk data by addressing several system and transfer challenges inherent to these environments. This work addresses issues involved in the efficient selection and access of replicated data in Grid environments in the context of the Globus Toolkit{trademark}, building middleware that (1) selects datasets in highly replicated environments, enabling efficient scheduling of data transfer requests; (2) predicts transfer times of bulk wide-area data transfers using extensive statistical analysis; and (3) co-allocates bulk data transfer requests, enabling parallel downloads from mirrored sites. These efforts have demonstrated a decentralizedmore » data scheduling architecture, a set of forecasting tools that predict bandwidth availability within 15% error and co-allocation architecture, and heuristics that expedites data downloads by up to 2 times.« less

Rethinking Traffic Management: Design of Optimizable Networks

DTIC Science & Technology

2008-06-01

Though this paper used optimization theory to design and analyze DaVinci , op- timization theory is one of many possible tools to enable a grounded...dynamically allocate bandwidth shares. The distributed protocols can be implemented using DaVinci : Dynamically Adaptive VIrtual Networks for a Customized...Internet. In DaVinci , each virtual network runs traffic-management protocols optimized for a traffic class, and link bandwidth is dynamically allocated

An enhanced DWBA algorithm in hybrid WDM/TDM EPON networks with heterogeneous propagation delays

NASA Astrophysics Data System (ADS)

Li, Chengjun; Guo, Wei; Jin, Yaohui; Sun, Weiqiang; Hu, Weisheng

2011-12-01

An enhanced dynamic wavelength and bandwidth allocation (DWBA) algorithm in hybrid WDM/TDM PON is proposed and experimentally demonstrated. In addition to the fairness of bandwidth allocation, this algorithm also considers the varying propagation delays between ONUs and OLT. The simulation based on MATLAB indicates that the improved algorithm has a better performance compared with some other algorithms.

Downhole drilling network using burst modulation techniques

DOEpatents

Hall,; David R. , Fox; Joe, [Spanish Fork, UT

2007-04-03

A downhole drilling system is disclosed in one aspect of the present invention as including a drill string and a transmission line integrated into the drill string. Multiple network nodes are installed at selected intervals along the drill string and are adapted to communicate with one another through the transmission line. In order to efficiently allocate the available bandwidth, the network nodes are configured to use any of numerous burst modulation techniques to transmit data.

Dynamic bandwidth allocation based on multiservice in software-defined wavelength-division multiplexing time-division multiplexing passive optical network

NASA Astrophysics Data System (ADS)

Wang, Fu; Liu, Bo; Zhang, Lijia; Jin, Feifei; Zhang, Qi; Tian, Qinghua; Tian, Feng; Rao, Lan; Xin, Xiangjun

2017-03-01

The wavelength-division multiplexing passive optical network (WDM-PON) is a potential technology to carry multiple services in an optical access network. However, it has the disadvantages of high cost and an immature technique for users. A software-defined WDM/time-division multiplexing PON was proposed to meet the requirements of high bandwidth, high performance, and multiple services. A reasonable and effective uplink dynamic bandwidth allocation algorithm was proposed. A controller with dynamic wavelength and slot assignment was introduced, and a different optical dynamic bandwidth management strategy was formulated flexibly for services of different priorities according to the network loading. The simulation compares the proposed algorithm with the interleaved polling with adaptive cycle time algorithm. The algorithm shows better performance in average delay, throughput, and bandwidth utilization. The results show that the delay is reduced to 62% and the throughput is improved by 35%.

Priority and Negotiation Based Dynamic Spectrum Allocation Scheme for Multiple Radio Access Network Operators

NASA Astrophysics Data System (ADS)

Kim, Hoon; Hyon, Taein; Lee, Yeonwoo

Most of previous works have presented the dynamic spectrum allocation (DSA) gain achieved by utilizing the time or regional variations in traffic demand between multi-network operators (NOs). In this paper, we introduce the functionalities required for the entities related with the spectrum sharing and allocation and propose a spectrum allocation algorithm while considering the long-term priority between NOs, the priority between multiple class services, and the urgent bandwidth request. To take into account the priorities among the NOs and the priorities of multiple class services, a spectrum sharing metric (SSM) is proposed, while a negotiation procedure is proposed to treat the urgent bandwidth request.

Performance Evaluation and Control of Distributed Computer Communication Networks.

DTIC Science & Technology

1984-09-01

including: L. Clare, L.A. De Moraes, J. Baker, M. Zuckerman, S. Katz, P. Rodrigues, R. Pazos , S. Resheff. Other participants are the following visiting...investigations have been reported in reference (1) and (2) below. References (1) M. Gerla, R. Pazos -Rangel "Bandwidth Allocation and Routing in ISDN’s," IEEE...and efficient methods for its solution are presented. (2) R.A. Pazos -Rangel "Evaluation and Design of Integrated Packet Switching and Circuit Switching

A Highly Flexible and Efficient Passive Optical Network Employing Dynamic Wavelength Allocation

NASA Astrophysics Data System (ADS)

Hsueh, Yu-Li; Rogge, Matthew S.; Yamamoto, Shu; Kazovsky, Leonid G.

2005-01-01

A novel and high-performance passive optical network (PON), the SUCCESS-DWA PON, employs dynamic wavelength allocation to provide bandwidth sharing across multiple physical PONs. In the downstream, tunable lasers, an arrayed waveguide grating, and coarse/fine filtering combine to create a flexible new optical access solution. In the upstream, several distributed and centralized schemes are proposed and investigated. The network performance is compared to conventional TDM-PONs under different traffic models, including the self-similar traffic model and the transaction-oriented model. Broadcast support and deployment issues are addressed. The network's excellent scalability can bridge the gap between conventional TDM-PONs and WDM-PONs. The powerful architecture is a promising candidate for next generation optical access networks.

Peak Satellite-to-Earth Data Rates Derived From Measurements of a 20 Gbps Bread-Board Modem

NASA Technical Reports Server (NTRS)

Landon, David G.; Simons, Rainee N.; Wintucky, Edwin G.; Sun, Jun Y.; Winn, James S.; Laraway, Stephen A.; McIntire, William K.; Metz, John L.; Smith, Francis J.

2011-01-01

A prototype data link using a Ka-band space qualified, high efficiency 200 W TWT amplifier and a bread-board modem emulator were created to explore the feasibility of very high speed communications in satellite-to-earth applications. Experiments were conducted using a DVB-S2-like waveform with modifications to support up to 20 Gbps through the addition of 128-Quadrature Amplitude Modulation (QAM). Limited by the bandwidth of the amplifier, a constant peak symbol rate of 3.2 Giga-symbols/sec was selected and the modulation order was varied to explore what peak data rate might be supported by an RF link through this amplifier. Using 128-QAM, an implementation loss of 3 dB was observed at 20 Gbps, and the loss decreased as data rate or bandwidth were reduced. Building on this measured data, realistic link budget calculations were completed. Low-Earth orbit (LEO) missions based on this TWTA with reasonable hardware assumptions and antenna sizing are found to be bandwidth-limited, rather than power-limited, making the spectral efficiency of 9/10-rate encoded 128-QAM very attractive. Assuming a bandwidth allocation of 1 GHz, these computations indicate that low-Earth orbit vehicles could achieve data rates up to 5 Gbps-an order of magnitude beyond the current state-of-practice, yet still within the processing power of a current FPGA-based software-defined modem. The measured performance results and a description of the experimental setup are presented to support these conclusions.

Dynamic Call Admission Control Scheme Based on Predictive User Mobility Behavior for Cellular Networks

NASA Astrophysics Data System (ADS)

Intarasothonchun, Silada; Thipchaksurat, Sakchai; Varakulsiripunth, Ruttikorn; Onozato, Yoshikuni

In this paper, we propose a modified scheme of MSODB and PMS, called Predictive User Mobility Behavior (PUMB) to improve performance of resource reservation and call admission control for cellular networks. This algorithm is proposed in which bandwidth is allocated more efficiently to neighboring cells by key mobility parameters in order to provide QoS guarantees for transferring traffic. The probability is used to form a cluster of cells and the shadow cluster, where a mobile unit is likely to visit. When a mobile unit may change the direction and migrate to the cell that does not belong to its shadow cluster, we can support it by making efficient use of predicted nonconforming call. Concomitantly, to ensure continuity of on-going calls with better utilization of resources, bandwidth is borrowed from predicted nonconforming calls and existing adaptive calls without affecting the minimum QoS guarantees. The performance of the PUMB is demonstrated by simulation results in terms of new call blocking probability, handoff call dropping probability, bandwidth utilization, call successful probability, and overhead message transmission when arrival rate and speed of mobile units are varied. Our results show that PUMB provides the better performances comparing with those of MSODB and PMS under different traffic conditions.

Network Enabled Operations: The Experiences of Senior Canadian Commanders

DTIC Science & Technology

2006-03-31

d’opérations par réseaux dans ce pays, qu’il n’y a pas de solution universelle car, selon les commandants interrogés, les besoins en réseaux...was provide by Lerhe who said that the commander must understand his communications systems sufficiently to appreciate the allocation of bandwidth...alter bandwidth allocation as he moves from the operational theatre (at sea) to port and vice versa. More specifically, this officer felt that a task

Design and implementation of flexible TWDM-PON with PtP WDM overlay based on WSS for next-generation optical access networks

NASA Astrophysics Data System (ADS)

Wu, Bin; Yin, Hongxi; Qin, Jie; Liu, Chang; Liu, Anliang; Shao, Qi; Xu, Xiaoguang

2016-09-01

Aiming at the increasing demand of the diversification services and flexible bandwidth allocation of the future access networks, a flexible passive optical network (PON) scheme combining time and wavelength division multiplexing (TWDM) with point-to-point wavelength division multiplexing (PtP WDM) overlay is proposed for the next-generation optical access networks in this paper. A novel software-defined optical distribution network (ODN) structure is designed based on wavelength selective switches (WSS), which can implement wavelength and bandwidth dynamical allocations and suits for the bursty traffic. The experimental results reveal that the TWDM-PON can provide 40 Gb/s downstream and 10 Gb/s upstream data transmission, while the PtP WDM-PON can support 10 GHz point-to-point dedicated bandwidth as the overlay complement system. The wavelengths of the TWDM-PON and PtP WDM-PON are allocated dynamically based on WSS, which verifies the feasibility of the proposed structure.

I/O-aware bandwidth allocation for petascale computing systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Zhou; Yang, Xu; Zhao, Dongfang

In the Big Data era, the gap between the storage performance and an appli- cation's I/O requirement is increasing. I/O congestion caused by concurrent storage accesses from multiple applications is inevitable and severely harms the performance. Conventional approaches either focus on optimizing an ap- plication's access pattern individually or handle I/O requests on a low-level storage layer without any knowledge from the upper-level applications. In this paper, we present a novel I/O-aware bandwidth allocation framework to coordinate ongoing I/O requests on petascale computing systems. The motivation behind this innovation is that the resource management system has a holistic view ofmore » both the system state and jobs' activities and can dy- namically control the jobs' status or allocate resource on the y during their execution. We treat a job's I/O requests as periodical subjobs within its lifecycle and transform the I/O congestion issue into a classical scheduling problem. Based on this model, we propose a bandwidth management mech- anism as an extension to the existing scheduling system. We design several bandwidth allocation policies with different optimization objectives either on user-oriented metrics or system performance. We conduct extensive trace- based simulations using real job traces and I/O traces from a production IBM Blue Gene/Q system at Argonne National Laboratory. Experimental results demonstrate that our new design can improve job performance by more than 30%, as well as increasing system performance.« less

A high performance long-reach passive optical network with a novel excess bandwidth distribution scheme

NASA Astrophysics Data System (ADS)

Chao, I.-Fen; Zhang, Tsung-Min

2015-06-01

Long-reach passive optical networks (LR-PONs) have been considered to be promising solutions for future access networks. In this paper, we propose a distributed medium access control (MAC) scheme over an advantageous LR-PON network architecture that reroutes the control information from and back to all ONUs through an (N + 1) × (N + 1) star coupler (SC) deployed near the ONUs, thereby overwhelming the extremely long propagation delay problem in LR-PONs. In the network, the control slot is designed to contain all bandwidth requirements of all ONUs and is in-band time-division-multiplexed with a number of data slots within a cycle. In the proposed MAC scheme, a novel profit-weight-based dynamic bandwidth allocation (P-DBA) scheme is presented. The algorithm is designed to efficiently and fairly distribute the amount of excess bandwidth based on a profit value derived from the excess bandwidth usage of each ONU, which resolves the problems of previously reported DBA schemes that are either unfair or inefficient. The simulation results show that the proposed decentralized algorithms exhibit a nearly three-order-of-magnitude improvement in delay performance compared to the centralized algorithms over LR-PONs. Moreover, the newly proposed P-DBA scheme guarantees low delay performance and fairness even when under attack by the malevolent ONU irrespective of traffic loads and burstiness.

Studies in integrated line-and packet-switched computer communication systems

NASA Astrophysics Data System (ADS)

Maglaris, B. S.

1980-06-01

The problem of efficiently allocating the bandwidth of a trunk to both types of traffic is handled for various system and traffic models. A performance analysis is carried out both for variable and fixed frame schemes. It is shown that variable frame schemes, adjusting the frame length according to the traffic variations, offer better trunk utilization at the cost of the additional hardware and software complexity needed because of the lack of synchronization. An optimization study on the fixed frame schemes follows. The problem of dynamically allocating the fixed frame to both types of traffic is formulated as a Markovian Decision process. It is shown that the movable boundary scheme, suggested for commercial implementations of integrated multiplexors, offers optimal or near optimal performance and simplicity of implementation. Finally, the behavior of the movable boundary integrated scheme is studied for tandem link connections. Under the assumptions made for the line-switched traffic, the forward allocation technique is found to offer the best alternative among different path set-up strategies.

OTACT: ONU Turning with Adaptive Cycle Times in Long-Reach PONs

NASA Astrophysics Data System (ADS)

Zare, Sajjad; Ghaffarpour Rahbar, Akbar

2015-01-01

With the expansion of PON networks as Long-Reach PON (LR-PON) networks, the problem of degrading the efficiency of centralized bandwidth allocation algorithms threatens this network due to high propagation delay. This is because these algorithms are based on bandwidth negotiation messages frequently exchanged between the optical line terminal (OLT) in the Central Office and optical network units (ONUs) near the users, which become seriously delayed when the network is extended. To solve this problem, some decentralized algorithms are proposed based on bandwidth negotiation messages frequently exchanged between the Remote Node (RN)/Local Exchange (LX) and ONUs near the users. The network has a relatively high delay since there are relatively large distances between RN/LX and ONUs, and therefore, control messages should travel twice between ONUs and RN/LX in order to go from one ONU to another ONU. In this paper, we propose a novel framework, called ONU Turning with Adaptive Cycle Times (OTACT), that uses Power Line Communication (PLC) to connect two adjacent ONUs. Since there is a large population density in urban areas, ONUs are closer to each other. Thus, the efficiency of the proposed method is high. We investigate the performance of the proposed scheme in contrast with other decentralized schemes under the worst case conditions. Simulation results show that the average upstream packet delay can be decreased under the proposed scheme.

Blocking performance approximation in flexi-grid networks

NASA Astrophysics Data System (ADS)

Ge, Fei; Tan, Liansheng

2016-12-01

The blocking probability to the path requests is an important issue in flexible bandwidth optical communications. In this paper, we propose a blocking probability approximation method of path requests in flexi-grid networks. It models the bundled neighboring carrier allocation with a group of birth-death processes and provides a theoretical analysis to the blocking probability under variable bandwidth traffic. The numerical results show the effect of traffic parameters to the blocking probability of path requests. We use the first fit algorithm in network nodes to allocate neighboring carriers to path requests in simulations, and verify approximation results.

Bandwidth, Broadband, and Planning for Public Access

ERIC Educational Resources Information Center

Blowers, Helene

2012-01-01

Broadband and bandwidth allocation is an essential technology planning activity that libraries should address on a continual basis. There are five key factors that will impact your network's performance: 1. infrastructure, 2. network load, 3. workstation performance, 4. prioritization of services, and 5. network management. The author thinks it's…

Cross-layer shared protection strategy towards data plane in software defined optical networks

NASA Astrophysics Data System (ADS)

Xiong, Yu; Li, Zhiqiang; Zhou, Bin; Dong, Xiancun

2018-04-01

In order to ensure reliable data transmission on the data plane and minimize resource consumption, a novel protection strategy towards data plane is proposed in software defined optical networks (SDON). Firstly, we establish a SDON architecture with hierarchical structure of data plane, which divides the data plane into four layers for getting fine-grained bandwidth resource. Then, we design the cross-layer routing and resource allocation based on this network architecture. Through jointly considering the bandwidth resource on all the layers, the SDN controller could allocate bandwidth resource to working path and backup path in an economical manner. Next, we construct auxiliary graphs and transform the shared protection problem into the graph vertex coloring problem. Therefore, the resource consumption on backup paths can be reduced further. The simulation results demonstrate that the proposed protection strategy can achieve lower protection overhead and higher resource utilization ratio.

Full-band TDM-OPDMA for OBI-reduced simultaneous multiple access in a single-wavelength optical access network.

PubMed

Jung, Sun-Young; Kim, Chang-Hun; Han, Sang-Kook

2018-05-14

Simultaneous multiple access (MA) within a single wavelength can increase the data rate and split ratio in a passive optical network while optical beat interference (OBI) becomes serious in the uplink. Previous techniques to reduce OBI were limited by their complexity and lack of extendibility; as well, bandwidth allocation among MA signals is needed for single photo diode (PD) detection. We proposed and experimentally demonstrated full-band optical pulse division multiplexing-based MA (OPDMA) in an optical access network, which can effectively reduce OBI with extendibility and fully utilize frequency resources of optical modulator without bandwidth allocation in a single-wavelength MA.

Cislan-2 extension final document by University of Twente (Netherlands)

NASA Astrophysics Data System (ADS)

Niemegeers, Ignas; Baumann, Frank; Beuwer, Wim; Jordense, Marcel; Pras, Aiko; Schutte, Leon; Tracey, Ian

1992-01-01

Results of worked performed under the so called Cislan extension contract are presented. The adaptation of the Cislan 2 prototype design to an environment of interconnected Local Area Networks (LAN's) instead of a single 802.5 token ring LAN is considered. In order to extend the network architecture, the Interconnection Function (IF) protocol layer was subdivided into two protocol layers: a new IF layer, and below the Medium Enhancement (ME) protocol layer. Some small enhancements to the distributed bandwidth allocation protocol were developed, which in fact are also applicable to the 'normal' Cislan 2 system. The new services and protocols are described together with some scenarios and requirements for the new internetting Cislan 2 system. How to overcome the degradation of the quality of speech due to packet loss on the LAN subsystem was studied. Experiments were planned in order to measure this speech quality degradation. Simulations were performed of two Cislan subsystems, the bandwidth allocation protocol and the clock synchronization mechanism. Results on both simulations, performed on SUN workstations using QNAP as a simulation tool, are given. Results of the simulations of the clock synchronization mechanism, and results of the simulation of the distributed bandwidth allocation protocol are given.

Decomposition method for zonal resource allocation problems in telecommunication networks

NASA Astrophysics Data System (ADS)

Konnov, I. V.; Kashuba, A. Yu

2016-11-01

We consider problems of optimal resource allocation in telecommunication networks. We first give an optimization formulation for the case where the network manager aims to distribute some homogeneous resource (bandwidth) among users of one region with quadratic charge and fee functions and present simple and efficient solution methods. Next, we consider a more general problem for a provider of a wireless communication network divided into zones (clusters) with common capacity constraints. We obtain a convex quadratic optimization problem involving capacity and balance constraints. By using the dual Lagrangian method with respect to the capacity constraint, we suggest to reduce the initial problem to a single-dimensional optimization problem, but calculation of the cost function value leads to independent solution of zonal problems, which coincide with the above single region problem. Some results of computational experiments confirm the applicability of the new methods.

Performance analysis of dynamic time-slot allocation system

NASA Astrophysics Data System (ADS)

Kong, Hongwei; Ruan, Fang; Feng, Chongxi

2001-10-01

Multi-service Access on the narrow-band DDN (Digital Data Network) leased lines to use the bandwidth more efficiently and reduce the cost has attracted much interest. In this paper, one novel multi-service multiplexing scheme based on DTSA (Dynamic Time-Slot Allocation) is given. This scheme can guarantee the QoS of the multiplexed services such as FAX, Voice and data and adapt to different link rates (64kb/s, 128kb/s, 256kb/s), A model is given in this paper to analyze the data behavior under this scheme. The simulation result and the model result have shown that the QoS guarantee to voice and FAX doesn't compromise the QoS of data service much in the meaning of delay and delay variance when the data load is not too high. The simulation result agrees with the model well when data load is not too high.

VENI, video, VICI: The merging of computer and video technologies

NASA Technical Reports Server (NTRS)

Horowitz, Jay G.

1993-01-01

The topics covered include the following: High Definition Television (HDTV) milestones; visual information bandwidth; television frequency allocation and bandwidth; horizontal scanning; workstation RGB color domain; NTSC color domain; American HDTV time-table; HDTV image size; digital HDTV hierarchy; task force on digital image architecture; open architecture model; future displays; and the ULTIMATE imaging system.

Optimized Autonomous Space In-situ Sensor-Web for volcano monitoring

USGS Publications Warehouse

Song, W.-Z.; Shirazi, B.; Kedar, S.; Chien, S.; Webb, F.; Tran, D.; Davis, A.; Pieri, D.; LaHusen, R.; Pallister, J.; Dzurisin, D.; Moran, S.; Lisowski, M.

2008-01-01

In response to NASA's announced requirement for Earth hazard monitoring sensor-web technology, a multidisciplinary team involving sensor-network experts (Washington State University), space scientists (JPL), and Earth scientists (USGS Cascade Volcano Observatory (CVO)), is developing a prototype dynamic and scaleable hazard monitoring sensor-web and applying it to volcano monitoring. The combined Optimized Autonomous Space -In-situ Sensor-web (OASIS) will have two-way communication capability between ground and space assets, use both space and ground data for optimal allocation of limited power and bandwidth resources on the ground, and use smart management of competing demands for limited space assets. It will also enable scalability and seamless infusion of future space and in-situ assets into the sensor-web. The prototype will be focused on volcano hazard monitoring at Mount St. Helens, which has been active since October 2004. The system is designed to be flexible and easily configurable for many other applications as well. The primary goals of the project are: 1) integrating complementary space (i.e., Earth Observing One (EO-1) satellite) and in-situ (ground-based) elements into an interactive, autonomous sensor-web; 2) advancing sensor-web power and communication resource management technology; and 3) enabling scalability for seamless infusion of future space and in-situ assets into the sensor-web. To meet these goals, we are developing: 1) a test-bed in-situ array with smart sensor nodes capable of making autonomous data acquisition decisions; 2) efficient self-organization algorithm of sensor-web topology to support efficient data communication and command control; 3) smart bandwidth allocation algorithms in which sensor nodes autonomously determine packet priorities based on mission needs and local bandwidth information in real-time; and 4) remote network management and reprogramming tools. The space and in-situ control components of the system will be integrated such that each element is capable of autonomously tasking the other. Sensor-web data acquisition and dissemination will be accomplished through the use of the Open Geospatial Consortium Sensorweb Enablement protocols. The three-year project will demonstrate end-to-end system performance with the in-situ test-bed at Mount St. Helens and NASA's EO-1 platform. ??2008 IEEE.

Energy-saving EPON Bandwidth Allocation Algorithm Supporting ONU's Sleep Mode

NASA Astrophysics Data System (ADS)

Zhang, Yinfa; Ren, Shuai; Liao, Xiaomin; Fang, Yuanyuan

2014-09-01

A new bandwidth allocation algorithm was presented by combining merits of the IPACT algorithm and the cyclic DBA algorithm based on the DBA algorithm for ONU's sleep mode. Simulation results indicate that compared with the normal mode ONU, the ONU's sleep mode can save about 74% of energy. The new algorithm has a smaller average packet delay and queue length in the upstream direction. While in the downstream direction, the average packet delay of the new algorithm is less than polling cycle Tcycle and the average queue length is less than the product of Tcycle and the maximum link rate. The new algorithm achieves a better compromise between energy-saving and ensuring quality of service.

A game-theoretical pricing mechanism for multiuser rate allocation for video over WiMAX

NASA Astrophysics Data System (ADS)

Chen, Chao-An; Lo, Chi-Wen; Lin, Chia-Wen; Chen, Yung-Chang

2010-07-01

In multiuser rate allocation in a wireless network, strategic users can bias the rate allocation by misrepresenting their bandwidth demands to a base station, leading to an unfair allocation. Game-theoretical approaches have been proposed to address the unfair allocation problems caused by the strategic users. However, existing approaches rely on a timeconsuming iterative negotiation process. Besides, they cannot completely prevent unfair allocations caused by inconsistent strategic behaviors. To address these problems, we propose a Search Based Pricing Mechanism to reduce the communication time and to capture a user's strategic behavior. Our simulation results show that the proposed method significantly reduce the communication time as well as converges stably to an optimal allocation.

Exascale Virtualized and Programmable Distributed Cyber Resource Control: Final Scientific Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoo, S.J.Ben; Lauer, Gregory S.

Extreme-science drives the need for distributed exascale processing and communications that are carefully, yet flexibly, managed. Exponential growth of data for scientific simulations, experimental data, collaborative data analyses, remote visualization and GRID computing requirements of scientists in fields as diverse as high energy physics, climate change, genomics, fusion, synchrotron radiation, material science, medicine, and other scientific disciplines cannot be accommodated by simply applying existing transport protocols to faster pipes. Further, scientific challenges today demand diverse research teams, heightening the need for and increasing the complexity of collaboration. To address these issues within the network layer and physical layer, we havemore » performed a number of research activities surrounding effective allocation and management of elastic optical network (EON) resources, particularly focusing on FlexGrid transponders. FlexGrid transponders support the opportunity to build Layer-1 connections at a wide range of bandwidths and to reconfigure them rapidly. The new flexibility supports complex new ways of using the physical layer that must be carefully managed and hidden from the scientist end-users. FlexGrid networks utilize flexible (or elastic) spectral bandwidths for each data link without using fixed wavelength grids. The flexibility in spectrum allocation brings many appealing features to network operations. Current networks are designed for the worst case impairments in transmission performance and the assigned spectrum is over-provisioned. In contrast, the FlexGrid networks can operate with the highest spectral efficiency and minimum bandwidth for the given traffic demand while meeting the minimum quality of transmission (QoT) requirement. Two primary focuses of our research are: (1) resource and spectrum allocation (RSA) for IP traffic over EONs, and (2) RSA for cross-domain optical networks. Previous work concentrates primarily on large file transfers within a single domain. Adding support for IP traffic changes the nature of the RSA problem: instead of choosing to accept or deny each request for network support, IP traffic is inherently elastic and thus lends itself to a bandwidth maximization formulation. We developed a number of algorithms that could be easily deployed within existing and new FlexGrid networks, leading to networks that better support scientific collaboration. Cross-domain RSA research is essential to support large-scale FlexGrid networks, since configuration information is generally not shared or coordinated across domains. The results presented here are in their early stages. They are technically feasible and practical, but still require coordination among organizations and equipment owners and a higher-layer framework for managing network requests.« less

Software defined multi-OLT passive optical network for flexible traffic allocation

NASA Astrophysics Data System (ADS)

Zhang, Shizong; Gu, Rentao; Ji, Yuefeng; Zhang, Jiawei; Li, Hui

2016-10-01

With the rapid growth of 4G mobile network and vehicular network services mobile terminal users have increasing demand on data sharing among different radio remote units (RRUs) and roadside units (RSUs). Meanwhile, commercial video-streaming, video/voice conference applications delivered through peer-to-peer (P2P) technology are still keep on stimulating the sharp increment of bandwidth demand in both business and residential subscribers. However, a significant issue is that, although wavelength division multiplexing (WDM) and orthogonal frequency division multiplexing (OFDM) technology have been proposed to fulfil the ever-increasing bandwidth demand in access network, the bandwidth of optical fiber is not unlimited due to the restriction of optical component properties and modulation/demodulation technology, and blindly increase the wavelength cannot meet the cost-sensitive characteristic of the access network. In this paper, we propose a software defined multi-OLT PON architecture to support efficient scheduling of access network traffic. By introducing software defined networking technology and wavelength selective switch into TWDM PON system in central office, multiple OLTs can be considered as a bandwidth resource pool and support flexible traffic allocation for optical network units (ONUs). Moreover, under the configuration of the control plane, ONUs have the capability of changing affiliation between different OLTs under different traffic situations, thus the inter-OLT traffic can be localized and the data exchange pressure of the core network can be released. Considering this architecture is designed to be maximum following the TWDM PON specification, the existing optical distribution network (ODN) investment can be saved and conventional EPON/GPON equipment can be compatible with the proposed architecture. What's more, based on this architecture, we propose a dynamic wavelength scheduling algorithm, which can be deployed as an application on control plane and achieve effective scheduling OLT wavelength resources between different OLTs based on various traffic situation. Simulation results show that, by using the scheduling algorithm, network traffic between different OLTs can be optimized effectively, and the wavelength utilization of the multi-OLT system can be improved due to the flexible wavelength scheduling.

Root Raised Cosine (RRC) Filters and Pulse Shaping in Communication Systems

NASA Technical Reports Server (NTRS)

Cubukcu, Erkin

2012-01-01

This presentation briefly discusses application of the Root Raised Cosine (RRC) pulse shaping in the space telecommunication. Use of the RRC filtering (i.e., pulse shaping) is adopted in commercial communications, such as cellular technology, and used extensively. However, its use in space communication is still relatively new. This will possibly change as the crowding of the frequency spectrum used in the space communication becomes a problem. The two conflicting requirements in telecommunication are the demand for high data rates per channel (or user) and need for more channels, i.e., more users. Theoretically as the channel bandwidth is increased to provide higher data rates the number of channels allocated in a fixed spectrum must be reduced. Tackling these two conflicting requirements at the same time led to the development of the RRC filters. More channels with wider bandwidth might be tightly packed in the frequency spectrum achieving the desired goals. A link model with the RRC filters has been developed and simulated. Using 90% power Bandwidth (BW) measurement definition showed that the RRC filtering might improve spectrum efficiency by more than 75%. Furthermore using the matching RRC filters both in the transmitter and receiver provides the improved Bit Error Rate (BER) performance. In this presentation the theory of three related concepts, namely pulse shaping, Inter Symbol Interference (ISI), and Bandwidth (BW) will be touched upon. Additionally the concept of the RRC filtering and some facts about the RRC filters will be presented

47 CFR 90.265 - Assignment and use of frequencies in the bands allocated for Federal use.

Code of Federal Regulations, 2010 CFR

2010-10-01

... bandwidth greater than 11.25 kHz until January 1, 2013. Such operations are limited by paragraphs (a)(6) and..., 2013, subject to the requirements of paragraphs (a)(6) and (a)(7) of this section. (b) The following..., 2005, and January 1, 2013, existing systems with an authorized bandwidth of greater than 11.25 kHz...

47 CFR 90.265 - Assignment and use of frequencies in the bands allocated for Federal use.

Code of Federal Regulations, 2011 CFR

2011-10-01

... bandwidth greater than 11.25 kHz until January 1, 2013. Such operations are limited by paragraphs (a)(6) and..., 2013, subject to the requirements of paragraphs (a)(6) and (a)(7) of this section. (b) The following..., 2005, and January 1, 2013, existing systems with an authorized bandwidth of greater than 11.25 kHz...

Auction-based bandwidth allocation in the Internet

NASA Astrophysics Data System (ADS)

Wei, Jiaolong; Zhang, Chi

2002-07-01

It has been widely accepted that auctioning which is the pricing approach with minimal information requirement is a proper tool to manage scare network resources. Previous works focus on Vickrey auction which is incentive compatible in classic auction theory. In the beginning of this paper, the faults of the most representative auction-based mechanisms are discussed. And then a new method called uniform-price auction (UPA), which has the simplest auction rule is proposed and it's incentive compatibility in the network environment is also proved. Finally, the basic mode is extended to support applications which require minimum bandwidth guarantees for a given time period by introducing derivative market, and a market mechanism for network resource allocation which is predictable, riskless, and simple for end-users is completed.

Programmable bandwidth management in software-defined EPON architecture

NASA Astrophysics Data System (ADS)

Li, Chengjun; Guo, Wei; Wang, Wei; Hu, Weisheng; Xia, Ming

2016-07-01

This paper proposes a software-defined EPON architecture which replaces the hardware-implemented DBA module with reprogrammable DBA module. The DBA module allows pluggable bandwidth allocation algorithms among multiple ONUs adaptive to traffic profiles and network states. We also introduce a bandwidth management scheme executed at the controller to manage the customized DBA algorithms for all date queues of ONUs. Our performance investigation verifies the effectiveness of this new EPON architecture, and numerical results show that software-defined EPONs can achieve less traffic delay and provide better support to service differentiation in comparison with traditional EPONs.

Error control techniques for satellite and space communications

NASA Technical Reports Server (NTRS)

Costello, Daniel J., Jr.

1988-01-01

During the period December 1, 1987 through May 31, 1988, progress was made in the following areas: construction of Multi-Dimensional Bandwidth Efficient Trellis Codes with MPSK modulation; performance analysis of Bandwidth Efficient Trellis Coded Modulation schemes; and performance analysis of Bandwidth Efficient Trellis Codes on Fading Channels.

Autonomous Distributed Congestion Control Scheme in WCDMA Network

NASA Astrophysics Data System (ADS)

Ahmad, Hafiz Farooq; Suguri, Hiroki; Choudhary, Muhammad Qaisar; Hassan, Ammar; Liaqat, Ali; Khan, Muhammad Umer

Wireless technology has become widely popular and an important means of communication. A key issue in delivering wireless services is the problem of congestion which has an adverse impact on the Quality of Service (QoS), especially timeliness. Although a lot of work has been done in the context of RRM (Radio Resource Management), the deliverance of quality service to the end user still remains a challenge. Therefore there is need for a system that provides real-time services to the users through high assurance. We propose an intelligent agent-based approach to guarantee a predefined Service Level Agreement (SLA) with heterogeneous user requirements for appropriate bandwidth allocation in QoS sensitive cellular networks. The proposed system architecture exploits Case Based Reasoning (CBR) technique to handle RRM process of congestion management. The system accomplishes predefined SLA through the use of Retrieval and Adaptation Algorithm based on CBR case library. The proposed intelligent agent architecture gives autonomy to Radio Network Controller (RNC) or Base Station (BS) in accepting, rejecting or buffering a connection request to manage system bandwidth. Instead of simply blocking the connection request as congestion hits the system, different buffering durations are allocated to diverse classes of users based on their SLA. This increases the opportunity of connection establishment and reduces the call blocking rate extensively in changing environment. We carry out simulation of the proposed system that verifies efficient performance for congestion handling. The results also show built-in dynamism of our system to cater for variety of SLA requirements.

Data analysis-based autonomic bandwidth adjustment in software defined multi-vendor optical transport networks.

PubMed

Li, Yajie; Zhao, Yongli; Zhang, Jie; Yu, Xiaosong; Jing, Ruiquan

2017-11-27

Network operators generally provide dedicated lightpaths for customers to meet the demand for high-quality transmission. Considering the variation of traffic load, customers usually rent peak bandwidth that exceeds the practical average traffic requirement. In this case, bandwidth provisioning is unmetered and customers have to pay according to peak bandwidth. Supposing that network operators could keep track of traffic load and allocate bandwidth dynamically, bandwidth can be provided as a metered service and customers would pay for the bandwidth that they actually use. To achieve cost-effective bandwidth provisioning, this paper proposes an autonomic bandwidth adjustment scheme based on data analysis of traffic load. The scheme is implemented in a software defined networking (SDN) controller and is demonstrated in the field trial of multi-vendor optical transport networks. The field trial shows that the proposed scheme can track traffic load and realize autonomic bandwidth adjustment. In addition, a simulation experiment is conducted to evaluate the performance of the proposed scheme. We also investigate the impact of different parameters on autonomic bandwidth adjustment. Simulation results show that the step size and adjustment period have significant influences on bandwidth savings and packet loss. A small value of step size and adjustment period can bring more benefits by tracking traffic variation with high accuracy. For network operators, the scheme can serve as technical support of realizing bandwidth as metered service in the future.

OSLG: A new granting scheme in WDM Ethernet passive optical networks

NASA Astrophysics Data System (ADS)

Razmkhah, Ali; Rahbar, Akbar Ghaffarpour

2011-12-01

Several granting schemes have been proposed to grant transmission window and dynamic bandwidth allocation (DBA) in passive optical networks (PON). Generally, granting schemes suffer from bandwidth wastage of granted windows. Here, we propose a new granting scheme for WDM Ethernet PONs, called optical network unit (ONU) Side Limited Granting (OSLG) that conserves upstream bandwidth, thus resulting in decreasing queuing delay and packet drop ratio. In OSLG instead of optical line terminal (OLT), each ONU determines its transmission window. Two OSLG algorithms are proposed in this paper: the OSLG_GA algorithm that determines the size of its transmission window in such a way that the bandwidth wastage problem is relieved, and the OSLG_SC algorithm that saves unused bandwidth for more bandwidth utilization later on. The OSLG can be used as granting scheme of any DBA to provide better performance in the terms of packet drop ratio and queuing delay. Our performance evaluations show the effectiveness of OSLG in reducing packet drop ratio and queuing delay under different DBA techniques.

Intelligent bandwidth compression

NASA Astrophysics Data System (ADS)

Tseng, D. Y.; Bullock, B. L.; Olin, K. E.; Kandt, R. K.; Olsen, J. D.

1980-02-01

The feasibility of a 1000:1 bandwidth compression ratio for image transmission has been demonstrated using image-analysis algorithms and a rule-based controller. Such a high compression ratio was achieved by first analyzing scene content using auto-cueing and feature-extraction algorithms, and then transmitting only the pertinent information consistent with mission requirements. A rule-based controller directs the flow of analysis and performs priority allocations on the extracted scene content. The reconstructed bandwidth-compressed image consists of an edge map of the scene background, with primary and secondary target windows embedded in the edge map. The bandwidth-compressed images are updated at a basic rate of 1 frame per second, with the high-priority target window updated at 7.5 frames per second. The scene-analysis algorithms used in this system together with the adaptive priority controller are described. Results of simulated 1000:1 bandwidth-compressed images are presented.

A Case Study on Neural Inspired Dynamic Memory Management Strategies for High Performance Computing.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vineyard, Craig Michael; Verzi, Stephen Joseph

As high performance computing architectures pursue more computational power there is a need for increased memory capacity and bandwidth as well. A multi-level memory (MLM) architecture addresses this need by combining multiple memory types with different characteristics as varying levels of the same architecture. How to efficiently utilize this memory infrastructure is an unknown challenge, and in this research we sought to investigate whether neural inspired approaches can meaningfully help with memory management. In particular we explored neurogenesis inspired re- source allocation, and were able to show a neural inspired mixed controller policy can beneficially impact how MLM architectures utilizemore » memory.« less

Flexible communications for battlespace 2000

NASA Astrophysics Data System (ADS)

Seiler, Thomas M.

2000-08-01

The advent of software-defined radios (products of DSP) with embedded processors capable of performing, communications functions (i.e., modulation) makes it possible for networks of radios to operate efficiently by changing its transmission characteristics (waveform) to fit the input data bandwidth requirements commensurate with received Eb/N0. It is also now feasible to have embedded within the network of radios a networking system capable of allocating bandwidth in accordance with current needs and priorities. The subject of battlefield networking can now also be addressed. A system with the multiple degrees of freedom (e.g., ability to manually and automatically change communications parameters to improve communications performance, spectrum management and the ability to incorporate different mission processing support) will provide the warfighter, those who support the warfighter and the rapidly expanding mission of our armed forces (i.e., peacekeeping, anti-terrorism) to meet an ever-changing mission and operational environment. This paper will address how such a robust communications system will enhance the mission of the specialist and make the products of his efforts a real-time tool for the shooter who must operate within the digitized battlespace.

Resource allocation using ANN in LTE

NASA Astrophysics Data System (ADS)

Yigit, Tuncay; Ersoy, Mevlut

2017-07-01

LTE is the 4th generation wireless network technology, which provides flexible bandwidth, higher data speeds and lower delay. Difficulties may be experienced upon an increase in the number of users in LTE. The objective of this study is to ensure a faster solution to any such resource allocation problems which might arise upon an increase in the number of users. A fast and effective solution has been obtained by making use of Artificial Neural Network. As a result, fast working artificial intelligence methods may be used in resource allocation problems during operation.

Holding-time-aware asymmetric spectrum allocation in virtual optical networks

NASA Astrophysics Data System (ADS)

Lyu, Chunjian; Li, Hui; Liu, Yuze; Ji, Yuefeng

2017-10-01

Virtual optical networks (VONs) have been considered as a promising solution to support current high-capacity dynamic traffic and achieve rapid applications deployment. Since most of the network services (e.g., high-definition video service, cloud computing, distributed storage) in VONs are provisioned by dedicated data centers, needing different amount of bandwidth resources in both directions, the network traffic is mostly asymmetric. The common strategy, symmetric provisioning of traffic in optical networks, leads to a waste of spectrum resources in such traffic patterns. In this paper, we design a holding-time-aware asymmetric spectrum allocation module based on SDON architecture and an asymmetric spectrum allocation algorithm based on the module is proposed. For the purpose of reducing spectrum resources' waste, the algorithm attempts to reallocate the idle unidirectional spectrum slots in VONs, which are generated due to the asymmetry of services' bidirectional bandwidth. This part of resources can be exploited by other requests, such as short-time non-VON requests. We also introduce a two-dimensional asymmetric resource model for maintaining idle spectrum resources information of VON in spectrum and time domains. Moreover, a simulation is designed to evaluate the performance of the proposed algorithm, and results show that our proposed asymmetric spectrum allocation algorithm can improve the resource waste and reduce blocking probability.

Highly efficient frequency conversion with bandwidth compression of quantum light

PubMed Central

Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

2017-01-01

Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks. PMID:28134242

Bandwidth characteristics of multimedia data traffic on a local area network

NASA Technical Reports Server (NTRS)

Chuang, Shery L.; Doubek, Sharon; Haines, Richard F.

1993-01-01

Limited spacecraft communication links call for users to investigate the potential use of video compression and multimedia technologies to optimize bandwidth allocations. The objective was to determine the transmission characteristics of multimedia data - motion video, text or bitmap graphics, and files transmitted independently and simultaneously over an ethernet local area network. Commercial desktop video teleconferencing hardware and software and Intel's proprietary Digital Video Interactive (DVI) video compression algorithm were used, and typical task scenarios were selected. The transmission time, packet size, number of packets, and network utilization of the data were recorded. Each data type - compressed motion video, text and/or bitmapped graphics, and a compressed image file - was first transmitted independently and its characteristics recorded. The results showed that an average bandwidth of 7.4 kilobits per second (kbps) was used to transmit graphics; an average bandwidth of 86.8 kbps was used to transmit an 18.9-kilobyte (kB) image file; a bandwidth of 728.9 kbps was used to transmit compressed motion video at 15 frames per second (fps); and a bandwidth of 75.9 kbps was used to transmit compressed motion video at 1.5 fps. Average packet sizes were 933 bytes for graphics, 498.5 bytes for the image file, 345.8 bytes for motion video at 15 fps, and 341.9 bytes for motion video at 1.5 fps. Simultaneous transmission of multimedia data types was also characterized. The multimedia packets used transmission bandwidths of 341.4 kbps and 105.8kbps. Bandwidth utilization varied according to the frame rate (frames per second) setting for the transmission of motion video. Packet size did not vary significantly between the data types. When these characteristics are applied to Space Station Freedom (SSF), the packet sizes fall within the maximum specified by the Consultative Committee for Space Data Systems (CCSDS). The uplink of imagery to SSF may be performed at minimal frame rates and/or within seconds of delay, depending on the user's allocated bandwidth. Further research to identify the acceptable delay interval and its impact on human performance is required. Additional studies in network performance using various video compression algorithms and integrated multimedia techniques are needed to determine the optimal design approach for utilizing SSF's data communications system.

Handling Qualities of a Large Civil Tiltrotor in Hover using Translational Rate Command

NASA Technical Reports Server (NTRS)

Malpica, Carlos A.; Theodore, Colin R.; Lawrence, Ben; Lindsey, James; Blanken, Chris

2012-01-01

A Translational Rate Command (TRC) control law has been developed to enable low speed maneuvering of a large civil tiltrotor with minimal pitch changes by means of automatic nacelle angle deflections for longitudinal velocity control. The nacelle actuator bandwidth required to achieve Level 1 handling qualities in hover and the feasibility of additional longitudinal cyclic control to augment low bandwidth nacelle actuation were investigated. A frequency-domain handling qualities criterion characterizing TRC response in terms of bandwidth and phase delay was proposed and validated against a piloted simulation conducted on the NASA-Ames Vertical Motion Simulator. Seven experimental test pilots completed evaluations in the ADS-33E-PRF Hover Mission Task Element (MTE) for a matrix of nacelle actuator bandwidths, equivalent rise times and control response sensitivities, and longitudinal cyclic control allocations. Evaluated against this task, longitudinal phase delay shows the Level 1 boundary is around 0.4 0.5 s. Accordingly, Level 1 handling qualities were achieved either with a nacelle actuator bandwidth greater than 4 rad/s, or by employing longitudinal cyclic control to augment low bandwidth nacelle actuation.

Radiation Hardened, Modulator ASIC for High Data Rate Communications

NASA Technical Reports Server (NTRS)

McCallister, Ron; Putnam, Robert; Andro, Monty; Fujikawa, Gene

2000-01-01

Satellite-based telecommunication services are challenged by the need to generate down-link power levels adequate to support high quality (BER approx. equals 10(exp 12)) links required for modem broadband data services. Bandwidth-efficient Nyquist signaling, using low values of excess bandwidth (alpha), can exhibit large peak-to-average-power ratio (PAPR) values. High PAPR values necessitate high-power amplifier (HPA) backoff greater than the PAPR, resulting in unacceptably low HPA efficiency. Given the high cost of on-board prime power, this inefficiency represents both an economical burden, and a constraint on the rates and quality of data services supportable from satellite platforms. Constant-envelope signals offer improved power-efficiency, but only by imposing a severe bandwidth-efficiency penalty. This paper describes a radiation- hardened modulator which can improve satellite-based broadband data services by combining the bandwidth-efficiency of low-alpha Nyquist signals with high power-efficiency (negligible HPA backoff).

Modal analysis and control of flexible manipulator arms. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Neto, O. M.

1974-01-01

The possibility of modeling and controlling flexible manipulator arms was examined. A modal approach was used for obtaining the mathematical model and control techniques. The arm model was represented mathematically by a state space description defined in terms of joint angles and mode amplitudes obtained from truncation on the distributed systems, and included the motion of a two link two joint arm. Three basic techniques were used for controlling the system: pole allocation with gains obtained from the rigid system with interjoint feedbacks, Simon-Mitter algorithm for pole allocation, and sensitivity analysis with respect to parameter variations. An improvement in arm bandwidth was obtained. Optimization of some geometric parameters was undertaken to maximize bandwidth for various payload sizes and programmed tasks. The controlled system is examined under constant gains and using the nonlinear model for simulations following a time varying state trajectory.

Energy efficient flexible hybrid wavelength division multiplexing-time division multiplexing passive optical network with pay as you grow deployment

NASA Astrophysics Data System (ADS)

Garg, Amit Kumar; Madavi, Amresh Ashok; Janyani, Vijay

2017-02-01

A flexible hybrid wavelength division multiplexing-time division multiplexing passive optical network architecture that allows dual rate signals to be sent at 1 and 10 Gbps to each optical networking unit depending upon the traffic load is proposed. The proposed design allows dynamic wavelength allocation with pay-as-you-grow deployment capability. This architecture is capable of providing up to 40 Gbps of equal data rates to all optical distribution networks (ODNs) and up to 70 Gbps of a asymmetrical data rate to the specific ODN. The proposed design handles broadcasting capability with simultaneous point-to-point transmission, which further reduces energy consumption. In this architecture, each module sends a wavelength to each ODN, thus making the architecture fully flexible; this flexibility allows network providers to use only required OLT components and switch off others. The design is also reliable to any module or TRx failure and provides services without any service disruption. Dynamic wavelength allocation and pay-as-you-grow deployment support network extensibility and bandwidth scalability to handle future generation access networks.

Compact antenna arrays with wide bandwidth and low sidelobe levels

DOEpatents

Strassner, II, Bernd H.

2014-09-09

Highly efficient, low cost, easily manufactured SAR antenna arrays with lightweight low profiles, large instantaneous bandwidths and low SLL are disclosed. The array topology provides all necessary circuitry within the available antenna aperture space and between the layers of material that comprise the aperture. Bandwidths of 15.2 GHz to 18.2 GHz, with 30 dB SLLs azimuthally and elevationally, and radiation efficiencies above 40% may be achieved. Operation over much larger bandwidths is possible as well.

A micromachined efficient parametric array loudspeaker with a wide radiation frequency band.

PubMed

Je, Yub; Lee, Haksue; Been, Kyounghun; Moon, Wonkyu

2015-04-01

Parametric array (PA) loudspeakers generate directional audible sound via the PA effect, which can make private listening possible. The practical applications of PA loudspeakers include information technology devices that require large power efficiency transducers with a wide frequency bandwidth. Piezoelectric micromachined ultrasonic transducers (PMUTs) are compact and efficient units for PA sources [Je, Lee, and Moon, Ultrasonics 53, 1124-1134 (2013)]. This study investigated the use of an array of PMUTs to make a PA loudspeaker with high power efficiency and wide bandwidth. The achievable maximum radiation bandwidth of the driver was calculated, and an array of PMUTs with two distinct resonance frequencies (f1 = 100 kHz, f2 = 110 kHz) was designed. Out-of-phase driving was used with the dual-resonance transducer array to increase the bandwidth. The fabricated PMUT array exhibited an efficiency of up to 71%, together with a ±3-dB bandwidth of 17 kHz for directly radiated primary waves, and 19.5 kHz (500 Hz to 20 kHz) for the difference frequency waves (with equalization).

High performance photonic ADC for space applications

NASA Astrophysics Data System (ADS)

Pantoja, S.; Piqueras, M. A.; Villalba, P.; Martínez, B.; Rico, E.

2017-11-01

The flexibility required for future telecom payloads will require of more digital processing capabilities, moving from conventional analogue repeaters to more advanced and efficient analog subsystems or DSPbased solutions. Aggregate data throughputs will have to be handled onboard, creating the need for effective, ADC/DSP and DSP/DAC high speed links. Broadband payloads will have to receive, route and retransmit hundreds of channels and need to be designed so as to meet such requirements of larger bandwidth, system transparency and flexibility.[1][2] One important device in these new architectures is analog to digital converter (ADC) and its equivalent digital to analog converter (DAC). These will be the in/out interface for the use of digital processing in order to provide flexible beam to beam connectivity and variable bandwidth allocation. For telecom payloads having a large number of feeds and thus a large number of converters the mass and consumption of the mixer stage has become significant. Moreover, the inclusion of ADCs in the payload presents new trade-offs in design (jitter, quantization noise, ambiguity). This paper deals with an alternative solution of these two main problems with the exploitation of photonic techniques.

Power and Efficiency Optimized in Traveling-Wave Tubes Over a Broad Frequency Bandwidth

NASA Technical Reports Server (NTRS)

Wilson, Jeffrey D.

2001-01-01

A traveling-wave tube (TWT) is an electron beam device that is used to amplify electromagnetic communication waves at radio and microwave frequencies. TWT's are critical components in deep space probes, communication satellites, and high-power radar systems. Power conversion efficiency is of paramount importance for TWT's employed in deep space probes and communication satellites. A previous effort was very successful in increasing efficiency and power at a single frequency (ref. 1). Such an algorithm is sufficient for narrow bandwidth designs, but for optimal designs in applications that require high radiofrequency power over a wide bandwidth, such as high-density communications or high-resolution radar, the variation of the circuit response with respect to frequency must be considered. This work at the NASA Glenn Research Center is the first to develop techniques for optimizing TWT efficiency and output power over a broad frequency bandwidth (ref. 2). The techniques are based on simulated annealing, which has the advantage over conventional optimization techniques in that it enables the best possible solution to be obtained (ref. 3). Two new broadband simulated annealing algorithms were developed that optimize (1) minimum saturated power efficiency over a frequency bandwidth and (2) simultaneous bandwidth and minimum power efficiency over the frequency band with constant input power. The algorithms were incorporated into the NASA coupled-cavity TWT computer model (ref. 4) and used to design optimal phase velocity tapers using the 59- to 64-GHz Hughes 961HA coupled-cavity TWT as a baseline model. In comparison to the baseline design, the computational results of the first broad-band design algorithm show an improvement of 73.9 percent in minimum saturated efficiency (see the top graph). The second broadband design algorithm (see the bottom graph) improves minimum radiofrequency efficiency with constant input power drive by a factor of 2.7 at the high band edge (64 GHz) and increases simultaneous bandwidth by 500 MHz.

A distributed multichannel demand-adaptive P2P VoD system with optimized caching and neighbor-selection

NASA Astrophysics Data System (ADS)

Zhang, Hao; Chen, Minghua; Parekh, Abhay; Ramchandran, Kannan

2011-09-01

We design a distributed multi-channel P2P Video-on-Demand (VoD) system using "plug-and-play" helpers. Helpers are heterogenous "micro-servers" with limited storage, bandwidth and number of users they can serve simultaneously. Our proposed system has the following salient features: (1) it jointly optimizes over helper-user connection topology, video storage distribution and transmission bandwidth allocation; (2) it minimizes server load, and is adaptable to varying supply and demand patterns across multiple video channels irrespective of video popularity; and (3) it is fully distributed and requires little or no maintenance overhead. The combinatorial nature of the problem and the system demand for distributed algorithms makes the problem uniquely challenging. By utilizing Lagrangian decomposition and Markov chain approximation based arguments, we address this challenge by designing two distributed algorithms running in tandem: a primal-dual storage and bandwidth allocation algorithm and a "soft-worst-neighbor-choking" topology-building algorithm. Our scheme provably converges to a near-optimal solution, and is easy to implement in practice. Packet-level simulation results show that the proposed scheme achieves minimum sever load under highly heterogeneous combinations of supply and demand patterns, and is robust to system dynamics of user/helper churn, user/helper asynchrony, and random delays in the network.

Trade-off between bandwidth and efficiency in semipolar (20 2 ¯ 1 ¯) InGaN/GaN single- and multiple-quantum-well light-emitting diodes

NASA Astrophysics Data System (ADS)

Monavarian, M.; Rashidi, A.; Aragon, A. A.; Nami, M.; Oh, S. H.; DenBaars, S. P.; Feezell, D.

2018-05-01

InGaN/GaN light-emitting diodes (LEDs) with large modulation bandwidths are desirable for visible-light communication. Along with modulation speed, the consideration of the internal quantum efficiency (IQE) under operating conditions is also important. Here, we report the modulation characteristics of semipolar (20 2 ¯ 1 ¯ ) InGaN/GaN (LEDs) with single-quantum well (SQW) and multiple-quantum-well (MQW) active regions grown on free-standing semipolar GaN substrates with peak internal quantum efficiencies (IQEs) of 0.93 and 0.73, respectively. The MQW LEDs exhibit on average about 40-80% higher modulation bandwidth, reaching 1.5 GHz at 13 kA/cm2, but about 27% lower peak IQE than the SQW LEDs. We extract the differential carrier lifetimes (DLTs), RC parasitics, and carrier escape lifetimes and discuss their role in the bandwidth and IQE characteristics. A coulomb-enhanced capture process is shown to rapidly reduce the DLT of the MQW LED at high current densities. Auger recombination is also shown to play little role in increasing the speed of the LEDs. Finally, we investigate the trade-offs between the bandwidth and efficiency and introduce the bandwidth-IQE product as a potential figure of merit for optimizing speed and efficiency in InGaN/GaN LEDs.

Providing wireless bandwidth for high-speed rail operations : final report.

DOT National Transportation Integrated Search

2016-07-01

This project examined the possibility of providing wireless communication for train control systems on American high-speed trains. In this : study, the key issue is that the frequencies allocated for rail operations in the U.S. and the frequencies us...

All-optical OFDM network coding scheme for all-optical virtual private communication in PON

NASA Astrophysics Data System (ADS)

Li, Lijun; Gu, Rentao; Ji, Yuefeng; Bai, Lin; Huang, Zhitong

2014-03-01

A novel optical orthogonal frequency division multiplexing (OFDM) network coding scheme is proposed over passive optical network (PON) system. The proposed scheme for all-optical virtual private network (VPN) does not only improve transmission efficiency, but also realize full-duplex communication mode in a single fiber. Compared with the traditional all-optical VPN architectures, the all-optical OFDM network coding scheme can support higher speed, more flexible bandwidth allocation, and higher spectrum efficiency. In order to reduce the difficulty of alignment for encoding operation between inter-communication traffic, the width of OFDM subcarrier pulse is stretched in our proposed scheme. The feasibility of all-optical OFDM network coding scheme for VPN is verified, and the relevant simulation results show that the full-duplex inter-communication traffic stream can be transmitted successfully. Furthermore, the tolerance of misalignment existing in inter-ONUs traffic is investigated and analyzed for all-optical encoding operation, and the difficulty of pulse alignment is proved to be lower.

Fully Controllable Pancharatnam-Berry Metasurface Array with High Conversion Efficiency and Broad Bandwidth

PubMed Central

Liu, Chuanbao; Bai, Yang; Zhao, Qian; Yang, Yihao; Chen, Hongsheng; Zhou, Ji; Qiao, Lijie

2016-01-01

Metasurfaces have powerful abilities to manipulate the properties of electromagnetic waves flexibly, especially the modulation of polarization state for both linearly polarized (LP) and circularly polarized (CP) waves. However, the transmission efficiency of cross-polarization conversion by a single-layer metasurface has a low theoretical upper limit of 25% and the bandwidth is usually narrow, which cannot be resolved by their simple additions. Here, we efficiently manipulate polarization coupling in multilayer metasurface to promote the transmission of cross-polarization by Fabry-Perot resonance, so that a high conversion coefficient of 80–90% of CP wave is achieved within a broad bandwidth in the metasurface with C-shaped scatters by theoretical calculation, numerical simulation and experiments. Further, fully controlling Pancharatnam-Berry phase enables to realize polarized beam splitter, which is demonstrated to produce abnormal transmission with high conversion efficiency and broad bandwidth. PMID:27703254

High-throughput and low-latency 60GHz small-cell network architectures over radio-over-fiber technologies

NASA Astrophysics Data System (ADS)

Pleros, N.; Kalfas, G.; Mitsolidou, C.; Vagionas, C.; Tsiokos, D.; Miliou, A.

2017-01-01

Future broadband access networks in the 5G framework will need to be bilateral, exploiting both optical and wireless technologies. This paper deals with new approaches and synergies on radio-over-fiber (RoF) technologies and how those can be leveraged to seamlessly converge wireless technology for agility and mobility with passive optical networks (PON)-based backhauling. The proposed convergence paradigm is based upon a holistic network architecture mixing mm-wave wireless access with photonic integration, dynamic capacity allocation and network coding schemes to enable high bandwidth and low-latency fixed and 60GHz wireless personal area communications for gigabit rate per user, proposing and deploying on top a Medium-Transparent MAC (MT-MAC) protocol as a low-latency bandwidth allocation mechanism. We have evaluated alternative network topologies between the central office (CO) and the access point module (APM) for data rates up to 2.5 Gb/s and SC frequencies up to 60 GHz. Optical network coding is demonstrated for SCM-based signaling to enhance bandwidth utilization and facilitate optical-wireless convergence in 5G applications, reporting medium-transparent network coding directly at the physical layer between end-users communicating over a RoF infrastructure. Towards equipping the physical layer with the appropriate agility to support MT-MAC protocols, a monolithic InP-based Remote Antenna Unit optoelectronic PIC interface is shown that ensures control over the optical resource allocation assisting at the same time broadband wireless service. Finally, the MT-MAC protocol is analysed and simulation and analytical theoretical results are presented that are found to be in good agreement confirming latency values lower than 1msec for small- to mid-load conditions.

Widely bandwidth-tunable silicon filter with an unlimited free-spectral range.

PubMed

St-Yves, Jonathan; Bahrami, Hadi; Jean, Philippe; LaRochelle, Sophie; Shi, Wei

2015-12-01

Next-generation high-capacity optical networks require flexible allocation of spectrum resources, for which low-cost optical filters with an ultra-wide bandwidth tunability beyond 100 GHz are desired. We demonstrate an integrated band-pass filter with the bandwidth continuously tuned across 670 GHz (117-788 GHz) which, to the best of our knowledge, is the widest tuning span ever demonstrated on a silicon chip. The filter also features simultaneous wavelength tuning and an unlimited free spectral range. We measured an out-of-band contrast of up to 55 dB, low in-band ripples of less than 0.3 dB, and in-band group delay variation of less than 8 ps. This result was achieved using cascaded Bragg-grating-assisted contra-directional couplers and micro-heaters on the 220 nm silicon-on-insulator platform with a very compact footprint of less than 7000  μm2. Another design with the bandwidth continuously tunable from 50 GHz to 1 THz is also presented.

Intelligent bandwith compression

NASA Astrophysics Data System (ADS)

Tseng, D. Y.; Bullock, B. L.; Olin, K. E.; Kandt, R. K.; Olsen, J. D.

1980-02-01

The feasibility of a 1000:1 bandwidth compression ratio for image transmission has been demonstrated using image-analysis algorithms and a rule-based controller. Such a high compression ratio was achieved by first analyzing scene content using auto-cueing and feature-extraction algorithms, and then transmitting only the pertinent information consistent with mission requirements. A rule-based controller directs the flow of analysis and performs priority allocations on the extracted scene content. The reconstructed bandwidth-compressed image consists of an edge map of the scene background, with primary and secondary target windows embedded in the edge map. The bandwidth-compressed images are updated at a basic rate of 1 frame per second, with the high-priority target window updated at 7.5 frames per second. The scene-analysis algorithms used in this system together with the adaptive priority controller are described. Results of simulated 1000:1 band width-compressed images are presented. A video tape simulation of the Intelligent Bandwidth Compression system has been produced using a sequence of video input from the data base.

Quasi Path Restoration: A post-failure recovery scheme over pre-allocated backup resource for elastic optical networks

NASA Astrophysics Data System (ADS)

Yadav, Dharmendra Singh; Babu, Sarath; Manoj, B. S.

2018-03-01

Spectrum conflict during primary and backup routes assignment in elastic optical networks results in increased resource consumption as well as high Bandwidth Blocking Probability. In order to avoid such conflicts, we propose a new scheme, Quasi Path Restoration (QPR), where we divide the available spectrum into two: (1) primary spectrum (for primary routes allocation) and (2) backup spectrum (for rerouting the data on link failures). QPR exhibits three advantages over existing survivable strategies such as Shared Path Protection (SPP), Primary First Fit Backup Last Fit (PFFBLF), Jointly Releasing and re-establishment Defragmentation SPP (JRDSSPP), and Path Restoration (PR): (1) the conflict between primary and backup spectrum during route assignment is completely eliminated, (2) upon a link failure, connection recovery requires less backup resources compared to SPP, PFFBLF, and PR, and (3) availability of the same backup spectrum on each link improves the recovery guarantee. The performance of our scheme is analyzed with different primary backup spectrum partitions on varying connection-request demands and number of frequency slots. Our results show that QPR provides better connection recovery guarantee and Backup Resources Utilization (BRU) compared to bandwidth recovery of PR strategy. In addition, we compare QPR with Shared Path Protection and Primary First-Fit Backup Last Fit strategies in terms of Bandwidth Blocking Probability (BBP) and average frequency slots per connection request. Simulation results show that BBP of SPP, PFFBLF, and JRDSPP varies between 18.59% and 14.42%, while in QPR, BBP ranges from 2.55% to 17.76% for Cost239, NSFNET, and ARPANET topologies. Also, QPR provides bandwidth recovery between 93.61% and 100%, while in PR, the recovery ranges from 86.81% to 98.99%. It is evident from our analysis that QPR provides a reasonable trade-off between bandwidth blocking probability and connection recoverability.

Frequency allocations for a new satellite service - Digital audio broadcasting

NASA Technical Reports Server (NTRS)

Reinhart, Edward E.

1992-01-01

The allocation in the range 500-3000 MHz for digital audio broadcasting (DAB) is described in terms of key issues such as the transmission-system architectures. Attention is given to the optimal amount of spectrum for allocation and the technological considerations relevant to downlink bands for satellite and terrestrial transmissions. Proposals for DAB allocations are compared, and reference is made to factors impinging on the provision of ground/satellite feeder links. The allocation proposals describe the implementation of 50-60-MHz bandwidths for broadcasting in the ranges near 800 MHz, below 1525 MHz, near 2350 MHz, and near 2600 MHz. Three specific proposals are examined in terms of characteristics such as service areas, coverage/beam, channels/satellite beam, and FCC license status. Several existing problems are identified including existing services crowded with systems, the need for new bands in the 1000-3000-MHz range, and variations in the nature and intensity of implementations of existing allocations that vary from country to country.

Bandwidth compression of multispectral satellite imagery

NASA Technical Reports Server (NTRS)

Habibi, A.

1978-01-01

The results of two studies aimed at developing efficient adaptive and nonadaptive techniques for compressing the bandwidth of multispectral images are summarized. These techniques are evaluated and compared using various optimality criteria including MSE, SNR, and recognition accuracy of the bandwidth compressed images. As an example of future requirements, the bandwidth requirements for the proposed Landsat-D Thematic Mapper are considered.

Voltage-dependent K+ channels improve the energy efficiency of signalling in blowfly photoreceptors

PubMed Central

2017-01-01

Voltage-dependent conductances in many spiking neurons are tuned to reduce action potential energy consumption, so improving the energy efficiency of spike coding. However, the contribution of voltage-dependent conductances to the energy efficiency of analogue coding, by graded potentials in dendrites and non-spiking neurons, remains unclear. We investigate the contribution of voltage-dependent conductances to the energy efficiency of analogue coding by modelling blowfly R1-6 photoreceptor membrane. Two voltage-dependent delayed rectifier K+ conductances (DRs) shape the membrane's voltage response and contribute to light adaptation. They make two types of energy saving. By reducing membrane resistance upon depolarization they convert the cheap, low bandwidth membrane needed in dim light to the expensive high bandwidth membrane needed in bright light. This investment of energy in bandwidth according to functional requirements can halve daily energy consumption. Second, DRs produce negative feedback that reduces membrane impedance and increases bandwidth. This negative feedback allows an active membrane with DRs to consume at least 30% less energy than a passive membrane with the same capacitance and bandwidth. Voltage-dependent conductances in other non-spiking neurons, and in dendrites, might be organized to make similar savings. PMID:28381642

Voltage-dependent K+ channels improve the energy efficiency of signalling in blowfly photoreceptors.

PubMed

Heras, Francisco J H; Anderson, John; Laughlin, Simon B; Niven, Jeremy E

2017-04-01

Voltage-dependent conductances in many spiking neurons are tuned to reduce action potential energy consumption, so improving the energy efficiency of spike coding. However, the contribution of voltage-dependent conductances to the energy efficiency of analogue coding, by graded potentials in dendrites and non-spiking neurons, remains unclear. We investigate the contribution of voltage-dependent conductances to the energy efficiency of analogue coding by modelling blowfly R1-6 photoreceptor membrane. Two voltage-dependent delayed rectifier K + conductances (DRs) shape the membrane's voltage response and contribute to light adaptation. They make two types of energy saving. By reducing membrane resistance upon depolarization they convert the cheap, low bandwidth membrane needed in dim light to the expensive high bandwidth membrane needed in bright light. This investment of energy in bandwidth according to functional requirements can halve daily energy consumption. Second, DRs produce negative feedback that reduces membrane impedance and increases bandwidth. This negative feedback allows an active membrane with DRs to consume at least 30% less energy than a passive membrane with the same capacitance and bandwidth. Voltage-dependent conductances in other non-spiking neurons, and in dendrites, might be organized to make similar savings. © 2017 The Author(s).

A Self-organized MIMO-OFDM-based Cellular Network

NASA Astrophysics Data System (ADS)

Grünheid, Rainer; Fellenberg, Christian

2012-05-01

This paper presents a system proposal for a self-organized cellular network, which is based on the MIMO-OFDM transmission technique. Multicarrier transmission, combined with appropriate beamforming concepts, yields high bandwidth-efficiency and shows a robust behavior in multipath radio channels. Moreover, it provides a fine and tuneable granularity of space-time-frequency resources. Using a TDD approach and interference measurements in each cell, the Base Stations (BSs) decide autonomously which of the space-time-frequency resource blocks are allocated to the Mobile Terminals (MTs) in the cell, in order to fulfil certain Quality of Service (QoS) parameters. Since a synchronized Single Frequency Network (SFN), i.e., a re-use factor of one is applied, the resource blocks can be shared adaptively and flexibly among the cells, which is very advantageous in the case of a non-uniform MT distribution.

Bandwidth based methodology for designing a hybrid energy storage system for a series hybrid electric vehicle with limited all electric mode

NASA Astrophysics Data System (ADS)

Shahverdi, Masood

The cost and fuel economy of hybrid electrical vehicles (HEVs) are significantly dependent on the power-train energy storage system (ESS). A series HEV with a minimal all-electric mode (AEM) permits minimizing the size and cost of the ESS. This manuscript, pursuing the minimal size tactic, introduces a bandwidth based methodology for designing an efficient ESS. First, for a mid-size reference vehicle, a parametric study is carried out over various minimal-size ESSs, both hybrid (HESS) and non-hybrid (ESS), for finding the highest fuel economy. The results show that a specific type of high power battery with 4.5 kWh capacity can be selected as the winning candidate to study for further minimization. In a second study, following the twin goals of maximizing Fuel Economy (FE) and improving consumer acceptance, a sports car class Series-HEV (SHEV) was considered as a potential application which requires even more ESS minimization. The challenge with this vehicle is to reduce the ESS size compared to 4.5 kWh, because the available space allocation is only one fourth of the allowed battery size in the mid-size study by volume. Therefore, an advanced bandwidth-based controller is developed that allows a hybridized Subaru BRZ model to be realized with a light ESS. The result allows a SHEV to be realized with 1.13 kWh ESS capacity. In a third study, the objective is to find optimum SHEV designs with minimal AEM assumption which cover the design space between the fuel economies in the mid-size car study and the sports car study. Maximizing FE while minimizing ESS cost is more aligned with customer acceptance in the current state of market. The techniques applied to manage the power flow between energy sources of the power-train significantly affect the results of this optimization. A Pareto Frontier, including ESS cost and FE, for a SHEV with limited AEM, is introduced using an advanced bandwidth-based control strategy teamed up with duty ratio control. This controller allows the series hybrid's advantage of tightly managing engine efficiency to be extended to lighter ESS, as compared to the size of the ESS in available products in the market.

An Optimized Autonomous Space In-situ Sensorweb (OASIS) for Volcano Monitoring

NASA Astrophysics Data System (ADS)

Song, W.; Shirazi, B.; Lahusen, R.; Chien, S.; Kedar, S.; Webb, F.

2006-12-01

In response to NASA's announced requirement for Earth hazard monitoring sensor-web technology, we are developing a prototype real-time Optimized Autonomous Space In-situ Sensorweb. The prototype will be focused on volcano hazard monitoring at Mount St. Helens, which has been in continuous eruption since October 2004. The system is designed to be flexible and easily configurable for many other applications as well. The primary goals of the project are: 1) integrating complementary space (i.e., Earth Observing One (EO- 1) satellite) and in-situ (ground-based) elements into an interactive, autonomous sensor-web; 2) advancing sensor-web power and communication resource management technology; and 3) enabling scalability for seamless infusion of future space and in-situ assets into the sensor-web. To meet these goals, we are developing: 1) a test-bed in-situ array with smart sensor nodes capable of making autonomous data acquisition decisions; 2) efficient self-organization algorithm of sensor-web topology to support efficient data communication and command control; 3) smart bandwidth allocation algorithms in which sensor nodes autonomously determine packet priorities based on mission needs and local bandwidth information in real- time; and 4) remote network management and reprogramming tools. The space and in-situ control components of the system will be integrated such that each element is capable of triggering the other. Sensor-web data acquisition and dissemination will be accomplished through the use of SensorML language standards for geospatial information. The three-year project will demonstrate end-to-end system performance with the in-situ test-bed at Mount St. Helens and NASA's EO-1 platform.

Optimal Golomb Ruler Sequences Generation for Optical WDM Systems: A Novel Parallel Hybrid Multi-objective Bat Algorithm

NASA Astrophysics Data System (ADS)

Bansal, Shonak; Singh, Arun Kumar; Gupta, Neena

2017-02-01

In real-life, multi-objective engineering design problems are very tough and time consuming optimization problems due to their high degree of nonlinearities, complexities and inhomogeneity. Nature-inspired based multi-objective optimization algorithms are now becoming popular for solving multi-objective engineering design problems. This paper proposes original multi-objective Bat algorithm (MOBA) and its extended form, namely, novel parallel hybrid multi-objective Bat algorithm (PHMOBA) to generate shortest length Golomb ruler called optimal Golomb ruler (OGR) sequences at a reasonable computation time. The OGRs found their application in optical wavelength division multiplexing (WDM) systems as channel-allocation algorithm to reduce the four-wave mixing (FWM) crosstalk. The performances of both the proposed algorithms to generate OGRs as optical WDM channel-allocation is compared with other existing classical computing and nature-inspired algorithms, including extended quadratic congruence (EQC), search algorithm (SA), genetic algorithms (GAs), biogeography based optimization (BBO) and big bang-big crunch (BB-BC) optimization algorithms. Simulations conclude that the proposed parallel hybrid multi-objective Bat algorithm works efficiently as compared to original multi-objective Bat algorithm and other existing algorithms to generate OGRs for optical WDM systems. The algorithm PHMOBA to generate OGRs, has higher convergence and success rate than original MOBA. The efficiency improvement of proposed PHMOBA to generate OGRs up to 20-marks, in terms of ruler length and total optical channel bandwidth (TBW) is 100 %, whereas for original MOBA is 85 %. Finally the implications for further research are also discussed.

PIYAS-proceeding to intelligent service oriented memory allocation for flash based data centric sensor devices in wireless sensor networks.

PubMed

Rizvi, Sanam Shahla; Chung, Tae-Sun

2010-01-01

Flash memory has become a more widespread storage medium for modern wireless devices because of its effective characteristics like non-volatility, small size, light weight, fast access speed, shock resistance, high reliability and low power consumption. Sensor nodes are highly resource constrained in terms of limited processing speed, runtime memory, persistent storage, communication bandwidth and finite energy. Therefore, for wireless sensor networks supporting sense, store, merge and send schemes, an efficient and reliable file system is highly required with consideration of sensor node constraints. In this paper, we propose a novel log structured external NAND flash memory based file system, called Proceeding to Intelligent service oriented memorY Allocation for flash based data centric Sensor devices in wireless sensor networks (PIYAS). This is the extended version of our previously proposed PIYA [1]. The main goals of the PIYAS scheme are to achieve instant mounting and reduced SRAM space by keeping memory mapping information to a very low size of and to provide high query response throughput by allocation of memory to the sensor data by network business rules. The scheme intelligently samples and stores the raw data and provides high in-network data availability by keeping the aggregate data for a longer period of time than any other scheme has done before. We propose effective garbage collection and wear-leveling schemes as well. The experimental results show that PIYAS is an optimized memory management scheme allowing high performance for wireless sensor networks.

Asynchronous Incremental Stochastic Dual Descent Algorithm for Network Resource Allocation

NASA Astrophysics Data System (ADS)

Bedi, Amrit Singh; Rajawat, Ketan

2018-05-01

Stochastic network optimization problems entail finding resource allocation policies that are optimum on an average but must be designed in an online fashion. Such problems are ubiquitous in communication networks, where resources such as energy and bandwidth are divided among nodes to satisfy certain long-term objectives. This paper proposes an asynchronous incremental dual decent resource allocation algorithm that utilizes delayed stochastic {gradients} for carrying out its updates. The proposed algorithm is well-suited to heterogeneous networks as it allows the computationally-challenged or energy-starved nodes to, at times, postpone the updates. The asymptotic analysis of the proposed algorithm is carried out, establishing dual convergence under both, constant and diminishing step sizes. It is also shown that with constant step size, the proposed resource allocation policy is asymptotically near-optimal. An application involving multi-cell coordinated beamforming is detailed, demonstrating the usefulness of the proposed algorithm.

A novel biasing dependent circuit model of resonant cavity enhanced avalanche photodetectors (RCE-APDs)

NASA Astrophysics Data System (ADS)

Abdelhamid, Mostafa R.; El-Batawy, Yasser M.; Deen, M. Jamal

2018-02-01

In Resonant Cavity Enhanced Photodetectors (RCE-PDs), the trade-off between the bandwidth and the quantum efficiency in the conventional photodetectors is overcome. In RCE-PDs, large bandwidth can be achieved using a thin absorption layer while the use of a resonant cavity allows for multiple passes of light in the absorption which boosts the quantum efficiency. In this paper, a complete bias-dependent model for the Resonant Cavity Enhanced-Separated Absorption Graded Charge Multiplication-Avalanche Photodetector (RCE-SAGCM-APD) is presented. The proposed model takes into account the case of drift velocities other than the saturation velocity, thus modeling this effect on the photodetector different design parameters such as Gain, Bandwidth and Gain-Bandwidth product.

Energy-saving framework for passive optical networks with ONU sleep/doze mode.

PubMed

Van, Dung Pham; Valcarenghi, Luca; Dias, Maluge Pubuduni Imali; Kondepu, Koteswararao; Castoldi, Piero; Wong, Elaine

2015-02-09

This paper proposes an energy-saving passive optical network framework (ESPON) that aims to incorporate optical network unit (ONU) sleep/doze mode into dynamic bandwidth allocation (DBA) algorithms to reduce ONU energy consumption. In the ESPON, the optical line terminal (OLT) schedules both downstream (DS) and upstream (US) transmissions in the same slot in an online and dynamic fashion whereas the ONU enters sleep mode outside the slot. The ONU sleep time is maximized based on both DS and US traffic. Moreover, during the slot, the ONU might enter doze mode when only its transmitter is idle to further improve energy efficiency. The scheduling order of data transmission, control message exchange, sleep period, and doze period defines an energy-efficient scheme under the ESPON. Three schemes are designed and evaluated in an extensive FPGA-based evaluation. Results show that whilst all the schemes significantly save ONU energy for different evaluation scenarios, the scheduling order has great impact on their performance. In addition, the ESPON allows for a scheduling order that saves ONU energy independently of the network reach.

Region-of-interest determination and bit-rate conversion for H.264 video transcoding

NASA Astrophysics Data System (ADS)

Huang, Shu-Fen; Chen, Mei-Juan; Tai, Kuang-Han; Li, Mian-Shiuan

2013-12-01

This paper presents a video bit-rate transcoder for baseline profile in H.264/AVC standard to fit the available channel bandwidth for the client when transmitting video bit-streams via communication channels. To maintain visual quality for low bit-rate video efficiently, this study analyzes the decoded information in the transcoder and proposes a Bayesian theorem-based region-of-interest (ROI) determination algorithm. In addition, a curve fitting scheme is employed to find the models of video bit-rate conversion. The transcoded video will conform to the target bit-rate by re-quantization according to our proposed models. After integrating the ROI detection method and the bit-rate transcoding models, the ROI-based transcoder allocates more coding bits to ROI regions and reduces the complexity of the re-encoding procedure for non-ROI regions. Hence, it not only keeps the coding quality but improves the efficiency of the video transcoding for low target bit-rates and makes the real-time transcoding more practical. Experimental results show that the proposed framework gets significantly better visual quality.

Efficient traffic grooming with dynamic ONU grouping for multiple-OLT-based access network

NASA Astrophysics Data System (ADS)

Zhang, Shizong; Gu, Rentao; Ji, Yuefeng; Wang, Hongxiang

2015-12-01

Fast bandwidth growth urges large-scale high-density access scenarios, where the multiple Passive Optical Networking (PON) system clustered deployment can be adopted as an appropriate solution to fulfill the huge bandwidth demands, especially for a future 5G mobile network. However, the lack of interaction between different optical line terminals (OLTs) results in part of the bandwidth resources waste. To increase the bandwidth efficiency, as well as reduce bandwidth pressure at the edge of a network, we propose a centralized flexible PON architecture based on Time- and Wavelength-Division Multiplexing PON (TWDM PON). It can provide flexible affiliation for optical network units (ONUs) and different OLTs to support access network traffic localization. Specifically, a dynamic ONU grouping algorithm (DGA) is provided to obtain the minimal OLT outbound traffic. Simulation results show that DGA obtains an average 25.23% traffic gain increment under different OLT numbers within a small ONU number situation, and the traffic gain will increase dramatically with the increment of the ONU number. As the DGA can be deployed easily as an application running above the centralized control plane, the proposed architecture can be helpful to improve the network efficiency for future traffic-intensive access scenarios.

A mechanism design approach to bandwidth allocation in tactical data networks

NASA Astrophysics Data System (ADS)

Mour, Ankur

The defense sector is undergoing a phase of rapid technological advancement, in the pursuit of its goal of information superiority. This goal depends on a large network of complex interconnected systems - sensors, weapons, soldiers - linked through a maze of heterogeneous networks. The sheer scale and size of these networks prompt behaviors that go beyond conglomerations of systems or `system-of-systems'. The lack of a central locus and disjointed, competing interests among large clusters of systems makes this characteristic of an Ultra Large Scale (ULS) system. These traits of ULS systems challenge and undermine the fundamental assumptions of today's software and system engineering approaches. In the absence of a centralized controller it is likely that system users may behave opportunistically to meet their local mission requirements, rather than the objectives of the system as a whole. In these settings, methods and tools based on economics and game theory (like Mechanism Design) are likely to play an important role in achieving globally optimal behavior, when the participants behave selfishly. Against this background, this thesis explores the potential of using computational mechanisms to govern the behavior of ultra-large-scale systems and achieve an optimal allocation of constrained computational resources Our research focusses on improving the quality and accuracy of the common operating picture through the efficient allocation of bandwidth in tactical data networks among self-interested actors, who may resort to strategic behavior dictated by self-interest. This research problem presents the kind of challenges we anticipate when we have to deal with ULS systems and, by addressing this problem, we hope to develop a methodology which will be applicable for ULS system of the future. We build upon the previous works which investigate the application of auction-based mechanism design to dynamic, performance-critical and resource-constrained systems of interest to the defense community. In this thesis, we consider a scenario where a number of military platforms have been tasked with the goal of detecting and tracking targets. The sensors onboard a military platform have a partial and inaccurate view of the operating picture and need to make use of data transmitted from neighboring sensors in order to improve the accuracy of their own measurements. The communication takes place over tactical data networks with scarce bandwidth. The problem is compounded by the possibility that the local goals of military platforms might not be aligned with the global system goal. Such a scenario might occur in multi-flag, multi-platform military exercises, where the military commanders of each platform are more concerned with the well-being of their own platform over others. Therefore there is a need to design a mechanism that efficiently allocates the flow of data within the network to ensure that the resulting global performance maximizes the information gain of the entire system, despite the self-interested actions of the individual actors. We propose a two-stage mechanism based on modified strictly-proper scoring rules, with unknown costs, whereby multiple sensor platforms can provide estimates of limited precisions and the center does not have to rely on knowledge of the actual outcome when calculating payments. In particular, our work emphasizes the importance of applying robust optimization techniques to deal with the uncertainty in the operating environment. We apply our robust optimization - based scoring rules algorithm to an agent-based model framework of the combat tactical data network, and analyze the results obtained. Through the work we hope to demonstrate how mechanism design, perched at the intersection of game theory and microeconomics, is aptly suited to address one set of challenges of the ULS system paradigm - challenges not amenable to traditional system engineering approaches.

Analysis and Simulation of Traffic Control for Resource Management in DVB-Based Broadband Satellite Access Networks

NASA Astrophysics Data System (ADS)

Impemba, Ernesto; Inzerilli, Tiziano

2003-07-01

Integration of satellite access networks with the Internet is seen as a strategic goal to achieve in order to provide ubiquitous broadband access to Internet services in Next Generation Networks (NGNs). One of the main interworking aspects which has been most studied is an efficient management of satellite resources, i.e. bandwidth and buffer space, in order to satisfy most demanding application requirements as to delay control and bandwidth assurance. In this context, resource management in DVB-S/DVB-RCS satellite technologies, emerging technologies for broadband satellite access and transport of IP applications, is a research issue largely investigated as a means to provide efficient bi-directional communications across satellites. This is in particular one of the principal goals of the SATIP6 project, sponsored within the 5th EU Research Programme Framework, i.e. IST. In this paper we present a possible approach to efficiently exploit bandwidth, the most critical resource in a broadband satellite access network, while pursuing satisfaction of delay and bandwidth requirements for applications with guaranteed QoS through a traffic control architecture to be implemented in ground terminals. Performance of this approach is assessed in terms of efficient exploitation of the uplink bandwidth and differentiation and minimization of queuing delays for most demanding applications over a time-varying capacity. Opnet simulations is used as analysis tool.

Concatenated Coding Using Trellis-Coded Modulation

NASA Technical Reports Server (NTRS)

Thompson, Michael W.

1997-01-01

In the late seventies and early eighties a technique known as Trellis Coded Modulation (TCM) was developed for providing spectrally efficient error correction coding. Instead of adding redundant information in the form of parity bits, redundancy is added at the modulation stage thereby increasing bandwidth efficiency. A digital communications system can be designed to use bandwidth-efficient multilevel/phase modulation such as Amplitude Shift Keying (ASK), Phase Shift Keying (PSK), Differential Phase Shift Keying (DPSK) or Quadrature Amplitude Modulation (QAM). Performance gain can be achieved by increasing the number of signals over the corresponding uncoded system to compensate for the redundancy introduced by the code. A considerable amount of research and development has been devoted toward developing good TCM codes for severely bandlimited applications. More recently, the use of TCM for satellite and deep space communications applications has received increased attention. This report describes the general approach of using a concatenated coding scheme that features TCM and RS coding. Results have indicated that substantial (6-10 dB) performance gains can be achieved with this approach with comparatively little bandwidth expansion. Since all of the bandwidth expansion is due to the RS code we see that TCM based concatenated coding results in roughly 10-50% bandwidth expansion compared to 70-150% expansion for similar concatenated scheme which use convolution code. We stress that combined coding and modulation optimization is important for achieving performance gains while maintaining spectral efficiency.

Ultrahigh Responsivity-Bandwidth Product in a Compact InP Nanopillar Phototransistor Directly Grown on Silicon

NASA Astrophysics Data System (ADS)

Ko, Wai Son; Bhattacharya, Indrasen; Tran, Thai-Truong D.; Ng, Kar Wei; Adair Gerke, Stephen; Chang-Hasnain, Connie

2016-09-01

Highly sensitive and fast photodetectors can enable low power, high bandwidth on-chip optical interconnects for silicon integrated electronics. III-V compound semiconductor direct-bandgap materials with high absorption coefficients are particularly promising for photodetection in energy-efficient optical links because of the potential to scale down the absorber size, and the resulting capacitance and dark current, while maintaining high quantum efficiency. We demonstrate a compact bipolar junction phototransistor with a high current gain (53.6), bandwidth (7 GHz) and responsivity (9.5 A/W) using a single crystalline indium phosphide nanopillar directly grown on a silicon substrate. Transistor gain is obtained at sub-picowatt optical power and collector bias close to the CMOS line voltage. The quantum efficiency-bandwidth product of 105 GHz is the highest for photodetectors on silicon. The bipolar junction phototransistor combines the receiver front end circuit and absorber into a monolithic integrated device, eliminating the wire capacitance between the detector and first amplifier stage.

Ultrahigh Responsivity-Bandwidth Product in a Compact InP Nanopillar Phototransistor Directly Grown on Silicon

PubMed Central

Ko, Wai Son; Bhattacharya, Indrasen; Tran, Thai-Truong D.; Ng, Kar Wei; Adair Gerke, Stephen; Chang-Hasnain, Connie

2016-01-01

Highly sensitive and fast photodetectors can enable low power, high bandwidth on-chip optical interconnects for silicon integrated electronics. III-V compound semiconductor direct-bandgap materials with high absorption coefficients are particularly promising for photodetection in energy-efficient optical links because of the potential to scale down the absorber size, and the resulting capacitance and dark current, while maintaining high quantum efficiency. We demonstrate a compact bipolar junction phototransistor with a high current gain (53.6), bandwidth (7 GHz) and responsivity (9.5 A/W) using a single crystalline indium phosphide nanopillar directly grown on a silicon substrate. Transistor gain is obtained at sub-picowatt optical power and collector bias close to the CMOS line voltage. The quantum efficiency-bandwidth product of 105 GHz is the highest for photodetectors on silicon. The bipolar junction phototransistor combines the receiver front end circuit and absorber into a monolithic integrated device, eliminating the wire capacitance between the detector and first amplifier stage. PMID:27659796

Sharing the 620-790 MHz band allocated to terrestrial television with an audio-bandwidth social service satellite system

NASA Technical Reports Server (NTRS)

Smith, E. K.; Reinhart, E. E.

1977-01-01

A study was carried out to identify the optimum uplink and downlink frequencies for audio-bandwidth channels for use by a satellite system distributing social services. The study considered functional-user-need models for five types of social services and identified a general baseline system that is appropriate for most of them. Technical aspects and costs of this system and of the frequency bands that it might use were reviewed, leading to the identification of the 620-790 MHz band as a perferred candidate for both uplink and downlink transmissions for nonmobile applications. The study also led to some ideas as to how to configure the satellite system.

Terahertz wireless communications based on photonics technologies.

PubMed

Nagatsuma, Tadao; Horiguchi, Shogo; Minamikata, Yusuke; Yoshimizu, Yasuyuki; Hisatake, Shintaro; Kuwano, Shigeru; Yoshimoto, Naoto; Terada, Jun; Takahashi, Hiroyuki

2013-10-07

There has been an increasing interest in the application of terahertz (THz) waves to broadband wireless communications. In particular, use of frequencies above 275 GHz is one of the strong concerns among radio scientists and engineers, because these frequency bands have not yet been allocated at specific active services, and there is a possibility to employ extremely large bandwidths for ultra-broadband wireless communications. Introduction of photonics technologies for signal generation, modulation and detection is effective not only to enhance the bandwidth and/or the data rate, but also to combine fiber-optic (wired) and wireless networks. This paper reviews recent progress in THz wireless communications using telecom-based photonics technologies towards 100 Gbit/s.

Minimum variance optimal rate allocation for multiplexed H.264/AVC bitstreams.

PubMed

Tagliasacchi, Marco; Valenzise, Giuseppe; Tubaro, Stefano

2008-07-01

Consider the problem of transmitting multiple video streams to fulfill a constant bandwidth constraint. The available bit budget needs to be distributed across the sequences in order to meet some optimality criteria. For example, one might want to minimize the average distortion or, alternatively, minimize the distortion variance, in order to keep almost constant quality among the encoded sequences. By working in the rho-domain, we propose a low-delay rate allocation scheme that, at each time instant, provides a closed form solution for either the aforementioned problems. We show that minimizing the distortion variance instead of the average distortion leads, for each of the multiplexed sequences, to a coding penalty less than 0.5 dB, in terms of average PSNR. In addition, our analysis provides an explicit relationship between model parameters and this loss. In order to smooth the distortion also along time, we accommodate a shared encoder buffer to compensate for rate fluctuations. Although the proposed scheme is general, and it can be adopted for any video and image coding standard, we provide experimental evidence by transcoding bitstreams encoded using the state-of-the-art H.264/AVC standard. The results of our simulations reveal that is it possible to achieve distortion smoothing both in time and across the sequences, without sacrificing coding efficiency.

SDN control of optical nodes in metro networks for high capacity inter-datacentre links

NASA Astrophysics Data System (ADS)

Magalhães, Eduardo; Perry, Philip; Barry, Liam

2017-11-01

Worldwide demand for bandwidth has been growing fast for some years and continues to do so. To cover this, mega datacentres need scalable connectivity to provide rich connectivity to handle the heavy traffic across them. Therefore, hardware infrastructures must be able to play different roles according to service and traffic requirements. In this context, software defined networking (SDN) decouples the network control and forwarding functions enabling the network control to become directly programmable and the underlying infrastructure to be abstracted for applications and network services. In addition, elastic optical networking (EON) technologies enable efficient spectrum utilization by allocating variable bandwidth to each user according to their actual needs. In particular, flexible transponders and reconfigurable optical add/drop multiplexers (ROADMs) are key elements since they can offer degrees of freedom to self adapt accordingly. Thus, it is crucial to design control methods in order to optimize the hardware utilization and offer high reconfigurability, flexibility and adaptability. In this paper, we propose and analyze, using a simulation framework, a method of capacity maximization through optical power profile manipulation for inter datacentre links that use existing metropolitan optical networks by exploiting the global network view afforded by SDN. Results show that manipulating the loss profiles of the ROADMs in the metro-network can yield optical signal-to-noise ratio (OSNR) improvements up to 10 dB leading to an increase in 112% in total capacity.

Operation bandwidth optimization of photonic differentiators.

PubMed

Yan, Siqi; Zhang, Yong; Dong, Jianji; Zheng, Aoling; Liao, Shasha; Zhou, Hailong; Wu, Zhao; Xia, Jinsong; Zhang, Xinliang

2015-07-27

We theoretically investigate the operation bandwidth limitation of the photonic differentiator including the upper limitation, which is restrained by the device operation bandwidth and the lower limitation, which is restrained by the energy efficiency (EE) and detecting noise level. Taking the silicon photonic crystal L3 nano-cavity (PCN) as an example, for the first time, we experimentally demonstrate that the lower limitation of the operation bandwidth does exist and differentiators with different bandwidths have significantly different acceptable pulse width range of input signals, which are consistent to the theoretical prediction. Furthermore, we put forward a novel photonic differentiator scheme employing cascaded PCNs with different Q factors, which is likely to expand the operation bandwidth range of photonic differentiator dramatically.

Modulated method for efficient, narrow-bandwidth, laser Compton X-ray and gamma-ray sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barty, Christopher P. J.

A method of x-ray and gamma-ray generation via laser Compton scattering uses the interaction of a specially-formatted, highly modulated, long duration, laser pulse with a high-frequency train of high-brightness electron bunches to both create narrow bandwidth x-ray and gamma-ray sources and significantly increase the laser to Compton photon conversion efficiency.

Method for efficient, narrow-bandwidth, laser compton x-ray and gamma-ray sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barty, Christopher P. J.

A method of x-ray and gamma-ray generation via laser Compton scattering uses the interaction of a specially-formatted, highly modulated, long duration, laser pulse with a high-frequency train of high-brightness electron bunches to both create narrow bandwidth x-ray and gamma-ray sources and significantly increase the laser to Compton photon conversion efficiency.

Bandwidth efficient coding for satellite communications

NASA Technical Reports Server (NTRS)

Lin, Shu; Costello, Daniel J., Jr.; Miller, Warner H.; Morakis, James C.; Poland, William B., Jr.

1992-01-01

An error control coding scheme was devised to achieve large coding gain and high reliability by using coded modulation with reduced decoding complexity. To achieve a 3 to 5 dB coding gain and moderate reliability, the decoding complexity is quite modest. In fact, to achieve a 3 dB coding gain, the decoding complexity is quite simple, no matter whether trellis coded modulation or block coded modulation is used. However, to achieve coding gains exceeding 5 dB, the decoding complexity increases drastically, and the implementation of the decoder becomes very expensive and unpractical. The use is proposed of coded modulation in conjunction with concatenated (or cascaded) coding. A good short bandwidth efficient modulation code is used as the inner code and relatively powerful Reed-Solomon code is used as the outer code. With properly chosen inner and outer codes, a concatenated coded modulation scheme not only can achieve large coding gains and high reliability with good bandwidth efficiency but also can be practically implemented. This combination of coded modulation and concatenated coding really offers a way of achieving the best of three worlds, reliability and coding gain, bandwidth efficiency, and decoding complexity.

A comparison of foveated acquisition and tracking performance relative to uniform resolution approaches

NASA Astrophysics Data System (ADS)

Dubuque, Shaun; Coffman, Thayne; McCarley, Paul; Bovik, A. C.; Thomas, C. William

2009-05-01

Foveated imaging has been explored for compression and tele-presence, but gaps exist in the study of foveated imaging applied to acquisition and tracking systems. Results are presented from two sets of experiments comparing simple foveated and uniform resolution targeting (acquisition and tracking) algorithms. The first experiments measure acquisition performance when locating Gabor wavelet targets in noise, with fovea placement driven by a mutual information measure. The foveated approach is shown to have lower detection delay than a notional uniform resolution approach when using video that consumes equivalent bandwidth. The second experiments compare the accuracy of target position estimates from foveated and uniform resolution tracking algorithms. A technique is developed to select foveation parameters that minimize error in Kalman filter state estimates. Foveated tracking is shown to consistently outperform uniform resolution tracking on an abstract multiple target task when using video that consumes equivalent bandwidth. Performance is also compared to uniform resolution processing without bandwidth limitations. In both experiments, superior performance is achieved at a given bandwidth by foveated processing because limited resources are allocated intelligently to maximize operational performance. These findings indicate the potential for operational performance improvements over uniform resolution systems in both acquisition and tracking tasks.

Designing Two-Layer Optical Networks with Statistical Multiplexing

NASA Astrophysics Data System (ADS)

Addis, B.; Capone, A.; Carello, G.; Malucelli, F.; Fumagalli, M.; Pedrin Elli, E.

The possibility of adding multi-protocol label switching (MPLS) support to transport networks is considered an important opportunity by telecom carriers that want to add packet services and applications to their networks. However, the question that arises is whether it is suitable to have MPLS nodes just at the edge of the network to collect packet traffic from users, or also to introduce MPLS facilities on a subset of the core nodes in order to exploit packet switching flexibility and multiplexing, thus providing induction of a better bandwidth allocation. In this article, we address this complex decisional problem with the support of a mathematical programming approach. We consider two-layer networks where MPLS is overlaid on top of transport networks-synchronous digital hierarchy (SDH) or wavelength division multiplexing (WDM)-depending on the required link speed. The discussions' decisions take into account the trade-off between the cost of adding MPLS support in the core nodes and the savings in the link bandwidth allocation due to the statistical multiplexing and the traffic grooming effects induced by MPLS nodes. The traffic matrix specifies for each point-to-point request a pair of values: a mean traffic value and an additional one. Using this traffic model, the effect of statistical multiplexing on a link allows the allocation of a capacity equal to the sum of all the mean values of the traffic demands routed on the link and only the highest additional one. The proposed approach is suitable to solve real instances in reasonable time.

Bandwidth Management in Universities in Zimbabwe: Towards a Responsible User Base through Effective Policy Implementation

ERIC Educational Resources Information Center

Chitanana, Lockias

2012-01-01

This research was undertaken to investigate the issue of how to maximise or make efficient use of bandwidth. In particular, the research sought to find out about what universities in Zimbabwe are doing to manage their bandwidth. It was, therefore, appropriate to survey a sample of five universities and to catalogue their experiences. Results show…

A 0.4-2.3 GHz broadband power amplifier extended continuous class-F design technology

NASA Astrophysics Data System (ADS)

Chen, Peng; He, Songbai

2015-08-01

A 0.4-2.3 GHz broadband power amplifier (PA) extended continuous class-F design technology is proposed in this paper. Traditional continuous class-F PA performs in high-efficiency only in one octave bandwidth. With the increasing development of wireless communication, the PA is in demand to cover the mainstream communication standards' working frequencies from 0.4 GHz to 2.2 GHz. In order to achieve this objective, the bandwidths of class-F and continuous class-F PA are analysed and discussed by Fourier series. Also, two criteria, which could reduce the continuous class-F PA's implementation complexity, are presented and explained to investigate the overlapping area of the transistor's current and voltage waveforms. The proposed PA design technology is based on the continuous class-F design method and divides the bandwidth into two parts: the first part covers the bandwidth from 1.3 GHz to 2.3 GHz, where the impedances are designed by the continuous class-F method; the other part covers the bandwidth from 0.4 GHz to 1.3 GHz, where the impedance to guarantee PA to be in high-efficiency over this bandwidth is selected and controlled. The improved particle swarm optimisation is employed for realising the multi-impedances of output and input network. A PA based on a commercial 10 W GaN high electron mobility transistor is designed and fabricated to verify the proposed design method. The simulation and measurement results show that the proposed PA could deliver 40-76% power added efficiency and more than 11 dB power gain with more than 40 dBm output power over the bandwidth from 0.4-2.3 GHz.

A data envelope analysis to assess factors affecting technical and economic efficiency of individual broiler breeder hens.

PubMed

Romero, L F; Zuidhof, M J; Jeffrey, S R; Naeima, A; Renema, R A; Robinson, F E

2010-08-01

This study evaluated the effect of feed allocation and energetic efficiency on technical and economic efficiency of broiler breeder hens using the data envelope analysis methodology and quantified the effect of variables affecting technical efficiency. A total of 288 Ross 708 pullets were placed in individual cages at 16 wk of age and assigned to 1 of 4 feed allocation groups. Three of them had feed allocated on a group basis with divergent BW targets: standard, high (standard x 1.1), and low (standard x 0.9). The fourth group had feed allocated on an individual bird basis following the standard BW target. Birds were classified in 3 energetic efficiency categories: low, average, and high, based on estimated maintenance requirements. Technical efficiency considered saleable chicks as output and cumulative ME intake and time as inputs. Economic efficiency of feed allocation treatments was analyzed under different cost scenarios. Birds with low feed allocation exhibited a lower technical efficiency (69.4%) than standard (72.1%), which reflected a reduced egg production rate. Feed allocation of the high treatment could have been reduced by 10% with the same chick production as the standard treatment. The low treatment exhibited reduced economic efficiency at greater capital costs, whereas high had reduced economic efficiency at greater feed costs. The average energetic efficiency hens had a lower technical efficiency in the low compared with the standard feed allocation. A 1% increment in estimated maintenance requirement changed technical efficiency by -0.23%, whereas a 1% increment in ME intake had a -0.47% effect. The negative relationship between technical efficiency and ME intake was counterbalanced by a positive correlation of ME intake and egg production. The negative relationship of technical efficiency and maintenance requirements was synergized by a negative correlation of hen maintenance and egg production. Economic efficiency methodologies are effective tools to assess the economic effect of selection and flock management programs because biological, allocative, and economic factors can be independently analyzed.

TCP Pacing Developed

NASA Technical Reports Server (NTRS)

Ivancic, William D.

2002-01-01

Transmission control protocol (TCP) was conceived and designed to run over a variety of communication links, including wireless and high-bandwidth links. However, with recent technological advances in satellite and fiber-optic networks, researchers are reevaluating the flexibility of TCP. The TCP pacing and packet pair probing implementation may help overcome two of the major obstacles identified for efficient bandwidth utilization over communication links with large delay-bandwidth products.

Impact of crystal orientation on the modulation bandwidth of InGaN/GaN light-emitting diodes

NASA Astrophysics Data System (ADS)

Monavarian, M.; Rashidi, A.; Aragon, A. A.; Oh, S. H.; Rishinaramangalam, A. K.; DenBaars, S. P.; Feezell, D.

2018-01-01

High-speed InGaN/GaN blue light-emitting diodes (LEDs) are needed for future gigabit-per-second visible-light communication systems. Large LED modulation bandwidths are typically achieved at high current densities, with reports close to 1 GHz bandwidth at current densities ranging from 5 to 10 kA/cm2. However, the internal quantum efficiency (IQE) of InGaN/GaN LEDs is quite low at high current densities due to the well-known efficiency droop phenomenon. Here, we show experimentally that nonpolar and semipolar orientations of GaN enable higher modulation bandwidths at low current densities where the IQE is expected to be higher and power dissipation is lower. We experimentally compare the modulation bandwidth vs. current density for LEDs on nonpolar (10 1 ¯ 0 ), semipolar (20 2 ¯ 1 ¯) , and polar (" separators="|0001 ) orientations. In agreement with wavefunction overlap considerations, the experimental results indicate a higher modulation bandwidth for the nonpolar and semipolar LEDs, especially at relatively low current densities. At 500 A/cm2, the nonpolar LED has a 3 dB bandwidth of ˜1 GHz, while the semipolar and polar LEDs exhibit bandwidths of 260 MHz and 75 MHz, respectively. A lower carrier density for a given current density is extracted from the RF measurements for the nonpolar and semipolar LEDs, consistent with the higher wavefunction overlaps in these orientations. At large current densities, the bandwidth of the polar LED approaches that of the nonpolar and semipolar LEDs due to coulomb screening of the polarization field. The results support using nonpolar and semipolar orientations to achieve high-speed LEDs at low current densities.

Gain and power optimization of the wireless optical system with multilevel modulation.

PubMed

Liu, Xian

2008-06-01

When used in an outdoor environment to expedite networking access, the performance of wireless optical communication systems is affected by transmitter sway. In the design of such systems, much attention has been paid to developing power-efficient schemes. However, the bandwidth efficiency is also an important issue. One of the most natural approaches to promote bandwidth efficiency is to use multilevel modulation. This leads to multilevel pulse amplitude modulation in the context of intensity modulation and direct detection. We develop a model based on the four-level pulse amplitude modulation. We show that the model can be formulated as an optimization problem in terms of the transmitter power, bit error probability, transmitter gain, and receiver gain. The technical challenges raised by modeling and solving the problem include the analytical and numerical treatments for the improper integrals of the Gaussian functions coupled with the erfc function. The results demonstrate that, at the optimal points, the power penalty paid to the doubled bandwidth efficiency is around 3 dB.

Research on allocation efficiency of the daisy chain allocation algorithm

NASA Astrophysics Data System (ADS)

Shi, Jingping; Zhang, Weiguo

2013-03-01

With the improvement of the aircraft performance in reliability, maneuverability and survivability, the number of the control effectors increases a lot. How to distribute the three-axis moments into the control surfaces reasonably becomes an important problem. Daisy chain method is simple and easy to be carried out in the design of the allocation system. But it can not solve the allocation problem for entire attainable moment subset. For the lateral-directional allocation problem, the allocation efficiency of the daisy chain can be directly measured by the area of its subset of attainable moments. Because of the non-linear allocation characteristic, the subset of attainable moments of daisy-chain method is a complex non-convex polygon, and it is difficult to solve directly. By analyzing the two-dimensional allocation problems with a "micro-element" idea, a numerical calculation algorithm is proposed to compute the area of the non-convex polygon. In order to improve the allocation efficiency of the algorithm, a genetic algorithm with the allocation efficiency chosen as the fitness function is proposed to find the best pseudo-inverse matrix.

The routing, modulation level, and spectrum allocation algorithm in the virtual optical network mapping

NASA Astrophysics Data System (ADS)

Wang, Yunyun; Li, Hui; Liu, Yuze; Ji, Yuefeng; Li, Hongfa

2017-10-01

With the development of large video services and cloud computing, the network is increasingly in the form of services. In SDON, the SDN controller holds the underlying physical resource information, thus allocating the appropriate resources and bandwidth to the VON service. However, for some services that require extremely strict QoT (quality of transmission), the shortest distance path algorithm is often unable to meet the requirements because it does not take the link spectrum resources into account. And in accordance with the choice of the most unoccupied links, there may be more spectrum fragments. So here we propose a new RMLSA (the routing, modulation Level, and spectrum allocation) algorithm to reduce the blocking probability. The results show about 40% less blocking probability than the shortest-distance algorithm and the minimum usage of the spectrum priority algorithm. This algorithm is used to satisfy strict request of QoT for demands.

Economic model for QoS guarantee on the Internet

NASA Astrophysics Data System (ADS)

Zhang, Chi; Wei, Jiaolong

2001-09-01

This paper describes a QoS guarantee architecture suited for best-effort environments, based on ideas from microeconomics and non-cooperative game theory. First, an analytic model is developed for the study of the resource allocation in the Internet. Then we show that with a simple pricing mechanism (from network implementation and users' points-of-view), we were able to provide QoS guarantee at per flow level without resource allocation or complicated scheduling mechanisms or maintaining per flow state in the core network. Unlike the previous work on this area, we extend the basic model to support inelastic applications which require minimum bandwidth guarantees for a given time period by introducing derivative market.

Error control techniques for satellite and space communications

NASA Technical Reports Server (NTRS)

Costello, Daniel J., Jr.

1989-01-01

The performance of bandwidth efficient trellis codes on channels with phase jitter, or those disturbed by jamming and impulse noise is analyzed. An heuristic algorithm for construction of bandwidth efficient trellis codes with any constraint length up to about 30, any signal constellation, and any code rate was developed. Construction of good distance profile trellis codes for sequential decoding and comparison of random coding bounds of trellis coded modulation schemes are also discussed.

Nonlinear Detection, Estimation, and Control for Free-Space Optical Communication

DTIC Science & Technology

2008-08-17

original message. The promising features of this communication scheme such as high-bandwidth, power efficiency, and security, render it a viable means...bandwidth, power efficiency, and security, render it a viable means for high data rate point-to-point communication. In this dissertation, we adopt a...Department of Electrical and Computer Engineering In free-space optical communication, the intensity of a laser beam is modulated by a message, the beam

Real-time distributed scheduling algorithm for supporting QoS over WDM networks

NASA Astrophysics Data System (ADS)

Kam, Anthony C.; Siu, Kai-Yeung

1998-10-01

Most existing or proposed WDM networks employ circuit switching, typically with one session having exclusive use of one entire wavelength. Consequently they are not suitable for data applications involving bursty traffic patterns. The MIT AON Consortium has developed an all-optical LAN/MAN testbed which provides time-slotted WDM service and employs fast-tunable transceivers in each optical terminal. In this paper, we explore extensions of this service to achieve fine-grained statistical multiplexing with different virtual circuits time-sharing the wavelengths in a fair manner. In particular, we develop a real-time distributed protocol for best-effort traffic over this time-slotted WDM service with near-optical fairness and throughput characteristics. As an additional design feature, our protocol supports the allocation of guaranteed bandwidths to selected connections. This feature acts as a first step towards supporting integrated services and quality-of-service guarantees over WDM networks. To achieve high throughput, our approach is based on scheduling transmissions, as opposed to collision- based schemes. Our distributed protocol involves one MAN scheduler and several LAN schedulers (one per LAN) in a master-slave arrangement. Because of propagation delays and limits on control channel capacities, all schedulers are designed to work with partial, delayed traffic information. Our distributed protocol is of the `greedy' type to ensure fast execution in real-time in response to dynamic traffic changes. It employs a hybrid form of rate and credit control for resource allocation. We have performed extensive simulations, which show that our protocol allocates resources (transmitters, receivers, wavelengths) fairly with high throughput, and supports bandwidth guarantees.

Mixed Linear/Square-Root Encoded Single-Slope Ramp Provides Low-Noise ADC with High Linearity for Focal Plane Arrays

NASA Technical Reports Server (NTRS)

Wrigley, Chris J.; Hancock, Bruce R.; Newton, Kenneth W.; Cunningham, Thomas J.

2013-01-01

Single-slope analog-to-digital converters (ADCs) are particularly useful for onchip digitization in focal plane arrays (FPAs) because of their inherent monotonicity, relative simplicity, and efficiency for column-parallel applications, but they are comparatively slow. Squareroot encoding can allow the number of code values to be reduced without loss of signal-to-noise ratio (SNR) by keeping the quantization noise just below the signal shot noise. This encoding can be implemented directly by using a quadratic ramp. The reduction in the number of code values can substantially increase the quantization speed. However, in an FPA, the fixed pattern noise (FPN) limits the use of small quantization steps at low signal levels. If the zero-point is adjusted so that the lowest column is onscale, the other columns, including those at the center of the distribution, will be pushed up the ramp where the quantization noise is higher. Additionally, the finite frequency response of the ramp buffer amplifier and the comparator distort the shape of the ramp, so that the effective ramp value at the time the comparator trips differs from the intended value, resulting in errors. Allowing increased settling time decreases the quantization speed, while increasing the bandwidth increases the noise. The FPN problem is solved by breaking the ramp into two portions, with some fraction of the available code values allocated to a linear ramp and the remainder to a quadratic ramp. To avoid large transients, both the value and the slope of the linear and quadratic portions should be equal where they join. The span of the linear portion must cover the minimum offset, but not necessarily the maximum, since the fraction of the pixels above the upper limit will still be correctly quantized, albeit with increased quantization noise. The required linear span, maximum signal and ratio of quantization noise to shot noise at high signal, along with the continuity requirement, determines the number of code values that must be allocated to each portion. The distortion problem is solved by using a lookup table to convert captured code values back to signal levels. The values in this table will be similar to the intended ramp value, but with a correction for the finite bandwidth effects. Continuous-time comparators are used, and their bandwidth is set below the step rate, which smoothes the ramp and reduces the noise. No settling time is needed, as would be the case for clocked comparators, but the low bandwidth enhances the distortion of the non-linear portion. This is corrected by use of a return lookup table, which differs from the one used to generate the ramp. The return lookup table is obtained by calibrating against a stepped precision DC reference. This results in a residual non-linearity well below the quantization noise. This method can also compensate for differential non-linearity (DNL) in the DAC used to generate the ramp. The use of a ramp with a combination of linear and quadratic portions for a single-slope ADC is novel. The number of steps is minimized by keeping the step size just below the photon shot noise. This in turn maximizes the speed of the conversion. High resolution is maintained by keeping small quantization steps at low signals, and noise is minimized by allowing the lowest analog bandwidth, all without increasing the quantization noise. A calibrated return lookup table allows the system to maintain excellent linearity.

Method and apparatus for telemetry adaptive bandwidth compression

NASA Technical Reports Server (NTRS)

Graham, Olin L.

1987-01-01

Methods and apparatus are provided for automatic and/or manual adaptive bandwidth compression of telemetry. An adaptive sampler samples a video signal from a scanning sensor and generates a sequence of sampled fields. Each field and range rate information from the sensor are hence sequentially transmitted to and stored in a multiple and adaptive field storage means. The field storage means then, in response to an automatic or manual control signal, transfers the stored sampled field signals to a video monitor in a form for sequential or simultaneous display of a desired number of stored signal fields. The sampling ratio of the adaptive sample, the relative proportion of available communication bandwidth allocated respectively to transmitted data and video information, and the number of fields simultaneously displayed are manually or automatically selectively adjustable in functional relationship to each other and detected range rate. In one embodiment, when relatively little or no scene motion is detected, the control signal maximizes sampling ratio and causes simultaneous display of all stored fields, thus maximizing resolution and bandwidth available for data transmission. When increased scene motion is detected, the control signal is adjusted accordingly to cause display of fewer fields. If greater resolution is desired, the control signal is adjusted to increase the sampling ratio.

Elastic all-optical multi-hop interconnection in data centers with adaptive spectrum allocation

NASA Astrophysics Data System (ADS)

Hong, Yuanyuan; Hong, Xuezhi; Chen, Jiajia; He, Sailing

2017-01-01

In this paper, a novel flex-grid all-optical interconnect scheme that supports transparent multi-hop connections in data centers is proposed. An inter-rack all-optical multi-hop connection is realized with an optical loop employed at flex-grid wavelength selective switches (WSSs) in an intermediate rack rather than by relaying through optical-electric-optical (O-E-O) conversions. Compared with the conventional O-E-O based approach, the proposed all-optical scheme is able to off-load the traffic at intermediate racks, leading to a reduction of the power consumption and cost. The transmission performance of the proposed flex-grid multi-hop all-optical interconnect scheme with various modulation formats, including both coherently detected and directly detected approaches, are investigated by Monte-Carlo simulations. To enhance the spectrum efficiency (SE), number-of-hop adaptive bandwidth allocation is introduced. Numerical results show that the SE can be improved by up to 33.3% at 40 Gbps, and by up to 25% at 100 Gbps. The impact of parameters, such as targeted bit error rate (BER) level and insertion loss of components, on the transmission performance of the proposed approach are also explored. The results show that the maximum SE improvement of the adaptive approach over the non-adaptive one is enhanced with the decrease of the targeted BER levels and the component insertion loss.

Scalable Active Optical Access Network Using Variable High-Speed PLZT Optical Switch/Splitter

NASA Astrophysics Data System (ADS)

Ashizawa, Kunitaka; Sato, Takehiro; Tokuhashi, Kazumasa; Ishii, Daisuke; Okamoto, Satoru; Yamanaka, Naoaki; Oki, Eiji

This paper proposes a scalable active optical access network using high-speed Plumbum Lanthanum Zirconate Titanate (PLZT) optical switch/splitter. The Active Optical Network, called ActiON, using PLZT switching technology has been presented to increase the number of subscribers and the maximum transmission distance, compared to the Passive Optical Network (PON). ActiON supports the multicast slot allocation realized by running the PLZT switch elements in the splitter mode, which forces the switch to behave as an optical splitter. However, the previous ActiON creates a tradeoff between the network scalability and the power loss experienced by the optical signal to each user. It does not use the optical power efficiently because the optical power is simply divided into 0.5 to 0.5 without considering transmission distance from OLT to each ONU. The proposed network adopts PLZT switch elements in the variable splitter mode, which controls the split ratio of the optical power considering the transmission distance from OLT to each ONU, in addition to PLZT switch elements in existing two modes, the switching mode and the splitter mode. The proposed network introduces the flexible multicast slot allocation according to the transmission distance from OLT to each user and the number of required users using three modes, while keeping the advantages of ActiON, which are to support scalable and secure access services. Numerical results show that the proposed network dramatically reduces the required number of slots and supports high bandwidth efficiency services and extends the coverage of access network, compared to the previous ActiON, and the required computation time for selecting multicast users is less than 30msec, which is acceptable for on-demand broadcast services.

A Low Cross-Polarization Smooth-Walled Horn with Improved Bandwidth

NASA Technical Reports Server (NTRS)

Zeng, Lingzhen; Bennette, Charles L.; Chuss, David T.; Wollack, Edward J.

2009-01-01

Corrugated feed horns offer excellent beam symmetry, main beam efficiency, and cross-polar response over wide bandwidths, but can be challenging to fabricate. An easier-to-manufacture smooth-walled feed is explored that approximates these properties over a finite bandwidth. The design, optimization and measurement of a monotonically-profiled, smooth-walled scalar feedhorn with a diffraction-limited approx. 14deg FWHM beam is presented. The feed was demonstrated to have low cross polarization (<-30 dB) across the frequency range 33-45 GHz (30% fractional bandwidth). A power reflection below -28 dB was measured across the band.

Naval Airborne ESM Systems Analysis

DTIC Science & Technology

1989-09-01

basically three different kinds of receivers available in a very mature technoiogical state: a.) Crystal Video Receivers (CVR), b.) Instantaneous...filtered out by the narrow bandwidth of the video stage. This is referred to sometimes as "Processing Gain", and it is proportional to the ratio of the...Acceptance Bandwidth (Ba) to the Video Bandwidth (By), where gamma is the integration efficiency. Brf Bn = (3-3) Brf gamma 2 Bv Gamma varies from 0.5

Proposal for implementation of CCSDS standards for use with spacecraft engineering/housekeeping data

NASA Technical Reports Server (NTRS)

Welch, Dave

1994-01-01

Many of today's low earth orbiting spacecraft are using the Consultative Committee for Space Data Systems (CCSDS) protocol for better optimization of down link RF bandwidth and onboard storage space. However, most of the associated housekeeping data has continued to be generated and down linked in a synchronous, Time Division Multiplexed (TDM) fashion. There are many economies that the CCSDS protocol will allow to better utilize the available bandwidth and storage space in order to optimize the housekeeping data for use in operational trending and analysis work. By only outputting what is currently important or of interest, finer resolution of critical items can be obtained. This can be accomplished by better utilizing the normally allocated housekeeping data down link and storage areas rather than taking space reserved for science.

Proposal for implementation of CCSDS standards for use with spacecraft engineering/housekeeping data

NASA Astrophysics Data System (ADS)

Welch, Dave

1994-11-01

Many of today's low earth orbiting spacecraft are using the Consultative Committee for Space Data Systems (CCSDS) protocol for better optimization of down link RF bandwidth and onboard storage space. However, most of the associated housekeeping data has continued to be generated and down linked in a synchronous, Time Division Multiplexed (TDM) fashion. There are many economies that the CCSDS protocol will allow to better utilize the available bandwidth and storage space in order to optimize the housekeeping data for use in operational trending and analysis work. By only outputting what is currently important or of interest, finer resolution of critical items can be obtained. This can be accomplished by better utilizing the normally allocated housekeeping data down link and storage areas rather than taking space reserved for science.

Smart LED allocation scheme for efficient multiuser visible light communication networks.

PubMed

Sewaiwar, Atul; Tiwari, Samrat Vikramaditya; Chung, Yeon Ho

2015-05-18

In a multiuser bidirectional visible light communication (VLC), a large number of LEDs or an LED array needs to be allocated in an efficient manner to ensure sustainable data rate and link quality. Moreover, in order to support an increasing or decreasing number of users in the network, the LED allocation is required to be performed dynamically. In this paper, a novel smart LED allocation scheme for efficient multiuser VLC networks is presented. The proposed scheme allocates RGB LEDs to multiple users in a dynamic and efficient fashion, while satisfying illumination requirements in an indoor environment. The smart LED array comprised of RGB LEDs is divided into sectors according to the location of the users. The allocated sectors then provide optical power concentration toward the users for efficient and reliable data transmission. An algorithm for the dynamic allocation of the LEDs is also presented. To verify its effective resource allocation feature of the proposed scheme, simulations were performed. It is found that the proposed smart LED allocation scheme provides the effect of optical beamforming toward individual users, thereby increasing the collective power concentration of the optical signals on the desirable users and resulting in significantly increased data rate, while ensuring sufficient illumination in a multiuser VLC environment.

Bandwidth-variable tunable optical filter unit for illumination and spectral imaging systems using thin-film optical band-pass filters.

PubMed

Hennig, Georg; Brittenham, Gary M; Sroka, Ronald; Kniebühler, Gesa; Vogeser, Michael; Stepp, Herbert

2013-04-01

An optical filter unit is demonstrated, which uses two successively arranged tunable thin-film optical band-pass filters and allows for simultaneous adjustment of the central wavelength in the spectral range 522-555 nm and of the spectral bandwidth in the range 3-16 nm with a wavelength switching time of 8 ms∕nm. Different spectral filter combinations can cover the complete visible spectral range. The transmitted intensity was found to decrease only linearly with the spectral bandwidth for bandwidths >6 nm, allowing a high maximum transmission efficiency of >75%. The image of a fiber bundle was spectrally filtered and analyzed in terms of position-dependency of the transmitted bandwidth and central wavelength.

Energy-efficient virtual optical network mapping approaches over converged flexible bandwidth optical networks and data centers.

PubMed

Chen, Bowen; Zhao, Yongli; Zhang, Jie

2015-09-21

In this paper, we develop a virtual link priority mapping (LPM) approach and a virtual node priority mapping (NPM) approach to improve the energy efficiency and to reduce the spectrum usage over the converged flexible bandwidth optical networks and data centers. For comparison, the lower bound of the virtual optical network mapping is used for the benchmark solutions. Simulation results show that the LPM approach achieves the better performance in terms of power consumption, energy efficiency, spectrum usage, and the number of regenerators compared to the NPM approach.

Multiple Power-Saving MSSs Scheduling Methods for IEEE802.16e Broadband Wireless Networks

PubMed Central

2014-01-01

This work proposes two enhanced multiple mobile subscriber stations (MSSs) power-saving scheduling methods for IEEE802.16e broadband wireless networks. The proposed methods are designed for the Unsolicited Grant Service (UGS) of IEEE802.16e. To reduce the active periods of all power-saving MSSs, the base station (BS) allocates each MSS fewest possible transmission frames to retrieve its data from the BS. The BS interlaces the active periods of each MSS to increase the amount of scheduled MSSs and splits the overflowing transmission frames to maximize the bandwidth utilization. Simulation results reveal that interlacing the active periods of MSSs can increase the number of scheduled MSSs to more than four times of that in the Direct scheduling method. The bandwidth utilization can thus be improved by 60%–70%. Splitting the overflowing transmission frames can improve bandwidth utilization by more than 10% over that achieved using the method of interlacing active periods, with a sacrifice of only 1% of the sleep periods in the interlacing active period method. PMID:24523656

Unmanned Aircraft System Control and ATC Communications Bandwidth Requirements

NASA Technical Reports Server (NTRS)

Henriksen, Steve

2008-01-01

There are significant activities taking place to establish the procedures and requirements for safe and routine operation of unmanned aircraft systems (UAS) in the National Airspace System (NAS). Among the barriers to overcome in achieving this goal is the lack of sufficient frequency spectrum necessary for the UAS control and air traffic control (ATC) communications links. This shortcoming is compounded by the fact that the UAS control communications links will likely be required to operate in protected frequency spectrum, just as ATC communications links are, because they relate to "safety and regularity of flight." To support future International Telecommunications Union (ITU) World Radio Conference (WRC) agenda items concerning new frequency allocations for UAS communications links, and to augment the Future Communications Study (FCS) Technology Evaluation Group efforts, NASA Glenn Research Center has sponsored a task to estimate the UAS control and ATC communications bandwidth requirements for safe, reliable, and routine operation of UAS in the NAS. This report describes the process and results of that task. The study focused on long-term bandwidth requirements for UAS approximately through 2030.

Tailoring Configuration to User’s Tasks under Uncertainty

DTIC Science & Technology

2008-04-28

CARISMA is the problem being solved. CARISMA applies microeconom- ics and game theory to make runtime decisions about allocating scarce resources among...scarce resources, these applications are running on be- half of one user. Thus, our problem has no game theoretic aspects. 2.2 Task Oriented...prediction tool [15] is based on the RPS tool and allows prediction of bandwidth online . There is additional evidence (see, for example [49

Bandwidth Allocation to Interactive Users in DBS-Based Hybrid Internet

DTIC Science & Technology

1998-01-01

policies 12 3.1 Framework for queuing analysis: ON/OFF source traffic model . 13 3.2 Service quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14...minimizing the queuing delay. In consequence, we were interested in ob- taining improvements in the service quality , as perceived by the users. A...the service quality as per- ceived by users. The merit of this approach, first introduced in [8], is the ability to capture the characteristics of the

Multifunction Multiband Airborne Radio Architecture Study.

DTIC Science & Technology

1982-01-01

30 to 88, 108 to 156, and 255 to 400 MHz band allocations . (ii) On designated operating channels: two in the 225 to 400 MHz bandwidth, one in each of...altimeter, direction finding, and relay. 2.2 BASELINE SYSTEM APPROACH This subsection describes the TRW-proposed baseline design for the MFBARS system...problem and SINCGARS application. Major efforts were directed toward reducing the overall costs while retaining required performance. Significantly, cost

Enhanced speed in fluorescence imaging using beat frequency multiplexing

NASA Astrophysics Data System (ADS)

Mikami, Hideharu; Kobayashi, Hirofumi; Wang, Yisen; Hamad, Syed; Ozeki, Yasuyuki; Goda, Keisuke

2016-03-01

Fluorescence imaging using radiofrequency-tagged emission (FIRE) is an emerging technique that enables higher imaging speed (namely, temporal resolution) in fluorescence microscopy compared to conventional fluorescence imaging techniques such as confocal microscopy and wide-field microscopy. It works based on the principle that it uses multiple intensity-modulated fields in an interferometric setup as excitation fields and applies frequency-division multiplexing to fluorescence signals. Unfortunately, despite its high potential, FIRE has limited imaging speed due to two practical limitations: signal bandwidth and signal detection efficiency. The signal bandwidth is limited by that of an acousto-optic deflector (AOD) employed in the setup, which is typically 100-200 MHz for the spectral range of fluorescence excitation (400-600 nm). The signal detection efficiency is limited by poor spatial mode-matching between two interfering fields to produce a modulated excitation field. Here we present a method to overcome these limitations and thus to achieve higher imaging speed than the prior version of FIRE. Our method achieves an increase in signal bandwidth by a factor of two and nearly optimal mode matching, which enables the imaging speed limited by the lifetime of the target fluorophore rather than the imaging system itself. The higher bandwidth and better signal detection efficiency work synergistically because higher bandwidth requires higher signal levels to avoid the contribution of shot noise and amplifier noise to the fluorescence signal. Due to its unprecedentedly high-speed performance, our method has a wide variety of applications in cancer detection, drug discovery, and regenerative medicine.

Video Compression Study: h.265 vs h.264

NASA Technical Reports Server (NTRS)

Pryor, Jonathan

2016-01-01

H.265 video compression (also known as High Efficiency Video Encoding (HEVC)) promises to provide double the video quality at half the bandwidth, or the same quality at half the bandwidth of h.264 video compression [1]. This study uses a Tektronix PQA500 to determine the video quality gains by using h.265 encoding. This study also compares two video encoders to see how different implementations of h.264 and h.265 impact video quality at various bandwidths.

System-level power optimization for real-time distributed embedded systems

NASA Astrophysics Data System (ADS)

Luo, Jiong

Power optimization is one of the crucial design considerations for modern electronic systems. In this thesis, we present several system-level power optimization techniques for real-time distributed embedded systems, based on dynamic voltage scaling, dynamic power management, and management of peak power and variance of the power profile. Dynamic voltage scaling has been widely acknowledged as an important and powerful technique to trade off dynamic power consumption and delay. Efficient dynamic voltage scaling requires effective variable-voltage scheduling mechanisms that can adjust voltages and clock frequencies adaptively based on workloads and timing constraints. For this purpose, we propose static variable-voltage scheduling algorithms utilizing criticalpath driven timing analysis for the case when tasks are assumed to have uniform switching activities, as well as energy-gradient driven slack allocation for a more general scenario. The proposed techniques can achieve closeto-optimal power savings with very low computational complexity, without violating any real-time constraints. We also present algorithms for power-efficient joint scheduling of multi-rate periodic task graphs along with soft aperiodic tasks. The power issue is addressed through both dynamic voltage scaling and power management. Periodic task graphs are scheduled statically. Flexibility is introduced into the static schedule to allow the on-line scheduler to make local changes to PE schedules through resource reclaiming and slack stealing, without interfering with the validity of the global schedule. We provide a unified framework in which the response times of aperiodic tasks and power consumption are dynamically optimized simultaneously. Interconnection network fabrics point to a new generation of power-efficient and scalable interconnection architectures for distributed embedded systems. As the system bandwidth continues to increase, interconnection networks become power/energy limited as well. Variable-frequency links have been designed by circuit designers for both parallel and serial links, which can adaptively regulate the supply voltage of transceivers to a desired link frequency, to exploit the variations in bandwidth requirement for power savings. We propose solutions for simultaneous dynamic voltage scaling of processors and links. The proposed solution considers real-time scheduling, flow control, and packet routing jointly. It can trade off the power consumption on processors and communication links via efficient slack allocation, and lead to more power savings than dynamic voltage scaling on processors alone. For battery-operated systems, the battery lifespan is an important concern. Due to the effects of discharge rate and battery recovery, the discharge pattern of batteries has an impact on the battery lifespan. Battery models indicate that even under the same average power consumption, reducing peak power current and variance in the power profile can increase the battery efficiency and thereby prolong battery lifetime. To take advantage of these effects, we propose battery-driven scheduling techniques for embedded applications, to reduce the peak power and the variance in the power profile of the overall system under real-time constraints. The proposed scheduling algorithms are also beneficial in addressing reliability and signal integrity concerns by effectively controlling peak power and variance of the power profile.

Enhanced and Tunable Optical Quantum Efficiencies from Plasmon Bandwidth Engineering in Bimetallic CoAg Nanoparticles (Open Access Publisher’s Version)

DTIC Science & Technology

2016-08-01

Engineering Engineering -- Faculty Publications and Other Works 8-2016 Enhanced and tunable optical quantum efficiencies from plasmon bandwidth engineering ...this and additional works at: http://trace.tennessee.edu/utk_matepubs Part of the Materials Science and Engineering Commons This Article is brought to...you for free and open access by the Engineering -- Faculty Publications and Other Works at Trace: Tennessee Research and Creative Exchange. It has been

Low-power, transparent optical network interface for high bandwidth off-chip interconnects.

PubMed

Liboiron-Ladouceur, Odile; Wang, Howard; Garg, Ajay S; Bergman, Keren

2009-04-13

The recent emergence of multicore architectures and chip multiprocessors (CMPs) has accelerated the bandwidth requirements in high-performance processors for both on-chip and off-chip interconnects. For next generation computing clusters, the delivery of scalable power efficient off-chip communications to each compute node has emerged as a key bottleneck to realizing the full computational performance of these systems. The power dissipation is dominated by the off-chip interface and the necessity to drive high-speed signals over long distances. We present a scalable photonic network interface approach that fully exploits the bandwidth capacity offered by optical interconnects while offering significant power savings over traditional E/O and O/E approaches. The power-efficient interface optically aggregates electronic serial data streams into a multiple WDM channel packet structure at time-of-flight latencies. We demonstrate a scalable optical network interface with 70% improvement in power efficiency for a complete end-to-end PCI Express data transfer.

An Improved Scheduling Algorithm for Data Transmission in Ultrasonic Phased Arrays with Multi-Group Ultrasonic Sensors

PubMed Central

Tang, Wenming; Liu, Guixiong; Li, Yuzhong; Tan, Daji

2017-01-01

High data transmission efficiency is a key requirement for an ultrasonic phased array with multi-group ultrasonic sensors. Here, a novel FIFOs scheduling algorithm was proposed and the data transmission efficiency with hardware technology was improved. This algorithm includes FIFOs as caches for the ultrasonic scanning data obtained from the sensors with the output data in a bandwidth-sharing way, on the basis of which an optimal length ratio of all the FIFOs is achieved, allowing the reading operations to be switched among all the FIFOs without time slot waiting. Therefore, this algorithm enhances the utilization ratio of the reading bandwidth resources so as to obtain higher efficiency than the traditional scheduling algorithms. The reliability and validity of the algorithm are substantiated after its implementation in the field programmable gate array (FPGA) technology, and the bandwidth utilization ratio and the real-time performance of the ultrasonic phased array are enhanced. PMID:29035345

High-bandwidth prefetcher for high-bandwidth memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehta, Sanyam; Kohn, James Robert; Ernst, Daniel Jonathan

A method for prefetching data into a cache is provided. The method allocates an outstanding request buffer ("ORB"). The method stores in an address field of the ORB an address and a number of blocks. The method issues prefetch requests for a degree number of blocks starting at the address. When a prefetch response is received for all the prefetch requests, the method adjusts the address of the next block to prefetch and adjusts the number of blocks remaining to be retrieved and then issues prefetch requests for a degree number of blocks starting at the adjusted address. The prefetchingmore » pauses when a maximum distance between the reads of the prefetched blocks and the last prefetched block is reached. When a read request for a prefetched block is received, the method resumes prefetching when a resume criterion is satisfied.« less

Vehicle Health Management Communications Requirements for AeroMACS

NASA Technical Reports Server (NTRS)

Kerczewski, Robert J.; Clements, Donna J.; Apaza, Rafael D.

2012-01-01

As the development of standards for the aeronautical mobile airport communications system (AeroMACS) progresses, the process of identifying and quantifying appropriate uses for the system is progressing. In addition to defining important elements of AeroMACS standards, indentifying the systems uses impacts AeroMACS bandwidth requirements. Although an initial 59 MHz spectrum allocation for AeroMACS was established in 2007, the allocation may be inadequate; studies have indicated that 100 MHz or more of spectrum may be required to support airport surface communications. Hence additional spectrum allocations have been proposed. Vehicle health management (VHM) systems, which can produce large volumes of vehicle health data, were not considered in the original bandwidth requirements analyses, and are therefore of interest in supporting proposals for additional AeroMACS spectrum. VHM systems are an emerging development in air vehicle safety, and preliminary estimates of the amount of data that will be produced and transmitted off an aircraft, both in flight and on the ground, have been prepared based on estimates of data produced by on-board vehicle health sensors and initial concepts of data processing approaches. This allowed an initial estimate of VHM data transmission requirements for the airport surface. More recently, vehicle-level systems designed to process and analyze VHM data and draw conclusions on the current state of vehicle health have been undergoing testing and evaluation. These systems make use of vehicle system data that is mostly different from VHM data considered previously for airport surface transmission, and produce processed system outputs that will be also need to be archived, thus generating additional data load for AeroMACS. This paper provides an analysis of airport surface data transmission requirements resulting from the vehicle level reasoning systems, within the context of overall VHM data requirements.

C4I Community of Interest C2 Roadmap

DTIC Science & Technology

2015-03-24

QoS -based services – Digital policy-based prioritization – Dynamic bandwidth allocation – Automated network management April 15 Slide 9...Co-Site Mitigation) NC-3 • LPD/LPI Comms NC-4 • Increased Range NC-7 • Increased Loss Tolerance & Recovery NC-7 • Mobile Ad Hoc Networking NC-8...Algorithms and Software • Systems and Processes Networks and Communications • Radios and Apertures • Networks • Information April 15 Slide 8

Configuration of Wireless Cooperative/Sensor Networks

DTIC Science & Technology

2008-05-25

WSN), the advantages of cooperation can be further exploited by optimally allocating the energy and bandwidth resources among users based on the... consumption and extend system lifetime [Sin98]. The implementation of a minimum energy routing protocol is discussed in [Dos02a, Dos02b]. An online...power consumption in the network given the required SER at the destination. For example, with source power Ps=20dB, the EP algorithm requires one relay

Invited article: Broadband highly-efficient dielectric metadevices for polarization control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruk, Sergey; Hopkins, Ben; Kravchenko, Ivan I.

Metadevices based on dielectric nanostructured surfaces with both electric and magnetic Mie-type resonances have resulted in the best efficiency to date for functional flat optics with only one disadvantage: a narrow operational bandwidth. Here we experimentally demonstrate broadband transparent all-dielectric metasurfaces for highly efficient polarization manipulation. We utilize the generalized Huygens principle, with a superposition of the scattering contributions from several electric and magnetic multipolar modes of the constituent meta-atoms, to achieve destructive interference in reflection over a large spectral bandwidth. Furthermore, by employing this novel concept, we demonstrate reflectionless (~90% transmission) half-wave plates, quarter-wave plates, and vector beam q-platesmore » that can operate across multiple telecom bands with ~99% polarization conversion efficiency.« less

Invited article: Broadband highly-efficient dielectric metadevices for polarization control

DOE PAGES

Kruk, Sergey; Hopkins, Ben; Kravchenko, Ivan I.; ...

2016-06-06

Metadevices based on dielectric nanostructured surfaces with both electric and magnetic Mie-type resonances have resulted in the best efficiency to date for functional flat optics with only one disadvantage: a narrow operational bandwidth. Here we experimentally demonstrate broadband transparent all-dielectric metasurfaces for highly efficient polarization manipulation. We utilize the generalized Huygens principle, with a superposition of the scattering contributions from several electric and magnetic multipolar modes of the constituent meta-atoms, to achieve destructive interference in reflection over a large spectral bandwidth. Furthermore, by employing this novel concept, we demonstrate reflectionless (~90% transmission) half-wave plates, quarter-wave plates, and vector beam q-platesmore » that can operate across multiple telecom bands with ~99% polarization conversion efficiency.« less

Research on Evaluation of resource allocation efficiency of transportation system based on DEA

NASA Astrophysics Data System (ADS)

Zhang, Zhehui; Du, Linan

2017-06-01

In this paper, we select the time series data onto 1985-2015 years, construct the land (shoreline) resources, capital and labor as inputs. The index system of the output is freight volume and passenger volume, we use Quantitative analysis based on DEA method evaluated the resource allocation efficiency of railway, highway, water transport and civil aviation in China. Research shows that the resource allocation efficiency of various modes of transport has obvious difference, and the impact on scale efficiency is more significant. The most important two ways to optimize the allocation of resources to improve the efficiency of the combination of various modes of transport is promoting the co-ordination of various modes of transport and constructing integrated transportation system.

Path connectivity based spectral defragmentation in flexible bandwidth networks.

PubMed

Wang, Ying; Zhang, Jie; Zhao, Yongli; Zhang, Jiawei; Zhao, Jie; Wang, Xinbo; Gu, Wanyi

2013-01-28

Optical networks with flexible bandwidth provisioning have become a very promising networking architecture. It enables efficient resource utilization and supports heterogeneous bandwidth demands. In this paper, two novel spectrum defragmentation approaches, i.e. Maximum Path Connectivity (MPC) algorithm and Path Connectivity Triggering (PCT) algorithm, are proposed based on the notion of Path Connectivity, which is defined to represent the maximum variation of node switching ability along the path in flexible bandwidth networks. A cost-performance-ratio based profitability model is given to denote the prons and cons of spectrum defragmentation. We compare these two proposed algorithms with non-defragmentation algorithm in terms of blocking probability. Then we analyze the differences of defragmentation profitability between MPC and PCT algorithms.

Information access in a dual-task context: testing a model of optimal strategy selection.

PubMed

Wickens, C D; Seidler, K S

1997-09-01

Pilots were required to access information from a hierarchical aviation database by navigating under single-task conditions (Experiment 1) and when this task was time-shared with an altitude-monitoring task of varying bandwidth and priority (Experiment 2). In dual-task conditions, pilots had 2 viewports available, 1 always used for the information task and the other to be allocated to either task. Dual-task strategy, inferred from the decision of which task to allocate to the 2nd viewport, revealed that allocation was generally biased in favor of the monitoring task and was only partly sensitive to the difficulty of the 2 tasks and their relative priorities. Some dominant sources of navigational difficulties failed to adaptively influence selection strategy. The implications of the results are to provide tools for jumping to the top of the database, to provide 2 viewports into the common database, and to provide training as to the optimum viewport management strategy in a multitask environment.

Information access in a dual-task context: testing a model of optimal strategy selection

NASA Technical Reports Server (NTRS)

Wickens, C. D.; Seidler, K. S.

1997-01-01

Pilots were required to access information from a hierarchical aviation database by navigating under single-task conditions (Experiment 1) and when this task was time-shared with an altitude-monitoring task of varying bandwidth and priority (Experiment 2). In dual-task conditions, pilots had 2 viewports available, 1 always used for the information task and the other to be allocated to either task. Dual-task strategy, inferred from the decision of which task to allocate to the 2nd viewport, revealed that allocation was generally biased in favor of the monitoring task and was only partly sensitive to the difficulty of the 2 tasks and their relative priorities. Some dominant sources of navigational difficulties failed to adaptively influence selection strategy. The implications of the results are to provide tools for jumping to the top of the database, to provide 2 viewports into the common database, and to provide training as to the optimum viewport management strategy in a multitask environment.

Energy efficiency in cognitive radio network: Study of cooperative sensing using different channel sensing methods

NASA Astrophysics Data System (ADS)

Cui, Chenxuan

When cognitive radio (CR) operates, it starts by sensing spectrum and looking for idle bandwidth. There are several methods for CR to make a decision on either the channel is occupied or idle, for example, energy detection scheme, cyclostationary detection scheme and matching filtering detection scheme [1]. Among them, the most common method is energy detection scheme because of its algorithm and implementation simplicities [2]. There are two major methods for sensing, the first one is to sense single channel slot with varying bandwidth, whereas the second one is to sense multiple channels and each with same bandwidth. After sensing periods, samples are compared with a preset detection threshold and a decision is made on either the primary user (PU) is transmitting or not. Sometimes the sensing and decision results can be erroneous, for example, false alarm error and misdetection error may occur. In order to better control error probabilities and improve CR network performance (i.e. energy efficiency), we introduce cooperative sensing; in which several CR within a certain range detect and make decisions on channel availability together. The decisions are transmitted to and analyzed by a data fusion center (DFC) to make a final decision on channel availability. After the final decision is been made, DFC sends back the decision to the CRs in order to tell them to stay idle or start to transmit data to secondary receiver (SR) within a preset transmission time. After the transmission, a new cycle starts again with sensing. This thesis report is organized as followed: Chapter II review some of the papers on optimizing CR energy efficiency. In Chapter III, we study how to achieve maximal energy efficiency when CR senses single channel with changing bandwidth and with constrain on misdetection threshold in order to protect PU; furthermore, a case study is given and we calculate the energy efficiency. In Chapter IV, we study how to achieve maximal energy efficiency when CR senses multiple channels and each channel with same bandwidth, also, we preset a misdetection threshold and calculate the energy efficiency. A comparison will be shown between two sensing methods at the end of the chapter. Finally, Chapter V concludes this thesis.

Energy Efficient and QoS sensitive Routing Protocol for Ad Hoc Networks

NASA Astrophysics Data System (ADS)

Saeed Tanoli, Tariq; Khalid Khan, Muhammad

2013-12-01

Efficient routing is an important part of wireless ad hoc networks. Since in ad hoc networks we have limited resources, there are many limitations like bandwidth, battery consumption, and processing cycle etc. Reliability is also necessary since there is no allowance for invalid or incomplete information (and expired data is useless). There are various protocols that perform routing by considering one parameter but ignoring other parameters. In this paper we present a protocol that finds route on the basis of bandwidth, energy and mobility of the nodes participating in the communication.

A compact design for the Josephson mixer: The lumped element circuit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pillet, J.-D.; Collège de France, 11 place Marcelin Berthelot, 75005 Paris; Flurin, E.

2015-06-01

We present a compact and efficient design in terms of gain, bandwidth, and dynamical range for the Josephson mixer, the superconducting circuit performing three-wave mixing at microwave frequencies. In an all lumped-element based circuit with galvanically coupled ports, we demonstrate nondegenerate amplification for microwave signals over a bandwidth up to 50 MHz for a power gain of 20 dB. The quantum efficiency of the mixer is shown to be about 70%, and its saturation power reaches −112 dBm.

Si photonics technology for future optical interconnection

NASA Astrophysics Data System (ADS)

Zheng, Xuezhe; Krishnamoorthy, Ashok V.

2011-12-01

Scaling of computing systems require ultra-efficient interconnects with large bandwidth density. Silicon photonics offers a disruptive solution with advantages in reach, energy efficiency and bandwidth density. We review our progress in developing building blocks for ultra-efficient WDM silicon photonic links. Employing microsolder based hybrid integration with low parasitics and high density, we optimize photonic devices on SOI platforms and VLSI circuits on more advanced bulk CMOS technology nodes independently. Progressively, we successfully demonstrated single channel hybrid silicon photonic transceivers at 5 Gbps and 10 Gbps, and 80 Gbps arrayed WDM silicon photonic transceiver using reverse biased depletion ring modulators and Ge waveguide photo detectors. Record-high energy efficiency of less than 100fJ/bit and 385 fJ/bit were achieved for the hybrid integrated transmitter and receiver, respectively. Waveguide grating based optical proximity couplers were developed with low loss and large optical bandwidth to enable multi-layer intra/inter-chip optical interconnects. Thermal engineering of WDM devices by selective substrate removal, together with WDM link using synthetic wavelength comb, we significantly improved the device tuning efficiency and reduced the tuning range. Using these innovative techniques, two orders of magnitude tuning power reduction was achieved. And tuning cost of only a few 10s of fJ/bit is expected for high data rate WDM silicon photonic links.

Water Development, Allocation, and Institutions: A Role for Integrated Tools

NASA Astrophysics Data System (ADS)

Ward, F. A.

2008-12-01

Many parts of the world suffer from inadequate water infrastructure, inefficient water allocation, and weak water institutions. Each of these three challenges compounds the burdens imposed by inadequacies associated with the other two. Weak water infrastructure makes it hard to allocate water efficiently and undermines tracking of water rights and use, which blocks effective functioning of water institutions. Inefficient water allocation makes it harder to secure resources to develop new water infrastructure. Poorly developed water institutions undermine the security of water rights, which damages incentives to develop water infrastructure or use water efficiently. This paper reports on the development of a prototype basin scale economic optimization, in which existing water supplies are allocated more efficiently in the short run to provide resources for more efficient long-run water infrastructure development. Preliminary results provide the basis for designing water administrative proposals, building effective water infrastructure, increasing farm income, and meeting transboundary delivery commitments. The application is to the Kabul River Basin in Afghanistan, where food security has been compromised by a history of drought, war, damaged irrigation infrastructure, lack of reservoir storage, inefficient water allocation, and weak water institutions. Results illustrate increases in economic efficiency achievable when development programs simultaneously address interdependencies in water allocation, development, and institutions.

Allocative and implementation efficiency in HIV prevention and treatment for people who inject drugs.

PubMed

Benedikt, Clemens; Kelly, Sherrie L; Wilson, David; Wilson, David P

2016-12-01

Estimated global new HIV infections among people who inject drugs (PWID) remained stable over the 2010-2015 period and the target of a 50% reduction over this period was missed. To achieve the 2020 UNAIDS target of reducing adult HIV infections by 75% compared to 2010, accelerated action in scaling up HIV programs for PWID is required. In a context of diminishing external support to HIV programs in countries where most HIV-affected PWID live, it is essential that available resources are allocated and used as efficiently as possible. Allocative and implementation efficiency analysis methods were applied. Optima, a dynamic, population-based HIV model with an integrated program and economic analysis framework was applied in eight countries in Eastern Europe and Central Asia (EECA). Mathematical analyses established optimized allocations of resources. An implementation efficiency analysis focused on examining technical efficiency, unit costs, and heterogeneity of service delivery models and practices. Findings from the latest reported data revealed that countries allocated between 4% (Bulgaria) and 40% (Georgia) of total HIV resources to programs targeting PWID - with a median of 13% for the eight countries. When distributing the same amount of HIV funding optimally, between 9% and 25% of available HIV resources would be allocated to PWID programs with a median allocation of 16% and, in addition, antiretroviral therapy would be scaled up including for PWID. As a result of optimized allocations, new HIV infections are projected to decline by 3-28% and AIDS-related deaths by 7-53% in the eight countries. Implementation efficiencies identified involve potential reductions in drug procurement costs, service delivery models, and practices and scale of service delivery influencing cost and outcome. A high level of implementation efficiency was associated with high volumes of PWID clients accessing a drug harm reduction facility. A combination of optimized allocation of resources, improved implementation efficiency and increased investment of non-HIV resources is required to enhance coverage and improve outcomes of programs for PWID. Increasing efficiency of HIV programs for PWID is a key step towards avoiding implicit rationing and ensuring transparent allocation of resources where and how they would have the largest impact on the health of PWID, and thereby ensuring that funding spent on PWID becomes a global best buy in public health. Copyright © 2016. Published by Elsevier B.V.

Integrated Services Digital Network (ISDN).

DTIC Science & Technology

1985-06-01

U.S. Digital Networks," Telephony, February 6, 1984. Gerla, Mario and Pazos -Rangel, Rodolfo A ., "Bandwidth Allocation and Routing in ISDN’s," IEEE...111116o 1312. jf IL5 11111.4 MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS-1963 A • .4 i U-~ U. NAVAL POSTGRADUATE SCHOOL G ,.Monterey...Thesis Advisor: C. R. Jones P: A -nroved for nublic release; distribution unlimited 85o 09 s0 082 1--𔃻- S **. -: -* *.- -. ..-. * SECURITY CLASSIFICATION

Spectral diffraction efficiency characterization of broadband diffractive optical elements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Junoh; Cruz-Cabrera, Alvaro Augusto; Tanbakuchi, Anthony

Diffractive optical elements, with their thin profile and unique dispersion properties, have been studied and utilized in a number of optical systems, often yielding smaller and lighter systems. Despite the interest in and study of diffractive elements, the application has been limited to narrow spectral bands. This is due to the etch depths, which are optimized for optical path differences of only a single wavelength, consequently leading to rapid decline in efficiency as the working wavelength shifts away from the design wavelength. Various broadband diffractive design methodologies have recently been developed that improve spectral diffraction efficiency and expand the workingmore » bandwidth of diffractive elements. We have developed diffraction efficiency models and utilized the models to design, fabricate, and test two such extended bandwidth diffractive designs.« less

Family Differences in Aboveground Biomass Allocation in Loblolly Pine

Treesearch

Scott D. Roberts

2002-01-01

The proportion of tree growth allocated to stemwood is an important economic component of growth efficiency. Differences in growth efficiency between species, or between families within species, may therefore be related to how growth is proportionally allocated between the stem and other aboveground biomass components. This study examines genetically related...

Efficiency of Fiscal Allocations in Site-Based Empowered Schools

ERIC Educational Resources Information Center

Meyer, Jerome Jay

2011-01-01

This study implemented a two phase concurrent mixed-methods design to generate a greater understanding of how elementary schools with increased autonomy in fiscal decision making allocated their money, how their site-based decisions affected allocative efficiency, and how increased autonomy affected site-based decision making when compared with a…

77 FR 11602 - Self-Regulatory Organizations; The NASDAQ Stock Market LLC; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-27

... offers various bandwidth options for connectivity to NASDAQ, including a 10Gb fiber connection, a 1Gb copper connection, and a 100 MB connection.\\3\\ In keeping with changes in technology, the Exchange now proposes to provide an enhanced bandwidth option to enable its clients a more efficient connection to the...

Analysis of blocking probability for OFDM-based variable bandwidth optical network

NASA Astrophysics Data System (ADS)

Gong, Lei; Zhang, Jie; Zhao, Yongli; Lin, Xuefeng; Wu, Yuyao; Gu, Wanyi

2011-12-01

Orthogonal Frequency Division Multiplexing (OFDM) has recently been proposed as a modulation technique. For optical networks, because of its good spectral efficiency, flexibility, and tolerance to impairments, optical OFDM is much more flexible compared to traditional WDM systems, enabling elastic bandwidth transmissions, and optical networking is the future trend of development. In OFDM-based optical network the research of blocking rate has very important significance for network assessment. Current research for WDM network is basically based on a fixed bandwidth, in order to accommodate the future business and the fast-changing development of optical network, our study is based on variable bandwidth OFDM-based optical networks. We apply the mathematical analysis and theoretical derivation, based on the existing theory and algorithms, research blocking probability of the variable bandwidth of optical network, and then we will build a model for blocking probability.

Network bandwidth utilization forecast model on high bandwidth networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoo, Wuchert; Sim, Alex

With the increasing number of geographically distributed scientific collaborations and the scale of the data size growth, it has become more challenging for users to achieve the best possible network performance on a shared network. We have developed a forecast model to predict expected bandwidth utilization for high-bandwidth wide area network. The forecast model can improve the efficiency of resource utilization and scheduling data movements on high-bandwidth network to accommodate ever increasing data volume for large-scale scientific data applications. Univariate model is developed with STL and ARIMA on SNMP path utilization data. Compared with traditional approach such as Box-Jenkins methodology,more » our forecast model reduces computation time by 83.2%. It also shows resilience against abrupt network usage change. The accuracy of the forecast model is within the standard deviation of the monitored measurements.« less

Network Bandwidth Utilization Forecast Model on High Bandwidth Network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoo, Wucherl; Sim, Alex

With the increasing number of geographically distributed scientific collaborations and the scale of the data size growth, it has become more challenging for users to achieve the best possible network performance on a shared network. We have developed a forecast model to predict expected bandwidth utilization for high-bandwidth wide area network. The forecast model can improve the efficiency of resource utilization and scheduling data movements on high-bandwidth network to accommodate ever increasing data volume for large-scale scientific data applications. Univariate model is developed with STL and ARIMA on SNMP path utilization data. Compared with traditional approach such as Box-Jenkins methodology,more » our forecast model reduces computation time by 83.2percent. It also shows resilience against abrupt network usage change. The accuracy of the forecast model is within the standard deviation of the monitored measurements.« less

Quick Vegas: Improving Performance of TCP Vegas for High Bandwidth-Delay Product Networks

NASA Astrophysics Data System (ADS)

Chan, Yi-Cheng; Lin, Chia-Liang; Ho, Cheng-Yuan

An important issue in designing a TCP congestion control algorithm is that it should allow the protocol to quickly adjust the end-to-end communication rate to the bandwidth on the bottleneck link. However, the TCP congestion control may function poorly in high bandwidth-delay product networks because of its slow response with large congestion windows. In this paper, we propose an enhanced version of TCP Vegas called Quick Vegas, in which we present an efficient congestion window control algorithm for a TCP source. Our algorithm improves the slow-start and congestion avoidance techniques of original Vegas. Simulation results show that Quick Vegas significantly improves the performance of connections as well as remaining fair when the bandwidth-delay product increases.

Dynamic Online Bandwidth Adjustment Scheme Based on Kalai-Smorodinsky Bargaining Solution

NASA Astrophysics Data System (ADS)

Kim, Sungwook

Virtual Private Network (VPN) is a cost effective method to provide integrated multimedia services. Usually heterogeneous multimedia data can be categorized into different types according to the required Quality of Service (QoS). Therefore, VPN should support the prioritization among different services. In order to support multiple types of services with different QoS requirements, efficient bandwidth management algorithms are important issues. In this paper, I employ the Kalai-Smorodinsky Bargaining Solution (KSBS) for the development of an adaptive bandwidth adjustment algorithm. In addition, to effectively manage the bandwidth in VPNs, the proposed control paradigm is realized in a dynamic online approach, which is practical for real network operations. The simulations show that the proposed scheme can significantly improve the system performances.

Controlling satellite communication system unwanted emissions in congested RF spectrum

NASA Astrophysics Data System (ADS)

Olsen, Donald; Heymann, Roger

2007-09-01

The International Telecommunication Union (ITU), a United Nations (UN) agency, is the agency that, under an international treaty, sets radio spectrum usage regulations among member nations. Within the United States of America (USA), the organization that sets regulations, coordinates an application for use, and provides authorization for federal government/agency use of the radio frequency (RF) spectrum is the National Telecommunications and Information Administration (NTIA). In this regard, the NTIA defines which RF spectrum is available for federal government use in the USA, and how it is to be used. The NTIA is a component of the United States (U.S.) Department of Commerce of the federal government. The significance of ITU regulations is that ITU approval is required for U.S. federal government/agency permission to use the RF spectrum outside of U.S. boundaries. All member nations have signed a treaty to do so. U.S. federal regulations for federal use of the RF spectrum are found in the Manual of Regulations and Procedures for Federal Radio Frequency Management, and extracts of the manual are found in what is known as the Table of Frequency Allocations. Nonfederal government and private sector use of the RF spectrum within the U.S. is regulated by the Federal Communications Commission (FCC). There is a need to control "unwanted emissions" (defined to include out-of-band emissions, which are those immediately adjacent to the necessary and allocated bandwidth, plus spurious emissions) to preclude interference to all other authorized users. This paper discusses the causes, effects, and mitigation of unwanted RF emissions to systems in adjacent spectra. Digital modulations are widely used in today's satellite communications. Commercial communications sector standards are covered for the most part worldwide by Digital Video Broadcast - Satellite (DVB-S) and digital satellite news gathering (DSNG) evolutions and the second generation of DVB-S (DVB-S2) standard, developed by the European Telecommunications Standards Institute (ETSI). In the USA, the Advanced Television Systems Committee (ATSC) has adopted Europe's DVB-S and DVB-S2 standards for satellite digital transmission. With today's digital modulations, RF spectral side lobes can extend out many times the modulating frequency on either side of the carrier at excessive power levels unless filtered. Higher-order digital modulations include quadrature phase shift keying (QPSK), 8 PSK (8-ary phase shift keying), 16 APSK (also called 12-4 APSK (amplitude phase shift keying)), and 16 QAM (quadrature amplitude modulation); they are key for higher spectrum efficiency to enable higher data rate transmissions in limited available bandwidths. Nonlinear high-power amplifiers (HPAs) can regenerate frequency spectral side lobes on input-filtered digital modulations. The paper discusses technologies and techniques for controlling these spectral side lobes, such as the use of square root raised cosine (SRRC) filtering before or during the modulation process, HPA output power back-off (OPBO), and RF filters after the HPA. Spectral mask specifications are a common method of the NTIA and ITU to define spectral occupancy power limits. They are intended to reduce interference among RF spectrum users by limiting excessive radiation at frequencies beyond the regulatory allocated bandwidth.The focus here is on the communication systems of U.S. government satellites used for space research, space operations, Earth exploration satellite services (EESS), meteorological satellite services (METSATS), and other government services. The 8025 to 8400 megahertz (MHz) X band can be used to illustrate the "unwanted emissions" issue. 8025 to 8400 MHz abuts the 8400 to 8450 MHz band allocated by the NTIA and ITU to space research for space-to-Earth transmissions such as receiving very weak Deep Space Network signals. The views and ideas expressed in this paper are those of the authors and do not necessarily reflect those of The Aerospace Corporation or The National Oceanic and Atmospheric Administration (NOAA) and its National Environmental Satellite Service (NESDIS).

Tragic choices and moral compromise: the ethics of allocating kidneys for transplantation.

PubMed

Hoffmaster, Barry; Hooker, Cliff

2013-09-01

For almost a decade, the Kidney Transplantation Committee of the United Network for Organ Sharing has been striving to revise its approach to allocating kidneys from deceased donors for transplantation. Two fundamental values, equality and efficiency, are central to distributing this scarce resource. The prevailing approach gives primacy to equality in the temporal form of first-come, first-served, whereas the motivation for a new approach is to redeem efficiency by increasing the length of survival of transplanted kidneys and their recipients. But decision making about a better way of allocating kidneys flounders because it is constrained by the amorphous notion of "balancing" values. This article develops a more fitting, productive approach to resolving the conflict between equality and efficiency by embedding the notion of compromise in the analysis of a tragic choice provided by Guido Calabresi and Philip Bobbitt. For Calabresi and Bobbitt, the goals of public policy with respect to tragic choices are to limit tragedy and to deal with the irreducible minimum of tragedy in the least offensive way. Satisfying the value of efficiency limits tragedy, and satisfying the value of equality deals with the irreducible minimum of tragedy in the least offensive way. But both values cannot be completely satisfied simultaneously. Compromise is occasioned when not all the several obligations that exist in a situation can be met and when neglecting some obligations entirely in order to fulfill others entirely is improper. Compromise is amalgamated with the notion of a tragic choice and then used to assess proposals for revising the allocation of kidneys considered by the Kidney Transplantation Committee. Compromise takes two forms in allocating kidneys: it occurs within particular approaches to allocating kidneys because neither equality nor efficiency can be fully satisfied, and it occurs over the course of sequential approaches to allocating kidneys that cycle between preferring equality and efficiency. Ross and colleagues' Equal Opportunity Supplemented by Fair Innings proposal for allocating kidneys best exemplifies the rationality of compromise as a way of achieving the goals of making a tragic choice. The attempt to design a policy for allocating kidneys from deceased donors for transplantation by balancing the values of equality and efficiency is misguided and unhelpful. Instead policymaking should both incorporate compromise into discrete approaches to allocating kidneys and extend compromise over sequential approaches to allocating kidneys. © 2013 Milbank Memorial Fund.

An Efficient, Highly Flexible Multi-Channel Digital Downconverter Architecture

NASA Technical Reports Server (NTRS)

Goodhart, Charles E.; Soriano, Melissa A.; Navarro, Robert; Trinh, Joseph T.; Sigman, Elliott H.

2013-01-01

In this innovation, a digital downconverter has been created that produces a large (16 or greater) number of output channels of smaller bandwidths. Additionally, this design has the flexibility to tune each channel independently to anywhere in the input bandwidth to cover a wide range of output bandwidths (from 32 MHz down to 1 kHz). Both the flexibility in channel frequency selection and the more than four orders of magnitude range in output bandwidths (decimation rates from 32 to 640,000) presented significant challenges to be solved. The solution involved breaking the digital downconversion process into a two-stage process. The first stage is a 2 oversampled filter bank that divides the whole input bandwidth as a real input signal into seven overlapping, contiguous channels represented with complex samples. Using the symmetry of the sine and cosine functions in a similar way to that of an FFT (fast Fourier transform), this downconversion is very efficient and gives seven channels fixed in frequency. An arbitrary number of smaller bandwidth channels can be formed from second-stage downconverters placed after the first stage of downconversion. Because of the overlapping of the first stage, there is no gap in coverage of the entire input bandwidth. The input to any of the second-stage downconverting channels has a multiplexer that chooses one of the seven wideband channels from the first stage. These second-stage downconverters take up fewer resources because they operate at lower bandwidths than doing the entire downconversion process from the input bandwidth for each independent channel. These second-stage downconverters are each independent with fine frequency control tuning, providing extreme flexibility in positioning the center frequency of a downconverted channel. Finally, these second-stage downconverters have flexible decimation factors over four orders of magnitude The algorithm was developed to run in an FPGA (field programmable gate array) at input data sampling rates of up to 1,280 MHz. The current implementation takes a 1,280-MHz real input, and first breaks it up into seven 160-MHz complex channels, each spaced 80 MHz apart. The eighth channel at baseband was not required for this implementation, and led to more optimization. Afterwards, 16 second stage narrow band channels with independently tunable center frequencies and bandwidth settings are implemented A future implementation in a larger Xilinx FPGA will hold up to 32 independent second-stage channels.

Parallel Implementation of MAFFT on CUDA-Enabled Graphics Hardware.

PubMed

Zhu, Xiangyuan; Li, Kenli; Salah, Ahmad; Shi, Lin; Li, Keqin

2015-01-01

Multiple sequence alignment (MSA) constitutes an extremely powerful tool for many biological applications including phylogenetic tree estimation, secondary structure prediction, and critical residue identification. However, aligning large biological sequences with popular tools such as MAFFT requires long runtimes on sequential architectures. Due to the ever increasing sizes of sequence databases, there is increasing demand to accelerate this task. In this paper, we demonstrate how graphic processing units (GPUs), powered by the compute unified device architecture (CUDA), can be used as an efficient computational platform to accelerate the MAFFT algorithm. To fully exploit the GPU's capabilities for accelerating MAFFT, we have optimized the sequence data organization to eliminate the bandwidth bottleneck of memory access, designed a memory allocation and reuse strategy to make full use of limited memory of GPUs, proposed a new modified-run-length encoding (MRLE) scheme to reduce memory consumption, and used high-performance shared memory to speed up I/O operations. Our implementation tested in three NVIDIA GPUs achieves speedup up to 11.28 on a Tesla K20m GPU compared to the sequential MAFFT 7.015.

Flexible All-Digital Receiver for Bandwidth Efficient Modulations

NASA Technical Reports Server (NTRS)

Gray, Andrew; Srinivasan, Meera; Simon, Marvin; Yan, Tsun-Yee

2000-01-01

An all-digital high data rate parallel receiver architecture developed jointly by Goddard Space Flight Center and the Jet Propulsion Laboratory is presented. This receiver utilizes only a small number of high speed components along with a majority of lower speed components operating in a parallel frequency domain structure implementable in CMOS, and can currently process up to 600 Mbps with standard QPSK modulation. Performance results for this receiver for bandwidth efficient QPSK modulation schemes such as square-root raised cosine pulse shaped QPSK and Feher's patented QPSK are presented, demonstrating the flexibility of the receiver architecture.

Flattop wideband wavelength converters based on cascaded sum and difference-frequency generation using step-chirped gratings

NASA Astrophysics Data System (ADS)

Tehranchi, Amirhossein; Kashyap, Raman

2011-03-01

We investigate the role of step-chirped gratings (SCG) for flattening of conversion efficiency response and enhancing the pump bandwidth in cascaded sum and difference frequency generation (SFG + DFG) with a large pump wavelength difference. To obtain a flat response with maximum efficiency, using SCG instead of uniform grating with the same length, the appropriate critical period shifts are presented for the reasonable number of sections and chirp steps feasible for fabrication. Furthermore, it is shown that adding the section numbers for SCG structure increases the pump bandwidth.

Evaluation of health resource utilization efficiency in community health centers of Jiangsu Province, China.

PubMed

Xu, Xinglong; Zhou, Lulin; Antwi, Henry Asante; Chen, Xi

2018-02-20

While the demand for health services keep escalating at the grass roots or rural areas of China, a substantial portion of healthcare resources remain stagnant in the more developed cities and this has entrenched health inequity in many parts of China. At its conception, China's Deepen Medical Reform started in 2012 was intended to flush out possible disparities and promote a more equitable and efficient distribution of healthcare resources. Nearly half a decade of this reform, there are uncertainties as to whether the attainment of the objectives of the reform is in sight. Using a hybrid of panel data analysis and an augmented data envelopment analysis (DEA), we model human resources, material, finance to determine their technical and scale efficiency to comprehensively evaluate the transverse and longitudinal allocation efficiency of community health resources in Jiangsu Province. We observed that the Deepen Medical Reform in China has led to an increase concern to ensure efficient allocation of community health resources by health policy makers in the province. This has led to greater efficiency in health resource allocation in Jiangsu in general but serious regional or municipal disparities still exist. Using the DEA model, we note that the output from the Community Health Centers does not commensurate with the substantial resources (human resources, materials, and financial) invested in them. We further observe that the case is worst in less-developed Northern parts of Jiangsu Province. The government of Jiangsu Province could improve the efficiency of health resource allocation by improving the community health service system, rationalizing the allocation of health personnel, optimizing the allocation of material resources, and enhancing the level of health of financial resource allocation.

A Feasibility Study on the Control of a Generic Air Vehicle Using Control Moment Gyros

NASA Technical Reports Server (NTRS)

Lim, Kyong B.; Moerder, Daniel D.

2006-01-01

This paper examines feasibility and performance issues in using Control Moment Gyroscopes (CMGs) to control the attitude of a fixed-wing aircraft. The paper describes a control system structure that permits allocating control authority and bandwidth between a CMG system and conventional aerodynamic control surfaces to stabilize a vehicle with neutral aerodynamic stability. A simulation study explores the interplay between aerodynamic and CMG effects, and indicates desirable physical characteristics for a CMG system to be used for aircraft attitude control.

Study of the spectral bandwidth of a double-pass acousto-optic system [Invited].

PubMed

Champagne, Justine; Kastelik, Jean-Claude; Dupont, Samuel; Gazalet, Joseph

2018-04-01

Acousto-optic tunable filters are known as efficient instruments for spectral and spatial filtering of light. In this paper, we analyze the bandwidth dependence of a double-pass filter. The interaction geometry chosen allows the simultaneous diffraction of the ordinary and the extraordinary optical modes by a single ultrasonic frequency. We present the main parameters of a custom device (design, optical range, driving frequency) and experimental results concerning the angular deviation of the beams including the effect of optical birefringence. The spectral resolution and the side lobes' significance are discussed. Spectral bandwidth of such a system is analyzed.

Pulse Shaped 8-PSK Bandwidth Efficiency and Spectral Spike Elimination

NASA Technical Reports Server (NTRS)

Tao, Jian-Ping

1998-01-01

The most bandwidth-efficient communication methods are imperative to cope with the congested frequency bands. Pulse shaping methods have excellent effects on narrowing bandwidth and increasing band utilization. The position of the baseband filters for the pulse shaping is crucial. Post-modulation pulse shaping (a low pass filter is located after the modulator) can change signals from constant envelope to non-constant envelope, and non-constant envelope signals through non-linear device (a SSPA or TWT) can further spread the power spectra. Pre-modulation pulse shaping (a filter is located before the modulator) will have constant envelope. These two pulse shaping methods have different effects on narrowing the bandwidth and producing bit errors. This report studied the effect of various pre-modulation pulse shaping filters with respect to bandwidth, spectral spikes and bit error rate. A pre-modulation pulse shaped 8-ary Phase Shift Keying (8PSK) modulation was used throughout the simulations. In addition to traditional pulse shaping filters, such as Bessel, Butterworth and Square Root Raised Cosine (SRRC), other kinds of filters or pulse waveforms were also studied in the pre-modulation pulse shaping method. Simulations were conducted by using the Signal Processing Worksystem (SPW) software package on HP workstations which simulated the power spectral density of pulse shaped 8-PSK signals, end to end system performance and bit error rates (BERS) as a function of Eb/No using pulse shaping in an AWGN channel. These results are compared with the post-modulation pulse shaped 8-PSK results. The simulations indicate traditional pulse shaping filters used in pre-modulation pulse shaping may produce narrower bandwidth, but with worse BER than those in post-modulation pulse shaping. Theory and simulations show pre- modulation pulse shaping could also produce discrete line power spectra (spikes) at regular frequency intervals. These spikes may cause interference with adjacent channel and reduce power efficiency. Some particular pulses (filters), such as trapezoid and pulses with different transits (such as weighted raised cosine transit) were found to reduce bandwidth and not generate spectral spikes. Although a solid state power amplifier (SSPA) was simulated in the non-linear (saturation) region, output power spectra did not spread due to the constant envelope 8-PSK signals.

The relation between input-output transformation and gastrointestinal nematode infections on dairy farms.

PubMed

van der Voort, M; Van Meensel, J; Lauwers, L; Van Huylenbroeck, G; Charlier, J

2016-02-01

Efficiency analysis is used for assessing links between technical efficiency (TE) of livestock farms and animal diseases. However, previous studies often do not make the link with the allocation of inputs and mainly present average effects that ignore the often huge differences among farms. In this paper, we studied the relationship between exposure to gastrointestinal (GI) nematode infections, the TE and the input allocation on dairy farms. Although the traditional cost allocative efficiency (CAE) indicator adequately measures how a given input allocation differs from the cost-minimising input allocation, they do not represent the unique input allocation of farms. Similar CAE scores may be obtained for farms with different input allocations. Therefore, we propose an adjusted allocative efficiency index (AAEI) to measure the unique input allocation of farms. Combining this AAEI with the TE score allows determining the unique input-output position of each farm. The method is illustrated by estimating efficiency scores using data envelopment analysis (DEA) on a sample of 152 dairy farms in Flanders for which both accountancy and parasitic monitoring data were available. Three groups of farms with a different input-output position can be distinguished based on cluster analysis: (1) technically inefficient farms, with a relatively low use of concentrates per 100 l milk and a high exposure to infection, (2) farms with an intermediate TE, relatively high use of concentrates per 100 l milk and a low exposure to infection, (3) farms with the highest TE, relatively low roughage use per 100 l milk and a relatively high exposure to infection. Correlation analysis indicates for each group how the level of exposure to GI nematodes is associated or not with improved economic performance. The results suggest that improving both the economic performance and exposure to infection seems only of interest for highly TE farms. The findings indicate that current farm recommendations regarding GI nematode infections could be improved by also accounting for the allocation of inputs on the farm.

The Resource Usage Aware Backfilling

NASA Astrophysics Data System (ADS)

Guim, Francesc; Rodero, Ivan; Corbalan, Julita

Job scheduling policies for HPC centers have been extensively studied in the last few years, especially backfilling based policies. Almost all of these studies have been done using simulation tools. All the existent simulators use the runtime (either estimated or real) provided in the workload as a basis of their simulations. In our previous work we analyzed the impact on system performance of considering the resource sharing (memory bandwidth) of running jobs including a new resource model in the Alvio simulator. Based on this studies we proposed the LessConsume and LessConsume Threshold resource selection policies. Both are oriented to reduce the saturation of the shared resources thus increasing the performance of the system. The results showed how both resource allocation policies shown how the performance of the system can be improved by considering where the jobs are finally allocated.

Multi-carrier Communications over Time-varying Acoustic Channels

NASA Astrophysics Data System (ADS)

Aval, Yashar M.

Acoustic communication is an enabling technology for many autonomous undersea systems, such as those used for ocean monitoring, offshore oil and gas industry, aquaculture, or port security. There are three main challenges in achieving reliable high-rate underwater communication: the bandwidth of acoustic channels is extremely limited, the propagation delays are long, and the Doppler distortions are more pronounced than those found in wireless radio channels. In this dissertation we focus on assessing the fundamental limitations of acoustic communication, and designing efficient signal processing methods that cam overcome these limitations. We address the fundamental question of acoustic channel capacity (achievable rate) for single-input-multi-output (SIMO) acoustic channels using a per-path Rician fading model, and focusing on two scenarios: narrowband channels where the channel statistics can be approximated as frequency- independent, and wideband channels where the nominal path loss is frequency-dependent. In each scenario, we compare several candidate power allocation techniques, and show that assigning uniform power across all frequencies for the first scenario, and assigning uniform power across a selected frequency-band for the second scenario, are the best practical choices in most cases, because the long propagation delay renders the feedback information outdated for power allocation based on the estimated channel response. We quantify our results using the channel information extracted form the 2010 Mobile Acoustic Communications Experiment (MACE'10). Next, we focus on achieving reliable high-rate communication over underwater acoustic channels. Specifically, we investigate orthogonal frequency division multiplexing (OFDM) as the state-of-the-art technique for dealing with frequency-selective multipath channels, and propose a class of methods that compensate for the time-variation of the underwater acoustic channel. These methods are based on multiple-FFT demodulation, and are implemented as partial (P), shaped (S), fractional (F), and Taylor series expansion (T) FFT demodulation. They replace the conventional FFT demodulation with a few FFTs and a combiner. The input to each FFT is a specific transformation of the input signal (P,S,F,T), while the combiner performs weighted summation of the FFT outputs. We design an adaptive algorithm of stochastic gradient type to learn the combiner weights for coherent and differentially coherent detection. The algorithm is cast into the framework of multiple receiving elements to take advantage of spatial diversity. Synthetic data, as well as experimental data from the MACE'10 experiment are used to demonstrate the performance of the proposed methods, showing significant improvement over conventional detection techniques with or without inter-carrier interference equalization (5 dB--7 dB on average over multiple hours), as well as improved bandwidth efficiency.

Strategic Implications of Cloud Computing for Modeling and Simulation (Briefing)

DTIC Science & Technology

2016-04-01

of Promises with Cloud • Cost efficiency • Unlimited storage • Backup and recovery • Automatic software integration • Easy access to information...activities that wrap the actual exercise itself (e.g., travel for exercise support, data collection, integration , etc.). Cloud -based simulation would...requiring quick delivery rather than fewer large messages requiring high bandwidth. Cloud environments tend to be better at providing high-bandwidth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alloatti, L., E-mail: luca.alloatti@gmail.com; Cheian, D.; Ram, R. J.

A microring depletion modulator is demonstrated with T-shaped lateral p-n junctions used to realize efficient modulation while maximizing the RC limited bandwidth. The device having a 3 dB bandwidth of 13 GHz has been fabricated in a standard 45 nm microelectronics CMOS process. The cavity has a linewidth of 17 GHz and an average wavelength-shift of 9 pm/V in reverse-bias conditions.

Relative intensity noise transfer of large-bandwidth pump lasers in Raman fiber amplifiers

NASA Astrophysics Data System (ADS)

Keita, Kafing; Delaye, Philippe; Frey, Robert; Roosen, Gérald

2006-12-01

A theoretical analysis of the Raman amplification in optical fibers and the pump-to-signal relative intensity noise (RIN) transfer has been performed in the spectral domain. An efficient Raman amplification of a monochromatic signal beam by a large-bandwidth pump beam has been demonstrated for a pump bandwidth much smaller than the Raman linewidth. Under the same approximation the pump-to-signal RIN transfer has been calculated in both cases of copropagating and counterpropagating beams in the two limiting cases of modulated monochromatic and smooth-profile large-bandwidth pump beams. At low frequencies the excess of noise evidenced in the case of a modulated monochromatic pump beam did not exist in the case of large-bandwidth pseudoincoherent sources. As this noise reduction can be as large as 13 dB for a 40 dB net gain of the amplifier, such incoherent pumping sources must be considered for the purpose of low-noise Raman amplifiers.

Least loaded and route fragmentation aware RSA strategies for elastic optical networks

NASA Astrophysics Data System (ADS)

Batham, Deepak; Yadav, Dharmendra Singh; Prakash, Shashi

2017-12-01

Elastic optical networks (EONs) provide flexibility to assign wide range of spectral resources to the connection requests. In this manuscript, we address two issues related to spectrum assignment in EONs: the non uniform spectrum assignment along different links of the route and the spectrum fragmentation in the network. To address these issues, two routing and spectrum assignment (RSA) strategies have been proposed: Least Loaded RSA (LLRSA) and Route Fragmentation Aware RSA (RFARSA). The LLRSA allocates spectrum homogeneously along different links in the network, where as RFARSA accords priority to the routes which are less fragmented. To highlight the salient features of the two strategies, two new metrics, route fragmentation index (RFI) and standard deviation (SD) are introduced. RFI is defined as the ratio of non-contiguous FSs to the total available free FSs on the route, and SD relates to the measure of non-uniformity in the allocation of resources on the links in the network. A simulation program has been developed to evaluate the performance of the proposed (LLRSA and RFARSA) strategies, and the existing strategies of shortest path RSA (SPRSA) and spectrum compactness based defragmentation (SCD) strategies, on the metric of RFI, bandwidth blocking probability (BBP), network capacity utilized, and SD. The variation in the metrics on the basis of number of requests and the bandwidth (number of FSs) requested has been studied. It has been conclusively established that the proposed strategies (LLRSA and RFARSA) outperform the existing strategies in terms of all the metrics.

Information and communication technology needs for distributed communication and coordination during expedition-class spaceflight.

PubMed

Caldwell, B S

2000-09-01

AO-lU. Expedition-class missions are distinct from historical human presence in space in ways that significantly affect information flow and information technology designs for such missions. The centrality of Mission Control in these missions is challenged by the distances, associated communication delays, and durations of expeditions, all of which require crews to have more local resources available to manage on-board situations. The author's current research investigates how ground controllers effectively allocate communications bandwidth, cognitive resources, and knowledge sharing skills during time critical routine and non-routine situations. The research focus is on team-based information and communication technology (ICT) use to provide recommendations for improvements to support adaptive bandwidth allocations and improved sharing of data and knowledge in Mission Control contexts. In order to further improve communication and coordination between controllers and crew, additional ICT support resources will be needed to provide shared context knowledge and dynamic assessment of costs and benefits for accessing local information vs. remote expertise. Crew members will have critical needs to understand the goals, intentions, and situational constraints associated with mission information resources in order to use them most effectively in conditions where ground-based expertise is insufficient or requires more time to access and coordinate than local task demands permit. Results of this research will serve to improve the design and implementation of ICT systems to improve human performance capabilities and system operating tolerances for exploration missions. (Specific research data were not available at the time of publication.)

Structured Low-Density Parity-Check Codes with Bandwidth Efficient Modulation

NASA Technical Reports Server (NTRS)

Cheng, Michael K.; Divsalar, Dariush; Duy, Stephanie

2009-01-01

In this work, we study the performance of structured Low-Density Parity-Check (LDPC) Codes together with bandwidth efficient modulations. We consider protograph-based LDPC codes that facilitate high-speed hardware implementations and have minimum distances that grow linearly with block sizes. We cover various higher- order modulations such as 8-PSK, 16-APSK, and 16-QAM. During demodulation, a demapper transforms the received in-phase and quadrature samples into reliability information that feeds the binary LDPC decoder. We will compare various low-complexity demappers and provide simulation results for assorted coded-modulation combinations on the additive white Gaussian noise and independent Rayleigh fading channels.

Development of a (Hg, Cd)Te photodiode detector, Phase 2. [for 10.6 micron spectral region

NASA Technical Reports Server (NTRS)

1972-01-01

High speed sensitive (Hg,Cd)Te photodiode detectors operating in the 77 to 90 K temperature range have been developed for the 10.6 micron spectral region. P-N junctions formed by impurity (gold) diffusion in p-type (Hg, Cd) Te have been investigated. It is shown that the bandwidth and quantum efficiency of a diode are a constant for a fixed ratio of mobility/lifetime ratio of minority carriers. The minority carrier mobility and lifetime uniquely determine the bandwidth and quantum efficiency and indicate the shallow n on p (Hg,Cd) Te diodes are preferable as high performance, high frequency devices.

Nano-optomechanical transducer

DOEpatents

Rakich, Peter T; El-Kady, Ihab F; Olsson, Roy H; Su, Mehmet Fatih; Reinke, Charles; Camacho, Ryan; Wang, Zheng; Davids, Paul

2013-12-03

A nano-optomechanical transducer provides ultrabroadband coherent optomechanical transduction based on Mach-wave emission that uses enhanced photon-phonon coupling efficiencies by low impedance effective phononic medium, both electrostriction and radiation pressure to boost and tailor optomechanical forces, and highly dispersive electromagnetic modes that amplify both electrostriction and radiation pressure. The optomechanical transducer provides a large operating bandwidth and high efficiency while simultaneously having a small size and minimal power consumption, enabling a host of transformative phonon and signal processing capabilities. These capabilities include optomechanical transduction via pulsed phonon emission and up-conversion, broadband stimulated phonon emission and amplification, picosecond pulsed phonon lasers, broadband phononic modulators, and ultrahigh bandwidth true time delay and signal processing technologies.

Optical actuators for fly-by-light applications

NASA Astrophysics Data System (ADS)

Chee, Sonny H. S.; Liu, Kexing; Measures, Raymond M.

1993-04-01

A review of optomechanical interfaces is presented. A detailed quantitative and qualitative analysis of the University of Toronto Institute for Aerospace Studies (UTIAS) box, optopneumatics, optical activation of a bimetal, optical activation of the shape memory effect, and optical activation of the pyroelectric effects is given. The UTIAS box is found to display a good conversion efficiency and a high bandwidth. A preliminary UTIAS box design has achieved a conversion efficiency of about 1/6 of the theoretical limit and a bandwidth of 2 Hz. In comparison to previous optomechanical interfaces, the UTIAS box has the highest pressure development to optical power ratio (at least an order of magnitude greater).

Analysis of single band and dual band graphene based patch antenna for terahertz region

NASA Astrophysics Data System (ADS)

George, Jemima Nissiyah; Madhan, M. Ganesh

2017-10-01

A microstrip patch antenna is designed using a very thin layer of graphene as the radiating patch, which is fed by a microstrip transmission line. The graphene based patch is designed on a silicon substrate having a dielectric constant of 11.9, to radiate at a single frequency of 2.6 THz. Further, this antenna is made to resonate at dual frequencies of 2.48 THz and 3.35 THz, by changing the substrate height, which is reported for the first time. Various antenna parameters such as return loss, VSWR, gain, efficiency and bandwidth are also determined for the single and dual band operation. For the single band operation, a bandwidth of 145.4 GHz and an efficiency of 92% was achieved. For dual band operation, a maximum bandwidth of 140.5 GHz was obtained at 3.35 THz and an efficiency of 87.3% was obtained at the first resonant frequency of 2.48 THz. The absorption cross section of the antenna is also analysed for various substrate heights and has maximum peaks at the corresponding resonating frequencies. The simulation has been carried out by using a full wave electromagnetic simulator based on FDTD method.

Highly efficient generation of broadband cascaded four-wave mixing products.

PubMed

Cerqueira S, Arismar; Boggio, J M Chavez; Rieznik, A A; Hernandez-Figueroa, H E; Fragnito, H L; Knight, J C

2008-02-18

We propose a novel way to efficiently generate broadband cascaded Four-Wave Mixing (FWM) products. It consists of launching two strong pump waves near the zero-dispersion wavelength of a very short (of order a few meters) optical fiber. Simulations based on Split Step Fourier Method (SSFM) and experimental data demonstrate the efficiency of our new approach. Multiple FWM products have been investigated by using conventional fibers and ultra-flattened dispersion photonic crystal fibers (UFD-PCFs). Measured results present bandwidths of 300 nm with up to 118 FWM products. We have also demonstrated a flat bandwidth of 110 nm covering the C and L bands, with a small variation of only 1.2 dB between the powers of FWM products, has been achieved using highly nonlinear fibers (HNLFs). The use of UFD-PCFs has been shown interesting for improving the multiple FWM efficiency and reducing the separation between the pump wavelengths.

Using architecture information and real-time resource state to reduce power consumption and communication costs in parallel applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, James M.; Devine, Karen Dragon; Gentile, Ann C.

2014-09-01

As computer systems grow in both size and complexity, the need for applications and run-time systems to adjust to their dynamic environment also grows. The goal of the RAAMP LDRD was to combine static architecture information and real-time system state with algorithms to conserve power, reduce communication costs, and avoid network contention. We devel- oped new data collection and aggregation tools to extract static hardware information (e.g., node/core hierarchy, network routing) as well as real-time performance data (e.g., CPU uti- lization, power consumption, memory bandwidth saturation, percentage of used bandwidth, number of network stalls). We created application interfaces that allowedmore » this data to be used easily by algorithms. Finally, we demonstrated the benefit of integrating system and application information for two use cases. The first used real-time power consumption and memory bandwidth saturation data to throttle concurrency to save power without increasing application execution time. The second used static or real-time network traffic information to reduce or avoid network congestion by remapping MPI tasks to allocated processors. Results from our work are summarized in this report; more details are available in our publications [2, 6, 14, 16, 22, 29, 38, 44, 51, 54].« less

Hybrid digital-analog coding with bandwidth expansion for correlated Gaussian sources under Rayleigh fading

NASA Astrophysics Data System (ADS)

Yahampath, Pradeepa

2017-12-01

Consider communicating a correlated Gaussian source over a Rayleigh fading channel with no knowledge of the channel signal-to-noise ratio (CSNR) at the transmitter. In this case, a digital system cannot be optimal for a range of CSNRs. Analog transmission however is optimal at all CSNRs, if the source and channel are memoryless and bandwidth matched. This paper presents new hybrid digital-analog (HDA) systems for sources with memory and channels with bandwidth expansion, which outperform both digital-only and analog-only systems over a wide range of CSNRs. The digital part is either a predictive quantizer or a transform code, used to achieve a coding gain. Analog part uses linear encoding to transmit the quantization error which improves the performance under CSNR variations. The hybrid encoder is optimized to achieve the minimum AMMSE (average minimum mean square error) over the CSNR distribution. To this end, analytical expressions are derived for the AMMSE of asymptotically optimal systems. It is shown that the outage CSNR of the channel code and the analog-digital power allocation must be jointly optimized to achieve the minimum AMMSE. In the case of HDA predictive quantization, a simple algorithm is presented to solve the optimization problem. Experimental results are presented for both Gauss-Markov sources and speech signals.

Governance of preventive Health Intervention and On time Verification of its Efficiency: the GIOVE Study

PubMed Central

Baio, Gianluca; Montagano, Giuseppe; Cauzillo, Gabriella; Locuratolo, Francesco; Becce, Gerardo; Gitto, Lara; Marcellusi, Andrea; Zweifel, Peter; Capone, Alessandro; Favato, Giampiero

2012-01-01

Objectives The GIOVE Study was aimed to the achievement of allocative efficiency of the budget allocated to the prevention of human papillomavirus (HPV)-induced diseases. An ex-ante determination of the most efficient allocation of resources between screening and multicohort quadrivalent immunisation programmes was followed by the ex-post assessment of the allocative efficiency actually achieved after a 12-month period. Design A bound optimisation model was developed to determine the ex-ante allocative efficiency of resources. The alternatives compared were the screening programme alone and the quadrivalent immunisation with access to screening. A sensitivity analysis was carried out to assess the uncertainty associated with the main inputs of the model. Subsequently, a cohort of girls with a complete recorded vaccination history were enrolled in an observational retrospective study for 18 months to ensure full compliance with the recommended schedule of vaccination (0, 2, 6 months) within a 12-month time horizon. Setting Basilicata region, in the south of Italy. Participants 12 848 girls aged 12, 15, 18 or 25 years. Intervention Immunisation with quadrivalent anti-HPV vaccine. Outcome measures The vaccination coverage rate was considered to be the indicator of the best achievable benefit, given the budgetary constraints. Results Assuming a vaccine price of €100 per dose, a vaccination coverage rate of 59.6% was required for the most effective allocation of resources. The optimal rate of coverage was initially in favour of the multicohort strategy of vaccination against HPV (72.8%±2%). When the price paid for the quadrivalent vaccine dropped to €85 per dose, the most efficient coverage rate (69.5%) shifted closer to the immunisation rate actually achieved during the 12-month observation period. Conclusions The bound optimisation model demonstrated to be a useful approach to the ex-ante allocation and the ex-post assessment of the resources allocated to the implementation of a multicohort quadrivalent anti-HPV vaccination programme. PMID:22422918

Silicon Nitride Grating Coupler with Flexible Bandwidth Incorporating a Serially Concatenated Multimode Interference Filter

NASA Astrophysics Data System (ADS)

Kim, Woo-Ju; Lee, Hak-Soon; Lee, Sang-Shin

2012-04-01

A compact silicon nitride grating coupler with flexible bandwidth was demonstrated taking advantage of a basic grating integrated with a serially connected multistage multimode interference (MMI) filter. The spectral response could be tailored by varying the order of the MMI filter, without affecting the basic grating structure. The dependence of the spectral response of the proposed device on the order of the MMI stage was thoroughly investigated. As regards the fabricated grating coupler with a four-stage MMI filter, the observed spectral bandwidth was efficiently altered from 53 to 21 nm in the ˜1550 nm spectral band.

An adaptive two-stage energy-efficiency mechanism for the doze mode in EPON

NASA Astrophysics Data System (ADS)

Nikoukar, AliAkbar; Hwang, I.-Shyan; Su, Yu-Min; Liem, Andrew Tanny

2016-07-01

Sleep and doze power-saving modes are the common ways to reduce power consumption of optical network units (ONUs) in Ethernet passive optical network (EPON). The doze mode turns off the ONU transmitter when there is no traffic in the upstream direction while the sleep mode turns off the ONU transmitter and receiver. As the result, the sleep mode is more efficient compared to the doze mode, but it introduces additional complexity of scheduling and signaling, losses the clock synchronization and requires long clock recovery time; furthermore, it requires the cooperation of the optical line terminal (OLT) in the downstream direction to queue frames. To improve the energy-saving in the doze mode, a new two-stage mechanism is introduced that the doze sleep duration is extended for longer time with acceptable quality-of-services (QoS) metrics when ONU is idle in the current cycle. By this way the ONU enters the doze mode even in the high load traffic; moreover, the green dynamic bandwidth allocation (GBA) is proposed to calculate the doze sleep duration based on the ONU queue state and incoming traffic ratio. Simulation results show that the proposed mechanism significantly improves the energy-saving 74% and 54% when traffic load is from the light load to the high load in different traffic situations, and also promises the QoS performance.

Photonic generation of low phase noise arbitrary chirped microwave waveforms with large time-bandwidth product.

PubMed

Xie, Weilin; Xia, Zongyang; Zhou, Qian; Shi, Hongxiao; Dong, Yi; Hu, Weisheng

2015-07-13

We present a photonic approach for generating low phase noise, arbitrary chirped microwave waveforms based on heterodyne beating between high order correlated comb lines extracted from frequency-agile optical frequency comb. Using the dual heterodyne phase transfer scheme, extrinsic phase noises induced by the separate optical paths are efficiently suppressed by 42-dB at 1-Hz offset frequency. Linearly chirped microwave waveforms are achieved within 30-ms temporal duration, contributing to a large time-bandwidth product. The linearity measurement leads to less than 90 kHz RMS frequency error during the entire chirp duration, exhibiting excellent linearity for the microwave and sub-THz waveforms. The capability of generating arbitrary waveforms up to sub-THz band with flexible temporal duration, long repetition period, broad bandwidth, and large time-bandwidth product is investigated and discussed.

Performance of computer-designed small-size multistage depressed collectors for a high-perveance traveling wave tube

NASA Technical Reports Server (NTRS)

Ramins, P.

1984-01-01

Computer designed axisymmetric 2.4-cm-diameter three-, four-, and five-stage depressed collectors were evaluated in conjunction with an octave bandwidth, high-perveance, and high-electronic-efficiency, griddled-gun traveling wave tube (TWT). Spent-beam refocusing was used to condition the beam for optimum entry into the depressed collectors. Both the TWT and multistage depressed collector (MDC) efficiencies were measured, as well as the MDC current, dissipated thermal power, and DC input power distributions, for the TWT operating both at saturation over its bandwidth and over its full dynamic range. Relatively high collector efficiencies were obtained, leading to a very substantial improvement in the overall TWT efficiency. In spite of large fixed TWT body losses (due largely to the 6 to 8 percent beam interception), average overall efficiencies of 45 to 47 percent (for three to five collector stages) were obtained at saturation across the 2.5-, to 5.5-GHz operating band. For operation below saturation the collector efficiencies improved steadily, leading to reasonable ( 20 percent) overall efficiencies as far as 6 dB below saturation.

Single-longitudinal-mode, narrow bandwidth double-ring fiber laser stabilized by an efficiently taper-coupled high roundness microsphere resonator

NASA Astrophysics Data System (ADS)

Wan, Hongdan; Liu, Linqian; Ding, Zuoqin; Wang, Jie; Xiao, Yu; Zhang, Zuxing

2018-06-01

This paper proposes and demonstrates a single-longitudinal-mode, narrow bandwidth fiber laser, using an ultra-high roundness microsphere resonator (MSR) with a stabilized package as the single-longitudinal-mode selector inside a double-ring fiber cavity. By improving the heating technology and surface cleaning process, MSR with high Q factor are obtained. With the optimized coupling condition, light polarization state and fiber taper diameter, we achieve whispering gallery mode (WGM) spectra with a high extinction ratio of 23 dB, coupling efficiency of 99.5%, a 3 dB bandwidth of 1 pm and a side-mode-suppression-ratio of 14.5 dB. The proposed fiber laser produces single-longitudinal-mode laser output with a 20-dB frequency linewidth of about 340 kHz, a signal-to-background ratio of 54 dB and a high long-term stability without mode-hopping, which is potential for optical communication and sensing applications.

Evaluation on equality and efficiency of health resources allocation and health services utilization in China.

PubMed

Sun, Jian; Luo, Hongye

2017-07-14

China is faced with a daunting challenge to equality and efficiency in health resources allocation and health services utilization in the context of rapid economic growth. This study sought to evaluate the equality and efficiency of health resources allocation and health services utilization in China. Demographic, economic, and geographic area data was sourced from China Statistical Yearbook 2012-2016. Data related to health resources and health services was obtained from China Health Statistics Yearbook 2012-2016. Furthermore, we evaluated the equality of health resources allocation based on Gini coefficient. Concentration index was used to measure the equality in utilization of health services. Data envelopment analysis (DEA) was employed to assess the efficiency of health resources allocation. From 2011 to 2015, the Gini coefficients for health resources by population ranged between 0.0644 and 0.1879, while the Gini coefficients for the resources by geographic area ranged from 0.6136 to 0.6568. Meanwhile, the concentration index values for health services utilization ranged from -0.0392 to 0.2110. Moreover, in 2015, 10 provinces (32.26%) were relatively efficient in terms of health resources allocation, while 7 provinces (22.58%) and 14 provinces (45.16%) were weakly efficient and inefficient, respectively. There exist distinct regional disparities in the distribution of health resources in China, which are mainly reflected in the geographic distribution of health resources. Furthermore, the people living in the eastern developed areas are more likely to use outpatient care, while the people living in western underdeveloped areas are more likely to use inpatient care. Moreover, the efficiency of health resources allocation in 21 provinces (67.74%) of China was low and needs to be improved. Thus, the government should pay more attention to the equality based on geographic area, guide patients to choose medical treatment rationally, and optimize the resource investments for different provinces.

Genetic expression programming-based DBA for enhancing peer-assisted music-on-demand service in EPON

NASA Astrophysics Data System (ADS)

Liem, Andrew Tanny; Hwang, I.-Shyan; Nikoukar, AliAkbar; Lee, Jhong-Yue

2015-03-01

Today, the popularity of peer-assisted music-on-demand (MoD) has increased significantly worldwide. This service allows users to access large music library tracks, listen to music, and share their playlist with other users. Unlike the conventional voice traffic, such an application maintains music quality that ranges from 160 kbps to 320 kbps, which most likely consumes more bandwidth than other traffics. In the access network, Ethernet passive optical network (EPON) is one of the best candidates for delivering such a service because of being cost-effective and with high bandwidth. To maintain music quality, a stutter needs to be prevented because of either network effects or when the due user was not receiving enough resources to play in a timely manner. Therefore, in this paper, we propose two genetic expression programming (GEP)-based dynamic bandwidth allocations (DBAs). The first DBA is a generic DBA that aims to find an optimum formula for voice, video, and data services. The second DBA aims to find optimum formulas so that Optical Line Terminal (OLT) can satisfy not only the voice and Peer-to-Peer (P2P) MoD traffics but also reduce the stutter. Optical Network Unit (ONU) traits such as REPORT and GATE messages, cycle time, and mean packet delay are set to be predictor variables. Simulation results show that our proposed DBAs can satisfy the voice and P2P MoD services packet delay and monitor other overall system performances such as expedited forwarding (EF) jitter, packet loss, bandwidth waste, and system throughputs.

Electromagnetic Counter-Counter Measure (ECCM) Techniques of the Digital Microwave Radio.

DTIC Science & Technology

1982-05-01

Frequency hopping requires special synthesizers and filter banks. Large bandwidth expansion in a microwave radio relay application can best be achieved with...34 processing gain " performance as a function of jammer modulation type " pulse jammer performance • emission bandwidth and spectral shaping 0... spectral efficiency, implementation complexity, and suitability for ECCK techniques will be considered. A sumary of the requirements and characteristics of

Vibrational energy harvesting by exploring structural benefits and nonlinear characteristics

NASA Astrophysics Data System (ADS)

Wei, Chongfeng; Jing, Xingjian

2017-07-01

Traditional energy harvesters are often of low efficiency due to very limited energy harvesting bandwidth, which should also be enough close to the ambient excitation frequency. To overcome this difficulty, some attempts can be seen in the literature typically with the purposes of either increasing the energy harvesting bandwidth with a harvester array, or enhancing the energy harvesting bandwidth and peak with nonlinear coupling effect etc. This paper presents an alternative way which can achieve tuneable resonant frequency (from high frequency to ultralow frequency) and improved energy harvesting bandwidth and peak simultaneously by employing special structural benefits and advantageous displacement-dependent nonlinear damping property. The proposed energy harvesting system employs a lever systems combined with an X-shape supporting structure and demonstrates very adjustable stiffness and unique nonlinear damping characteristics which are very beneficial for energy harvesting. It is shown that the energy harvesting performance of the proposed system is directly determined by several easy-to-tune structural parameters and also by the relative displacement in a special nonlinear manner, which provides a great flexibility and/or a unique tool for tuning and improving energy harvesting efficiency via matching excitation frequencies and covering a broader frequency band. This study potentially provides a new insight into the design of energy harvesting systems by employing structural benefits and geometrical nonlinearities.

Negative inductance circuits for metamaterial bandwidth enhancement

NASA Astrophysics Data System (ADS)

Avignon-Meseldzija, Emilie; Lepetit, Thomas; Ferreira, Pietro Maris; Boust, Fabrice

2017-12-01

Passive metamaterials have yet to be translated into applications on a large scale due in large part to their limited bandwidth. To overcome this limitation many authors have suggested coupling metamaterials to non-Foster circuits. However, up to now, the number of convincing demonstrations based on non-Foster metamaterials has been very limited. This paper intends to clarify why progress has been so slow, i.e., the fundamental difficulty in making a truly broadband and efficient non-Foster metamaterial. To this end, we consider two families of metamaterials, namely Artificial Magnetic Media and Artificial Magnetic Conductors. In both cases, it turns out that bandwidth enhancement requires negative inductance with almost zero resistance. To estimate bandwidth enhancement with actual non-Foster circuits, we consider two classes of such circuits, namely Linvill and gyrator. The issue of stability being critical, both metamaterial families are studied with equivalent circuits that include advanced models of these non-Foster circuits. Conclusions are different for Artificial Magnetic Media coupled to Linvill circuits and Artificial Magnetic Conductors coupled to gyrator circuits. In the first case, requirements for bandwidth enhancement and stability are very hard to meet simultaneously whereas, in the second case, an adjustment of the transistor gain does significantly increase bandwidth.

Cost-effectiveness analysis and efficient use of the pharmaceutical budget: the key role of clinical pharmacologists

PubMed Central

Edlin, Richard; Round, Jeff; Hulme, Claire; McCabe, Christopher

2010-01-01

The purpose of this paper is to provide information about cost-effectiveness analysis and the roles of clinical pharmacologists generally in providing efficient health care. The paper highlights the potential consequences of ‘off-label prescribing’ and ‘indication creep’ behaviour given slower growth (or potential cuts) in the NHS budget. This paper highlights the key roles of clinical pharmacologists in delivering an efficient health care system when resources are allocated using cost-effectiveness analyses. It describes what cost-effectiveness analysis (CEA) is and how incremental cost-effectiveness ratios (ICERs) are used to identify efficient options. After outlining the theoretical framework within which using CEA can promote the efficient allocation of the health care budget, it considers the place of disinvestment within achieving efficient resource allocation. Clinical pharmacologists are argued to be critical to providing improved population health under CEA-based resource allocation processes because of their roles in implementation and disinvestment. Given that the challenges facing the United Kingdom National Health Service (NHS) are likely to increase, this paper sets out the stark choices facing clinical pharmacologists. PMID:20716234

Cost-effectiveness analysis and efficient use of the pharmaceutical budget: the key role of clinical pharmacologists.

PubMed

Edlin, Richard; Round, Jeff; Hulme, Claire; McCabe, Christopher

2010-09-01

The purpose of this paper is to provide information about cost-effectiveness analysis and the roles of clinical pharmacologists generally in providing efficient health care. The paper highlights the potential consequences of 'off-label prescribing' and 'indication creep' behaviour given slower growth (or potential cuts) in the NHS budget. This paper highlights the key roles of clinical pharmacologists in delivering an efficient health care system when resources are allocated using cost-effectiveness analyses. It describes what cost-effectiveness analysis (CEA) is and how incremental cost-effectiveness ratios (ICERs) are used to identify efficient options. After outlining the theoretical framework within which using CEA can promote the efficient allocation of the health care budget, it considers the place of disinvestment within achieving efficient resource allocation. Clinical pharmacologists are argued to be critical to providing improved population health under CEA-based resource allocation processes because of their roles in implementation and disinvestment. Given that the challenges facing the United Kingdom National Health Service (NHS) are likely to increase, this paper sets out the stark choices facing clinical pharmacologists.

Game Theory for Wireless Sensor Networks: A Survey

PubMed Central

Shi, Hai-Yan; Wang, Wan-Liang; Kwok, Ngai-Ming; Chen, Sheng-Yong

2012-01-01

Game theory (GT) is a mathematical method that describes the phenomenon of conflict and cooperation between intelligent rational decision-makers. In particular, the theory has been proven very useful in the design of wireless sensor networks (WSNs). This article surveys the recent developments and findings of GT, its applications in WSNs, and provides the community a general view of this vibrant research area. We first introduce the typical formulation of GT in the WSN application domain. The roles of GT are described that include routing protocol design, topology control, power control and energy saving, packet forwarding, data collection, spectrum allocation, bandwidth allocation, quality of service control, coverage optimization, WSN security, and other sensor management tasks. Then, three variations of game theory are described, namely, the cooperative, non-cooperative, and repeated schemes. Finally, existing problems and future trends are identified for researchers and engineers in the field. PMID:23012533

Transceiver optics for interplanetary communications

NASA Astrophysics Data System (ADS)

Roberts, W. T.; Farr, W. H.; Rider, B.; Sampath, D.

2017-11-01

In-situ interplanetary science missions constantly push the spacecraft communications systems to support successively higher downlink rates. However, the highly restrictive mass and power constraints placed on interplanetary spacecraft significantly limit the desired bandwidth increases in going forward with current radio frequency (RF) technology. To overcome these limitations, we have evaluated the ability of free-space optical communications systems to make substantial gains in downlink bandwidth, while holding to the mass and power limits allocated to current state-of-the-art Ka-band communications systems. A primary component of such an optical communications system is the optical assembly, comprised of the optical support structure, optical elements, baffles and outer enclosure. We wish to estimate the total mass that such an optical assembly might require, and assess what form it might take. Finally, to ground this generalized study, we should produce a conceptual design, and use that to verify its ability to achieve the required downlink gain, estimate it's specific optical and opto-mechanical requirements, and evaluate the feasibility of producing the assembly.

Use of the 37-38 GHz and 40-40.5 GHz Ka-bands for Deep Space Communications

NASA Technical Reports Server (NTRS)

Morabito, David; Hastrup, Rolf

2004-01-01

This paper covers a wide variety of issues associated with the implementation and use of these frequency bands for deep space communications. Performance issues, such as ground station pointing stability, ground antenna gain, antenna pattern, and propagation effects such as due to atmospheric, charged-particle and space loss at 37 GHz, will be addressed in comparison to the 32 GHz Ka-band deep space allocation. Issues with the use of and competition for this spectrum also will be covered. The state of the hardware developed (or proposed) for operating in this frequency band will be covered from the standpoint of the prospects for achieving higher data rates that could be accommodated in the available bandwidth. Hardware areas to be explored include modulators, digital-to-analog converters, filters, power amplifiers, receivers, and antennas. The potential users of the frequency band will be explored as well as their anticipated methods to achieve the potential high data rates and the implications of the competition for bandwidth.

Packet Scheduling Mechanism to Improve Quality of Short Flows and Low-Rate Flows

NASA Astrophysics Data System (ADS)

Yokota, Kenji; Asaka, Takuya; Takahashi, Tatsuro

In recent years elephant flows are increasing by expansion of peer-to-peer (P2P) applications on the Internet. As a result, bandwidth is occupied by specific users triggering unfair resource allocation. The main packet-scheduling mechanism currently employed is first-in first-out (FIFO) where the available bandwidth of short flows is limited by elephant flows. Least attained service (LAS), which decides transfer priority of packets by the total amount of transferred data in all flows, was proposed to solve this problem. However, routers with LAS limit flows with large amount of transferred data even if they are low-rate. Therefore, it is necessary to improve the quality of low-rate flows with long holding times such as voice over Internet protocol (VoIP) applications. This paper proposes rate-based priority control (RBPC), which calculates the flow rate and control the priority by using it. Our proposed method can transfer short flows and low-rate flows in advance. Moreover, its fair performance is shown through simulations.

Test scheduling optimization for 3D network-on-chip based on cloud evolutionary algorithm of Pareto multi-objective

NASA Astrophysics Data System (ADS)

Xu, Chuanpei; Niu, Junhao; Ling, Jing; Wang, Suyan

2018-03-01

In this paper, we present a parallel test strategy for bandwidth division multiplexing under the test access mechanism bandwidth constraint. The Pareto solution set is combined with a cloud evolutionary algorithm to optimize the test time and power consumption of a three-dimensional network-on-chip (3D NoC). In the proposed method, all individuals in the population are sorted in non-dominated order and allocated to the corresponding level. Individuals with extreme and similar characteristics are then removed. To increase the diversity of the population and prevent the algorithm from becoming stuck around local optima, a competition strategy is designed for the individuals. Finally, we adopt an elite reservation strategy and update the individuals according to the cloud model. Experimental results show that the proposed algorithm converges to the optimal Pareto solution set rapidly and accurately. This not only obtains the shortest test time, but also optimizes the power consumption of the 3D NoC.

Generalized networking engineering: optimal pricing and routing in multiservice networks

NASA Astrophysics Data System (ADS)

Mitra, Debasis; Wang, Qiong

2002-07-01

One of the functions of network engineering is to allocate resources optimally to forecasted demand. We generalize the mechanism by incorporating price-demand relationships into the problem formulation, and optimizing pricing and routing jointly to maximize total revenue. We consider a network, with fixed topology and link bandwidths, that offers multiple services, such as voice and data, each having characteristic price elasticity of demand, and quality of service and policy requirements on routing. Prices, which depend on service type and origin-destination, determine demands, that are routed, subject to their constraints, so as to maximize revenue. We study the basic properties of the optimal solution and prove that link shadow costs provide the basis for both optimal prices and optimal routing policies. We investigate the impact of input parameters, such as link capacities and price elasticities, on prices, demand growth, and routing policies. Asymptotic analyses, in which network bandwidth is scaled to grow, give results that are noteworthy for their qualitative insights. Several numerical examples illustrate the analyses.

Optimal Bandwidth for High Efficiency Thermoelectrics

NASA Astrophysics Data System (ADS)

Zhou, Jun; Yang, Ronggui; Chen, Gang; Dresselhaus, Mildred S.

2011-11-01

The thermoelectric figure of merit (ZT) in narrow conduction bands of different material dimensionalities is investigated for different carrier scattering models. When the bandwidth is zero, the transport distribution function (TDF) is finite, not infinite as previously speculated by Mahan and Sofo [Proc. Natl. Acad. Sci. U.S.A. 93, 7436 (1996)PNASA60027-842410.1073/pnas.93.15.7436], even though the carrier density of states goes to infinity. Such a finite TDF results in a zero electrical conductivity and thus a zero ZT. We point out that the optimal ZT cannot be found in an extremely narrow conduction band. The existence of an optimal bandwidth for a maximal ZT depends strongly on the scattering models and the dimensionality of the material. A nonzero optimal bandwidth for maximizing ZT also depends on the lattice thermal conductivity. A larger maximum ZT can be obtained for materials with a smaller lattice thermal conductivity.

pathChirp: Efficient Available Bandwidth Estimation for Network Paths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cottrell, Les

2003-04-30

This paper presents pathChirp, a new active probing tool for estimating the available bandwidth on a communication network path. Based on the concept of ''self-induced congestion,'' pathChirp features an exponential flight pattern of probes we call a chirp. Packet chips offer several significant advantages over current probing schemes based on packet pairs or packet trains. By rapidly increasing the probing rate within each chirp, pathChirp obtains a rich set of information from which to dynamically estimate the available bandwidth. Since it uses only packet interarrival times for estimation, pathChirp does not require synchronous nor highly stable clocks at the sendermore » and receiver. We test pathChirp with simulations and Internet experiments and find that it provides good estimates of the available bandwidth while using only a fraction of the number of probe bytes that current state-of-the-art techniques use.« less

Design, fabrication, test and delivery of a K-band antenna breadboard model

NASA Technical Reports Server (NTRS)

1974-01-01

The results of a research effort to develop a Ku-Band single channel monopulse antenna with significant improvements in efficiency and bandwidth are reported. A single aperture, multimode horn, utilized in a near field Cassegrainian configuration, was the technique selected for achieving the desired efficiency and bandwidth performance. In order to provide wide polarization flexibility, a wire grid, space filter polarizer was developed. A solid state switching network with appropriate driving electronics provides the receive channel sum and difference signal interface with an existing Apollo type tracking electronics subsystem. A full scale breadboard model of the antenna was fabricated and tested. Performance of the model was well within the requirements and goals of the contract.

A bandwidth-efficient service for local information dissemination in sparse to dense roadways.

PubMed

Garcia-Lozano, Estrella; Campo, Celeste; Garcia-Rubio, Carlos; Cortes-Martin, Alberto; Rodriguez-Carrion, Alicia; Noriega-Vivas, Patricia

2013-07-05

Thanks to the research on Vehicular Ad Hoc Networks (VANETs), we will be able to deploy applications on roadways that will contribute to energy efficiency through a better planning of long trips. With this goal in mind, we have designed a gas/charging station advertising system, which takes advantage of the broadcast nature of the network. We have found that reducing the number of total sent packets is important, as it allows for a better use of the available bandwidth. We have designed improvements for a distance-based flooding scheme, so that it can support the advertising application with good results in sparse to dense roadway scenarios.

A Bandwidth-Efficient Service for Local Information Dissemination in Sparse to Dense Roadways

PubMed Central

Garcia-Lozano, Estrella; Campo, Celeste; Garcia-Rubio, Carlos; Cortes-Martin, Alberto; Rodriguez-Carrion, Alicia; Noriega-Vivas, Patricia

2013-01-01

Thanks to the research on Vehicular Ad Hoc Networks (VANETs), we will be able to deploy applications on roadways that will contribute to energy efficiency through a better planning of long trips. With this goal in mind, we have designed a gas/charging station advertising system, which takes advantage of the broadcast nature of the network. We have found that reducing the number of total sent packets is important, as it allows for a better use of the available bandwidth. We have designed improvements for a distance-based flooding scheme, so that it can support the advertising application with good results in sparse to dense roadway scenarios. PMID:23881130

Declining spatial efficiency of global cropland nitrogen allocation

NASA Astrophysics Data System (ADS)

Mueller, Nathaniel D.; Lassaletta, Luis; Runck, Bryan C.; Billen, Gilles; Garnier, Josette; Gerber, James S.

2017-02-01

Efficiently allocating nitrogen (N) across space maximizes crop productivity for a given amount of N input and reduces N losses to the environment. Here we quantify changes in the global spatial efficiency of cropland N use by calculating historical trade-off frontiers relating N inputs to possible N yield assuming efficient allocation. Time series cropland N budgets from 1961 to 2009 characterize the evolution of N input-yield response functions across 12 regions and are the basis for constructing trade-off frontiers. Improvements in agronomic technology have substantially increased cropping system yield potentials and expanded N-driven crop production possibilities. However, we find that these gains are compromised by the declining spatial efficiency of N use across regions. Since the start of the Green Revolution, N inputs and yields have moved farther from the optimal frontier over time; in recent years (1994-2009), global N surplus has grown to a value that is 69% greater than what is possible with efficient N allocation between regions. To reflect regional pollution and agricultural development goals, we construct scenarios that restrict reallocation, finding that these changes only slightly decrease potential gains in nitrogen use efficiency. Our results are inherently conservative due to the regional unit of analysis, meaning a larger potential exists than is quantified here for cross-scale policies to promote spatially efficient N use.

Information efficiency in visual communication

NASA Astrophysics Data System (ADS)

Alter-Gartenberg, Rachel; Rahman, Zia-ur

1993-08-01

This paper evaluates the quantization process in the context of the end-to-end performance of the visual-communication channel. Results show that the trade-off between data transmission and visual quality revolves around the information in the acquired signal, not around its energy. Improved information efficiency is gained by frequency dependent quantization that maintains the information capacity of the channel and reduces the entropy of the encoded signal. Restorations with energy bit-allocation lose both in sharpness and clarity relative to restorations with information bit-allocation. Thus, quantization with information bit-allocation is preferred for high information efficiency and visual quality in optimized visual communication.

Information efficiency in visual communication

NASA Technical Reports Server (NTRS)

Alter-Gartenberg, Rachel; Rahman, Zia-Ur

1993-01-01

This paper evaluates the quantization process in the context of the end-to-end performance of the visual-communication channel. Results show that the trade-off between data transmission and visual quality revolves around the information in the acquired signal, not around its energy. Improved information efficiency is gained by frequency dependent quantization that maintains the information capacity of the channel and reduces the entropy of the encoded signal. Restorations with energy bit-allocation lose both in sharpness and clarity relative to restorations with information bit-allocation. Thus, quantization with information bit-allocation is preferred for high information efficiency and visual quality in optimized visual communication.

Contribution and efficiency of labor allocation analysis of income in household industry using raw material of agricultural commodity in South Sulawesi.

NASA Astrophysics Data System (ADS)

Tenriawaru, A. N.; Mahyuddin; Jamil, M. H.; Fudjaja, L.; Nurbaya, S.

2018-05-01

In South Sulawesi, various home industry businesses have grown. This industry is actually the basis of community livelihoods that need to be developed and nurtured by the government so family income get increased and the absorption of workers will improve the regional economy in general. The purpose of this study is to analyse the contribution of income, and efficiency of labour allocation in household industries made from raw agricultural commodities. The method of determining the respondents is done by direct appointment (purposive) on the industry players made from raw agricultural commodities. The type of research is quantitative descriptive and data are analysed using income analysis, cost analysis, income contribution analysis, Working Day (HOK) analysis and efficiency analysis of labour allocation. The results showed that the average income earned per year ranged from IDR. 16,866,867.- up to IDR. 125,271,500.-. There are 2 industries that have high contribution to family income such as banana chips industry and rice milling industry with value of 96.3% and 68.7% respectively. In the meantime, there are 5 industries with high average labour allocation efficiency of IDR. 218,135.- / HOK per day and above the efficiency standard of labour allocation based on UMR in South Sulawesi Province.

Solid-State Laser Source of Tunable Narrow-Bandwidth Ultraviolet Radiation

NASA Technical Reports Server (NTRS)

Goldberg, Lew; Kliner, Dahv A.; Koplow, Jeffrey P.

1998-01-01

A solid-state laser source of tunable and narrow-bandwidth UV light is disclosed. The system relies on light from a diode laser that preferably generates light at infrared frequencies. The light from the seed diode laser is pulse amplified in a light amplifier, and converted into the ultraviolet by frequency tripling, quadrupling, or quintupling the infrared light. The narrow bandwidth, or relatively pure light, of the seed laser is preserved, and the pulse amplifier generates high peak light powers to increase the efficiency of the nonlinear crystals in the frequency conversion stage. Higher output powers may be obtained by adding a fiber amplifier to power amplify the pulsed laser light prior to conversion.

A reduced complexity highly power/bandwidth efficient coded FQPSK system with iterative decoding

NASA Technical Reports Server (NTRS)

Simon, M. K.; Divsalar, D.

2001-01-01

Based on a representation of FQPSK as a trellis-coded modulation, this paper investigates the potential improvement in power efficiency obtained from the application of simple outer codes to form a concatenated coding arrangement with iterative decoding.

Power allocation strategies to minimize energy consumption in wireless body area networks.

PubMed

Kailas, Aravind

2011-01-01

The wide scale deployment of wireless body area networks (WBANs) hinges on designing energy efficient communication protocols to support the reliable communication as well as to prolong the network lifetime. Cooperative communications, a relatively new idea in wireless communications, offers the benefits of multi-antenna systems, thereby improving the link reliability and boosting energy efficiency. In this short paper, the advantages of resorting to cooperative communications for WBANs in terms of minimized energy consumption are investigated. Adopting an energy model that encompasses energy consumptions in the transmitter and receiver circuits, and transmitting energy per bit, it is seen that cooperative transmission can improve energy efficiency of the wireless network. In particular, the problem of optimal power allocation is studied with the constraint of targeted outage probability. Two strategies of power allocation are considered: power allocation with and without posture state information. Using analysis and simulation-based results, two key points are demonstrated: (i) allocating power to the on-body sensors making use of the posture information can reduce the total energy consumption of the WBAN; and (ii) when the channel condition is good, it is better to recruit less relays for cooperation to enhance energy efficiency.

Optical datacenter network employing slotted (TDMA) operation for dynamic resource allocation

NASA Astrophysics Data System (ADS)

Bakopoulos, P.; Tokas, K.; Spatharakis, C.; Patronas, I.; Landi, G.; Christodoulopoulos, K.; Capitani, M.; Kyriakos, A.; Aziz, M.; Reisis, D.; Varvarigos, E.; Zahavi, E.; Avramopoulos, H.

2018-02-01

The soaring traffic demands in datacenter networks (DCNs) are outpacing progresses in CMOS technology, challenging the bandwidth and energy scalability of currently established technologies. Optical switching is gaining traction as a promising path for sustaining the explosive growth of DCNs; however, its practical deployment necessitates extensive modifications to the network architecture and operation, tailored to the technological particularities of optical switches (i.e. no buffering, limitations in radix size and speed). European project NEPHELE is developing an optical network infrastructure that leverages optical switching within a software-defined networking (SDN) framework to overcome the bandwidth and energy scaling challenges of datacenter networks. An experimental validation of the NEPHELE data plane is reported based on commercial off-the-shelf optical components controlled by FPGA boards. To facilitate dynamic allocation of the network resources and perform collision-free routing in a lossless network environment, slotted operation is employed (i.e. using time-division multiple-access - TDMA). Error-free operation of the NEPHELE data plane is verified for 200 μs slots in various scenarios that involve communication between Ethernet hosts connected to custom-designed top-of-rack (ToR) switches, located in the same or in different datacenter pods. Control of the slotted data plane is obtained through an SDN framework comprising an OpenDaylight controller with appropriate add-ons. Communication between servers in the optical-ToR is demonstrated with various routing scenarios, concerning communication between hosts located in the same rack or in different racks, within the same or different datacenter pods. Error-free operation is confirmed for all evaluated scenarios, underpinning the feasibility of the NEPHELE architecture.

Mathematical programming for the efficient allocation of health care resources.

PubMed

Stinnett, A A; Paltiel, A D

1996-10-01

Previous discussions of methods for the efficient allocation of health care resources subject to a budget constraint have relied on unnecessarily restrictive assumptions. This paper makes use of established optimization techniques to demonstrate that a general mathematical programming framework can accommodate much more complex information regarding returns to scale, partial and complete indivisibility and program interdependence. Methods are also presented for incorporating ethical constraints into the resource allocation process, including explicit identification of the cost of equity.

Resource allocation in shared spectrum access communications for operators with diverse service requirements

NASA Astrophysics Data System (ADS)

Kibria, Mirza Golam; Villardi, Gabriel Porto; Ishizu, Kentaro; Kojima, Fumihide; Yano, Hiroyuki

2016-12-01

In this paper, we study inter-operator spectrum sharing and intra-operator resource allocation in shared spectrum access communication systems and propose efficient dynamic solutions to address both inter-operator and intra-operator resource allocation optimization problems. For inter-operator spectrum sharing, we present two competent approaches, namely the subcarrier gain-based sharing and fragmentation-based sharing, which carry out fair and flexible allocation of the available shareable spectrum among the operators subject to certain well-defined sharing rules, traffic demands, and channel propagation characteristics. The subcarrier gain-based spectrum sharing scheme has been found to be more efficient in terms of achieved throughput. However, the fragmentation-based sharing is more attractive in terms of computational complexity. For intra-operator resource allocation, we consider resource allocation problem with users' dissimilar service requirements, where the operator supports users with delay constraint and non-delay constraint service requirements, simultaneously. This optimization problem is a mixed-integer non-linear programming problem and non-convex, which is computationally very expensive, and the complexity grows exponentially with the number of integer variables. We propose less-complex and efficient suboptimal solution based on formulating exact linearization, linear approximation, and convexification techniques for the non-linear and/or non-convex objective functions and constraints. Extensive simulation performance analysis has been carried out that validates the efficiency of the proposed solution.

A high-efficiency tunable TEM-TE11 mode converter for high-power microwave applications

NASA Astrophysics Data System (ADS)

Wang, Xiao-Yu; Fan, Yu-Wei; Shu, Ting; Yuan, Cheng-wei; Zhang, Qiang

2017-03-01

The tunable high power microwave source (HPM's) is considered to be an important research direction. However, the corresponding mode converter has been researched little. In this paper, a high-efficiency tunable mode converter (HETMC) is investigated for high-power microwave applications. The HETMC that is consisted of coaxial inner and outer conductors, with four metal plates arranged radially, at 90° in the coaxial gap, and matching rods can transform coaxial transverse electromagnetic (TEM) mode to TE11 coaxial waveguide mode. The results show that adjusting the length of the downstream plate, and the distance between the rods installed upstream and the closest edges of the plates, can improve the conversion efficiency and bandwidth remarkably. Moreover, when the frequency ranges from 1.63 GHz to 2.12 GHz, the conversion efficiency is above 95% between 1.63 GHz and 2.12 GHz with a bandwidth of 26.1%. Besides, the unwished reflection and transmission can be eliminated effectively in the HETMC.

A Hierarchical Auction-Based Mechanism for Real-Time Resource Allocation in Cloud Robotic Systems.

PubMed

Wang, Lujia; Liu, Ming; Meng, Max Q-H

2017-02-01

Cloud computing enables users to share computing resources on-demand. The cloud computing framework cannot be directly mapped to cloud robotic systems with ad hoc networks since cloud robotic systems have additional constraints such as limited bandwidth and dynamic structure. However, most multirobotic applications with cooperative control adopt this decentralized approach to avoid a single point of failure. Robots need to continuously update intensive data to execute tasks in a coordinated manner, which implies real-time requirements. Thus, a resource allocation strategy is required, especially in such resource-constrained environments. This paper proposes a hierarchical auction-based mechanism, namely link quality matrix (LQM) auction, which is suitable for ad hoc networks by introducing a link quality indicator. The proposed algorithm produces a fast and robust method that is accurate and scalable. It reduces both global communication and unnecessary repeated computation. The proposed method is designed for firm real-time resource retrieval for physical multirobot systems. A joint surveillance scenario empirically validates the proposed mechanism by assessing several practical metrics. The results show that the proposed LQM auction outperforms state-of-the-art algorithms for resource allocation.

Dynamic optical resource allocation for mobile core networks with software defined elastic optical networking.

PubMed

Zhao, Yongli; Chen, Zhendong; Zhang, Jie; Wang, Xinbo

2016-07-25

Driven by the forthcoming of 5G mobile communications, the all-IP architecture of mobile core networks, i.e. evolved packet core (EPC) proposed by 3GPP, has been greatly challenged by the users' demands for higher data rate and more reliable end-to-end connection, as well as operators' demands for low operational cost. These challenges can be potentially met by software defined optical networking (SDON), which enables dynamic resource allocation according to the users' requirement. In this article, a novel network architecture for mobile core network is proposed based on SDON. A software defined network (SDN) controller is designed to realize the coordinated control over different entities in EPC networks. We analyze the requirement of EPC-lightpath (EPCL) in data plane and propose an optical switch load balancing (OSLB) algorithm for resource allocation in optical layer. The procedure of establishment and adjustment of EPCLs is demonstrated on a SDON-based EPC testbed with extended OpenFlow protocol. We also evaluate the OSLB algorithm through simulation in terms of bandwidth blocking ratio, traffic load distribution, and resource utilization ratio compared with link-based load balancing (LLB) and MinHops algorithms.

Efficient and equitable spatial allocation of renewable power plants at the country scale

NASA Astrophysics Data System (ADS)

Drechsler, Martin; Egerer, Jonas; Lange, Martin; Masurowski, Frank; Meyerhoff, Jürgen; Oehlmann, Malte

2017-09-01

Globally, the production of renewable energy is undergoing rapid growth. One of the most pressing issues is the appropriate allocation of renewable power plants, as the question of where to produce renewable electricity is highly controversial. Here we explore this issue through analysis of the efficient and equitable spatial allocation of wind turbines and photovoltaic power plants in Germany. We combine multiple methods, including legal analysis, economic and energy modelling, monetary valuation and numerical optimization. We find that minimum distances between renewable power plants and human settlements should be as small as is legally possible. Even small reductions in efficiency lead to large increases in equity. By considering electricity grid expansion costs, we find a more even allocation of power plants across the country than is the case when grid expansion costs are neglected.

A Cascaded Self-Similar Rat-Race Hybrid Coupler Architecture and its Compact Ka-Band Implementation

DTIC Science & Technology

2017-03-01

real-estate and limit the system-level performance, including bandwidth, gain, and energy - efficiency. These many challenges are positioning passive...and are used in numerous RF/mm-wave systems for radar and wireless communications. Although a Marchand balun covers a large bandwidth, it is...requires multiple λ/4 transmission lines (t-lines), making its on-chip designs very costly even for RF/mm-wave bands. Reported miniaturized rat-race

Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

PubMed

Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

2010-06-15

We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

Spectral bandwidth-efficient four-wave mixing minimization scheme for C-band dense wavelength division multiplexed system

NASA Astrophysics Data System (ADS)

Singh, Gurpreet; Singh, Maninder Lal

2017-07-01

A hybrid suboptimum channel separation (S-CS) scheme is presented. The distinct feature of the scheme is that it selectively minimizes the four-wave mixing (FWM) effect on the worst-affected channels and enhances the performance and spectral bandwidth efficiency in a controlled way. The scheme is helpful in the precise adjustment of tradeoff between immunity from FWM and spectral bandwidth requirement. The simulative comparison of the S-CS with optimum unequal channel separation (OUCS) and equal channel separation (ECS) schemes is performed to show its effectiveness. A dense wavelength division multiplexed system having a total capacity of 1.64 Tb/s in C band is implemented using the presented scheme. A maximum of 82 channels spaced at minimum CS of 50 GHz operating at a data rate of 20 Gb/s for each of the channels is realized using a S-CS (n=12) hybrid scheme. The simulations are performed in the presence of all the linear and nonlinear impairments and noises. A maximum of 480- and 300-km distances using SSMF and ITUT.G655 fibers, respectively, is realized using dispersion-compensating fibers for 82 channels. The ECS and hybrid OUCS can be realized to cover the same distances but with 73 and 79 channels, respectively, due to the realization problem and bandwidth inefficiency.

A bandwidth efficient coding scheme for the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Pietrobon, Steven S.; Costello, Daniel J., Jr.

1991-01-01

As a demonstration of the performance capabilities of trellis codes using multidimensional signal sets, a Viterbi decoder was designed. The choice of code was based on two factors. The first factor was its application as a possible replacement for the coding scheme currently used on the Hubble Space Telescope (HST). The HST at present uses the rate 1/3 nu = 6 (with 2 (exp nu) = 64 states) convolutional code with Binary Phase Shift Keying (BPSK) modulation. With the modulator restricted to a 3 Msym/s, this implies a data rate of only 1 Mbit/s, since the bandwidth efficiency K = 1/3 bit/sym. This is a very bandwidth inefficient scheme, although the system has the advantage of simplicity and large coding gain. The basic requirement from NASA was for a scheme that has as large a K as possible. Since a satellite channel was being used, 8PSK modulation was selected. This allows a K of between 2 and 3 bit/sym. The next influencing factor was INTELSAT's intention of transmitting the SONET 155.52 Mbit/s standard data rate over the 72 MHz transponders on its satellites. This requires a bandwidth efficiency of around 2.5 bit/sym. A Reed-Solomon block code is used as an outer code to give very low bit error rates (BER). A 16 state rate 5/6, 2.5 bit/sym, 4D-8PSK trellis code was selected. This code has reasonable complexity and has a coding gain of 4.8 dB compared to uncoded 8PSK (2). This trellis code also has the advantage that it is 45 deg rotationally invariant. This means that the decoder needs only to synchronize to one of the two naturally mapped 8PSK signals in the signal set.

Advanced Silicon Photonic Device Architectures for Optical Communications: Proposals and Demonstrations

NASA Astrophysics Data System (ADS)

Sacher, Wesley David

Photonic integrated circuits implemented on silicon (Si) hold the potential for densely integrated electro-optic and passive devices manufactured by the high-volume fabrication and sophisticated assembly processes used for complementary metal-oxide-semiconductor (CMOS) electronics. However, high index contrast Si photonics has a number of functional limitations. In this thesis, several devices are proposed, designed, and experimentally demonstrated to overcome challenges in the areas of resonant modulation, waveguide loss, fiber-to-chip coupling, and polarization control. The devices were fabricated using foundry services at IBM and A*STAR Institute of Microelectronics (IME). First, we describe coupling modulated microrings, in which the coupler between a microring and the bus waveguide is modulated. The device circumvents the modulation bandwidth vs. resonator linewidth trade-off of conventional intracavity modulated microrings. We demonstrate a Si coupling modulated microring with a small-signal modulation response free of the parasitic resonator linewidth limitations at frequencies up to about 6x the linewidth. Comparisons of eye diagrams show that coupling modulation achieved data rates > 2x the rate attainable with intracavity modulation. Second, we demonstrate a silicon nitride (Si3N4)-on-Si photonic platform with independent Si3N4 and Si waveguides and taper transitions to couple light between the layers. The platform combines the excellent passive waveguide properties of Si3N4 and the compatibility of Si waveguides with electro-optic devices. Within the platform, we propose and demonstrate dual-level, Si3N 4-on-Si, fiber-to-chip grating couplers that simultaneously have wide bandwidths and high coupling efficiencies. Conventional Si and Si3N 4 grating couplers suffer from a trade-off between bandwidth and coupling efficiency. The dual-level grating coupler achieved a peak coupling efficiency of -1.3 dB and a 1-dB bandwidth of 80 nm, a record for the coupling efficiency-bandwidth product. Finally, we describe polarization rotator-splitters and controllers based on mode conversion between the fundamental transverse magnetic polarized mode and a high order transverse electric polarized mode in vertically asymmetric waveguides. We demonstrate the first polarization rotator-splitters and controllers that are fully compatible with standard active Si photonic platforms and extend the concept to our Si3N4-on-Si photonic platform.

High Performance Power Amplifiers Utilizing Novel Balun Design Techniques

NASA Astrophysics Data System (ADS)

Stameroff, Alexander Nicholas

In this PhD. research, a new power amplifier architecture is introduced. This work develops the push-pull architecture into a multifunctional matching network and combiner to create a high power, high efficiency, linear power amplifier (PA) that operates over a wide bandwidth. The traditional push-pull architecture uses an input balun to split a single ended signal into a differential signal, amplify it, and recombine it. This new technique realizes this architecture as a planar, hybrid, PA in X band. The first contribution of this work is the development of planar Marchand baluns that operate over a wide bandwidth. An analysis technique is developed and broadside coupled, Marchand baluns in an inhomogeneous medium are employed. These baluns operate over a bandwidth from 5 to 26 GHz with amplitude and phase imbalances less than 0.5 dB and 5 °, respectively. The even and odd mode behavior of the Marchand balun is utilized to provide harmonic matching for the PA. The balun inherently presents an open circuit to common mode signals at its center frequency. This is utilized to match the second harmonic to an open circuit condition. A band-stop filter is used as a harmonic trap to match the third harmonic to a short circuit. This achieves inverse class F matching for high efficiency operation. This network simultaneously acts as a combiner and matching network for high power and efficiency. A prototype PA was fabricated to prove this concept and achieves a saturated output power, Psat, greater than 33 dBm and a power added efficiency, PAE, greater than 62% over the bandwidth from 9.7 to 10.3 GHz. This technique was refined to operate over a wide bandwidth. The harmonic trap was removed and the out-of-band behavior of the balun was used to provide the short circuit matching at the third harmonic. A prototype PA was fabricated that achieved a 1 dB compressed power, P1dB, and PAE greater than 40 dBm and 55% respectively over the band from 8 to 12 GHz. Finally, the technique was extended to combine power from four transistors by the development of a 4-to-1 balun. A prototype PA was fabricated to prove this concept and achieves a P1dB and PAE greater than 43 dBm and 55% over the band from 8 to 12 GHz.

Advanced Broadband Links for TIER III UAV Data Communication

NASA Astrophysics Data System (ADS)

Griethe, Wolfgang; Gregory, Mark; Heine, Frank; Kampfner, Hartmut

2011-08-01

Unmanned Aeronautical Vehicle (UAV) are getting more and more importance because of their prominent role as national reconnaissance systems, for disaster monitoring, and environmental mapping. However, the existence of reliable and robust data links are indispensable for Unmanned Aircraft System (UAS) missions. In particular for Beyond Line-Of-Sight operations (BLOS) of Tier III UAVs, satellite data links are a key element since extensive sensor data have to be transmitted preferably in real-time or near real-time.The paper demonstrates that the continuously increasing number of UAS and the intensified use of high resolution sensors will reveal RF-bandwidth as a limitating factor in the communication chain of Tier III UAVs. The RF-bandwidth gap can be partly closed by use of high-order modulation, of course, but much more progress in terms of bandwidth allocation can be achieved by using optical transmission technology. Consequently, the paper underlines that meanwhile this technology has been sufficiently verified in space, and shows that optical links are suited as well for broadband communications of Tier III UAVs. Moreover, the advantages of LaserCom in UAV scenarios and its importance for Network Centric Warfare (NCW) as well as for Command, Control, Communications, Computers, Intelligens, Surveillance, and Reconnaissance (C4ISR) are emphasized. Numerous practical topics and design requirements, relevant for the establishment of optical links onboard of Tier III UAVs, are discussed.

Efficient Visible Light Communication Transmitters Based on Switching-Mode dc-dc Converters.

PubMed

Rodríguez, Juan; Lamar, Diego G; Aller, Daniel G; Miaja, Pablo F; Sebastián, Javier

2018-04-07

Visible light communication (VLC) based on solid-state lighting (SSL) is a promising option either to supplement or to substitute existing radio frequency (RF) wireless communication in indoor environments. VLC systems take advantage of the fast modulation of the visible light that light emitting diodes (LEDs) enable. The switching-mode dc-to-dc converter (SMC dc-dc ) must be the cornerstone of the LED driver of VLC transmitters in order to incorporate the communication functionality into LED lighting, keeping high power efficiency. However, the new requirements related to the communication, especially the high bandwidth that the LED driver must achieve, converts the design of the SMC dc-dc into a very challenging task. In this work, three different methods for achieving such a high bandwidth with an SMC dc-dc are presented: increasing the order of the SMC dc-dc output filter, increasing the number of voltage inputs, and increasing the number of phases. These three strategies are combinable and the optimum design depends on the particular VLC application, which determines the requirements of the VLC transmitter. As an example, an experimental VLC transmitter based on a two-phase buck converter with a fourth-order output filter will demonstrate that a bandwidth of several hundred kilohertz (kHz) can be achieved with output power levels close to 10 W and power efficiencies between 85% and 90%. In conclusion, the design strategy presented allows us to incorporate VLC into SSL, achieving high bit rates without damaging the power efficiency of LED lighting.

Efficient Visible Light Communication Transmitters Based on Switching-Mode dc-dc Converters

PubMed Central

2018-01-01

Visible light communication (VLC) based on solid-state lighting (SSL) is a promising option either to supplement or to substitute existing radio frequency (RF) wireless communication in indoor environments. VLC systems take advantage of the fast modulation of the visible light that light emitting diodes (LEDs) enable. The switching-mode dc-to-dc converter (SMCdc-dc) must be the cornerstone of the LED driver of VLC transmitters in order to incorporate the communication functionality into LED lighting, keeping high power efficiency. However, the new requirements related to the communication, especially the high bandwidth that the LED driver must achieve, converts the design of the SMCdc-dc into a very challenging task. In this work, three different methods for achieving such a high bandwidth with an SMCdc-dc are presented: increasing the order of the SMCdc-dc output filter, increasing the number of voltage inputs, and increasing the number of phases. These three strategies are combinable and the optimum design depends on the particular VLC application, which determines the requirements of the VLC transmitter. As an example, an experimental VLC transmitter based on a two-phase buck converter with a fourth-order output filter will demonstrate that a bandwidth of several hundred kilohertz (kHz) can be achieved with output power levels close to 10 W and power efficiencies between 85% and 90%. In conclusion, the design strategy presented allows us to incorporate VLC into SSL, achieving high bit rates without damaging the power efficiency of LED lighting. PMID:29642455

Channel access schemes and fiber optic configurations for integrated-services local area networks

NASA Astrophysics Data System (ADS)

Nassehi, M. Mehdi

1987-03-01

Local Area Networks are in common use for data communications and have enjoyed great success. Recently, there is a growing interest in using a single network to support many applications in addition to traditional data traffic. These additional applications introduce new requirements in terms of volume of traffic and real-time delivery of data which are not met by existing networks. To satisfy these requirements, a high-bandwidth tranmission medium, such as fiber optics, and a distributed channel access scheme for the efficient sharing of the bandwidth among the various applications are needed. As far as the throughput-delay requirements of the various application are concerned, a network structure along with a distributed channel access are proposed which incorporate appropriate scheduling policies for the transmission of outstanding messages on the network. A dynamic scheduling policy was devised which outperforms all existing policies in terms of minimizing the expected cost per message. A broadcast mechanism was devised for the efficient dissemination of all relevant information. Fiber optic technology is considered for the high-bandwidth transmisison medium.

The Effect of Pulse Shaping QPSK on Bandwidth Efficiency

NASA Technical Reports Server (NTRS)

Purba, Josua Bisuk Mubyarto; Horan, Shelia

1997-01-01

This research investigates the effect of pulse shaping QPSK on bandwidth efficiency over a non-linear channel. This investigation will include software simulations and the hardware implementation. Three kinds of filters: the 5th order Butterworth filter, the 3rd order Bessel filter and the Square Root Raised Cosine filter with a roll off factor (alpha) of 0.25,0.5 and 1, have been investigated as pulse shaping filters. Two different high power amplifiers, one a Traveling Wave Tube Amplifier (TWTA) and the other a Solid State Power Amplifier (SSPA) have been investigated in the hardware implementation. A significant improvement in the bandwidth utilization (rho) for the filtered data compared to unfiltered data through the non-linear channel is shown in the results. This method promises strong performance gains in a bandlimited channel when compared to unfiltered systems. This work was conducted at NMSU in the Center for Space Telemetering, and Telecommunications Systems in the Klipsch School of Electrical and Computer Engineering Department and is supported by a grant from the National Aeronautics and Space Administration (NASA) NAG5-1491.

Channel access schemes and fiber optic configurations for integrated-services local area networks. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Nassehi, M. Mehdi

1987-01-01

Local Area Networks are in common use for data communications and have enjoyed great success. Recently, there is a growing interest in using a single network to support many applications in addition to traditional data traffic. These additional applications introduce new requirements in terms of volume of traffic and real-time delivery of data which are not met by existing networks. To satisfy these requirements, a high-bandwidth tranmission medium, such as fiber optics, and a distributed channel access scheme for the efficient sharing of the bandwidth among the various applications are needed. As far as the throughput-delay requirements of the various application are concerned, a network structure along with a distributed channel access are proposed which incorporate appropriate scheduling policies for the transmission of outstanding messages on the network. A dynamic scheduling policy was devised which outperforms all existing policies in terms of minimizing the expected cost per message. A broadcast mechanism was devised for the efficient dissemination of all relevant information. Fiber optic technology is considered for the high-bandwidth transmisison medium.

Exercise, physiological function, and the selection of participants for aging research.

PubMed

Lazarus, Norman R; Harridge, Stephen D R

2010-08-01

Regular and vigorous exercisers appear to be the logical choice for studying the inherent aging process as they are essentially free from the complications of disuse. Cross-sectional studies of aging tend to depict an essentially smooth and progressive decrement of physiological function with increasing chronological age. On closer examination of such data, it is seen that although the young have high functional values and the very old low, between these limits, values are widely scattered. We have reevaluated published data from a meta-analysis of 242 studies on men and from a similar study on women. From both data sets, where VO2max was plotted against chronological age, we stratified the VO2max values into bandwidth intervals of 5 ml/kg/minute and then allocated data points to their respective bandwidth irrespective of chronological age. When replotted into bandwidths of functional equivalence, these data show that at the extremes of function, the young are separated from the old. Between these values, each functional bandwidth accommodates a wide age range. The decrement in function with chronological age is not smooth or well defined. We suggest that participants for research into healthy aging should be initially segregated into bands of functionally equivalent VO2max values irrespective of their chronological age. Subsequently, other physiological measurements should be made on every participant in the band in order to begin to define the physiological profile of the participants. By conducting longitudinal studies on every individual, it will be possible to chart the physiological history of each participant through various ages. Segregating participants into cohorts of functional equivalence with data handling blinded to chronological age may be of great utility in increasing our understanding of the inherent aging process.

Performance Analysis of a Hardware Implemented Complex Signal Kurtosis Radio-Frequency Interference Detector

NASA Technical Reports Server (NTRS)

Schoenwald, Adam J.; Bradley, Damon C.; Mohammed, Priscilla N.; Piepmeier, Jeffrey R.; Wong, Mark

2016-01-01

Radio-frequency interference (RFI) is a known problem for passive remote sensing as evidenced in the L-band radiometers SMOS, Aquarius and more recently, SMAP. Various algorithms have been developed and implemented on SMAP to improve science measurements. This was achieved by the use of a digital microwave radiometer. RFI mitigation becomes more challenging for microwave radiometers operating at higher frequencies in shared allocations. At higher frequencies larger bandwidths are also desirable for lower measurement noise further adding to processing challenges. This work focuses on finding improved RFI mitigation techniques that will be effective at additional frequencies and at higher bandwidths. To aid the development and testing of applicable detection and mitigation techniques, a wide-band RFI algorithm testing environment has been developed using the Reconfigurable Open Architecture Computing Hardware System (ROACH) built by the Collaboration for Astronomy Signal Processing and Electronics Research (CASPER) Group. The testing environment also consists of various test equipment used to reproduce typical signals that a radiometer may see including those with and without RFI. The testing environment permits quick evaluations of RFI mitigation algorithms as well as show that they are implementable in hardware. The algorithm implemented is a complex signal kurtosis detector which was modeled and simulated. The complex signal kurtosis detector showed improved performance over the real kurtosis detector under certain conditions. The real kurtosis is implemented on SMAP at 24 MHz bandwidth. The complex signal kurtosis algorithm was then implemented in hardware at 200 MHz bandwidth using the ROACH. In this work, performance of the complex signal kurtosis and the real signal kurtosis are compared. Performance evaluations and comparisons in both simulation as well as experimental hardware implementations were done with the use of receiver operating characteristic (ROC) curves.

Solar-pumped gas laser development

NASA Technical Reports Server (NTRS)

Wilson, J. W.

1980-01-01

A survey of gas properties through detailed kinetic models led to the identification of critical gas parameters for use in choosing appropriate gas combinations for solar pumped lasers. Broadband photoabsorption in the visible or near UV range is required to excite large volumes of gas and to insure good solar absorption efficiency. The photoexcitation density is independent of the absorption bandwidth. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than 10 A to insure lasing threshold over reasonable gain lengths. The system should show a high degree of chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. Although photoexcitation of electronic vibrational transitions is considered as a possible system if the emission bands sufficiently narrow, it appears that photodissociation into atomic metastables is more likely to result in a successful solar pumped laser system.

Bandwidth Efficient Wireless Digital Modem Developed

NASA Technical Reports Server (NTRS)

Kifle, Muli

1999-01-01

NASA Lewis Research Center has developed a digital approach for broadcasting highfidelity audio (nearly compact disk (CD) quality sound) in the commercial frequencymodulated (FM) broadcast band. This digital approach provides a means of achieving high data transmission rates with low hardware complexity--including low mass, size, and power consumption. Lewis has completed the design and prototype development of a bandwidth-efficient digital modem (modulator and demodulator) that uses a spectrally efficient modulation scheme: 16-ary rectangular quadrature amplitude modulation, or 16- ary QAM. The digital implementation is based strictly on inexpensive, commercial off-theshelf digital signal processing (DSP) hardware to perform up and down conversions and pulse shaping. The digital modem transmits data at rates up to 76 kilobits per second (kbps), which is almost 3 times faster than standard 28.8-kbps telephone modems. In addition, the modem offers improved power and spectral performance, flexible operation, and low-cost implementation.

Efficiency enhancement of dual-mode traveling wave tubes at saturation and in the linear range by use of spent-beam refocusing and multistage depressed collectors

NASA Technical Reports Server (NTRS)

Ramins, P.; Fox, T. A.

1979-01-01

An axisymmetric, multistage depressed collector of fixed geometric design was evaluated in conjunction with an octave-bandwidth, dual-mode TWT. The TWT was operated over a wide range of conditions to simulate different applications. The collector was operated in three-, four-, and five-stage configurations, and its performance was optimized (within the constraint of fixed geometric design) over the range of TWT operating conditions covered. For operation of the dual-mode TWT at and near saturation, the collectors increased the TWT overall efficiency by a factor of 2 1/2 to 3 1/2. Collector performance was relatively constant for both the high and low TWT modes and for operation of the TWT across an octave bandwidth. For operation of the TWT in the linear, low-distortion range, collector efficiencies of 90 percent and greater were obtained, leading to a five- to twelvefold increase in the TWT overall efficiency for the range of operating conditions covered and reasonably high (greater than 25 percent) overall efficiencies well below saturation.

Decomposing Cost Efficiency in Regional Long-term Care Provision in Japan.

PubMed

Yamauchi, Yasuhiro

2015-07-12

Many developed countries face a growing need for long-term care provision because of population ageing. Japan is one such example, given its population's longevity and low birth rate. In this study, we examine the efficiency of Japan's regional long-term care system in FY2010 by performing a data envelopment analysis, a non-parametric frontier approach, on prefectural data and separating cost efficiency into technical, allocative, and price efficiencies under different average unit costs across regions. In doing so, we elucidate the structure of cost inefficiency by incorporating a method for restricting weight flexibility to avoid unrealistic concerns arising from zero optimal weight. The results indicate that technical inefficiency accounts for the highest share of losses, followed by price inefficiency and allocation inefficiency. Moreover, the majority of technical inefficiency losses stem from labor costs, particularly those for professional caregivers providing institutional services. We show that the largest share of allocative inefficiency losses can also be traced to labor costs for professional caregivers providing institutional services, while the labor provision of in-home care services shows an efficiency gain. However, although none of the prefectures gains efficiency by increasing the number of professional caregivers for institutional services, quite a few prefectures would gain allocative efficiency by increasing capital inputs for institutional services. These results indicate that preferred policies for promoting efficiency might vary from region to region, and thus, policy implications should be drawn with care.

Hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering at flame temperatures using a second-harmonic bandwidth-compressed probe.

PubMed

Kearney, Sean P; Scoglietti, Daniel J

2013-03-15

We demonstrate an approach for picosecond probe-beam generation that enables hybrid femtosecond/picosecond pure-rotational coherent anti-Stokes Raman scattering (CARS) measurements in flames. Sum-frequency generation of bandwidth-compressed picosecond radiation from femtosecond pumps with phase-conjugate chirps provides probe pulses with energies in excess of 1 mJ that are temporally locked to the femtosecond pump/Stokes preparation. This method overcomes previous limitations on hybrid femtosecond/picosecond rotational CARS techniques, which have relied upon less efficient bandwidth-reduction processes that have generally resulted in prohibitively low probe energy for flame measurements. We provide the details of the second-harmonic approach and demonstrate the technique in near-adiabatic hydrogen/air flames.

Joint transform correlator optical encryption system: Extensions of the recorded encrypted signal and its inverse Fourier transform

NASA Astrophysics Data System (ADS)

Galizzi, Gustavo E.; Cuadrado-Laborde, Christian

2015-10-01

In this work we study the joint transform correlator setup, finding two analytical expressions for the extensions of the joint power spectrum and its inverse Fourier transform. We found that an optimum efficiency is reached, when the bandwidth of the key code is equal to the sum of the bandwidths of the image plus the random phase mask (RPM). The quality of the decryption is also affected by the ratio between the bandwidths of the RPM and the input image, being better as this ratio increases. In addition, the effect on the decrypted image when the detection area is lower than the encrypted signal extension was analyzed. We illustrate these results through several numerical examples.

Frequency tracking and variable bandwidth for line noise filtering without a reference.

PubMed

Kelly, John W; Collinger, Jennifer L; Degenhart, Alan D; Siewiorek, Daniel P; Smailagic, Asim; Wang, Wei

2011-01-01

This paper presents a method for filtering line noise using an adaptive noise canceling (ANC) technique. This method effectively eliminates the sinusoidal contamination while achieving a narrower bandwidth than typical notch filters and without relying on the availability of a noise reference signal as ANC methods normally do. A sinusoidal reference is instead digitally generated and the filter efficiently tracks the power line frequency, which drifts around a known value. The filter's learning rate is also automatically adjusted to achieve faster and more accurate convergence and to control the filter's bandwidth. In this paper the focus of the discussion and the data will be electrocorticographic (ECoG) neural signals, but the presented technique is applicable to other recordings.

Investigation of Bandwidth-Efficient Coding and Modulation Techniques

NASA Technical Reports Server (NTRS)

Osborne, William P.

1992-01-01

The necessary technology was studied to improve the bandwidth efficiency of the space-to-ground communications network using the current capabilities of that network as a baseline. The study was aimed at making space payloads, for example the Hubble Space Telescope, more capable without the need to completely redesign the link. Particular emphasis was placed on the following concepts: (1) what the requirements are which are necessary to convert an existing standard 4-ary phase shift keying communications link to one that can support, as a minimum, 8-ary phase shift keying with error corrections applied; and (2) to determine the feasibility of using the existing equipment configurations with additional signal processing equipment to realize the higher order modulation and coding schemes.

Health care market deviations from the ideal market.

PubMed

Mwachofi, Ari; Al-Assaf, Assaf F

2011-08-01

A common argument in the health policy debate is that market forces allocate resources efficiently in health care, and that government intervention distorts such allocation. Rarely do those making such claims state explicitly that the market they refer to is an ideal in economic theory which can only exist under very strict conditions. This paper explores the strict conditions necessary for that ideal market in the context of health care as a means of examining the claim that market forces do allocate resources efficiently in health care.

Development of trivalent ytterbium doped fluorapatites for diode-pumped laser applications

NASA Astrophysics Data System (ADS)

Bayramian, Andrew James

2000-11-01

A major motivator of this work is the Mercury Project, a one kilowatt diode-pumped solid-state laser system under development at Lawrence Livermore National Laboratory (LLNL), which incorporates ytterbium doped strontium fluorapatite, Sr5(PO4)3F (S-FAP), as the amplifier gain medium. The primary focus of this thesis is a full understanding of the properties of this material, which is necessary for proper design and modeling of the system. Ytterbium-doped fluorapatites were investigated at LLNL prior to this work and found to be ideal candidate materials for high-power amplifier systems providing high absorption and emission cross sections, long radiative lifetimes, and high efficiency. A family of barium substituted S-FAP crystals was grown in an effort to modify the pump and emission bandwidths for application to broadband diode pumping and short pulse generation. Crystals of Yb 3+:Srs5-xBax(PO4) 3F where x < 1 showed homogeneous lines offering 8.4 nm (1.8X enhancement) of absorption bandwidth and 6.9 nm (1.4X enhancement) of emission bandwidth. The gain saturation fluence of Yb:S-FAP was measured to be 3.2 J/cm 2 with homogeneous extraction using a pump-probe experiment where the probe laser was a high intensity Q-switched master oscillator power amplifier system. The crystal quality of Czochralski grown Yb:S-FAP boules, which is effected by defects such as cracking, cloudiness, bubble core, slip dislocations, and anomalous absorption, was investigated interferometrically and quantified by means of Power Spectral Density (PSD) plots. Stimulated Raman Scattering (SRS) losses were evaluated by first measuring the SRS gain coefficient to be 1.3 cm/GW, then modeling the losses in the Mercury amplifier system. Countermeasures including the addition of bandwidth to the extraction beam and wedging of amplifier surfaces are shown to reduce the SRS losses allowing efficient laser gain extraction at higher intensities. Finally, an efficient Q-switched Yb:S-FAP oscillator was developed which operates three-level at 985 nm with a 21% slope efficiency. Frequency conversion of the 985 nm light to the 2nd harmonic at 492.5 nm was achieved with a 31% conversion efficiency. A diode pumped, doubled Yb:S-FAP laser at 492.5 nm would make possible a compact, efficient, high-power blue laser source.

622-Mbps Orthogonal Frequency Division Multiplexing (OFDM) Digital Modem Implemented

NASA Technical Reports Server (NTRS)

Kifle, Muli; Bizon, Thomas P.; Nguyen, Nam T.; Tran, Quang K.; Mortensen, Dale J.

2002-01-01

Future generation space communications systems feature significantly higher data rates and relatively smaller frequency spectrum allocations than systems currently deployed. This requires the application of bandwidth- and power-efficient signal transmission techniques. There are a number of approaches to implementing such techniques, including analog, digital, mixed-signal, single-channel, or multichannel systems. In general, the digital implementations offer more advantages; however, a fully digital implementation is very difficult because of the very high clock speeds required. Multichannel techniques are used to reduce the sampling rate. One such technique, multicarrier modulation, divides the data into a number of low-rate channels that are stacked in frequency. Orthogonal frequency division multiplexing (OFDM), a form of multicarrier modulation, is being proposed for numerous systems, including mobile wireless and digital subscriber link communication systems. In response to this challenge, NASA Glenn Research Center's Communication Technology Division has developed an OFDM digital modem (modulator and demodulator) with an aggregate information throughput of 622 Mbps. The basic OFDM waveform is constructed by dividing an incoming data stream into four channels, each using either 16- ary quadrature amplitude modulation (16-QAM) or 8-phase shift keying (8-PSK). An efficient implementation for an OFDM architecture is being achieved using the combination of a discrete Fourier transform (DFT) at the transmitter to digitally stack the individual carriers, inverse DFT at the receiver to perform the frequency translations, and a polyphase filter to facilitate the pulse shaping.

Manycast routing, modulation level and spectrum assignment over elastic optical networks

NASA Astrophysics Data System (ADS)

Luo, Xiao; Zhao, Yang; Chen, Xue; Wang, Lei; Zhang, Min; Zhang, Jie; Ji, Yuefeng; Wang, Huitao; Wang, Taili

2017-07-01

Manycast is a point to multi-point transmission framework that requires a subset of destination nodes successfully reached. It is particularly applicable for dealing with large amounts of data simultaneously in bandwidth-hungry, dynamic and cloud-based applications. As rapid increasing of traffics in these applications, the elastic optical networks (EONs) may be relied on to achieve high throughput manycast. In terms of finer spectrum granularity, the EONs could reach flexible accessing to network spectrum and efficient providing exact spectrum resource to demands. In this paper, we focus on the manycast routing, modulation level and spectrum assignment (MA-RMLSA) problem in EONs. Both EONs planning with static manycast traffic and EONs provisioning with dynamic manycast traffic are investigated. An integer linear programming (ILP) model is formulated to derive MA-RMLSA problem in static manycast scenario. Then corresponding heuristic algorithm called manycast routing, modulation level and spectrum assignment genetic algorithm (MA-RMLSA-GA) is proposed to adapt for both static and dynamic manycast scenarios. The MA-RMLSA-GA optimizes MA-RMLSA problem in destination nodes selection, routing light-tree constitution, modulation level allocation and spectrum resource assignment jointly, to achieve an effective improvement in network performance. Simulation results reveal that MA-RMLSA strategies offered by MA-RMLSA-GA have slightly disparity from the optimal solutions provided by ILP model in static scenario. Moreover, the results demonstrate that MA-RMLSA-GA realizes a highly efficient MA-RMLSA strategy with the lowest blocking probability in dynamic scenario compared with benchmark algorithms.

Experimental demonstration of a 16.9 Gb/s link for coherent OFDM PON robust to frequency offset and timing error

NASA Astrophysics Data System (ADS)

Ma, Qian; Liu, Yu; Xiang, Yuanjiang

2018-07-01

Due to its merits of flexible bandwidth allocation and robustness towards fiber transmission impairments, coherent optical orthogonal frequency division multiplexing (CO-OFDM) technology draws a lot of attention for passive optical networks (PON). However, a CO-OFDM system is vulnerable to frequency offsets between modulated optical signals and optical local oscillators (OLO). This is particularly serious for low cost PONs where low cost lasers are used. Thus, it is of great interest to develop efficient algorithms for frequency synchronization in CO-OFDM systems. Usually frequency synchronization proposed in CO-OFDM systems are done by detecting the phase shift in time domain. In such a way, there is a trade-off between estimation accuracy and range. Considering that the integer frequency offset (IFO) contributes to the major frequency offset, a more efficient method to estimate IFO is of demand. By detecting IFO induced circular channel rotation (CCR), the frequency offset can be directly estimated after fast Fourier transforming (FFT). In this paper, circular acquisition offset frequency and timing synchronization (CAO-FTS) scheme is proposed. A specially-designed frequency domain pseudo noise (PN) sequence is used for CCR detection and timing synchronization. Full-range frequency offset compensation and non-plateau timing synchronization are experimentally demonstrated in presence of fiber dispersion. Based on CAO-FTS, 16.9 Gb/s CO-OFDM signal is successfully delivered over a span of 80-km single mode fiber.

Ultra-Wideband Array in PCB for Millimeter-Wave 5G and ISM

NASA Technical Reports Server (NTRS)

Novak, Markus H.; Volakis, John L.; Miranda, Felix A.

2017-01-01

Next generation 5G mobile architectures will take advantage of the millimeter-wave spectrum to deliver unprecedented bandwidth. Concurrently, there is a need to consolidate numerous disparate allocations into a single, multi-functional array. Existing arrays are either narrow-band, prohibitively expensive or cannot be scaled to these frequencies. In this paper, we present the first ultra-wideband millimeter-wave array to operate across the six 5G and ISM bands spanning 24-71 GHz. Critically, the array is realized using low-cost PCB. The design concept and optimized layout are presented, and fabrication and measurement considerations are discussed.

Fault identification and localization for Ethernet Passive Optical Network using L-band ASE source and various types of fiber Bragg grating

NASA Astrophysics Data System (ADS)

Naim, Nani Fadzlina; Bakar, A. Ashrif A.; Ab-Rahman, Mohammad Syuhaimi

2018-01-01

This paper presents a centralized and fault localization technique for Ethernet Passive Optical Access Network. This technique employs L-band Amplified Spontaneous Emission (ASE) as the monitoring source and various fiber Bragg Gratings (FBGs) as the fiber's identifier. An FBG with a unique combination of Bragg wavelength, reflectivity and bandwidth is inserted at each distribution fiber. The FBG reflection spectrum will be analyzed using an optical spectrum analyzer (OSA) to monitor the condition of the distribution fiber. Various FBGs reflection spectra is employed to optimize the limited bandwidth of monitoring source, thus allows more fibers to be monitored. Basically, one Bragg wavelength is shared by two distinct FBGs with different reflectivity and bandwidth. The experimental result shows that the system is capable to monitor up to 32 customers with OSNR value of ∼1.2 dB and monitoring power received of -24 dBm. This centralized and simple monitoring technique demonstrates a low power, cost efficient and low bandwidth requirement system.

Optical-domain subsampling for data efficient depth ranging in Fourier-domain optical coherence tomography

PubMed Central

Siddiqui, Meena; Vakoc, Benjamin J.

2012-01-01

Recent advances in optical coherence tomography (OCT) have led to higher-speed sources that support imaging over longer depth ranges. Limitations in the bandwidth of state-of-the-art acquisition electronics, however, prevent adoption of these advances into the clinical applications. Here, we introduce optical-domain subsampling as a method for imaging at high-speeds and over extended depth ranges but with a lower acquisition bandwidth than that required using conventional approaches. Optically subsampled laser sources utilize a discrete set of wavelengths to alias fringe signals along an extended depth range into a bandwidth limited frequency window. By detecting the complex fringe signals and under the assumption of a depth-constrained signal, optical-domain subsampling enables recovery of the depth-resolved scattering signal without overlapping artifacts from this bandwidth-limited window. We highlight key principles behind optical-domain subsampled imaging, and demonstrate this principle experimentally using a polygon-filter based swept-source laser that includes an intra-cavity Fabry-Perot (FP) etalon. PMID:23038343

Generalized Chirp Scaling Combined with Baseband Azimuth Scaling Algorithm for Large Bandwidth Sliding Spotlight SAR Imaging

PubMed Central

Yi, Tianzhu; He, Zhihua; He, Feng; Dong, Zhen; Wu, Manqing

2017-01-01

This paper presents an efficient and precise imaging algorithm for the large bandwidth sliding spotlight synthetic aperture radar (SAR). The existing sub-aperture processing method based on the baseband azimuth scaling (BAS) algorithm cannot cope with the high order phase coupling along the range and azimuth dimensions. This coupling problem causes defocusing along the range and azimuth dimensions. This paper proposes a generalized chirp scaling (GCS)-BAS processing algorithm, which is based on the GCS algorithm. It successfully mitigates the deep focus along the range dimension of a sub-aperture of the large bandwidth sliding spotlight SAR, as well as high order phase coupling along the range and azimuth dimensions. Additionally, the azimuth focusing can be achieved by this azimuth scaling method. Simulation results demonstrate the ability of the GCS-BAS algorithm to process the large bandwidth sliding spotlight SAR data. It is proven that great improvements of the focus depth and imaging accuracy are obtained via the GCS-BAS algorithm. PMID:28555057

Pre-emphasis determination for an S-band constant bandwidth FM/FM station

NASA Technical Reports Server (NTRS)

Wallace, G. R.; Salter, W. E.

1972-01-01

Pre-emphasis schedules are given for 11 constant-bandwidth FM subcarriers modulating an S band transmitter at three receiver signal to noise ratios (i.e., 9, 15, and 25 dB). The criterion for establishing these pre-emphasis curves is the achievement, at various receiver intermediate frequency signal to noise ratios, of equal receiver output signal to noise ratios for all channels. It is realized that these curves may not be the optimum pre-emphasis curves based on overall efficiency or maximum utilization of the allotted spectrum, but they are near-optimum for data with channels which require equal output signal to noise ratios, such as spectral densities. The empirically derived results are compared with a simplified, analytically derived schedule and the primary differences are explained. The S band pre-emphasis schedule differs from the lower frequency VHF case. Since most proportional bandwidth and constant bandwidth systems use ground based recorders and some use flight recorders (as the Saturn systems did on VHF proportional bandwidth telemetry), the effects of these recorders are discussed and a modified pre-emphasis schedule is presented showing the results of this study phase.

Water Market-scale Agricultural Planning: Promoting Competing Water Resource Use Efficiency Through Agro-Economics

NASA Astrophysics Data System (ADS)

Delorit, J. D.; Block, P. J.

2017-12-01

Where strong water rights law and corresponding markets exist as a coupled econo-legal mechanism, water rights holders are permitted to trade allocations to promote economic water resource use efficiency. In locations where hydrologic uncertainty drives the assignment of annual per-water right allocation values by water resource managers, collaborative water resource decision making by water rights holders, specifically those involved in agricultural production, can result in both resource and economic Pareto efficiency. Such is the case in semi-arid North Chile, where interactions between representative farmer groups, treated as competitive bilateral monopolies, and modeled at water market-scale, can provide both price and water right allocation distribution signals for unregulated, temporary water right leasing markets. For the range of feasible per-water right allocation values, a coupled agricultural-economic model is developed to describe the equilibrium distribution of water, the corresponding market price of water rights and the net surplus generated by collaboration between competing agricultural uses. Further, this research describes a per-water right inflection point for allocations where economic efficiency is not possible, and where price negotiation among competing agricultural uses is required. An investigation of the effects of water right supply and demand inequality at the market-scale is completed to characterize optimal market performance under existing water rights law. The broader insights of this research suggest that water rights holders engaged in agriculture can achieve economic benefits from forming crop-type cooperatives and by accurately assessing the economic value of allocation.

[Integration design and diffraction characteristics analysis of prism-grating-prism].

PubMed

He, Tian-Bo; Bayanheshig; Li, Wen-Hao; Kong, Peng; Tang, Yu-Guo

2014-01-01

Prism-grating-prism (PGP) module is the important dispersing component in the hyper spectral imager. In order to effectively predict the distribution of diffraction efficiency of the whole PGP component and its diffraction characteristics before fabrication, a method of the PGP integration design is proposed. From the point of view of the volume phase holographic grating (VPHG) design, combined with the restrictive correlation between the various parameters of prisms and grating, we compiled the analysis software for calculating the whole PGP's diffraction efficiency. Furthermore, the effects of the structure parameters of prisms and grating on the PGP's diffraction characteristics were researched in detail. In particular we discussed the Bragg wavelength shift behaviour of the grating and a broadband PGP spectral component with high diffraction efficiency was designed for the imaging spectrometers. The result of simulation indicated that the spectral bandwidth of the PGP becomes narrower with the dispersion coefficient of prism 1 material decreasing; Bragg wavelength shift characteristics broaden the bandwidth of VPHG both spectrally and angularly, higher angular selectivity is desirable for selection requirements of the prism 1 material, and it can be easily tuned to achieve spectral bandwidth suitable for imaging PGP spectrograph; the vertex angle of prism 1, the film thickness and relative permittivity modulation of the grating have a significant impact on the distribution of PGP's diffraction efficiency, so precision control is necessary when fabrication. The diffraction efficiency of the whole PGP component designed by this method is no less than 50% in the wavelength range from 400 to 1000 nm, the specific design parameters have been given in this paper that have a certain reference value for PGP fabrication.

Grant management procedure for energy saving TDM-PONs

NASA Astrophysics Data System (ADS)

Alaelddin, Fuad Yousif Mohammed; Newaz, S. H. Shah; AL-Hazemi, Fawaz; Choi, Jun Kyun

2018-01-01

In order to minimize energy consumption in Time Division Multiplexing-Passive Optical Network (TDM-PON), IEEE and ITU-T have mandated sleep mode mechanism for Optical Network Units (ONUs) in the latest TDM-PON standards (e.g. IEEE P1904.1 SIEPON, ITU-T G.sup45). The sleep mode mechanism is a promising mean for maximizing energy saving in an ONU. An ONU in sleep mode flips between sleep and active state depending on the presence or absent of upstream and downstream frames. To ensure Quality of Service (QoS) of upstream frames, the recent TDM-PON standards introduced an early wake-up mechanism, in which an ONU is forced to leave the sleep state on upstream frame arrival. When the Optical Line Terminal (OLT) of a TDM-PON allows early wake-up of its connected ONUs, it allocates gratuitous grants for the sleeping ONUs along with allocating upstream grants for the ONUs in active state. Note that, the gratuitous grants control message sent periodically by the OLT on Inter-Gratuitous grant Interval (IGI) time. After leaving sleep state due to the arrival of upstream frame, the ONU uses its allocated gratuitous grant to send a control message mentioning the amount of upstream bandwidth (upstream grant) required in order to forward the remaining frames in its buffer. However, the existing early wake-up process of ONU can lead to increase the energy consumption of an ONU. It is because of the ONU wakes-up immediately from the sleep state on arrival of the upstream frame, but even so, it needs to wait for forwarding the frame until its allocated gratuitous grant period, resulting in spending energy unnecessarily. In addition, current energy saving solution for TDM-PONs do not provide a clear solution on how to manage different types of grants (e.g. listening grant, upstream transmission grant) within a Dynamic Bandwidth Allocation (DBA) polling cycle. To address this problem, we propose a state-of-art Grant Management Procedure (GMP) in order to maximize energy saving in a TDM-PON with sleep mode enabled ONUs. GMP contributes in defining the location of the different types of grants during a DBA polling cycle. Furthermore, GMP devises a mechanism so as to allow an ONU to predict its assigned gratuitous grant control message arrival time, thereby allowing an ONU to remain its transceiver unit powered off until the arrival period of the next gratuitous grant control message, increasing the energy saving of the ONU. Results show that, with the increment of IGI, the energy saving performance of an ONU with GMP increases noticeably in compare to a conventional ONU (an ONU that does not use GMP) without imposing any additional upstream frame delay.

A mathematical modeling approach to resource allocation for railroad-highway crossing safety upgrades.

PubMed

Konur, Dinçer; Golias, Mihalis M; Darks, Brandon

2013-03-01

State Departments of Transportation (S-DOT's) periodically allocate budget for safety upgrades at railroad-highway crossings. Efficient resource allocation is crucial for reducing accidents at railroad-highway crossings and increasing railroad as well as highway transportation safety. While a specific method is not restricted to S-DOT's, sorting type of procedures are recommended by the Federal Railroad Administration (FRA), United States Department of Transportation for the resource allocation problem. In this study, a generic mathematical model is proposed for the resource allocation problem for railroad-highway crossing safety upgrades. The proposed approach is compared to sorting based methods for safety upgrades of public at-grade railroad-highway crossings in Tennessee. The comparison shows that the proposed mathematical modeling approach is more efficient than sorting methods in reducing accidents and severity. Copyright © 2012 Elsevier Ltd. All rights reserved.

How resource allocation decisions are made in the health care market.

PubMed

Vogel, W B

2000-10-01

This paper describes how economists view resource allocation decisions in health care markets. The basic economic decisions that must be made in any economic system and the resource allocation decisions in a perfectly competitive market are described. An idealized market can achieve an efficient allocation of resources and is contrasted with a more realistic description of the numerous ways in which health care markets depart from the perfectly competitive ideal. The implications of these departures for health care policy are discussed, along with key controversies concerning reliance upon markets for resource allocation in health care. In particular, the failure of competitive markets to achieve what many consider an equitable distribution of health care is emphasized. The paper concludes with some practical observations on how pharmacists can use the increasing emphasis on economic efficiency to the advantage of their profession.

Multi-Modulator for Bandwidth-Efficient Communication

NASA Technical Reports Server (NTRS)

Gray, Andrew; Lee, Dennis; Lay, Norman; Cheetham, Craig; Fong, Wai; Yeh, Pen-Shu; King, Robin; Ghuman, Parminder; Hoy, Scott; Fisher, Dave

2009-01-01

A modulator circuit board has recently been developed to be used in conjunction with a vector modulator to generate any of a large number of modulations for bandwidth-efficient radio transmission of digital data signals at rates than can exceed 100 Mb/s. The modulations include quadrature phaseshift keying (QPSK), offset quadrature phase-shift keying (OQPSK), Gaussian minimum-shift keying (GMSK), and octonary phase-shift keying (8PSK) with square-root raised-cosine pulse shaping. The figure is a greatly simplified block diagram showing the relationship between the modulator board and the rest of the transmitter. The role of the modulator board is to encode the incoming data stream and to shape the resulting pulses, which are fed as inputs to the vector modulator. The combination of encoding and pulse shaping in a given application is chosen to maximize the bandwidth efficiency. The modulator board includes gallium arsenide serial-to-parallel converters at its input end. A complementary metal oxide/semiconductor (CMOS) field-programmable gate array (FPGA) performs the coding and modulation computations and utilizes parallel processing in doing so. The results of the parallel computation are combined and converted to pulse waveforms by use of gallium arsenide parallel-to-serial converters integrated with digital-to-analog converters. Without changing the hardware, one can configure the modulator to produce any of the designed combinations of coding and modulation by loading the appropriate bit configuration file into the FPGA.

Two essays on efficiency in the electric power industry: Measurement of technical and allocative efficiency

NASA Astrophysics Data System (ADS)

Gardiner, John Corby

The electric power industry market structure has changed over the last twenty years since the passage of the Public Utility Regulatory Policies Act (PURPA). These changes include the entry by unregulated generator plants and, more recently, the deregulation of entry and price in the retail generation market. Such changes have introduced and expanded competitive forces on the incumbent electric power plants. Proponents of this deregulation argued that the enhanced competition would lead to a more efficient allocation of resources. Previous studies of power plant technical and allocative efficiency have failed to measure technical and allocative efficiency at the plant level. In contrast, this study uses panel data on 35 power plants over 59 years to estimate technical and allocative efficiency of each plant. By using a flexible functional form, which is not constrained by the assumption that regulation is constant over the 59 years sampled, the estimation procedure accounts for changes in both state and national regulatory/energy policies that may have occurred over the sample period. The empirical evidence presented shows that most of the power plants examined have operated more efficiently since the passage of PURPA and the resultant increase of competitive forces. Chapter 2 extends the model used in Chapter 1 and clarifies some issues in the efficiency literature by addressing the case where homogeneity does not hold. A more general model is developed for estimating both input and output inefficiency simultaneously. This approach reveals more information about firm inefficiency than the single estimation approach that has previously been used in the literature. Using the more general model, estimates are provided on the type of inefficiency that occurs as well as the cost of inefficiency by type of inefficiency. In previous studies, the ranking of firms by inefficiency has been difficult because of the cardinal and ordinal differences between different types of inefficiency estimates. However, using the general approach, this study illustrates that plants can be ranked by overall efficiency.

Dynamic equilibrium strategy for drought emergency temporary water transfer and allocation management

NASA Astrophysics Data System (ADS)

Xu, Jiuping; Ma, Ning; Lv, Chengwei

2016-08-01

Efficient water transfer and allocation are critical for disaster mitigation in drought emergencies. This is especially important when the different interests of the multiple decision makers and the fluctuating water resource supply and demand simultaneously cause space and time conflicts. To achieve more effective and efficient water transfers and allocations, this paper proposes a novel optimization method with an integrated bi-level structure and a dynamic strategy, in which the bi-level structure works to deal with space dimension conflicts in drought emergencies, and the dynamic strategy is used to deal with time dimension conflicts. Combining these two optimization methods, however, makes calculation complex, so an integrated interactive fuzzy program and a PSO-POA are combined to develop a hybrid-heuristic algorithm. The successful application of the proposed model in a real world case region demonstrates its practicality and efficiency. Dynamic cooperation between multiple reservoirs under the coordination of a global regulator reflects the model's efficiency and effectiveness in drought emergency water transfer and allocation, especially in a fluctuating environment. On this basis, some corresponding management recommendations are proposed to improve practical operations.

Decomposing Cost Efficiency in Regional Long-term Care Provision in Japan

PubMed Central

Yamauchi, Yasuhiro

2016-01-01

Many developed countries face a growing need for long-term care provision because of population ageing. Japan is one such example, given its population's longevity and low birth rate. In this study, we examine the efficiency of Japan's regional long-term care system in FY2010 by performing a data envelopment analysis, a non-parametric frontier approach, on prefectural data and separating cost efficiency into technical, allocative, and price efficiencies under different average unit costs across regions. In doing so, we elucidate the structure of cost inefficiency by incorporating a method for restricting weight flexibility to avoid unrealistic concerns arising from zero optimal weight. The results indicate that technical inefficiency accounts for the highest share of losses, followed by price inefficiency and allocation inefficiency. Moreover, the majority of technical inefficiency losses stem from labor costs, particularly those for professional caregivers providing institutional services. We show that the largest share of allocative inefficiency losses can also be traced to labor costs for professional caregivers providing institutional services, while the labor provision of in-home care services shows an efficiency gain. However, although none of the prefectures gains efficiency by increasing the number of professional caregivers for institutional services, quite a few prefectures would gain allocative efficiency by increasing capital inputs for institutional services. These results indicate that preferred policies for promoting efficiency might vary from region to region, and thus, policy implications should be drawn with care. PMID:26493427

Measurement time and statistics for a noise thermometer with a synthetic-noise reference

NASA Astrophysics Data System (ADS)

White, D. R.; Benz, S. P.; Labenski, J. R.; Nam, S. W.; Qu, J. F.; Rogalla, H.; Tew, W. L.

2008-08-01

This paper describes methods for reducing the statistical uncertainty in measurements made by noise thermometers using digital cross-correlators and, in particular, for thermometers using pseudo-random noise for the reference signal. First, a discrete-frequency expression for the correlation bandwidth for conventional noise thermometers is derived. It is shown how an alternative frequency-domain computation can be used to eliminate the spectral response of the correlator and increase the correlation bandwidth. The corresponding expressions for the uncertainty in the measurement of pseudo-random noise in the presence of uncorrelated thermal noise are then derived. The measurement uncertainty in this case is less than that for true thermal-noise measurements. For pseudo-random sources generating a frequency comb, an additional small reduction in uncertainty is possible, but at the cost of increasing the thermometer's sensitivity to non-linearity errors. A procedure is described for allocating integration times to further reduce the total uncertainty in temperature measurements. Finally, an important systematic error arising from the calculation of ratios of statistical variables is described.

Health Care Market Deviations from the Ideal Market

PubMed Central

Mwachofi, Ari; Al-Assaf, Assaf F.

2011-01-01

A common argument in the health policy debate is that market forces allocate resources efficiently in health care, and that government intervention distorts such allocation. Rarely do those making such claims state explicitly that the market they refer to is an ideal in economic theory which can only exist under very strict conditions. This paper explores the strict conditions necessary for that ideal market in the context of health care as a means of examining the claim that market forces do allocate resources efficiently in health care. PMID:22087373

Sleeping arrangements and mass distribution of bed nets in six districts in central and northern Mozambique.

PubMed

Plucinski, M M; Chicuecue, S; Macete, E; Chambe, G A; Muguande, O; Matsinhe, G; Colborn, J; Yoon, S S; Doyle, T J; Kachur, S P; Aide, P; Alonso, P L; Guinovart, C; Morgan, J

2015-12-01

Universal coverage with insecticide-treated bed nets is a cornerstone of modern malaria control. Mozambique has developed a novel bed net allocation strategy, where the number of bed nets allocated per household is calculated on the basis of household composition and assumptions about who sleeps with whom. We set out to evaluate the performance of the novel allocation strategy. A total of 1994 households were visited during household surveys following two universal coverage bed net distribution campaigns in Sofala and Nampula provinces in 2010-2013. Each sleeping space was observed for the presence of a bed net, and the sleeping patterns for each household were recorded. The observed coverage and efficiency were compared to a simulated coverage and efficiency had conventional allocation strategies been used. A composite indicator, the product of coverage and efficiency, was calculated. Observed sleeping patterns were compared with the sleeping pattern assumptions. In households reached by the campaign, 93% (95% CI: 93-94%) of sleeping spaces in Sofala and 84% (82-86%) in Nampula were covered by campaign bed nets. The achieved efficiency was high, with 92% (91-93%) of distributed bed nets in Sofala and 93% (91-95%) in Nampula covering a sleeping space. Using the composite indicator, the novel allocation strategy outperformed all conventional strategies in Sofala and was tied for best in Nampula. The sleeping pattern assumptions were completely satisfied in 66% of households in Sofala and 56% of households in Nampula. The most common violation of the sleeping pattern assumptions was that male children 3-10 years of age tended not to share sleeping spaces with female children 3-10 or 10-16 years of age. The sleeping pattern assumptions underlying the novel bed net allocation strategy are generally valid, and net allocation using these assumptions can achieve high coverage and compare favourably with conventional allocation strategies. © 2015 The Authors. Tropical Medicine & International Health Published by John Wiley & Sons Ltd.

Photonic Integrated Circuits for Cost-Effective, High Port Density, and Higher Capacity Optical Communications Systems

NASA Astrophysics Data System (ADS)

Chiappa, Pierangelo

Bandwidth-hungry services, such as higher speed Internet, voice over IP (VoIP), and IPTV, allow people to exchange and store huge amounts of data among worldwide locations. In the age of global communications, domestic users, companies, and organizations around the world generate new contents making bandwidth needs grow exponentially, along with the need for new services. These bandwidth and connectivity demands represent a concern for operators who require innovative technologies to be ready for scaling. To respond efficiently to these demands, Alcatel-Lucent is fast moving toward photonic integration circuits technologies as the key to address best performances at the lowest "bit per second" cost. This article describes Alcatel-Lucent's contribution in strategic directions or achievements, as well as possible new developments.

Application-oriented integrated control center (AICC) for heterogeneous optical networks

NASA Astrophysics Data System (ADS)

Zhao, Yongli; Zhang, Jie; Cao, Xuping; Wang, Dajiang; Wu, Koubo; Cai, Yinxiang; Gu, Wanyi

2011-12-01

Various broad bandwidth services have being swallowing the bandwidth resource of optical networks, such as the data center application and cloud computation. There are still some challenges for future optical networks although the available bandwidth is increasing with the development of transmission technologies. The relationship between upper application layer and lower network resource layer is necessary to be researched further. In order to improve the efficiency of network resources and capability of service provisioning, heterogeneous optical networks resource can be abstracted as unified Application Programming Interfaces (APIs) which can be open to various upper applications through Application-oriented Integrated Control Center (AICC) proposed in the paper. A novel Openflow-based unified control architecture is proposed for the optimization of cross layer resources. Numeric results show good performance of AICC through simulation experiments.

Architecture and implementation considerations of a high-speed Viterbi decoder for a Reed-Muller subcode

NASA Technical Reports Server (NTRS)

Lin, Shu (Principal Investigator); Uehara, Gregory T.; Nakamura, Eric; Chu, Cecilia W. P.

1996-01-01

The (64, 40, 8) subcode of the third-order Reed-Muller (RM) code for high-speed satellite communications is proposed. The RM subcode can be used either alone or as an inner code of a concatenated coding system with the NASA standard (255, 233, 33) Reed-Solomon (RS) code as the outer code to achieve high performance (or low bit-error rate) with reduced decoding complexity. It can also be used as a component code in a multilevel bandwidth efficient coded modulation system to achieve reliable bandwidth efficient data transmission. The progress made toward achieving the goal of implementing a decoder system based upon this code is summarized. The development of the integrated circuit prototype sub-trellis IC, particularly focusing on the design methodology, is addressed.

Adaptive Code Division Multiple Access Protocol for Wireless Network-on-Chip Architectures

NASA Astrophysics Data System (ADS)

Vijayakumaran, Vineeth

Massive levels of integration following Moore's Law ushered in a paradigm shift in the way on-chip interconnections were designed. With higher and higher number of cores on the same die traditional bus based interconnections are no longer a scalable communication infrastructure. On-chip networks were proposed enabled a scalable plug-and-play mechanism for interconnecting hundreds of cores on the same chip. Wired interconnects between the cores in a traditional Network-on-Chip (NoC) system, becomes a bottleneck with increase in the number of cores thereby increasing the latency and energy to transmit signals over them. Hence, there has been many alternative emerging interconnect technologies proposed, namely, 3D, photonic and multi-band RF interconnects. Although they provide better connectivity, higher speed and higher bandwidth compared to wired interconnects; they also face challenges with heat dissipation and manufacturing difficulties. On-chip wireless interconnects is one other alternative proposed which doesn't need physical interconnection layout as data travels over the wireless medium. They are integrated into a hybrid NOC architecture consisting of both wired and wireless links, which provides higher bandwidth, lower latency, lesser area overhead and reduced energy dissipation in communication. However, as the bandwidth of the wireless channels is limited, an efficient media access control (MAC) scheme is required to enhance the utilization of the available bandwidth. This thesis proposes using a multiple access mechanism such as Code Division Multiple Access (CDMA) to enable multiple transmitter-receiver pairs to send data over the wireless channel simultaneously. It will be shown that such a hybrid wireless NoC with an efficient CDMA based MAC protocol can significantly increase the performance of the system while lowering the energy dissipation in data transfer. In this work it is shown that the wireless NoC with the proposed CDMA based MAC protocol outperformed the wired counterparts and several other wireless architectures proposed in literature in terms of bandwidth and packet energy dissipation. Significant gains were observed in packet energy dissipation and bandwidth even with scaling the system to higher number of cores. Non-uniform traffic simulations showed that the proposed CDMA-WiNoC was consistent in bandwidth across all traffic patterns. It is also shown that the CDMA based MAC scheme does not introduce additional reliability concerns in data transfer over the on-chip wireless interconnects.

EMG-Torque Dynamics Change With Contraction Bandwidth.

PubMed

Golkar, Mahsa A; Jalaleddini, Kian; Kearney, Robert E

2018-04-01

An accurate model for ElectroMyoGram (EMG)-torque dynamics has many uses. One of its applications which has gained high attention among researchers is its use, in estimating the muscle contraction level for the efficient control of prosthesis. In this paper, the dynamic relationship between the surface EMG and torque during isometric contractions at the human ankle was studied using system identification techniques. Subjects voluntarily modulated their ankle torque in dorsiflexion direction, by activating their tibialis anterior muscle, while tracking a pseudo-random binary sequence in a torque matching task. The effects of contraction bandwidth, described by torque spectrum, on EMG-torque dynamics were evaluated by varying the visual command switching time. Nonparametric impulse response functions (IRF) were estimated between the processed surface EMG and torque. It was demonstrated that: 1) at low contraction bandwidths, the identified IRFs had unphysiological anticipatory (i.e., non-causal) components, whose amplitude decreased as the contraction bandwidth increased. We hypothesized that this non-causal behavior arose, because the EMG input contained a component due to feedback from the output torque, i.e., it was recorded from within a closed-loop. Vision was not the feedback source since the non-causal behavior persisted when visual feedback was removed. Repeating the identification using a nonparametric closed-loop identification algorithm yielded causal IRFs at all bandwidths, supporting this hypothesis. 2) EMG-torque dynamics became faster and the bandwidth of system increased as contraction modulation rate increased. Thus, accurate prediction of torque from EMG signals must take into account the contraction bandwidth sensitivity of this system.

How a new funding model will shift allocations from the Global Fund to Fight AIDS, tuberculosis, and malaria.

PubMed

Fan, Victoria Y; Glassman, Amanda; Silverman, Rachel L

2014-12-01

Policy makers deciding how to fund global health programs in low- and middle-income countries face important but difficult questions about how to allocate resources across countries. In this article we present a typology of three allocation methodologies to align allocations with priorities. We then apply our typology to the Global Fund to Fight AIDS, Tuberculosis, and Malaria. We examined the Global Fund's historical HIV allocations and its predicted allocations under a new funding model that creates an explicit allocation methodology. We found that under the new funding model, substantial shifts in the Global Fund's portfolio are likely to result from concentrating resources in countries with more HIV cases and lower per capita incomes. For example, South Africa, which had 15.8 percent of global HIV cases in 2009, could see its Global Fund HIV funding more than triple, from historic levels that averaged 3.0 percent to 9.7 percent of total Global Fund allocations. The new funding model methodology is expected, but not guaranteed, to improve the efficiency of Global Fund allocations in comparison to historical practice. We conclude with recommendations for the Global Fund and other global health donors to further develop their allocation methodologies and processes to improve efficiency and transparency. Project HOPE—The People-to-People Health Foundation, Inc.

Intra-Chip Free-Space Optical Interconnect: System, Device, Integration and Prototyping

NASA Astrophysics Data System (ADS)

Ciftcioglu, Berkehan

Currently, on-chip optical interconnect schemes already proposed utilize circuit switching using wavelength division multiplexing (WDM) or all-optical packet switching, all based on planar optical waveguides and related photonic devices such as microrings. These proposed approaches pose significant challenges in latency, energy efficiency, integration, and scalability. This thesis presents a new alternative approach by utilizing free-space optics. This 3-D integrated intra-chip free-space optical interconnect (FSOI) leverages mature photonic devices such as integrated lasers, photodiodes, microlenses and mirrors. It takes full advantages of the latest developments in 3-D integration technologies. This interconnect system provides point-to-point free-space optical links between any two communication nodes to construct an all-to-all intra-chip communication network with little or no arbitration. Therefore, it has significant networking advantages over conventional electrical and waveguide-based optical interconnects. An FSOI system is evaluated based on the real device parameters, predictive technology models and International Roadmap of Semiconductor's predictions. A single FSOI link achieves 10-Gbps data rate with 0.5-pJ/bit energy efficiency and less than 10--12 bit-error-rate (BER). A system using this individual link can provide scalability up to 36 nodes, providing 10-Tbps aggregate bandwidth. A comparison analysis performed between a WDM-based waveguide interconnect system and the proposed FSOI system shows that FSOI achieves better energy efficiency than the WDM one as the technology scales. Similarly, network simulation on a 16-core microprocessor using the proposed FSOI system instead of mesh networks has been shown to speed up the system by 12% and reduce the energy consumption by 33%. As a part of the development of a 3-D integrated FSOI system, operating at 850 nm with a 10-Gbps data rate per optical link, the photonics devices and optical components are individually designed and fabricated. The photodiodes (PDs) are designed to have large area for efficient light coupling and low capacitance to achieve large bandwidth, while achieving reasonably high responsivity. A metal-semiconductor-metal (MSM) structure is chosen over p-i-n ones to reduce parasitic capacitance per area, to allow less stringent microlens-to-PD alignment for efficient light coupling with a large bandwidth. A novel MSM germanium PD is implemented using an amorphous silicon (a-Si) layer on top of the undoped germanium substrate, serving as a barrier enhancement layer, mitigating the low Schottky barrier height for holes due to fermi level pinning and a surface passivation layer, preventing charge accumulation and image force lowering of the barrier. Therefore, the dark current is reduced and low-frequency gain is eliminated. The PDs achieve a 13-GHz bandwidth with a 0.315-A/W responsivity and a 1.7-nAmum² dark current density. The microlenses are fabricated on a fused silica substrate based on the photoresist melt-and-reflow technique, followed by dry etching into fused silica substrate. The measured focal length of a 220-mum aperture size microlens is 350-mum away from the backside of the substrate. The vertical-cavity surface-emitting lasers (VCSELs) are fabricated on a commercial molecular beam epitaxially (MBE) grown GaAs wafer. The fabricated 8-mum aperture size VCSEL can achieve 0.65-mW optical power at a 1.5-mA forward bias current with a threshold current of 0.48 mA and a 0.67-A/W slope efficiency. Three prototypes are implemented via integrating the individually fabricated components using non-conductive epoxy and wirebonding. The first prototype, built on a printed circuit board (PCB) using commercial VCSEL arrays, achieves a 5-dB transmission loss and less than -30-dB crosstalk at 1-cm distance with a small-signal bandwidth of 10 GHz, limited by the VCSEL. The second board-level prototype uses all fabricated components integrated on a PCB. The prototype achieves a 9-dB transmission loss at 3-cm distance and a 4.4-GHz bandwidth. The chip-level prototype is built on a germanium carrier with integrated MSM Ge PDs, microlenses on fused silica and VCSEL chip on GaAs substrates. The prototype achieves 4-dB transmission loss at 1 cm and 3.3-GHz bandwidth, limited by commercial VCSEL bandwidth. (Abstract shortened by UMI.)

Compression of digital images over local area networks. Appendix 1: Item 3. M.S. Thesis

NASA Technical Reports Server (NTRS)

Gorjala, Bhargavi

1991-01-01

Differential Pulse Code Modulation (DPCM) has been used with speech for many years. It has not been as successful for images because of poor edge performance. The only corruption in DPC is quantizer error but this corruption becomes quite large in the region of an edge because of the abrupt changes in the statistics of the signal. We introduce two improved DPCM schemes; Edge correcting DPCM and Edge Preservation Differential Coding. These two coding schemes will detect the edges and take action to correct them. In an Edge Correcting scheme, the quantizer error for an edge is encoded using a recursive quantizer with entropy coding and sent to the receiver as side information. In an Edge Preserving scheme, when the quantizer input falls in the overload region, the quantizer error is encoded and sent to the receiver repeatedly until the quantizer input falls in the inner levels. Therefore these coding schemes increase the bit rate in the region of an edge and require variable rate channels. We implement these two variable rate coding schemes on a token wing network. Timed token protocol supports two classes of messages; asynchronous and synchronous. The synchronous class provides a pre-allocated bandwidth and guaranteed response time. The remaining bandwidth is dynamically allocated to the asynchronous class. The Edge Correcting DPCM is simulated by considering the edge information under the asynchronous class. For the simulation of the Edge Preserving scheme, the amount of information sent each time is fixed, but the length of the packet or the bit rate for that packet is chosen depending on the availability capacity. The performance of the network, and the performance of the image coding algorithms, is studied.

Spectrum Efficiency Improvements via PHY-Layer and PDCP-Layer Techniques

ERIC Educational Resources Information Center

Wu, Wenhao

2017-01-01

The past decades have witnessed an ever-growing demand for higher network capacity. Given practical radio resource constraints such as bandwidth and power, a wide variety of spectral efficiency techniques have been thoroughly explored by research efforts around the world. In this dissertation, we examine two less conventional approaches to boost…

N-Consecutive-Phase Encoder

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Lee, Ho-Kyoung; Weber, Charles

1995-01-01

N-consecutive-phase encoder (NCPE) is conceptual encoder for generating alphabet of N consecutive full-response continuous-phase-modulation (CPM) signals. Enables use of binary preencoder of higher rate than used with simple continuous-phase encoder (CPE). NCPE makes possible to achieve power efficiencies and bandwidth efficiencies greater than conventional trellis coders with continuous-phase frequency-shift keying (CPFSK).

Hubless satellite communications networks

NASA Technical Reports Server (NTRS)

Robinson, Peter Alan

1994-01-01

Frequency Comb Multiple Access (FCMA) is a new combined modulation and multiple access method which will allow cheap hubless Very Small Aperture Terminal (VSAT) networks to be constructed. Theoretical results show bandwidth efficiency and power efficiency improvements over other modulation and multiple access methods. Costs of the VSAT network are reduced dramatically since a hub station is not required.

Frequency Domain Beamforming for a Deep Space Network Downlink Array

NASA Technical Reports Server (NTRS)

Navarro, Robert

2012-01-01

This paper describes a frequency domain beamformer to array up to 8 antennas of NASA's Deep Space Network currently in development. The objective of this array is to replace and enhance the capability of the DSN 70m antennas with multiple 34m antennas for telemetry, navigation and radio science use. The array will coherently combine the entire 500 MHz of usable bandwidth available to DSN receivers. A frequency domain beamforming architecture was chosen over a time domain based architecture to handle the large signal bandwidth and efficiently perform delay and phase calibration. The antennas of the DSN are spaced far enough apart that random atmospheric and phase variations between antennas need to be calibrated out on an ongoing basis in real-time. The calibration is done using measurements obtained from a correlator. This DSN Downlink Array expands upon a proof of concept breadboard array built previously to develop the technology and will become an operational asset of the Deep Space Network. Design parameters for frequency channelization, array calibration and delay corrections will be presented as well a method to efficiently calibrate the array for both wide and narrow bandwidth telemetry.

Efficient green lasers for high-resolution scanning micro-projector displays

NASA Astrophysics Data System (ADS)

Bhatia, Vikram; Bauco, Anthony S.; Oubei, Hassan M.; Loeber, David A. S.

2010-02-01

Laser-based projectors are gaining increased acceptance in mobile device market due to their low power consumption, superior image quality and small size. The basic configuration of such micro-projectors is a miniature mirror that creates an image by raster scanning the collinear red, blue and green laser beams that are individually modulated on a pixel-bypixel basis. The image resolution of these displays can be limited by the modulation bandwidth of the laser sources, and the modulation speed of the green laser has been one of the key limitations in the development of these displays. We will discuss how this limitation is fundamental to the architecture of many laser designs and then present a green laser configuration which overcomes these difficulties. In this green laser architecture infra-red light from a distributed Bragg-reflector (DBR) laser diode undergoes conversion to green light in a waveguided second harmonic generator (SHG) crystal. The direct doubling in a single pass through the SHG crystal allows the device to operate at the large modulation bandwidth of the DBR laser. We demonstrate that the resultant product has a small footprint (<0.7 cc envelope volume), high efficiency (>9% electrical-to-optical conversion) and large modulation bandwidth (>100 MHz).

Fingerprint multicast in secure video streaming.

PubMed

Zhao, H Vicky; Liu, K J Ray

2006-01-01

Digital fingerprinting is an emerging technology to protect multimedia content from illegal redistribution, where each distributed copy is labeled with unique identification information. In video streaming, huge amount of data have to be transmitted to a large number of users under stringent latency constraints, so the bandwidth-efficient distribution of uniquely fingerprinted copies is crucial. This paper investigates the secure multicast of anticollusion fingerprinted video in streaming applications and analyzes their performance. We first propose a general fingerprint multicast scheme that can be used with most spread spectrum embedding-based multimedia fingerprinting systems. To further improve the bandwidth efficiency, we explore the special structure of the fingerprint design and propose a joint fingerprint design and distribution scheme. From our simulations, the two proposed schemes can reduce the bandwidth requirement by 48% to 87%, depending on the number of users, the characteristics of video sequences, and the network and computation constraints. We also show that under the constraint that all colluders have the same probability of detection, the embedded fingerprints in the two schemes have approximately the same collusion resistance. Finally, we propose a fingerprint drift compensation scheme to improve the quality of the reconstructed sequences at the decoder's side without introducing extra communication overhead.

Metasurface Salisbury screen: achieving ultra-wideband microwave absorption.

PubMed

Zhou, Ziheng; Chen, Ke; Zhao, Junming; Chen, Ping; Jiang, Tian; Zhu, Bo; Feng, Yijun; Li, Yue

2017-11-27

The metasurfaces have recently been demonstrated to provide full control of the phase responses of electromagnetic (EM) wave scattering over subwavelength scales, enabling a wide range of practical applications. Here, we propose a comprehensive scheme for the efficient and flexible design of metasurface Salisbury screen (MSS) capable of absorbing the impinging EM wave in an ultra-wide frequency band. We show that properly designed reflective metasurface can be used to substitute the metallic ground of conventional Salisbury screen for generating diverse resonances in a desirable way, thus providing large controllability over the absorption bandwidth. Based on this concept, we establish an equivalent circuit model to qualitatively analysis the resonances in MSS and design algorithms to optimize the overall performance of the MSS. Experiments have been carried out to demonstrate that the absorption bandwidth from 6 GHz to 30 GHz with an efficiency higher than 85% can be achieved by the proposal, which is apparently much larger than that of conventional Salisbury screen (7 GHz - 17 GHz). The proposed concept of MSS could offer opportunities for flexibly designing thin electromagnetic absorbers with simultaneously ultra-wide bandwidth, polarization insensitivity, and wide incident angle, exhibiting promising potentials for many applications such as in EM compatibility, stealth technique, etc.

Experimental and theoretical investigation of an impact vibration harvester with triboelectric transduction

NASA Astrophysics Data System (ADS)

Ibrahim, Alwathiqbellah; Ramini, Abdallah; Towfighian, Shahrzad

2018-03-01

There has been remarkable interest in triboelectric mechanisms because of their high efficiency, wide availability, and low-cost generation of sustainable power. Using impact vibrations, we introduce piece-wise stiffness to the system to enlarge frequency bandwidth. The triboelectric layers consist of Aluminum, which also serves as an electrode, and Polydimethylsiloxane (PDMS) with micro semi-cylindrical patterns. At the bottom of the PDMS layer, there is another Al electrode. The layers are sandwiched between the center mass of a clamped-clamped beam and its base. The center mass enhances the impact force on the triboelectric layers subjected to external vibrations. Upon impact, alternating current, caused by the contact electrification and electrostatic induction, flows between the Al electrodes. Because of the impact, the equivalent stiffness of the structure increases and as a result, the frequency bandwidth gets wider. The output voltage and power reach as large as 5.5 V, 15 μW, respectively at 0.8 g vibrational amplitude. In addition, we report how the surface charge density increases with the excitation levels. The analysis delineates the interactions between impact vibrations and triboelectric transductions. The ability of the system to achieve wider bandwidth paves the way for efficient triboelectric vibrational energy harvesters.

Wideband LTE power amplifier with integrated novel analog pre-distorter linearizer for mobile wireless communications.

PubMed

Uthirajoo, Eswaran; Ramiah, Harikrishnan; Kanesan, Jeevan; Reza, Ahmed Wasif

2014-01-01

For the first time, a new circuit to extend the linear operation bandwidth of a LTE (Long Term Evolution) power amplifier, while delivering a high efficiency is implemented in less than 1 mm2 chip area. The 950 µm × 900 µm monolithic microwave integrated circuit (MMIC) power amplifier (PA) is fabricated in a 2 µm InGaP/GaAs process. An on-chip analog pre-distorter (APD) is designed to improve the linearity of the PA, up to 20 MHz channel bandwidth. Intended for 1.95 GHz Band 1 LTE application, the PA satisfies adjacent channel leakage ratio (ACLR) and error vector magnitude (EVM) specifications for a wide LTE channel bandwidth of 20 MHz at a linear output power of 28 dBm with corresponding power added efficiency (PAE) of 52.3%. With a respective input and output return loss of 30 dB and 14 dB, the PA's power gain is measured to be 32.5 dB while exhibiting an unconditional stability characteristic from DC up to 5 GHz. The proposed APD technique serves to be a good solution to improve linearity of a PA without sacrificing other critical performance metrics.

Wideband LTE Power Amplifier with Integrated Novel Analog Pre-Distorter Linearizer for Mobile Wireless Communications

PubMed Central

Uthirajoo, Eswaran; Ramiah, Harikrishnan; Kanesan, Jeevan; Reza, Ahmed Wasif

2014-01-01

For the first time, a new circuit to extend the linear operation bandwidth of a LTE (Long Term Evolution) power amplifier, while delivering a high efficiency is implemented in less than 1 mm2 chip area. The 950 µm × 900 µm monolithic microwave integrated circuit (MMIC) power amplifier (PA) is fabricated in a 2 µm InGaP/GaAs process. An on-chip analog pre-distorter (APD) is designed to improve the linearity of the PA, up to 20 MHz channel bandwidth. Intended for 1.95 GHz Band 1 LTE application, the PA satisfies adjacent channel leakage ratio (ACLR) and error vector magnitude (EVM) specifications for a wide LTE channel bandwidth of 20 MHz at a linear output power of 28 dBm with corresponding power added efficiency (PAE) of 52.3%. With a respective input and output return loss of 30 dB and 14 dB, the PA’s power gain is measured to be 32.5 dB while exhibiting an unconditional stability characteristic from DC up to 5 GHz. The proposed APD technique serves to be a good solution to improve linearity of a PA without sacrificing other critical performance metrics. PMID:25033049

Energy-efficient downlink resource management in self-organized OFDMA-based two-tier femtocell networks

NASA Astrophysics Data System (ADS)

Shahid, Adnan; Aslam, Saleem; Kim, Hyung Seok; Lee, Kyung-Geun

2015-12-01

Femtocell is a novel technology that is used for escalating indoor coverage as well as the capacity of traditional cellular networks. However, interference is the limiting factor for performance improvement due to co-channel deployment between macrocells and femtocells. The traditional network planning is not feasible because of the random deployment of femtocells. Therefore, self-organization approaches are the key to having successful deployment of femtocells. This study presents the joint resource block (RB) and power allocation task for the two-tier femtocell network in a self-organizing manner, with the concern to minimizing the impact of interference and maximizing the energy efficiency. In this study, we analyze the performance of the system in terms of the energy efficiency, which is composed of both the transmission and circuit power. Most of the previous studies investigate the performance regarding the throughput requirement of the two-tier femtocell network while the energy efficiency aspect is largely ignored. Here, the joint allocation task is modeled as a non-cooperative game which is demonstrated to exhibit pure and unique Nash equilibrium. In order to reduce the complexity of the proposed non-cooperative game, the joint RB and power allocation task is divided into two subproblems: an RB allocation and a particle swarm optimization-based power allocation. The analysis of the proposed game is carried out in terms of not only energy efficiency but also throughput. With practical 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) parameters, the simulation results illustrate the superior performance of the proposed game as compared to the traditional methods. Also, the comparison is carried out with the joint allocation scheme which only considers the throughput as the objective function. The results illustrate that significant performance improvement is achieved in terms of energy efficiency with slight loss in the throughput. The analysis in regard to energy efficiency and throughput of the two-tier femtocell network is carried out in terms of the performance metrics, which include convergence, impact of varying RBs, impact of femtocell density, and the fairness index.

On the Allocation of Resources for Secondary Schools

ERIC Educational Resources Information Center

Haelermans, Carla; De Witte, Kristof; Blank, Jos L. T.

2012-01-01

This paper studies the optimal allocation of resources--in terms of school management, teachers, supporting employees and materials--in secondary schools. We use a flexible budget constrained output distance function model to estimate both technical and allocative efficiency scores for 448 Dutch secondary schools between 2002 and 2007. The results…

Design and Analysis of Self-Adapted Task Scheduling Strategies in Wireless Sensor Networks

PubMed Central

Guo, Wenzhong; Xiong, Naixue; Chao, Han-Chieh; Hussain, Sajid; Chen, Guolong

2011-01-01

In a wireless sensor network (WSN), the usage of resources is usually highly related to the execution of tasks which consume a certain amount of computing and communication bandwidth. Parallel processing among sensors is a promising solution to provide the demanded computation capacity in WSNs. Task allocation and scheduling is a typical problem in the area of high performance computing. Although task allocation and scheduling in wired processor networks has been well studied in the past, their counterparts for WSNs remain largely unexplored. Existing traditional high performance computing solutions cannot be directly implemented in WSNs due to the limitations of WSNs such as limited resource availability and the shared communication medium. In this paper, a self-adapted task scheduling strategy for WSNs is presented. First, a multi-agent-based architecture for WSNs is proposed and a mathematical model of dynamic alliance is constructed for the task allocation problem. Then an effective discrete particle swarm optimization (PSO) algorithm for the dynamic alliance (DPSO-DA) with a well-designed particle position code and fitness function is proposed. A mutation operator which can effectively improve the algorithm’s ability of global search and population diversity is also introduced in this algorithm. Finally, the simulation results show that the proposed solution can achieve significant better performance than other algorithms. PMID:22163971

Recent Improvements in AMSR2 Ground-Based RFI Filtering

NASA Astrophysics Data System (ADS)

Scott, J. P.; Gentemann, C. L.; Wentz, F. J.

2015-12-01

Passive satellite radiometer measurements in the microwave frequencies (6-89 GHz) are useful in providing geophysical retrievals of sea surface temperature (SST), atmospheric water vapor, wind speed, rain rate, and more. However, radio frequency interference (RFI) is one of the fastest growing sources of error in these retrievals. RFI can originate from broadcasting satellites, as well as from ground-based instrumentation that makes use of the microwave range. The microwave channel bandwidths used by passive satellite radiometers are often wider than the protected bands allocated for this type of remote sensing, a common practice in microwave radiometer design used to reduce the effect of instrument noise in the observed signal. However, broad channel bandwidths allow greater opportunity for RFI to affect these observations and retrievals. For ground-based RFI, a signal is broadcast directly into the atmosphere which may interfere with the radiometer - its antenna, cold mirror, hot load or the internal workings of the radiometer itself. It is relatively easy to identify and flag RFI from large sources, but more difficult to do so from small, sporadic sources. Ground-based RFI has high spatial and temporal variability, requiring constant, automated detection and removal to avoid spurious trends leaching into the geophysical retrievals. Ascension Island in the South Atlantic Ocean has been one of these notorious ground-based RFI sources, affecting many microwave radiometers, including the AMSR2 radiometer onboard JAXA's GCOM-W1 satellite. Ascension Island RFI mainly affects AMSR2's lower frequency channels (6.9, 7.3, and 10.65 GHz) over a broad spatial region in the South Atlantic Ocean, which makes it challenging to detect and flag this RFI using conventional channel and geophysical retrieval differencing techniques. The authors have developed a new method of using the radiometer's earth counts and hot counts, for the affected channels, to detect an Ascension Island RFI event and flag the data efficiently and accurately, thereby reducing false detections and optimizing retrieval quality and data preservation.

Comparison of FDMA and CDMA for second generation land-mobile satellite communications

NASA Technical Reports Server (NTRS)

Yongacoglu, A.; Lyons, R. G.; Mazur, B. A.

1990-01-01

Code Division Multiple Access (CDMA) and Frequency Division Multiple Access (FDMA) (both analog and digital) systems capacities are compared on the basis of identical link availabilities and physical propagation models. Parameters are optimized for a bandwidth limited, multibeam environment. For CDMA, the benefits of voice activated carriers, antenna discrimination, polarization reuse, return link power control and multipath suppression are included in the analysis. For FDMA, the advantages of bandwidth efficient modulation/coding combinations, voice activated carriers, polarization reuse, beam placement, and frequency staggering were taken into account.

Frequency agile microwave photonic notch filter with anomalously high stopband rejection.

PubMed

Marpaung, David; Morrison, Blair; Pant, Ravi; Eggleton, Benjamin J

2013-11-01

We report a novel class microwave photonic (MWP) notch filter with a very narrow isolation bandwidth (10 MHz), an ultrahigh stopband rejection (>60 dB), a wide frequency tuning (1-30 GHz), and flexible bandwidth reconfigurability (10-65 MHz). This performance is enabled by a new concept of sideband amplitude and phase controls using an electro-optic modulator and an optical filter. This concept enables energy efficient operation in active MWP notch filters, and opens up a pathway toward enabling low-power nanophotonic devices as high-performance RF filters.

Virtual optical network mapping and core allocation in elastic optical networks using multi-core fibers

NASA Astrophysics Data System (ADS)

Xuan, Hejun; Wang, Yuping; Xu, Zhanqi; Hao, Shanshan; Wang, Xiaoli

2017-11-01

Virtualization technology can greatly improve the efficiency of the networks by allowing the virtual optical networks to share the resources of the physical networks. However, it will face some challenges, such as finding the efficient strategies for virtual nodes mapping, virtual links mapping and spectrum assignment. It is even more complex and challenging when the physical elastic optical networks using multi-core fibers. To tackle these challenges, we establish a constrained optimization model to determine the optimal schemes of optical network mapping, core allocation and spectrum assignment. To solve the model efficiently, tailor-made encoding scheme, crossover and mutation operators are designed. Based on these, an efficient genetic algorithm is proposed to obtain the optimal schemes of the virtual nodes mapping, virtual links mapping, core allocation. The simulation experiments are conducted on three widely used networks, and the experimental results show the effectiveness of the proposed model and algorithm.

Extending the BEAGLE library to a multi-FPGA platform.

PubMed

Jin, Zheming; Bakos, Jason D

2013-01-19

Maximum Likelihood (ML)-based phylogenetic inference using Felsenstein's pruning algorithm is a standard method for estimating the evolutionary relationships amongst a set of species based on DNA sequence data, and is used in popular applications such as RAxML, PHYLIP, GARLI, BEAST, and MrBayes. The Phylogenetic Likelihood Function (PLF) and its associated scaling and normalization steps comprise the computational kernel for these tools. These computations are data intensive but contain fine grain parallelism that can be exploited by coprocessor architectures such as FPGAs and GPUs. A general purpose API called BEAGLE has recently been developed that includes optimized implementations of Felsenstein's pruning algorithm for various data parallel architectures. In this paper, we extend the BEAGLE API to a multiple Field Programmable Gate Array (FPGA)-based platform called the Convey HC-1. The core calculation of our implementation, which includes both the phylogenetic likelihood function (PLF) and the tree likelihood calculation, has an arithmetic intensity of 130 floating-point operations per 64 bytes of I/O, or 2.03 ops/byte. Its performance can thus be calculated as a function of the host platform's peak memory bandwidth and the implementation's memory efficiency, as 2.03 × peak bandwidth × memory efficiency. Our FPGA-based platform has a peak bandwidth of 76.8 GB/s and our implementation achieves a memory efficiency of approximately 50%, which gives an average throughput of 78 Gflops. This represents a ~40X speedup when compared with BEAGLE's CPU implementation on a dual Xeon 5520 and 3X speedup versus BEAGLE's GPU implementation on a Tesla T10 GPU for very large data sizes. The power consumption is 92 W, yielding a power efficiency of 1.7 Gflops per Watt. The use of data parallel architectures to achieve high performance for likelihood-based phylogenetic inference requires high memory bandwidth and a design methodology that emphasizes high memory efficiency. To achieve this objective, we integrated 32 pipelined processing elements (PEs) across four FPGAs. For the design of each PE, we developed a specialized synthesis tool to generate a floating-point pipeline with resource and throughput constraints to match the target platform. We have found that using low-latency floating-point operators can significantly reduce FPGA area and still meet timing requirement on the target platform. We found that this design methodology can achieve performance that exceeds that of a GPU-based coprocessor.

Efficient and flexible memory architecture to alleviate data and context bandwidth bottlenecks of coarse-grained reconfigurable arrays

NASA Astrophysics Data System (ADS)

Yang, Chen; Liu, LeiBo; Yin, ShouYi; Wei, ShaoJun

2014-12-01

The computational capability of a coarse-grained reconfigurable array (CGRA) can be significantly restrained due to data and context memory bandwidth bottlenecks. Traditionally, two methods have been used to resolve this problem. One method loads the context into the CGRA at run time. This method occupies very small on-chip memory but induces very large latency, which leads to low computational efficiency. The other method adopts a multi-context structure. This method loads the context into the on-chip context memory at the boot phase. Broadcasting the pointer of a set of contexts changes the hardware configuration on a cycle-by-cycle basis. The size of the context memory induces a large area overhead in multi-context structures, which results in major restrictions on application complexity. This paper proposes a Predictable Context Cache (PCC) architecture to address the above context issues by buffering the context inside a CGRA. In this architecture, context is dynamically transferred into the CGRA. Utilizing a PCC significantly reduces the on-chip context memory and the complexity of the applications running on the CGRA is no longer restricted by the size of the on-chip context memory. Data preloading is the most frequently used approach to hide input data latency and speed up the data transmission process for the data bandwidth issue. Rather than fundamentally reducing the amount of input data, the transferred data and computations are processed in parallel. However, the data preloading method cannot work efficiently because data transmission becomes the critical path as the reconfigurable array scale increases. This paper also presents a Hierarchical Data Memory (HDM) architecture as a solution to the efficiency problem. In this architecture, high internal bandwidth is provided to buffer both reused input data and intermediate data. The HDM architecture relieves the external memory from the data transfer burden so that the performance is significantly improved. As a result of using PCC and HDM, experiments running mainstream video decoding programs achieved performance improvements of 13.57%-19.48% when there was a reasonable memory size. Therefore, 1080p@35.7fps for H.264 high profile video decoding can be achieved on PCC and HDM architecture when utilizing a 200 MHz working frequency. Further, the size of the on-chip context memory no longer restricted complex applications, which were efficiently executed on the PCC and HDM architecture.

Multistage depressed collector with efficiency of 90 to 94 percent for operation of a dual-mode traveling wave tube in the linear region

NASA Technical Reports Server (NTRS)

Ramins, P.; Fox, T. A.

1980-01-01

An axisymmetric, multistage, depressed collector of fixed geometric design was evaluated in conjunction with an octave bandwidth, dual mode traveling wave tube (TWT). The TWT was operated over a wide range of conditions to simulate different applications. The collector performance was optimized (within the constraint of fixed geometric design) over the range of TWT operating conditions covered. For operation of the TWT in the linear, low distortion range, 90 percent and greater collector efficiencies were obtained leading to TWT overall efficiencies of 20 to 35 percent, as compared with 2 to 5 percent with an undepressed collector. With collectors of this efficiency and minimized beam interception losses, it becomes practical to design dual mode TWT's such that the low mode can represent operation well below saturation. Consequently, the required pulse up in beam current can be reduced or eliminated, and this mitigates beam control and dual mode TWT circuit design problems. For operation of the dual mode TWT at saturation, average collector efficiencies in excess of 85 percent were obtained for both the low and high modes across an octave bandwidth, leading to a three to fourfold increase in the TWT overall efficiency.

Optical slotted circuit switched network: a bandwidth efficient alternative to wavelength-routed network

NASA Astrophysics Data System (ADS)

Li, Yan; Collier, Martin

2007-11-01

Wavelength-routed networks have received enormous attention due to the fact that they are relatively simple to implement and implicitly offer Quality of Service (QoS) guarantees. However, they suffer from a bandwidth inefficiency problem and require complex Routing and Wavelength Assignment (RWA). Most attempts to address the above issues exploit the joint use of WDM and TDM technologies. The resultant TDM-based wavelength-routed networks partition the wavelength bandwidth into fixed-length time slots organized as a fixed-length frame. Multiple connections can thus time-share a wavelength and the grooming of their traffic leads to better bandwidth utilization. The capability of switching in both wavelength and time domains in such networks also mitigates the RWA problem. However, TMD-based wavelength-routed networks work in synchronous mode and strict synchronization among all network nodes is required. Global synchronization for all-optical networks which operate at extremely high speed is technically challenging, and deploying an optical synchronizer for each wavelength involves considerable cost. An Optical Slotted Circuit Switching (OSCS) architecture is proposed in this paper. In an OSCS network, slotted circuits are created to better utilize the wavelength bandwidth than in classic wavelength-routed networks. The operation of the protocol is such as to avoid the need for global synchronization required by TDM-based wavelength-routed networks.

Effective bandwidth guaranteed routing schemes for MPLS traffic engineering

NASA Astrophysics Data System (ADS)

Wang, Bin; Jain, Nidhi

2001-07-01

In this work, we present online algorithms for dynamic routing bandwidth guaranteed label switched paths (LSPs) where LSP set-up requests (in terms of a pair of ingress and egress routers as well as its bandwidth requirement) arrive one by one and there is no a priori knowledge regarding future LSP set-up requests. In addition, we consider rerouting of LSPs in this work. Rerouting of LSPs has not been well studied in previous work on LSP routing. The need of LSP rerouting arises in a number of ways: occurrence of faults (link and/or node failures), re-optimization of existing LSPs' routes to accommodate traffic fluctuation, requests with higher priorities, and so on. We formulate the bandwidth guaranteed LSP routing with rerouting capability as a multi-commodity flow problem. The solution to this problem is used as the benchmark for comparing other computationally less costly algorithms studied in this paper. Furthermore, to more efficiently utilize the network resources, we propose online routing algorithms which route bandwidth demands over multiple paths at the ingress router to satisfy the customer requests while providing better service survivability. Traffic splitting and distribution over the multiple paths are carefully handled using table-based hashing schemes while the order of packets within a flow is preserved. Preliminary simulations are conducted to show the performance of different design choices and the effectiveness of the rerouting and multi-path routing algorithms in terms of LSP set-up request rejection probability and bandwidth blocking probability.

On efficiency of fire simulation realization: parallelization with greater number of computational meshes

NASA Astrophysics Data System (ADS)

Valasek, Lukas; Glasa, Jan

2017-12-01

Current fire simulation systems are capable to utilize advantages of high-performance computer (HPC) platforms available and to model fires efficiently in parallel. In this paper, efficiency of a corridor fire simulation on a HPC computer cluster is discussed. The parallel MPI version of Fire Dynamics Simulator is used for testing efficiency of selected strategies of allocation of computational resources of the cluster using a greater number of computational cores. Simulation results indicate that if the number of cores used is not equal to a multiple of the total number of cluster node cores there are allocation strategies which provide more efficient calculations.

A review of alternative approaches to healthcare resource allocation.

PubMed

Petrou, S; Wolstenholme, J

2000-07-01

The resources available for healthcare are limited compared with demand, if not need, and all healthcare systems, regardless of their financing and organisation, employ mechanisms to ration or prioritise finite healthcare resources. This paper reviews alternative approaches that can be used to allocate healthcare resources. It discusses the problems encountered when allocating healthcare resources according to free market principles. It then proceeds to discuss the advantages and disadvantages of alternative resource allocation approaches that can be applied to public health systems. These include: (i) approaches based on the concept of meeting the needs of the population to maximising its capacity to benefit from interventions; (ii) economic approaches that identify the most efficient allocation of resources with the view of maximising health benefits or other measures of social welfare; (iii) approaches that seek to ration healthcare by age; and (iv) approaches that resolve resource allocation disputes through debate and bargaining. At present, there appears to be no consensus about the relative importance of the potentially conflicting principles that can be used to guide resource allocation decisions. It is concluded that whatever shape tomorrow's health service takes, the requirement to make equitable and efficient use of finite healthcare resources will remain.

IR Bandwidth and Crystal Thickness Effects on THG Efficiency and Temporal Shaping of Quasi-Rectangular UV Pulses: Part II - Incident IR Ripple

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolton, Paul R.; Limborg-Deprey, Cecile; /SLAC

We have investigated the effect of incident ir spectral bandwidth and crystal thickness, on uv pulses produced by third harmonic generation (THG) in a crystal pair. Our focus is on the third harmonic generation efficiency and longitudinal uv intensity profile parameters of SNLO predictions that are evaluated for three incident ir spectral bandwidths and a range of crystal thicknesses. These results represent a continuation of earlier work in which the effects of the same selected ir bandwidths and range of crystal thicknesses were investigated using a pair of BBO Type I crystals in a simplistic geometry for which the longitudinalmore » intensity plateau has a zero slope, 'flattop' profile. The current work is distinguished from the previous work by an imposed ripple on the ir intensity longitudinal profile and constitutes a portion of a Part II effort to which we have made reference. As with preceding work, all third harmonic data are net results at the exit of the second BBO crystal. Predictions are obtained with the modified SNLO code developed by Arlee Smith at the Sandia National Laboratories. This modification has allowed us to pursue the 'coupled' case in which the output of the first BBO crystal is used as input to the second one. This includes both the fundamental and second harmonic light. Defined parameters are consistent with previous work. The presented cases are best results. The criteria for selection of these reported cases are highest THG efficiency combined with minimum intensity ripple in the plateau. The incident ir pulse is quasi-rectangular with an imposed 5.2 % (rms) intensity ripple added to the plateau. The ir pulse bandwidth is centered at 800 nm. Second harmonic generation occurs in the first BBO crystal and THG occurs in the second crystal as a consequence of sum frequency generation. Type I phase matching is used throughout, so that for a negative uniaxial crystal: n{sub 2}{sup e}({theta}) = n{sub 1}{sup o};(SHG) (1.1) 3n{sub 3}{sup 3}({theta}) = 2n{sub 2}{sup o} + n{sub 1}{sup o};(THG) where n{sub 2}{sup e}({theta}) and n{sub 3}{sup e}({theta}) are the angle dependent extraordinary refractive indices for the second and third harmonics respectively, and n{sub 1}{sup 1} and n{sub 2}{sup o} are the ordinary refractive indices for the fundamental and second harmonic respectively. Although our goal at this stage has not been to comply with all the LCLS injector laser specifications, the results provided here represent a parameter study that can be used to determine candidate bandwidth dependent, crystal thickness combinations for the detailed design of compliant THG subsystems. This simplistic geometry better elucidates acceptance bandwidth limitations that are intrinsic to the crystal material.« less

Adaptive Video Streaming Using Bandwidth Estimation for 3.5G Mobile Network

NASA Astrophysics Data System (ADS)

Nam, Hyeong-Min; Park, Chun-Su; Jung, Seung-Won; Ko, Sung-Jea

Currently deployed mobile networks including High Speed Downlink Packet Access (HSDPA) offer only best-effort Quality of Service (QoS). In wireless best effort networks, the bandwidth variation is a critical problem, especially, for mobile devices with small buffers. This is because the bandwidth variation leads to packet losses caused by buffer overflow as well as picture freezing due to high transmission delay or buffer underflow. In this paper, in order to provide seamless video streaming over HSDPA, we propose an efficient real-time video streaming method that consists of the available bandwidth (AB) estimation for the HSDPA network and the transmission rate control to prevent buffer overflows/underflows. In the proposed method, the client estimates the AB and the estimated AB is fed back to the server through real-time transport control protocol (RTCP) packets. Then, the server adaptively adjusts the transmission rate according to the estimated AB and the buffer state obtained from the RTCP feedback information. Experimental results show that the proposed method achieves seamless video streaming over the HSDPA network providing higher video quality and lower transmission delay.

Time-Series Forecast Modeling on High-Bandwidth Network Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoo, Wucherl; Sim, Alex

With the increasing number of geographically distributed scientific collaborations and the growing sizes of scientific data, it has become challenging for users to achieve the best possible network performance on a shared network. In this paper, we have developed a model to forecast expected bandwidth utilization on high-bandwidth wide area networks. The forecast model can improve the efficiency of the resource utilization and scheduling of data movements on high-bandwidth networks to accommodate ever increasing data volume for large-scale scientific data applications. A univariate time-series forecast model is developed with the Seasonal decomposition of Time series by Loess (STL) and themore » AutoRegressive Integrated Moving Average (ARIMA) on Simple Network Management Protocol (SNMP) path utilization measurement data. Compared with the traditional approach such as Box-Jenkins methodology to train the ARIMA model, our forecast model reduces computation time up to 92.6 %. It also shows resilience against abrupt network usage changes. Finally, our forecast model conducts the large number of multi-step forecast, and the forecast errors are within the mean absolute deviation (MAD) of the monitored measurements.« less

Electrically-driven GHz range ultrafast graphene light emitter (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kim, Youngduck; Gao, Yuanda; Shiue, Ren-Jye; Wang, Lei; Aslan, Ozgur Burak; Kim, Hyungsik; Nemilentsau, Andrei M.; Low, Tony; Taniguchi, Takashi; Watanabe, Kenji; Bae, Myung-Ho; Heinz, Tony F.; Englund, Dirk R.; Hone, James

2017-02-01

Ultrafast electrically driven light emitter is a critical component in the development of the high bandwidth free-space and on-chip optical communications. Traditional semiconductor based light sources for integration to photonic platform have therefore been heavily studied over the past decades. However, there are still challenges such as absence of monolithic on-chip light sources with high bandwidth density, large-scale integration, low-cost, small foot print, and complementary metal-oxide-semiconductor (CMOS) technology compatibility. Here, we demonstrate the first electrically driven ultrafast graphene light emitter that operate up to 10 GHz bandwidth and broadband range (400 1600 nm), which are possible due to the strong coupling of charge carriers in graphene and surface optical phonons in hBN allow the ultrafast energy and heat transfer. In addition, incorporation of atomically thin hexagonal boron nitride (hBN) encapsulation layers enable the stable and practical high performance even under the ambient condition. Therefore, electrically driven ultrafast graphene light emitters paves the way towards the realization of ultrahigh bandwidth density photonic integrated circuits and efficient optical communications networks.

Characteristic analysis of diaphragm-type transducer that is thick relative to its size

NASA Astrophysics Data System (ADS)

Ishiguro, Yuya; Zhu, Jing; Tagawa, Norio; Okubo, Tsuyoshi; Okubo, Kan

2017-07-01

In recent years, high-performance piezoelectric micromachined ultrasonic transducers (PMUTs) have been fabricated by micro electro mechanical systems (MEMS) technology. For high-resolution imaging, it is important to broaden the frequency bandwidth. By reducing the diaphragm size to increase the resonance frequency, the film thickness becomes relatively larger and hence the transmitting and receiving characteristics may different from those of a usual thin diaphragm. In this study, we examine the performance of a square-diaphragm-type lead zirconate titanate (PZT) transducer through simulations. To realize the desired resonance frequency of 20 MHz, firstly, the diaphragm size and the thickness of the layers of PZT and Si constituting a PMUT are examined, and then, three PZT/Si models with different thicknesses are selected. Subsequently, using the models, we analyze the transmitting efficiency, transmitting bandwidth, receiving sensitivity (piezoelectric voltage/electric charge), and receiving bandwidth using an FEM simulator. It is found that the proposed models can transmit ultrasound independently of the diaphragm vibration and have wide bandwidth of the receiving frequency as compared with that of a typical PMUT.

Time-Series Forecast Modeling on High-Bandwidth Network Measurements

DOE PAGES

Yoo, Wucherl; Sim, Alex

2016-06-24

With the increasing number of geographically distributed scientific collaborations and the growing sizes of scientific data, it has become challenging for users to achieve the best possible network performance on a shared network. In this paper, we have developed a model to forecast expected bandwidth utilization on high-bandwidth wide area networks. The forecast model can improve the efficiency of the resource utilization and scheduling of data movements on high-bandwidth networks to accommodate ever increasing data volume for large-scale scientific data applications. A univariate time-series forecast model is developed with the Seasonal decomposition of Time series by Loess (STL) and themore » AutoRegressive Integrated Moving Average (ARIMA) on Simple Network Management Protocol (SNMP) path utilization measurement data. Compared with the traditional approach such as Box-Jenkins methodology to train the ARIMA model, our forecast model reduces computation time up to 92.6 %. It also shows resilience against abrupt network usage changes. Finally, our forecast model conducts the large number of multi-step forecast, and the forecast errors are within the mean absolute deviation (MAD) of the monitored measurements.« less

High Power High Efficiency Ka-Band Power Combiners for Solid-State Devices

NASA Technical Reports Server (NTRS)

Freeman, Jon C.; Wintucky, Edwin G.; Chevalier, Christine T.

2006-01-01

Wide-band power combining units for Ka-band are simulated for use as MMIC amplifier applications. Short-slot couplers as well as magic-tees are the basic elements for the combiners. Wide bandwidth (5 GHz) and low insertion (approx.0.2 dB) and high combining efficiencies (approx.90 percent) are obtained.

A scalable diffraction-based scanning 3D colour video display as demonstrated by using tiled gratings and a vertical diffuser.

PubMed

Jia, Jia; Chen, Jhensi; Yao, Jun; Chu, Daping

2017-03-17

A high quality 3D display requires a high amount of optical information throughput, which needs an appropriate mechanism to distribute information in space uniformly and efficiently. This study proposes a front-viewing system which is capable of managing the required amount of information efficiently from a high bandwidth source and projecting 3D images with a decent size and a large viewing angle at video rate in full colour. It employs variable gratings to support a high bandwidth distribution. This concept is scalable and the system can be made compact in size. A horizontal parallax only (HPO) proof-of-concept system is demonstrated by projecting holographic images from a digital micro mirror device (DMD) through rotational tiled gratings before they are realised on a vertical diffuser for front-viewing.

Bandwidth Efficient Modulation and Coding Techniques for NASA's Existing Ku/Ka-Band 225 MHz Wide Service

NASA Technical Reports Server (NTRS)

Gioannini, Bryan; Wong, Yen; Wesdock, John

2005-01-01

The National Aeronautics and Space Administration (NASA) has recently established the Tracking and Data Relay Satellite System (TDRSS) K-band Upgrade Project (TKUP), a project intended to enhance the TDRSS Ku-band and Ka-band Single Access Return 225 MHz (Ku/KaSAR-225) data service by adding the capability to process bandwidth efficient signal design and to replace the White Sand Complex (WSC) KSAR high data rate ground equipment and high rate switches which are nearing obsolescence. As a precursor to this project, a modulation and coding study was performed to identify signal structures which maximized the data rate through the Ku/KaSAR-225 channel, minimized the required customer EIRP and ensured acceptable hardware complexity on the customer platform. This paper presents the results and conclusions of the TKUP modulation and coding study.

Broadband unidirectional cloaks based on flat metasurface focusing lenses

NASA Astrophysics Data System (ADS)

Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Wang, Jiafu; Pang, Yongqiang; Xu, Zhuo; Zhang, Anxue

2015-08-01

Bandwidth extension and thickness reduction are now the two key issues of cloaks. In this paper, we propose to achieve broadband, thin uni-directional electromagnetic (EM) cloaks using metasurfaces. To this end, a wideband flat focusing lens is firstly devised based on high-efficiency transmissive metasurfaces. Due to the nearly dispersionless parabolic phase profile along the metasurface in the operating band, incident plane waves can be focused efficiently after passing through the metasurface. Broadband unidirectional EM cloaks were then designed by combining two identical flat lenses. Upon illumination, the incident plane waves are firstly focused by one lens and then are restored by the other lens, avoiding the cloaked region. Both simulation and experiment results verify the broadband unidirectional cloak. The broad bandwidth and small thickness of such cloaks have potential applications in achieving invisibility for electrically large objects.

A Fully Reconfigurable Low-Noise Biopotential Sensing Amplifier With 1.96 Noise Efficiency Factor.

PubMed

Tzu-Yun Wang; Min-Rui Lai; Twigg, Christopher M; Sheng-Yu Peng

2014-06-01

A fully reconfigurable biopotential sensing amplifier utilizing floating-gate transistors is presented in this paper. By using the complementary differential pairs along with the current reuse technique, the theoretical limit for the noise efficiency factor of the proposed amplifier is below 1.5. Without consuming any extra power, floating-gate transistors are employed to program the low-frequency cutoff corner of the amplifier and to implement the common-mode feedback. A concept proving prototype chip was designed and fabricated in a 0.35 μm CMOS process occupying 0.17 mm (2) silicon area. With a supply voltage of 2.5 V, the measured midband gain is 40.7 dB and the measured input-referred noise is 2.8 μVrms. The chip was tested under several configurations with the amplifier bandwidth being programmed to 100 Hz, 1 kHz , and 10 kHz. The measured noise efficiency factors in these bandwidth settings are 1.96, 2.01, and 2.25, respectively, which are among the best numbers reported to date. The measured common-mode rejection and the supply rejection are above 70 dB . When the bandwidth is configured to be 10 kHz, the dynamic range measured at 1 kHz is 60 dB with total harmonic distortion less than 0.1%. The proposed amplifier is also demonstrated by recording electromyography (EMG), electrocardiography (ECG), electrooculography (EOG), and electroencephalography (EEG) signals from human bodies.

Next-generation optical wireless communications for data centers

NASA Astrophysics Data System (ADS)

Arnon, Shlomi

2015-01-01

Data centers collect and process information with a capacity that has been increasing from year to year at an almost exponential pace. Traditional fiber/cable data center network interconnections suffer from bandwidth overload, as well as flexibility and scalability issues. Therefore, a technology-shift from the fiber and cable to wireless has already been initiated in order to meet the required data-rate, flexibility and scalability demands for next-generation data center network interconnects. In addition, the shift to wireless reduces the volume allocated to the cabling/fiber and increases the cooling efficiency. Optical wireless communication (OWC), or free space optics (FSO), is one of the most effective wireless technologies that could be used in future data centers and could provide ultra-high capacity, very high cyber security and minimum latency, due to the low index of refraction of air in comparison to fiber technologies. In this paper we review the main concepts and configurations for next generation OWC for data centers. Two families of technologies are reviewed: the first technology regards interconnects between rack units in the same rack and the second technology regards the data center network that connects the server top of rack (TOR) to the switch. A comparison between different network technologies is presented.

Exploiting artificial intelligence for in-situ analysis of high-resolution radio emission measurements on a CubeSat

NASA Astrophysics Data System (ADS)

Isham, Brett; Bergman, Jan; Krause, Linda; Rincon-Charris, Amilcar; Bruhn, Fredrik; Funk, Peter; Stramkals, Arturs

2016-07-01

CubeSat missions are intentionally constrained by the limitations of their small platform. Mission payloads designed for low volume, mass, and power, may however be disproportionally limited by available telemetry allocations. In many cases, it is the data delivered to the ground which determines the value of the mission. However, transmitting more data does not necessarily guarantee high value, since the value also depends on data quality. By exploiting fast on-board computing and efficient artificial intelligence (AI) algorithms for analysis and data selection, the usage of the telemetry link can be optimized and value added to the mission. This concept is being implemented on the Puerto Rico CubeSat, which will make measurements of ambient ionospheric radio waves and ion irregularities and turbulence. Principle project goals include providing aerospace and systems engineering experiences to students. Science objectives include the study of natural space plasma processes to aid in better understanding of space weather and the Sun to Earth connection, and in-situ diagnostics of ionospheric modification experiments using high-power ground-based radio transmitters. We hope that this project might point the way to the productive use of AI in space and other remote, low-data-bandwidth environments.

The UTMOST: A Hybrid Digital Signal Processor Transforms the Molonglo Observatory Synthesis Telescope

NASA Astrophysics Data System (ADS)

Bailes, M.; Jameson, A.; Flynn, C.; Bateman, T.; Barr, E. D.; Bhandari, S.; Bunton, J. D.; Caleb, M.; Campbell-Wilson, D.; Farah, W.; Gaensler, B.; Green, A. J.; Hunstead, R. W.; Jankowski, F.; Keane, E. F.; Krishnan, V. Venkatraman; Murphy, Tara; O'Neill, M.; Osłowski, S.; Parthasarathy, A.; Ravi, V.; Rosado, P.; Temby, D.

2017-10-01

The Molonglo Observatory Synthesis Telescope (MOST) is an 18000 m2 radio telescope located 40 km from Canberra, Australia. Its operating band (820-851 MHz) is partly allocated to telecommunications, making radio astronomy challenging. We describe how the deployment of new digital receivers, Field Programmable Gate Array-based filterbanks, and server-class computers equipped with 43 Graphics Processing Units, has transformed the telescope into a versatile new instrument (UTMOST) for studying the radio sky on millisecond timescales. UTMOST has 10 times the bandwidth and double the field of view compared to the MOST, and voltage record and playback capability has facilitated rapid implementaton of many new observing modes, most of which operate commensally. UTMOST can simultaneously excise interference, make maps, coherently dedisperse pulsars, and perform real-time searches of coherent fan-beams for dispersed single pulses. UTMOST operates as a robotic facility, deciding how to efficiently target pulsars and how long to stay on source via real-time pulsar folding, while searching for single pulse events. Regular timing of over 300 pulsars has yielded seven pulsar glitches and three Fast Radio Bursts during commissioning. UTMOST demonstrates that if sufficient signal processing is applied to voltage streams, innovative science remains possible even in hostile radio frequency environments.

Self-organizing feature maps for dynamic control of radio resources in CDMA microcellular networks

NASA Astrophysics Data System (ADS)

Hortos, William S.

1998-03-01

The application of artificial neural networks to the channel assignment problem for cellular code-division multiple access (CDMA) cellular networks has previously been investigated. CDMA takes advantage of voice activity and spatial isolation because its capacity is only interference limited, unlike time-division multiple access (TDMA) and frequency-division multiple access (FDMA) where capacities are bandwidth-limited. Any reduction in interference in CDMA translates linearly into increased capacity. To satisfy the high demands for new services and improved connectivity for mobile communications, microcellular and picocellular systems are being introduced. For these systems, there is a need to develop robust and efficient management procedures for the allocation of power and spectrum to maximize radio capacity. Topology-conserving mappings play an important role in the biological processing of sensory inputs. The same principles underlying Kohonen's self-organizing feature maps (SOFMs) are applied to the adaptive control of radio resources to minimize interference, hence, maximize capacity in direct-sequence (DS) CDMA networks. The approach based on SOFMs is applied to some published examples of both theoretical and empirical models of DS/CDMA microcellular networks in metropolitan areas. The results of the approach for these examples are informally compared to the performance of algorithms, based on Hopfield- Tank neural networks and on genetic algorithms, for the channel assignment problem.

Examination of Resource Allocation in Education: Connecting Spending to Student Performance. Research Report.

ERIC Educational Resources Information Center

Pan, Diane; Rudo, Zena H.; Schneider, Cynthia L.; Smith-Hansen, Lotte

This document reports on a study on the relationship between resources and student performance. The study examined district-level patterns of resource allocation, district and school resource practices implemented to improve student performance, and barriers and challenges to efficient resource allocation faced by districts and schools. The study…

Surface normal coupling to multiple-slot and cover-slotted silicon nanocrystalline waveguides and ring resonators

NASA Astrophysics Data System (ADS)

Covey, John; Chen, Ray T.

2014-03-01

Grating couplers are ideal for coupling into the tightly confined propagation modes of semiconductor waveguides. In addition, nonlinear optics has benefited from the sub-diffraction limit confinement of horizontal slot waveguides. By combining these two advancements, slot-based nonlinear optics with mode areas less than 0.02 μm2 can become as routine as twisting fiber connectors together. Surface normal fiber alignment to a chip is also highly desirable from time, cost, and manufacturing considerations. To meet these considerable design challenges, a custom genetic algorithm is created which, starting from purely random designs, creates a unique four stage grating coupler for two novel horizontal slot waveguide platforms. For horizontal multiple-slot waveguides filled with silicon nanocrystal, a theoretical fiber-towaveguide coupling efficiency of 68% is obtained. For thin silicon waveguides clad with optically active silicon nanocrystal, known as cover-slot waveguides, a theoretical fiber-to-waveguide coupling efficiency of 47% is obtained, and 1 dB and 3 dB theoretical bandwidths of 70 nm and 150 nm are obtained, respectively. Both waveguide platforms are fabricated from scratch, and their respective on-chip grating couplers are experimentally measured from a standard single mode fiber array that is mounted surface normally. The horizontal multiple-slot grating coupler achieved an experimental 60% coupling efficiency, and the horizontal cover-slot grating coupler achieved an experimental 38.7% coupling efficiency, with an extrapolated 1 dB bandwidth of 66 nm. This report demonstrates the promise of genetic algorithm-based design by reducing to practice the first large bandwidth vertical grating coupler to a novel silicon nanocrystal horizontal cover-slot waveguide.

Efficient flattop ultra-wideband wavelength converters based on double-pass cascaded sum and difference frequency generation using engineered chirped gratings.

PubMed

Tehranchi, Amirhossein; Morandotti, Roberto; Kashyap, Raman

2011-11-07

High-efficiency ultra-broadband wavelength converters based on double-pass quasi-phase-matched cascaded sum and difference frequency generation including engineered chirped gratings in lossy lithium niobate waveguides are numerically investigated and compared to the single-pass counterparts, assuming a large twin-pump wavelength difference of 75 nm. Instead of uniform gratings, few-section chirped gratings with the same length, but with a small constant period change among sections with uniform gratings, are proposed to flatten the response and increase the mean efficiency by finding the common critical period shift and minimum number of sections for both single-pass and double-pass schemes whilst for the latter the efficiency is remarkably higher in a low-loss waveguide. It is also verified that for the same waveguide length and power, the efficiency enhancement expected due to the use of the double-pass scheme instead of the single-pass one, is finally lost if the waveguide loss increases above a certain value. For the double-pass scheme, the criteria for the design of the low-loss waveguide length, and the assignment of power in the pumps to achieve the desired efficiency, bandwidth and ripple are presented for the optimum 3-section chirped-gratings-based devices. Efficient conversions with flattop bandwidths > 84 nm for lengths < 3 cm can be obtained.

Labor costs incurred by anesthesiology groups because of operating rooms not being allocated and cases not being scheduled to maximize operating room efficiency.

PubMed

Abouleish, Amr E; Dexter, Franklin; Epstein, Richard H; Lubarsky, David A; Whitten, Charles W; Prough, Donald S

2003-04-01

Determination of operating room (OR) block allocation and case scheduling is often not based on maximizing OR efficiency, but rather on tradition and surgeon convenience. As a result, anesthesiology groups often incur additional labor costs. When negotiating financial support, heads of anesthesiology departments are often challenged to justify the subsidy necessary to offset these additional labor costs. In this study, we describe a method for calculating a statistically sound estimate of the excess labor costs incurred by an anesthesiology group because of inefficient OR allocation and case scheduling. OR information system and anesthesia staffing data for 1 yr were obtained from two university hospitals. Optimal OR allocation for each surgical service was determined by maximizing the efficiency of use of the OR staff. Hourly costs were converted to dollar amounts by using the nationwide median compensation for academic and private-practice anesthesia providers. Differences between actual costs and the optimal OR allocation were determined. For Hospital A, estimated annual excess labor costs were $1.6 million (95% confidence interval, $1.5-$1.7 million) and $2.0 million ($1.89-$2.05 million) when academic and private-practice compensation, respectively, was calculated. For Hospital B, excess labor costs were $1.0 million ($1.08-$1.17 million) and $1.4 million ($1.32-1.43 million) for academic and private-practice compensation, respectively. This study demonstrates a methodology for an anesthesiology group to estimate its excess labor costs. The group can then use these estimates when negotiating for subsidies with its hospital, medical school, or multispecialty medical group. We describe a new application for a previously reported statistical method to calculate operating room (OR) allocations to maximize OR efficiency. When optimal OR allocations and case scheduling are not implemented, the resulting increase in labor costs can be used in negotiations as a statistically sound estimate for the increased labor cost to the anesthesiology department.

High-efficiency fiber-to-chip grating couplers realized using an advanced CMOS-compatible silicon-on-insulator platform.

PubMed

Vermeulen, D; Selvaraja, S; Verheyen, P; Lepage, G; Bogaerts, W; Absil, P; Van Thourhout, D; Roelkens, G

2010-08-16

A new generation of Silicon-on-Insulator fiber-to-chip grating couplers which use a silicon overlay to enhance the directionality and thereby the coupling efficiency is presented. Devices are realized on a 200 mm wafer in a CMOS pilot line. The fabricated fiber couplers show a coupling efficiency of -1.6 dB and a 3 dB bandwidth of 80 nm.

Exploring SWAp's contribution to the efficient allocation and use of resources in the health sector in Zambia.

PubMed

Chansa, Collins; Sundewall, Jesper; McIntyre, Di; Tomson, Göran; Forsberg, Birger C

2008-07-01

Zambia introduced a sector-wide approach (SWAp) in the health sector in 1993. The goal was to improve efficiency in the use of domestic funds and externally sourced development assistance by integrating these into a joint sectoral framework. Over a decade into its existence, however, the SWAp remains largely unevaluated. This study explores whether the envisaged improvements have been achieved by studying developments in administrative, technical and allocative efficiency in the Zambian health sector from 1990-2006. A case study was conducted using interviews and analysis of secondary data. Respondents represented a cross-section of stakeholders in the Zambian health sector. Secondary data from 1990-2006 were collected for six indicators related to administrative, technical and allocative efficiency. The results showed small improvements in administrative efficiency. Transaction costs still appeared to be high despite the introduction of the SWAp. Indicators for technical efficiency showed a drop in hospital bed utilization rates and government share of funding for drugs. As for allocative efficiency, budget execution did not improve with the SWAp, although there were large variations between both donors and year. Funding levels had apparently improved at district level but declined for hospitals. Finally, the SWAp had not succeeded in bringing all external assistance together under a common framework. Despite strong commitment to implement the SWAp in Zambia, the envisaged efficiency improvements do not seem to have been attained. Possible explanations could be that the SWAp has not been fully developed or that not all parties have completely embraced it. SWAp is not ruled out as a coordination model, but the current setup in Zambia has not proved to be fully effective.

Performance Analysis of a Hardware Implemented Complex Signal Kurtosis Radio-Frequency Interference Detector

NASA Technical Reports Server (NTRS)

Schoenwald, Adam J.; Bradley, Damon C.; Mohammed, Priscilla N.; Piepmeier, Jeffrey R.; Wong, Mark

2016-01-01

Radio-frequency interference (RFI) is a known problem for passive remote sensing as evidenced in the L-band radiometers SMOS, Aquarius and more recently, SMAP. Various algorithms have been developed and implemented on SMAP to improve science measurements. This was achieved by the use of a digital microwave radiometer. RFI mitigation becomes more challenging for microwave radiometers operating at higher frequencies in shared allocations. At higher frequencies larger bandwidths are also desirable for lower measurement noise further adding to processing challenges. This work focuses on finding improved RFI mitigation techniques that will be effective at additional frequencies and at higher bandwidths. To aid the development and testing of applicable detection and mitigation techniques, a wide-band RFI algorithm testing environment has been developed using the Reconfigurable Open Architecture Computing Hardware System (ROACH) built by the Collaboration for Astronomy Signal Processing and Electronics Research (CASPER) Group. The testing environment also consists of various test equipment used to reproduce typical signals that a radiometer may see including those with and without RFI. The testing environment permits quick evaluations of RFI mitigation algorithms as well as show that they are implementable in hardware. The algorithm implemented is a complex signal kurtosis detector which was modeled and simulated. The complex signal kurtosis detector showed improved performance over the real kurtosis detector under certain conditions. The real kurtosis is implemented on SMAP at 24 MHz bandwidth. The complex signal kurtosis algorithm was then implemented in hardware at 200 MHz bandwidth using the ROACH. In this work, performance of the complex signal kurtosis and the real signal kurtosis are compared. Performance evaluations and comparisons in both simulation as well as experimental hardware implementations were done with the use of receiver operating characteristic (ROC) curves. The complex kurtosis algorithm has the potential to reduce data rate due to onboard processing in addition to improving RFI detection performance.

Motion-Based Piloted Simulation Evaluation of a Control Allocation Technique to Recover from Pilot Induced Oscillations

NASA Technical Reports Server (NTRS)

Craun, Robert W.; Acosta, Diana M.; Beard, Steven D.; Leonard, Michael W.; Hardy, Gordon H.; Weinstein, Michael; Yildiz, Yildiray

2013-01-01

This paper describes the maturation of a control allocation technique designed to assist pilots in the recovery from pilot induced oscillations (PIOs). The Control Allocation technique to recover from Pilot Induced Oscillations (CAPIO) is designed to enable next generation high efficiency aircraft designs. Energy efficient next generation aircraft require feedback control strategies that will enable lowering the actuator rate limit requirements for optimal airframe design. One of the common issues flying with actuator rate limits is PIOs caused by the phase lag between the pilot inputs and control surface response. CAPIO utilizes real-time optimization for control allocation to eliminate phase lag in the system caused by control surface rate limiting. System impacts of the control allocator were assessed through a piloted simulation evaluation of a non-linear aircraft simulation in the NASA Ames Vertical Motion Simulator. Results indicate that CAPIO helps reduce oscillatory behavior, including the severity and duration of PIOs, introduced by control surface rate limiting.

Multichroic Antenna-Coupled Bolometers for CMB Polarization and Sub-mm Observations

NASA Astrophysics Data System (ADS)

Lee, Adrian

We propose to develop planar antenna-coupled superconducting bolometer arrays for observations at sub-millimeter to millimeter wavelengths. Our pixel architecture features a dual-polarization log-periodic antenna with a 4:1-bandwidth ratio, followed by a filter bank that divides the total bandwidth into several broad photometric bands. The advantages of this approach, compared with those using conventional single-color pixels, include a combination of greatly reduced focal-plane mass, higher array sensitivity, and a larger number of spectral bands. These advantages have the potential to greatly reduce the cost and/or increase the performance of NASA missions in the sub-millimeter to millimeter bands. For CMB polarization measurements, a wide frequency range of roughly 30 to 300 GHz is required to subtract galactic foregrounds. The multichroic architecture we propose enables a relatively low-cost 30-cm aperture space mission to have sufficient sensitivity to probe below the tensor-to-scalar ratio r = 0.01. For a larger aperture mission, such as the EPIC-IM concept, the proposed technology could reduce the focal-plane mass by a factor of 2-3, with great savings in required cryocooler performance and therefore cost. We have demonstrated the lens-coupled antenna concept in the POLARBEAR ground-based CMB polarization experiment now operating in Chile. That experiment uses a single-band planar antenna and produces excellent beam properties and optical efficiency. In the laboratory, we have measured two octaves of total bandwidth in the log-periodic sinuous antenna. We have built filter banks of 2, 3, and 7 bands with 4, 6, and 14 bolometers per pixel for two linear polarizations. Building on these accomplishments, the deliverables for the proposed work include: *Two pixel types that together cover the range from 30 to 300 GHz. The low-frequency pixel will have bands centered at 35, 50, and 80 GHz and the high frequency pixel will have bands centered at 120, 180, and 270 GHz. Both pixels will be built with filter banks that separate the incident radiation to three photometric (~ 30% fractional bandwidth) bands. *Improved efficiency at the high frequency range. Current pixels have high optical efficiency up to 150 GHz, but the efficiency drops with frequency. We will increase efficiency at the higher frequencies by improving our understanding of transmission-line, filter, and antenna losses. The antenna bandwidth will be extended at the high-frequency end by continuing the log-periodic antenna structure towards the center of the antenna. *A wide bandwidth anti-reflection coating for the dielectric lenses that can be mass produced at low or moderate cost. The multilayer coatings will be based on either molding the loaded epoxies that we have developed or by micromachining the surface of the silicon to obtain the required changes in index. This technology will be tested in the ground-based POLARBEAR experiment and is an excellent candidate for a balloon-borne experiment. We have assembled an experienced team that includes expertise in antenna design, RF superconducting circuits, microfabrication, and CMB observations. We will continue our collaboration with Gabriel Rebeiz at UCSD, an electromagnetics expert who did much of the foundational work on lens-coupled planar antennas. The rest of the team includes detector and CMB observation experts Bill Holzapfel, Adrian Lee, and Paul Richards.

VCSELs for exascale computing, computer farms, and green photonics

NASA Astrophysics Data System (ADS)

Hofmann, Werner; Moser, Philip; Wolf, Philip; Larisch, Gunter; Li, Hui; Li, Wei; Lott, James; Bimberg, Dieter

2012-11-01

The bandwidth-induced communication bottleneck due to the intrinsic limitations of metal interconnects is inhibiting the performance and environmental friendliness of todaýs supercomputers, data centers, and in fact all other modern electrically interconnected and interoperable networks such as data farms and "cloud" fabrics. The same is true for systems of optical interconnects (OIs), where even when the metal interconnects are replaced with OIs the systems remain limited by bandwidth, physical size, and most critically the power consumption and lifecycle operating costs. Vertical-cavity surface-emitting lasers (VCSELs) are ideally suited to solve this dilemma. Global communication providers like Google Inc., Intel Inc., HP Inc., and IBM Inc. are now producing optical interconnects based on VCSELs. The optimal bandwidth per link may be analyzed by by using Amdahĺs Law and depends on the architecture of the data center and the performance of the servers within the data center. According to Google Inc., a bandwidth of 40 Gb/s has to be accommodated in the future. IBM Inc. demands 80 Tbps interconnects between solitary server chips in 2020. We recently realized ultrahigh bit rate VCSELs up to 49 Gb/s suited for such optical interconnects emitting at 980 nm. These devices show error-free transmission at temperatures up to 155°C and operate beyond 200°C. Single channel data-rates of 40 Gb/s were achieved up to 75°C. Record high energy efficiencies close to 50 fJ/bit were demonstrated for VCSELs emitting at 850 nm. Our devices are fabricated using a full three-inch wafer process, and the apertures were formed by in-situ controlled selective wet oxidation using stainless steel-based vacuum equipment of our own design. assembly, and operation. All device data are measured, recorded, and evaluated by our proprietary fully automated wafer mapping probe station. The bandwidth density of our present devices is expected to be scalable from about 100 Gbps/mm² to a physical limit of roughly 15 Tbps/mm² based on the current 12.5 Gb/s VCSEL technology. Still more energy-efficient and smaller volume laser diode devices dissipating less heat are mandatory for further up scaling of the bandwidth. Novel metal-clad VCSELs enable a reduction of the device's footprint for potentially ultrashort range interconnects by 1 to 2 orders of magnitude compared to conventional VCSELs thus enabling a similar increase of device density and bandwidth.

Improving the detectability and imaging capability of ground penetrating radar using novel antenna concepts

NASA Astrophysics Data System (ADS)

Koyadan Koroth, Ajith; Bhattacharya, Amitabha

2017-04-01

Antennas are key components of Ground Penetrating Radar (GPR) instrumentation. A carefully designed antenna can improve the detectability and imaging capability of a GPR to a great extent without changing the other instrumentations. In this work, we propose four different types of antennas for GPR. They are modifications of a conventional bowtie antenna with great improvement in performance parameters. The designed antennas has also been tested in a stepped frequency type GPR and two dimensional scan images of various targets are presented. Bowtie antennas have been traditionally employed in GPR for its wide impedance bandwidth and radiation properties. The researchers proposed resistive loading to improve the bandwidth of the bowtie antenna and for low ringing pulse radiation. But this method was detrimental for antenna gain and efficiency. Bowtie antennas have a very wide impedance bandwidth. But the useful bandwidth of the antenna has been limited by the radiation pattern bandwidth. The boresight gain of bowtie antennas are found to be unstable beyond a 4:1 bandwidth. In this work, these problems have been addressed and maximum usable bandwidth for the bowtie antennas has been achieved. In this work, four antennas have been designed: namely, 1.) RC loaded bowtie antennas, 2.) RC loaded bowtie with metamaterial lens, 3.) Loop loaded bowtie, 4.) Loop loaded bowtie with directors. The designed antennas were characterized for different parameters like impedance bandwidth, radiation pattern and, gain. In antenna 1, a combined resistive-capacitive loading has been applied by periodic slot cut on the arms of the bowtie and pasting a planar graphite sheet over it. Graphite having a less conductance compared to copper acts as resistive loading. This would minimize the losses compared to lumped resistive loading. The antenna had a 10:1 impedance bandwidth and, a 5:1 pattern bandwidth. In antenna 2, a metamaterial lens has been designed to augment the antenna 1, to improve the forward gain. This antenna had the same impedance bandwidth of 10:1 while pattern bandwidth has been raised to 7:1. In antenna 3, a loop loaded bowtie antenna has been designed. This antenna do not employ any kind of resistive loading, yet achieves an impedance bandwidth of 11:1 and also a usable bandwidth of 11:1. The antenna 4 employs concentric offset loops which acts as directors to improve the directivity. This antenna achieved an impedance bandwidth and a pattern bandwidth of 13:1. All the antennas have a maximum size of about 0.3λ at lowest operating frequency. An experimental stepped frequency type GPR has been constructed to study the suitability of the fabricated antennas in detecting buried targets. Four experiments have been conducted viz. 1.) To detect a metallic pipe of 1in diameter, 2.) To detect a metallic pipe of 2in diameter 3.) To detect dry bamboo, 3.) To detect rebar in concrete. The detectability and imaging capability of GPR has been found to be improving from antenna 1 to 4.

High speed all-optical networks

NASA Technical Reports Server (NTRS)

Chlamtac, Imrich

1993-01-01

An inherent problem of conventional point-to-point WAN architectures is that they cannot translate optical transmission bandwidth into comparable user available throughput due to the limiting electronic processing speed of the switching nodes. This report presents the first solution to WDM based WAN networks that overcomes this limitation. The proposed Lightnet architecture takes into account the idiosyncrasies of WDM switching/transmission leading to an efficient and pragmatic solution. The Lightnet architecture trades the ample WDM bandwidth for a reduction in the number of processing stages and a simplification of each switching stage, leading to drastically increased effective network throughputs.

Sound absorption of a new oblique-section acoustic metamaterial with nested resonator

NASA Astrophysics Data System (ADS)

Gao, Nansha; Hou, Hong; Zhang, Yanni; Wu, Jiu Hui

2018-02-01

This study designs and investigates high-efficiency sound absorption of new oblique-section nested resonators. Impedance tube experiment results show that different combinations of oblique-section nest resonators have tunable low-frequency bandwidth characteristics. The sound absorption mechanism is due to air friction losses in the slotted region and the sample structure resonance. The acousto-electric analogy model demonstrates that the sound absorption peak and bandwidth can be modulated over an even wider frequency range by changing the geometric size and combinations of structures. The proposed structure can be easily fabricated and used in low-frequency sound absorption applications.

Digital CODEC for real-time processing of broadcast quality video signals at 1.8 bits/pixel

NASA Technical Reports Server (NTRS)

Shalkhauser, Mary JO; Whyte, Wayne A., Jr.

1989-01-01

Advances in very large-scale integration and recent work in the field of bandwidth efficient digital modulation techniques have combined to make digital video processing technically feasible and potentially cost competitive for broadcast quality television transmission. A hardware implementation was developed for a DPCM-based digital television bandwidth compression algorithm which processes standard NTSC composite color television signals and produces broadcast quality video in real time at an average of 1.8 bits/pixel. The data compression algorithm and the hardware implementation of the CODEC are described, and performance results are provided.

Digital CODEC for real-time processing of broadcast quality video signals at 1.8 bits/pixel

NASA Technical Reports Server (NTRS)

Shalkhauser, Mary JO; Whyte, Wayne A.

1991-01-01

Advances in very large scale integration and recent work in the field of bandwidth efficient digital modulation techniques have combined to make digital video processing technically feasible an potentially cost competitive for broadcast quality television transmission. A hardware implementation was developed for DPCM (differential pulse code midulation)-based digital television bandwidth compression algorithm which processes standard NTSC composite color television signals and produces broadcast quality video in real time at an average of 1.8 bits/pixel. The data compression algorithm and the hardware implementation of the codec are described, and performance results are provided.

Aeronautical audio broadcasting via satellite

NASA Technical Reports Server (NTRS)

Tzeng, Forrest F.

1993-01-01

A system design for aeronautical audio broadcasting, with C-band uplink and L-band downlink, via Inmarsat space segments is presented. Near-transparent-quality compression of 5-kHz bandwidth audio at 20.5 kbit/s is achieved based on a hybrid technique employing linear predictive modeling and transform-domain residual quantization. Concatenated Reed-Solomon/convolutional codes with quadrature phase shift keying are selected for bandwidth and power efficiency. RF bandwidth at 25 kHz per channel, and a decoded bit error rate at 10(exp -6) with E(sub b)/N(sub o) at 3.75 dB are obtained. An interleaver, scrambler, modem synchronization, and frame format were designed, and frequency-division multiple access was selected over code-division multiple access. A link budget computation based on a worst-case scenario indicates sufficient system power margins. Transponder occupancy analysis for 72 audio channels demonstrates ample remaining capacity to accommodate emerging aeronautical services.

Plate-slot polymer waveguide modulator on silicon-on-insulator.

PubMed

Qiu, Feng; Spring, Andrew M; Hong, Jianxun; Yokoyama, Shiyoshi

2018-04-30

Electro-optic (EO) modulators are vital for efficient "electrical to optical" transitions and high-speed optical interconnects. In this work, we applied an EO polymer to demonstrate modulators on silicon-on-insulator substrates. The fabricated Mach-Zehnder interferometer (MZI) and ring resonator consist of a Si and TiO 2 slot, in which the EO polymer was embedded to realize a low-driving and large bandwidth modulation. The designed optical and electrical constructions are able to provide a highly concentrated TM mode with low propagation loss and effective EO properties. The fabricated MZI modulator shows a π-voltage-length product of 0.66 V·cm and a 3-dB bandwidth of 31 GHz. The measured EO activity is advantageous to exploit the ring modulator with a resonant tunability of 0.065 nm/V and a 3-dB modulation bandwidth up to 13 GHz.

Design & Performance of Wearable Ultra Wide Band Textile Antenna for Medical Applications

NASA Astrophysics Data System (ADS)

Singh, Nikhil; Singh, Ashutosh Kumar; Singh, Vinod Kumar

2015-02-01

The concept of wearable products such as textile antenna are being developed which are capable of monitoring, alerting and demanding attention whenever hospital emergency is needed, hence minimizing labour and resource. In the proposed work by using textile material as a substrate the ultra wideband antenna is designed especially for medical applications.Simulated and measured results here shows that the proposed antenna design meets the requirements of wide working bandwidth and provides 13.08 GHz bandwidth with very small size, washable (if using conductive thread for conductive parts) and flexible materials. Results in terms of bandwidth, radiation pattern, return loss as well as gain and efficiency are presented to validate the usefulness of the current proposed design. The work done here has many implications for future research and it could help patients with such flexible and comfortable medical monitoring techniques.

A versatile design for resonant guided-wave parametric down-conversion sources for quantum repeaters

NASA Astrophysics Data System (ADS)

Brecht, Benjamin; Luo, Kai-Hong; Herrmann, Harald; Silberhorn, Christine

2016-05-01

Quantum repeaters—fundamental building blocks for long-distance quantum communication—are based on the interaction between photons and quantum memories. The photons must fulfil stringent requirements on central frequency, spectral bandwidth and purity in order for this interaction to be efficient. We present a design scheme for monolithically integrated resonant photon-pair sources based on parametric down-conversion in nonlinear waveguides, which facilitate the generation of such photons. We investigate the impact of different design parameters on the performance of our source. The generated photon spectral bandwidths can be varied between several tens of MHz up to around 1 GHz, facilitating an efficient coupling to different memories. The central frequency of the generated photons can be coarsely tuned by adjusting the pump frequency, poling period and sample temperature, and we identify stability requirements on the pump laser and sample temperature that can be readily fulfilled with off-the-shelf components. We find that our source is capable of generating high-purity photons over a wide range of photon bandwidths. Finally, the PDC emission can be frequency fine-tuned over several GHz by simultaneously adjusting the sample temperature and pump frequency. We conclude our study with demonstrating the adaptability of our source to different quantum memories.

Comparison between broadband Bessel beam launchers based on either Bessel or Hankel aperture distribution for millimeter wave short pulse generation.

PubMed

Pavone, Santi C; Mazzinghi, Agnese; Freni, Angelo; Albani, Matteo

2017-08-07

In this paper, a comparison is presented between Bessel beam launchers at millimeter waves based on either a cylindrical standing wave (CSW) or a cylindrical inward traveling wave (CITW) aperture distribution. It is theoretically shown that CITW launchers are better suited for the generation of electromagnetic short pulses because they maintain their performances over a larger bandwidth than those realizing a CSW aperture distribution. Moreover, the wavenumber dispersion of both the launchers is evaluated both theoretically and numerically. To this end, two planar Bessel beam launchers, one enforcing a CSW and the other enforcing a CITW aperture distribution, are designed at millimeter waves with a center operating frequency of f¯=60GHz and analyzed in the bandwidth 50 - 70 GHz by using an in-house developed numerical code to solve Maxwell's equations based on the method of moments. It is shown that a monochromatic Bessel beam can be efficiently generated by both the launchers over a wide fractional bandwidth. Finally, we investigate the generation of limited-diffractive electromagnetic pulses at millimeter waves, up to a certain non-diffractive range. Namely, it is shown that by feeding the launcher with a Gaussian short pulse, a spatially confined electromagnetic pulse can be efficiently generated in front of the launcher.

Toward allocative efficiency in the prescription drug industry.

PubMed

Guell, R C; Fischbaum, M

1995-01-01

Traditionally, monopoly power in the pharmaceutical industry has been measured by profits. An alternative method estimates the deadweight loss of consumer surplus associated with the exercise of monopoly power. Although upper and lower bound estimates for this inefficiency are far apart, they at least suggest a dramatically greater welfare loss than measures of industry profitability would imply. A proposed system would have the U.S. government employing its power of eminent domain to "take" and distribute pharmaceutical patents, providing as "just compensation" the present value of the patent's expected future monopoly profits. Given the allocative inefficiency of raising taxes to pay for the program, the impact of the proposal on allocative efficiency would be at least as good at our lower bound estimate of monopoly costs while substantially improving efficiency at or near our upper bound estimate.

Highly Efficient Broadband Multiplexed Millimeter-Wave Vortices from Metasurface-Enabled Transmit-Arrays of Subwavelength Thickness

NASA Astrophysics Data System (ADS)

Jiang, Zhi Hao; Kang, Lei; Hong, Wei; Werner, Douglas H.

2018-06-01

Structured electromagnetic waves carrying nonvanishing orbital angular momentum (OAM) have recently opened up alternative frontiers in the field of wave physics, holding great promise for a wide range of potential applications. By leveraging geometric phases originating from spin-to-orbital interactions, spin-dependent wave phenomena can be created, leading to a more versatile realm of dispersionless wave-front manipulation. However, the currently available transmissive vortex-beam generators suffer from a narrow bandwidth, require an optically thick device profile, or are limited by a low efficiency, severely restricting their integration into systems and/or widespread usage for practical applications. We present the design methodology and a physical analysis and complete experimental characterization of a class of millimeter-wave Pancharatnam-Berry transmit-arrays with a thickness of about λ0/3 , which enables highly efficient generation and separation of spin-controlled vortex beams over a broad bandwidth, achieving an unprecedented peak efficiency of 88% for a single vortex beam and 71% for dual vortex beams. The proposed transmit-array, which is capable of providing two-dimensional OAM multiplexing and demultiplexing without normal-mode background interference, overcomes all previous roadblocks and paves the way for high-efficiency electromagnetic vortex-beam generation as well as other wave-front-shaping devices from microwave frequencies to optical wavelengths.

Optimal Time-Resource Allocation for Energy-Efficient Physical Activity Detection

PubMed Central

Thatte, Gautam; Li, Ming; Lee, Sangwon; Emken, B. Adar; Annavaram, Murali; Narayanan, Shrikanth; Spruijt-Metz, Donna; Mitra, Urbashi

2011-01-01

The optimal allocation of samples for physical activity detection in a wireless body area network for health-monitoring is considered. The number of biometric samples collected at the mobile device fusion center, from both device-internal and external Bluetooth heterogeneous sensors, is optimized to minimize the transmission power for a fixed number of samples, and to meet a performance requirement defined using the probability of misclassification between multiple hypotheses. A filter-based feature selection method determines an optimal feature set for classification, and a correlated Gaussian model is considered. Using experimental data from overweight adolescent subjects, it is found that allocating a greater proportion of samples to sensors which better discriminate between certain activity levels can result in either a lower probability of error or energy-savings ranging from 18% to 22%, in comparison to equal allocation of samples. The current activity of the subjects and the performance requirements do not significantly affect the optimal allocation, but employing personalized models results in improved energy-efficiency. As the number of samples is an integer, an exhaustive search to determine the optimal allocation is typical, but computationally expensive. To this end, an alternate, continuous-valued vector optimization is derived which yields approximately optimal allocations and can be implemented on the mobile fusion center due to its significantly lower complexity. PMID:21796237

Design and implementation of priority and time-window based traffic scheduling and routing-spectrum allocation mechanism in elastic optical networks

NASA Astrophysics Data System (ADS)

Wang, Honghuan; Xing, Fangyuan; Yin, Hongxi; Zhao, Nan; Lian, Bizhan

2016-02-01

With the explosive growth of network services, the reasonable traffic scheduling and efficient configuration of network resources have an important significance to increase the efficiency of the network. In this paper, an adaptive traffic scheduling policy based on the priority and time window is proposed and the performance of this algorithm is evaluated in terms of scheduling ratio. The routing and spectrum allocation are achieved by using the Floyd shortest path algorithm and establishing a node spectrum resource allocation model based on greedy algorithm, which is proposed by us. The fairness index is introduced to improve the capability of spectrum configuration. The results show that the designed traffic scheduling strategy can be applied to networks with multicast and broadcast functionalities, and makes them get real-time and efficient response. The scheme of node spectrum configuration improves the frequency resource utilization and gives play to the efficiency of the network.

Bandwidth efficient bidirectional 5 Gb/s overlapped-SCM WDM PON with electronic equalization and forward-error correction.

PubMed

Buset, Jonathan M; El-Sahn, Ziad A; Plant, David V

2012-06-18

We demonstrate an improved overlapped-subcarrier multiplexed (O-SCM) WDM PON architecture transmitting over a single feeder using cost sensitive intensity modulation/direct detection transceivers, data re-modulation and simple electronics. Incorporating electronic equalization and Reed-Solomon forward-error correction codes helps to overcome the bandwidth limitation of a remotely seeded reflective semiconductor optical amplifier (RSOA)-based ONU transmitter. The O-SCM architecture yields greater spectral efficiency and higher bit rates than many other SCM techniques while maintaining resilience to upstream impairments. We demonstrate full-duplex 5 Gb/s transmission over 20 km and analyze BER performance as a function of transmitted and received power. The architecture provides flexibility to network operators by relaxing common design constraints and enabling full-duplex operation at BER ∼ 10(-10) over a wide range of OLT launch powers from 3.5 to 8 dBm.

A scalable diffraction-based scanning 3D colour video display as demonstrated by using tiled gratings and a vertical diffuser

PubMed Central

Jia, Jia; Chen, Jhensi; Yao, Jun; Chu, Daping

2017-01-01

A high quality 3D display requires a high amount of optical information throughput, which needs an appropriate mechanism to distribute information in space uniformly and efficiently. This study proposes a front-viewing system which is capable of managing the required amount of information efficiently from a high bandwidth source and projecting 3D images with a decent size and a large viewing angle at video rate in full colour. It employs variable gratings to support a high bandwidth distribution. This concept is scalable and the system can be made compact in size. A horizontal parallax only (HPO) proof-of-concept system is demonstrated by projecting holographic images from a digital micro mirror device (DMD) through rotational tiled gratings before they are realised on a vertical diffuser for front-viewing. PMID:28304371

Distributed reservation control protocols for random access broadcasting channels

NASA Technical Reports Server (NTRS)

Greene, E. P.; Ephremides, A.

1981-01-01

Attention is given to a communication network consisting of an arbitrary number of nodes which can communicate with each other via a time-division multiple access (TDMA) broadcast channel. The reported investigation is concerned with the development of efficient distributed multiple access protocols for traffic consisting primarily of single packet messages in a datagram mode of operation. The motivation for the design of the protocols came from the consideration of efficient multiple access utilization of moderate to high bandwidth (4-40 Mbit/s capacity) communication satellite channels used for the transmission of short (1000-10,000 bits) fixed length packets. Under these circumstances, the ratio of roundtrip propagation time to packet transmission time is between 100 to 10,000. It is shown how a TDMA channel can be adaptively shared by datagram traffic and constant bandwidth users such as in digital voice applications. The distributed reservation control protocols described are a hybrid between contention and reservation protocols.

Four-dimensional modulation and coding: An alternate to frequency-reuse

NASA Technical Reports Server (NTRS)

Wilson, S. G.; Sleeper, H. A.

1983-01-01

Four dimensional modulation as a means of improving communication efficiency on the band-limited Gaussian channel, with the four dimensions of signal space constituted by phase orthogonal carriers (cos omega sub c t and sin omega sub c t) simultaneously on space orthogonal electromagnetic waves are discussed. "Frequency reuse' techniques use such polarization orthogonality to reuse the same frequency slot, but the modulation is not treated as four dimensional, rather a product of two-d modulations, e.g., QPSK. It is well known that, higher dimensionality signalling affords possible improvements in the power bandwidth sense. Four-D modulations based upon subsets of lattice-packings in four-D, which afford simplification of encoding and decoding are described. Sets of up to 1024 signals are constructed in four-D, providing a (Nyquist) spectral efficiency of up to 10 bps/Hz. Energy gains over the reuse technique are in the one to three dB range t equal bandwidth.

Four-dimensional modulation and coding - An alternate to frequency-reuse

NASA Technical Reports Server (NTRS)

Wilson, S. G.; Sleeper, H. A.; Srinath, N. K.

1984-01-01

Four dimensional modulation as a means of improving communication efficiency on the band-limited Gaussian channel, with the four dimensions of signal space constituted by phase orthogonal carriers (cos omega sub c t and sin omega sub c t) simultaneously on space orthogonal electromagnetic waves are discussed. 'Frequency reuse' techniques use such polarization orthogonality to reuse the same frequency slot, but the modulation is not treated as four dimensional, rather a product of two-D modulations, e.g., QPSK. It is well known that, higher dimensionality signalling affords possible improvements in the power bandwidth sense. Four-D modulations based upon subsets of lattice-packings in four-D, which afford simplification of encoding and decoding are described. Sets of up to 1024 signals are constructed in four-D, providing a (Nyquist) spectral efficiency of up to 10 bps/Hz. Energy gains over the reuse technique are in the one to three dB range t equal bandwidth.

520-µJ mid-infrared femtosecond laser at 2.8 µm by 1-kHz KTA optical parametric amplifier

NASA Astrophysics Data System (ADS)

He, Huijun; Wang, Zhaohua; Hu, Chenyang; Jiang, Jianwang; Qin, Shuang; He, Peng; Zhang, Ninghua; Yang, Peilong; Li, Zhiyuan; Wei, Zhiyi

2018-02-01

We report on a 520-µJ, 1-kHz mid-infrared femtosecond optical parametric amplifier system driven by a Ti:sapphire laser system. The seeding signal was generated from white-light continuum in YAG plate and then amplified in four non-collinear amplification stages and the idler was obtained in the last stage with central wavelength at 2.8 µm and bandwidth of 525 nm. To maximize the bandwidth of the idler, a theoretical method was developed to give an optimum non-collinear angle and estimate the conversion efficiency and output spectrum. As an experimental result, laser pulse energy up to 1.8 mJ for signal wave and 520 µJ for idler wave were obtained in the last stage under 10-mJ pump energy, corresponding to a pump-to-idler conversion efficiency of 5.2%, which meets well with the numerical calculation.

Cosmic Microwave Background Polarization Detector with High Efficiency, Broad Bandwidth, and Highly Symmetric Coupling to Transition Edge Sensor Bolometers

NASA Technical Reports Server (NTRS)

Wollack, E.; Cao, N.; Chuss, D.; Denis, K.; Hsieh, W.-T.; Moseley, S. Harvey; Schneider, G.; Stevenson, T.; Travers, D.; U-yen, K.

2008-01-01

Four probe antennas transfer signals from waveguide to microstrip lines. The probes not only provide broadband impedance matching, but also thermally isolate waveguide and detector. In addition, we developed a new photonic waveguide choke joint design, with four-fold symmetry, to suppress power leakage at the interface. We have developed facilities to test superconducting circuit elements using a cryogenic microwave probe station, and more complete systems in waveguide. We used the ring resonator shown below to measure a dielectric loss tangent < 7x10(exp -4) over 10 - 45 GHz. We have combined component simulations to predict the overall coupling from waveguide modes to bolometers. The result below shows the planar circuit and waveguide interface can utilize the high beam symmetry of HE11 circular feedhorns with > 99% coupling efficiency over 30% fractional bandwidth.

Achromatic electromagnetic metasurface for generating a vortex wave with orbital angular momentum (OAM).

PubMed

Jiang, Shan; Chen, Chang; Zhang, Hualiang; Chen, Weidong

2018-03-05

The vortex wave that carries orbital angular momentum has attracted much attention due to the fact that it can provide an extra degree of freedom for optical communication, imaging and other applications. In spite of this, the method of OAM generation at high frequency still suffers from limitations, such as chromatic aberration and low efficiency. In this paper, an azimuthally symmetric electromagnetic metasurface with wide bandwidth is designed, fabricated and experimentally demonstrated to efficiently convert a left-handed (right-handed) circularly polarized incident plane wave (with a spin angular momentum (SAM) of ћ) to a right-handed (left-handed) circularly polarized vortex wave with OAM. The design methodology based on the field equivalence principle is discussed in detail. The simulation and measurement results confirm that the proposed method provides an effective way for generating OAM-carrying vortex wave with comparative performance across a broad bandwidth.

Management of time-dependent multimedia data

NASA Astrophysics Data System (ADS)

Little, Thomas D.; Gibbon, John F.

1993-01-01

A number of approaches have been proposed for supporting high-bandwidth time-dependent multimedia data in a general purpose computing environment. Much of this work assumes the availability of ample resources such as CPU performance, bus, I/O, and communication bandwidth. However, many multimedia applications have large variations in instantaneous data presentation requirements (e.g., a dynamic range of order 100,000). By using a statistical scheduling approach these variations are effectively smoothed and, therefore, more applications are made viable. The result is a more efficient use of available bandwidth and the enabling of applications that have large short-term bandwidth requirements such as simultaneous video and still image retrieval. Statistical scheduling of multimedia traffic relies on accurate characterization or guarantee of channel bandwidth and delay. If guaranteed channel characteristics are not upheld due to spurious channel overload, buffer overflow and underflow can occur at the destination. The result is the loss of established source-destination synchronization and the introduction of intermedia skew. In this paper we present an overview of a proposed synchronization mechanism to limit the effects of such anomalous behavior. The proposed mechanism monitors buffer levels to detect impending low and high levels on frame basis and regulates the destination playout rate. Intermedia skew is controlled by a similar control algorithm. This mechanism is used in conjunction with a statistical source scheduling approach to provide an overall multimedia transmission and resynchronization system supporting graceful service degradation.

Data Acquisition Based on Stable Matching of Bipartite Graph in Cooperative Vehicle–Infrastructure Systems †

PubMed Central

Tang, Xiaolan; Hong, Donghui; Chen, Wenlong

2017-01-01

Existing studies on data acquisition in vehicular networks often take the mobile vehicular nodes as data carriers. However, their autonomous movements, limited resources and security risks impact the quality of services. In this article, we propose a data acquisition model using stable matching of bipartite graph in cooperative vehicle-infrastructure systems, namely, DAS. Contents are distributed to roadside units, while vehicular nodes support supplementary storage. The original distribution problem is formulated as a stable matching problem of bipartite graph, where the data and the storage cells compose two sides of vertices. Regarding the factors relevant with the access ratio and delay, the preference rankings for contents and roadside units are calculated, respectively. With a multi-replica preprocessing algorithm to handle the potential one-to-many mapping, the matching problem is addressed in polynomial time. In addition, vehicular nodes carry and forward assistant contents to deliver the failed packets because of bandwidth competition. Furthermore, an incentive strategy is put forward to boost the vehicle cooperation and to achieve a fair bandwidth allocation at roadside units. Experiments show that DAS achieves a high access ratio and a small storage cost with an acceptable delay. PMID:28594359

How Green Water Flows structure be a decision indicator for ecological water allocation in arid Ejina Delta, China.

NASA Astrophysics Data System (ADS)

Yu, J.; Du, C.; Zhang, Y.; Liu, X.

2014-12-01

Green water flows, a key ecohydrological process, dominates the hydrological cycle in arid region. The structure of green water flows reflects the landscape water consumption characteristics and can be easily obtained by means of remote sensing approach. In arid region, limited fresh water and fragile environment resulted in sharp contradictions between economy and natural ecosystem concerning water demands. To rationally allocate economic and ecological water use, to maximize the regional freshwater use efficiency, is the route one must take for sustainable development in arid area. The pursuit of the most necessary ecological protection function and the maximum ecological water use efficiency is the key to ecological water allocation. However, we are short of simple and quick detectable variables or indexes to assess ecological water allocation decision. This paper introduced the green water flows structure as a decision variable, chose Heihe river flow allocation to downstream Ejina Delta for ecological protection as an example, put forward why and how green water flows structure could be used for ecological water allocation decision. The authors expect to provide reference for integrated fresh water resources management practice in arid region.

Supply chain carbon footprinting and responsibility allocation under emission regulations.

PubMed

Chen, Jin-Xiao; Chen, Jian

2017-03-01

Reduction of greenhouse gas emissions has become an enormous challenge for any single enterprise and its supply chain because of the increasing concern on global warming. This paper investigates carbon footprinting and responsibility allocation for supply chains involved in joint production. Our study is conducted from the perspective of a social planner who aims to achieve social value optimization. The carbon footprinting model is based on operational activities rather than on firms because joint production blurs the organizational boundaries of footprints. A general model is proposed for responsibility allocation among firms who seek to maximize individual profits. This study looks into ways for the decentralized supply chain to achieve centralized optimality of social value under two emission regulations. Given a balanced allocation for the entire supply chain, we examine the necessity of over-allocation to certain firms under specific situations and find opportunities for the firms to avoid over-allocation. The comparison of the two regulations reveals that setting an emission standard per unit of product will motivate firms to follow the standard and improve their emission efficiencies. Hence, a more efficient and promising policy is needed in contrast to existing regulations on total production. Copyright © 2016 Elsevier Ltd. All rights reserved.

IEEE 802.15.4 MAC with GTS transmission for heterogeneous devices with application to wheelchair body-area sensor networks.

PubMed

Shrestha, Bharat; Hossain, Ekram; Camorlinga, Sergio

2011-09-01

In wireless personal area networks, such as wireless body-area sensor networks, stations or devices have different bandwidth requirements and, thus, create heterogeneous traffics. For such networks, the IEEE 802.15.4 medium access control (MAC) can be used in the beacon-enabled mode, which supports guaranteed time slot (GTS) allocation for time-critical data transmissions. This paper presents a general discrete-time Markov chain model for the IEEE 802.15.4-based networks taking into account the slotted carrier sense multiple access with collision avoidance and GTS transmission phenomena together in the heterogeneous traffic scenario and under nonsaturated condition. For this purpose, the standard GTS allocation scheme is modified. For each non-identical device, the Markov model is solved and the average service time and the service utilization factor are analyzed in the non-saturated mode. The analysis is validated by simulations using network simulator version 2.33. Also, the model is enhanced with a wireless propagation model and the performance of the MAC is evaluated in a wheelchair body-area sensor network scenario.

Opto-microwave, Butler matrixes based front-end for a multi-beam large direct radiating array antenna

NASA Astrophysics Data System (ADS)

Piqueras, M. A.; Mengual, T.; Navasquillo, O.; Sotom, M.; Caille, G.

2017-11-01

The evolution of broadband communication satellites shows a clear trend towards beam forming and beamswitching systems with efficient multiple access schemes with wide bandwidths, for which to be economically viable, the communication price shall be as low as possible. In such applications, the most demanding antenna concept is the Direct Radiating Array (DRA) since its use allows a flexible power allocation between beams and may afford failures in their active chains with low impact on the antenna radiating pattern. Forming multiple antenna beams, as for `multimedia via satellite' missions, can be done mainly in three ways: in microwave domain, by digital or optical processors: - Microwave beam-formers are strongly constrained by the mass and volume of microwave devices and waveguides - the bandwidth of digital processors is limited due to power consumption and complexity constraints. - The microwave photonics is an enabling technology that can improve the antenna feeding network performances, overcoming the limitations of the traditional technology in the more demanding scenarios, and may overcome the conventional RF beam-former issues, to generate accurately the very numerous time delays or phase shifts required in a DRA with a large number of beams and of radiating elements. Integrated optics technology can play a crucial role as an alternative technology for implementing beam-forming structures for satellite applications thanks to the well known advantages of this technology such as low volume and weight, huge electrical bandwidth, electro-magnetic interference immunity, low consumption, remote delivery capability with low-attenuation (by carrying all microwave signals over optical fibres) and the robustness and precision that exhibits integrated optics. Under the ESA contract 4000105095/12/NL/RA the consortium formed by DAS Photonics, Thales Alenia Space and the Nanophotonic Technology Center of Valencia is developing a three-dimensional Optical Beamforming Network (OBFN) based on integrated photonics, with fibre-optics remote antenna feeding capabilities, that addresses the requirements of SoA DRA antennas in space communications, able to feed potentially hundreds of antenna elements with hundred of simultaneous, orthogonal beams. The core of this OBFN is a Photonic Integrated Circuit (PIC) implementing a passive Butler matrix similar to the structure well known by the RF community, but overcoming the issues of scalability, size, compactness and manufacturability associated to the fact of addressing hundred of elements. This fully-integrated beam-former solution also overcomes the opto-mechanical issues and environmental sensitivity of other free-space based OBFNs.

Dependencies of surface plasmon coupling effects on the p-GaN thickness of a thin-p-type light-emitting diode.

PubMed

Su, Chia-Ying; Lin, Chun-Han; Yao, Yu-Feng; Liu, Wei-Heng; Su, Ming-Yen; Chiang, Hsin-Chun; Tsai, Meng-Che; Tu, Charng-Gan; Chen, Hao-Tsung; Kiang, Yean-Woei; Yang, C C

2017-09-04

The high performance of a light-emitting diode (LED) with the total p-type thickness as small as 38 nm is demonstrated. By increasing the Mg doping concentration in the p-AlGaN electron blocking layer through an Mg pre-flow process, the hole injection efficiency can be significantly enhanced. Based on this technique, the high LED performance can be maintained when the p-type layer thickness is significantly reduced. Then, the surface plasmon coupling effects, including the enhancement of internal quantum efficiency, increase in output intensity, reduction of efficiency droop, and increase of modulation bandwidth, among the thin p-type LED samples of different p-type thicknesses that are compared. These advantageous effects are stronger as the p-type layer becomes thinner. However, the dependencies of these effects on p-type layer thickness are different. With a circular mesa size of 10 μm in radius, through surface plasmon coupling, we achieve the record-high modulation bandwidth of 625.6 MHz among c-plane GaN-based LEDs.

Bandwidth efficient CCSDS coding standard proposals

NASA Technical Reports Server (NTRS)

Costello, Daniel J., Jr.; Perez, Lance C.; Wang, Fu-Quan

1992-01-01

The basic concatenated coding system for the space telemetry channel consists of a Reed-Solomon (RS) outer code, a symbol interleaver/deinterleaver, and a bandwidth efficient trellis inner code. A block diagram of this configuration is shown. The system may operate with or without the outer code and interleaver. In this recommendation, the outer code remains the (255,223) RS code over GF(2 exp 8) with an error correcting capability of t = 16 eight bit symbols. This code's excellent performance and the existence of fast, cost effective, decoders justify its continued use. The purpose of the interleaver/deinterleaver is to distribute burst errors out of the inner decoder over multiple codewords of the outer code. This utilizes the error correcting capability of the outer code more efficiently and reduces the probability of an RS decoder failure. Since the space telemetry channel is not considered bursty, the required interleaving depth is primarily a function of the inner decoding method. A diagram of an interleaver with depth 4 that is compatible with the (255,223) RS code is shown. Specific interleaver requirements are discussed after the inner code recommendations.

Design of a graphene-based dual-slot hybrid plasmonic electro-absorption modulator with high-modulation efficiency and broad optical bandwidth for on-chip communication.

PubMed

Wu, Zhongwei; Xu, Yin

2018-04-20

The hybrid plasmonic effect with lower loss and comparable light confinement than surface plasmon polariton opens new avenues for strengthening light-matter interactions with low loss. Here, we propose and numerically analyze a graphene-based electro-absorption modulator (EAM) with high-modulation efficiency and broad optical bandwidth using a dual-slot hybrid plasmonic waveguide (HPW), which consists of a central dual-slot HPW connected with two taper transitions and two additional dual-slot HPWs for coupling it with the input and output silicon nanowires, where graphene layers are located at the bottom and top side of the whole dual-slot HPW region. By combining the huge light enhancement effect of the dual-slot HPW and graphene's tunable conductivity, we obtain a high-modulation efficiency (ME) of 1.76 dB/μm for the graphene-based dual-slot HPW (higher ME of 2.19 dB/μm can also be obtained). Based upon this promising result, we further design a graphene-based hybrid plasmonic EAM, achieving a modulation depth (MD) of 15.95 dB and insertion loss of 1.89 dB @1.55 μm, respectively, in a total length of only 10 μm, where its bandwidth can reach over 500 nm for keeping MD>15  dB; MD can also be improved by slightly increasing the device length or shrinking the waveguide thickness, showing strong advantages for applying it into on-chip high-performance silicon modulators.

Torque blending and wheel slip control in EVs with in-wheel motors

NASA Astrophysics Data System (ADS)

de Castro, Ricardo; Araújo, Rui E.; Tanelli, Mara; Savaresi, Sergio M.; Freitas, Diamantino

2012-01-01

Among the many opportunities offered by electric vehicles (EVs), the design of power trains based on in-wheel electric motors represents, from the vehicle dynamics point of view, a very attractive prospect, mainly due to the torque-vectoring capabilities. However, this distributed propulsion also poses some practical challenges, owing to the constraints arising from motor installation in a confined space, to the increased unsprung mass weight and to the integration of the electric motor with the friction brakes. This last issue is the main theme of this work, which, in particular, focuses on the design of the anti-lock braking system (ABS). The proposed structure for the ABS is composed of a tyre slip controller, a wheel torque allocator and a braking supervisor. To address the slip regulation problem, an adaptive controller is devised, offering robustness to uncertainties in the tyre-road friction and featuring a gain-scheduling mechanism based on the vehicle velocity. Further, an optimisation framework is employed in the torque allocator to determine the optimal split between electric and friction brake torque based on energy performance metrics, actuator constraints and different actuators bandwidth. Finally, based on the EV working condition, the priorities of this allocation scheme are adapted by the braking supervisor unit. Simulation results obtained with the CarSim vehicle model, demonstrate the effectiveness of the overall approach.

112 Gb/s sub-cycle 16-QAM Nyquist-SCM for intra-datacenter connectivity

NASA Astrophysics Data System (ADS)

Bakopoulos, Paraskevas; Dris, Stefanos; Argyris, Nikolaos; Spatharakis, Christos; Avramopoulos, Hercules

2016-03-01

Datacenter traffic is exploding. Ongoing advancements in network infrastructure that ride on Moore's law are unable to keep up, necessitating the introduction of multiplexing and advanced modulation formats for optical interconnects in order to overcome bandwidth limitations, and scale lane speeds with energy- and cost-efficiency to 100 Gb/s and beyond. While the jury is still out as to how this will be achieved, schemes relying on intensity modulation with direct detection (IM/DD) are regarded as particularly attractive, due to their inherent implementation simplicity. Moreover, the scaling-out of datacenters calls for longer transmission reach exceeding 300 m, requiring single-mode solutions. In this work we advocate using 16-QAM sub-cycle Nyquist-SCM as a simpler alternative to discrete multitone (DMT), but which is still more bandwidth-efficient than PAM-4. The proposed optical interconnect is demonstrated at 112 Gb/s, which, to the best of our knowledge, is the highest rate achieved in a single-polarization implementation of SCM. Off-the-shelf components are used: A DFB laser, a 24.3 GHz electro-absorption modulator (EAM) and a limiting photoreceiver, combined with equalization through digital signal processing (DSP) at the receiver. The EAM is driven by a low-swing (<1 V) arbitrary waveform generator (AWG), which produces a 28 Gbaud 16-QAM electrical signal with carrier frequency at ~15 GHz. Tight spectral shaping is leveraged as a means of maintaining signal fidelity when using low-bandwidth electro-optic components; matched root-raised-cosine transmit and receive filters with 0.1 excess bandwidth are thus employed. Performance is assessed through transmission experiments over 1250 m and 2000 m of SMF.

In-line interferometer for broadband near-field scanning optical spectroscopy.

PubMed

Brauer, Jens; Zhan, Jinxin; Chimeh, Abbas; Korte, Anke; Lienau, Christoph; Gross, Petra

2017-06-26

We present and investigate a novel approach towards broad-bandwidth near-field scanning optical spectroscopy based on an in-line interferometer for homodyne mixing of the near field and a reference field. In scattering-type scanning near-field optical spectroscopy, the near-field signal is usually obscured by a large amount of unwanted background scattering from the probe shaft and the sample. Here we increase the light reflected from the sample by a semi-transparent gold layer and use it as a broad-bandwidth, phase-stable reference field to amplify the near-field signal in the visible and near-infrared spectral range. We experimentally demonstrate that this efficiently suppresses the unwanted background signal in monochromatic near-field measurements. For rapid acquisition of complete broad-bandwidth spectra we employ a monochromator and a fast line camera. Using this fast acquisition of spectra and the in-line interferometer we demonstrate the measurement of pure near-field spectra. The experimental observations are quantitatively explained by analytical expressions for the measured optical signals, based on Fourier decomposition of background and near field. The theoretical model and in-line interferometer together form an important step towards broad-bandwidth near-field scanning optical spectroscopy.

High-fidelity and low-latency mobile fronthaul based on segment-wise TDM and MIMO-interleaved arraying.

PubMed

Li, Longsheng; Bi, Meihua; Miao, Xin; Fu, Yan; Hu, Weisheng

2018-01-22

In this paper, we firstly demonstrate an advanced arraying scheme in the TDM-based analog mobile fronthaul system to enhance the signal fidelity, in which the segment of the antenna carrier signal (AxC) with an appropriate length is served as the granularity for TDM aggregation. Without introducing extra processing, the entire system can be realized by simple DSP. The theoretical analysis is presented to verify the feasibility of this scheme, and to evaluate its effectiveness, the experiment with ~7-GHz bandwidth and 20 8 × 8 MIMO group signals are conducted. Results show that the segment-wise TDM is completely compatible with the MIMO-interleaved arraying, which is employed in an existing TDM scheme to improve the bandwidth efficiency. Moreover, compared to the existing TDM schemes, our scheme can not only satisfy the latency requirement of 5G but also significantly reduce the multiplexed signal bandwidth, hence providing higher signal fidelity in the bandwidth-limited fronthaul system. The experimental result of EVM verifies that 256-QAM is supportable using the segment-wise TDM arraying with only 250-ns latency, while with the ordinary TDM arraying, only 64-QAM is bearable.

Extending the BEAGLE library to a multi-FPGA platform

PubMed Central

2013-01-01

Background Maximum Likelihood (ML)-based phylogenetic inference using Felsenstein’s pruning algorithm is a standard method for estimating the evolutionary relationships amongst a set of species based on DNA sequence data, and is used in popular applications such as RAxML, PHYLIP, GARLI, BEAST, and MrBayes. The Phylogenetic Likelihood Function (PLF) and its associated scaling and normalization steps comprise the computational kernel for these tools. These computations are data intensive but contain fine grain parallelism that can be exploited by coprocessor architectures such as FPGAs and GPUs. A general purpose API called BEAGLE has recently been developed that includes optimized implementations of Felsenstein’s pruning algorithm for various data parallel architectures. In this paper, we extend the BEAGLE API to a multiple Field Programmable Gate Array (FPGA)-based platform called the Convey HC-1. Results The core calculation of our implementation, which includes both the phylogenetic likelihood function (PLF) and the tree likelihood calculation, has an arithmetic intensity of 130 floating-point operations per 64 bytes of I/O, or 2.03 ops/byte. Its performance can thus be calculated as a function of the host platform’s peak memory bandwidth and the implementation’s memory efficiency, as 2.03 × peak bandwidth × memory efficiency. Our FPGA-based platform has a peak bandwidth of 76.8 GB/s and our implementation achieves a memory efficiency of approximately 50%, which gives an average throughput of 78 Gflops. This represents a ~40X speedup when compared with BEAGLE’s CPU implementation on a dual Xeon 5520 and 3X speedup versus BEAGLE’s GPU implementation on a Tesla T10 GPU for very large data sizes. The power consumption is 92 W, yielding a power efficiency of 1.7 Gflops per Watt. Conclusions The use of data parallel architectures to achieve high performance for likelihood-based phylogenetic inference requires high memory bandwidth and a design methodology that emphasizes high memory efficiency. To achieve this objective, we integrated 32 pipelined processing elements (PEs) across four FPGAs. For the design of each PE, we developed a specialized synthesis tool to generate a floating-point pipeline with resource and throughput constraints to match the target platform. We have found that using low-latency floating-point operators can significantly reduce FPGA area and still meet timing requirement on the target platform. We found that this design methodology can achieve performance that exceeds that of a GPU-based coprocessor. PMID:23331707

New Bandwidth Efficient Parallel Concatenated Coding Schemes

NASA Technical Reports Server (NTRS)

Denedetto, S.; Divsalar, D.; Montorsi, G.; Pollara, F.

1996-01-01

We propose a new solution to parallel concatenation of trellis codes with multilevel amplitude/phase modulations and a suitable iterative decoding structure. Examples are given for throughputs 2 bits/sec/Hz with 8PSK and 16QAM signal constellations.

1998 NASA Review: Center for Space Telemetering and Telecommunication Systems

NASA Technical Reports Server (NTRS)

Cunningham, Garry

1998-01-01

The following topics are included in the conference proceedings following the program overview: (1) Coding and Carrier Recovery Techniques; (2) Carrier Frequency Estimation Under Unknown Doppler Shifts; (3) Small Satellite Experiments; (4) Bandwidth Efficient Modulation/Equalization Techniques.

Market Model for Resource Allocation in Emerging Sensor Networks with Reinforcement Learning

PubMed Central

Zhang, Yue; Song, Bin; Zhang, Ying; Du, Xiaojiang; Guizani, Mohsen

2016-01-01

Emerging sensor networks (ESNs) are an inevitable trend with the development of the Internet of Things (IoT), and intend to connect almost every intelligent device. Therefore, it is critical to study resource allocation in such an environment, due to the concern of efficiency, especially when resources are limited. By viewing ESNs as multi-agent environments, we model them with an agent-based modelling (ABM) method and deal with resource allocation problems with market models, after describing users’ patterns. Reinforcement learning methods are introduced to estimate users’ patterns and verify the outcomes in our market models. Experimental results show the efficiency of our methods, which are also capable of guiding topology management. PMID:27916841

Efficient Simulation Budget Allocation for Selecting an Optimal Subset

NASA Technical Reports Server (NTRS)

Chen, Chun-Hung; He, Donghai; Fu, Michael; Lee, Loo Hay

2008-01-01

We consider a class of the subset selection problem in ranking and selection. The objective is to identify the top m out of k designs based on simulated output. Traditional procedures are conservative and inefficient. Using the optimal computing budget allocation framework, we formulate the problem as that of maximizing the probability of correc tly selecting all of the top-m designs subject to a constraint on the total number of samples available. For an approximation of this corre ct selection probability, we derive an asymptotically optimal allocat ion and propose an easy-to-implement heuristic sequential allocation procedure. Numerical experiments indicate that the resulting allocatio ns are superior to other methods in the literature that we tested, and the relative efficiency increases for larger problems. In addition, preliminary numerical results indicate that the proposed new procedur e has the potential to enhance computational efficiency for simulation optimization.

Energy-Efficient Optimal Power Allocation in Integrated Wireless Sensor and Cognitive Satellite Terrestrial Networks

PubMed Central

Li, Guangxia; An, Kang; Gao, Bin; Zheng, Gan

2017-01-01

This paper proposes novel satellite-based wireless sensor networks (WSNs), which integrate the WSN with the cognitive satellite terrestrial network. Having the ability to provide seamless network access and alleviate the spectrum scarcity, cognitive satellite terrestrial networks are considered as a promising candidate for future wireless networks with emerging requirements of ubiquitous broadband applications and increasing demand for spectral resources. With the emerging environmental and energy cost concerns in communication systems, explicit concerns on energy efficient resource allocation in satellite networks have also recently received considerable attention. In this regard, this paper proposes energy-efficient optimal power allocation schemes in the cognitive satellite terrestrial networks for non-real-time and real-time applications, respectively, which maximize the energy efficiency (EE) of the cognitive satellite user while guaranteeing the interference at the primary terrestrial user below an acceptable level. Specifically, average interference power (AIP) constraint is employed to protect the communication quality of the primary terrestrial user while average transmit power (ATP) or peak transmit power (PTP) constraint is adopted to regulate the transmit power of the satellite user. Since the energy-efficient power allocation optimization problem belongs to the nonlinear concave fractional programming problem, we solve it by combining Dinkelbach’s method with Lagrange duality method. Simulation results demonstrate that the fading severity of the terrestrial interference link is favorable to the satellite user who can achieve EE gain under the ATP constraint comparing to the PTP constraint. PMID:28869546

Research on Coupling Method of Watershed Initial Water Rights Allocation in Daling River

NASA Astrophysics Data System (ADS)

Liu, J.; Fengping, W.

2016-12-01

Water scarcity is now a common occurrence in many countries. The situation of watershed initial water rights allocation has caused many benefit conflicts among regions and regional water sectors of domestic and ecology environment and industries in China. This study aims to investigate the method of watershed initial water rights allocation in the perspective of coupling in Daling River Watershed taking provincial initial water rights and watershed-level governmental reserved water as objects. First of all, regarding the allocation subsystem of initial water rights among provinces, this research calculates initial water rights of different provinces by establishing the coupling model of water quantity and quality on the principle of "rewarding efficiency and penalizing inefficiency" based on the two control objectives of water quantity and quality. Secondly, regarding the allocation subsystem of watershed-level governmental reserved water rights, the study forecasts the demand of watershed-level governmental reserved water rights by the combination of case-based reasoning and water supply quotas. Then, the bilaterally coupled allocation model on water supply and demand is designed after supply analysis to get watershed-level governmental reserved water rights. The results of research method applied to Daling River Watershed reveal the recommended scheme of watershed initial water rights allocation based on coordinated degree criterion. It's found that the feasibility of the iteration coupling model and put forward related policies and suggestions. This study owns the advantages of complying with watershed initial water rights allocation mechanism and meeting the control requirements of water quantity, water quality and water utilization efficiency, which help to achieve the effective allocation of water resources.

High Efficiency Power Combining of Ka-Band TWTs for High Data Rate Communications

NASA Technical Reports Server (NTRS)

Wintucky, E. G.; Simons, R. N.; Vaden, K. R.; Lesny, G. G.; Glass, J. L.

2006-01-01

Future NASA deep space exploration missions are expected in some cases to require telecommunication systems capable of operating at very high data rates (potentially 1 Gbps or more) for the transmission back to Earth of large volumes of scientific data, which means high frequency transmitters with large bandwidth. Among the Ka band frequencies of interest are the present 500 MHz Deep Space Network (DSN) band of 31.8 to 32.3 GHz and a broader band at 37-38 GHz allocated for space science [1]. The large distances and use of practical antenna sizes dictate the need for high transmitter power of up to 1 kW or more. High electrical efficiency is also a requirement. The approach investigated by NASA GRC is a novel wave guide power combiner architecture based on a hybrid magic-T junction for combining the power output from multiple TWTs [1,2]. This architecture was successfully demonstrated and is capable of both high efficiency (90-95%, depending on frequency) and high data rate transmission (up to 622 Mbps) in a two-way power combiner circuit for two different pairs of Ka band TWTs at two different frequency bands. One pair of TWTs, tested over a frequency range of 29.1 to 29.6 GHz, consisted of two 110-115W TWTs previously used in uplink data transmission evaluation terminals in the NASA Advanced Communications Technology Satellite (ACTS) program [1,2]. The second pair was two 100W TWTs (Boeing 999H) designed for high efficiency operation (greater than 55%) over the DSN frequency band of 31.8 to 32.3 GHz [3]. The presentation will provide a qualitative description of the wave guide circuit, results for power combining and data transmission measurements, and results of computer modeling of the magic-T and alternative hybrid junctions for improvements in efficiency and power handling capability. The power combiner results presented here are relevant not only to NASA deep space exploration missions, but also to other U.S. Government agency programs.

Sharing the cost of river basin adaptation portfolios to climate change: Insights from social justice and cooperative game theory

NASA Astrophysics Data System (ADS)

Girard, Corentin; Rinaudo, Jean-Daniel; Pulido-Velazquez, Manuel

2016-10-01

The adaptation of water resource systems to the potential impacts of climate change requires mixed portfolios of supply and demand adaptation measures. The issue is not only to select efficient, robust, and flexible adaptation portfolios but also to find equitable strategies of cost allocation among the stakeholders. Our work addresses such cost allocation problems by applying two different theoretical approaches: social justice and cooperative game theory in a real case study. First of all, a cost-effective portfolio of adaptation measures at the basin scale is selected using a least-cost optimization model. Cost allocation solutions are then defined based on economic rationality concepts from cooperative game theory (the Core). Second, interviews are conducted to characterize stakeholders' perceptions of social justice principles associated with the definition of alternatives cost allocation rules. The comparison of the cost allocation scenarios leads to contrasted insights in order to inform the decision-making process at the river basin scale and potentially reap the efficiency gains from cooperation in the design of river basin adaptation portfolios.

Auctions with Dynamic Populations: Efficiency and Revenue Maximization

NASA Astrophysics Data System (ADS)

Said, Maher

We study a stochastic sequential allocation problem with a dynamic population of privately-informed buyers. We characterize the set of efficient allocation rules and show that a dynamic VCG mechanism is both efficient and periodic ex post incentive compatible; we also show that the revenue-maximizing direct mechanism is a pivot mechanism with a reserve price. We then consider sequential ascending auctions in this setting, both with and without a reserve price. We construct equilibrium bidding strategies in this indirect mechanism where bidders reveal their private information in every period, yielding the same outcomes as the direct mechanisms. Thus, the sequential ascending auction is a natural institution for achieving either efficient or optimal outcomes.

Potential of dynamic spectrum allocation in LTE macro networks

NASA Astrophysics Data System (ADS)

Hoffmann, H.; Ramachandra, P.; Kovács, I. Z.; Jorguseski, L.; Gunnarsson, F.; Kürner, T.

2015-11-01

In recent years Mobile Network Operators (MNOs) worldwide are extensively deploying LTE networks in different spectrum bands and utilising different bandwidth configurations. Initially, the deployment is coverage oriented with macro cells using the lower LTE spectrum bands. As the offered traffic (i.e. the requested traffic from the users) increases the LTE deployment evolves with macro cells expanded with additional capacity boosting LTE carriers in higher frequency bands complemented with micro or small cells in traffic hotspot areas. For MNOs it is crucial to use the LTE spectrum assets, as well as the installed network infrastructure, in the most cost efficient way. The dynamic spectrum allocation (DSA) aims at (de)activating the available LTE frequency carriers according to the temporal and spatial traffic variations in order to increase the overall LTE system performance in terms of total network capacity by reducing the interference. This paper evaluates the DSA potential of achieving the envisaged performance improvement and identifying in which system and traffic conditions the DSA should be deployed. A self-optimised network (SON) DSA algorithm is also proposed and evaluated. The evaluations have been carried out in a hexagonal and a realistic site-specific urban macro layout assuming a central traffic hotspot area surrounded with an area of lower traffic with a total size of approximately 8 × 8 km2. The results show that up to 47 % and up to 40 % possible DSA gains are achievable with regards to the carried system load (i.e. used resources) for homogenous traffic distribution with hexagonal layout and for realistic site-specific urban macro layout, respectively. The SON DSA algorithm evaluation in a realistic site-specific urban macro cell deployment scenario including realistic non-uniform spatial traffic distribution shows insignificant cell throughput (i.e. served traffic) performance gains. Nevertheless, in the SON DSA investigations, a gain of up to 25 % has been observed when analysing the resource utilisation in the non-hotspot cells.

Remote Energy Monitoring System via Cellular Network

NASA Astrophysics Data System (ADS)

Yunoki, Shoji; Tamaki, Satoshi; Takada, May; Iwaki, Takashi

Recently, improvement on power saving and cost efficiency by monitoring the operation status of various facilities over the network has gained attention. Wireless network, especially cellular network, has advantage in mobility, coverage, and scalability. On the other hand, it has disadvantage of low reliability, due to rapid changes in the available bandwidth. We propose a transmission control scheme based on data priority and instantaneous available bandwidth to realize a highly reliable remote monitoring system via cellular network. We have developed our proposed monitoring system and evaluated the effectiveness of our scheme, and proved it reduces the maximum transmission delay of sensor status to 1/10 compared to best effort transmission.

Flat-top passband filter based on parallel-coupled double microring resonators in silicon

NASA Astrophysics Data System (ADS)

Huang, Qingzhong; Xiao, Xi; Li, Yuntao; Li, Zhiyong; Yu, Yude; Yu, Jinzhong

2009-08-01

Optical filters with box-like response were designed and realized based on parallel-coupled double microrings in silicon-on-insulator. The properties of this design are simulated, considering the impact of the center-to-center distance of two rings, and coupling efficiency. Flat-top passband in the drop channel of the fabricated device was demonstrated with a 1dB bandwidth of 0.82nm, a 1dB/10dB bandwidth ratio of 0.51, an out of band rejection ratio of 14.6dB, as well as a free spectrum range of 13.6nm.

Livermore Big Artificial Neural Network Toolkit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Essen, Brian Van; Jacobs, Sam; Kim, Hyojin

2016-07-01

LBANN is a toolkit that is designed to train artificial neural networks efficiently on high performance computing architectures. It is optimized to take advantages of key High Performance Computing features to accelerate neural network training. Specifically it is optimized for low-latency, high bandwidth interconnects, node-local NVRAM, node-local GPU accelerators, and high bandwidth parallel file systems. It is built on top of the open source Elemental distributed-memory dense and spars-direct linear algebra and optimization library that is released under the BSD license. The algorithms contained within LBANN are drawn from the academic literature and implemented to work within a distributed-memory framework.

Broadband chirality and asymmetric transmission in ultrathin 90°-twisted Babinet-inverted metasurfaces

NASA Astrophysics Data System (ADS)

Shi, J. H.; Ma, H. F.; Guan, C. Y.; Wang, Z. P.; Cui, T. J.

2014-04-01

A broadband asymmetric transmission of linearly polarized waves with totally suppressed copolarization transmission is experimentally demonstrated in ultrathin 90°-twisted Babinet-inverted metasurfaces constructed by an array of asymmetrically split ring apertures. The only accessible direction-dependent cross-polarization transmission is allowed in this anisotropic chiral metamaterial. Through full-wave simulation and experiment results, the bilayered Babinet-inverted metasurface reveals broadband artificial chirality and asymmetric transmission, with a transmission contrast that is better than 17.7 dB within a 50% relative bandwidth for two opposite directions. In particular, we can modify polarization conversion efficiency and the bandwidth of asymmetric transmission via parametric study.

Enhancement of color saturation and color gamut enabled by a dual-band color filter exhibiting an adjustable spectral response.

PubMed

Shrestha, Vivek Raj; Park, Chul-Soon; Lee, Sang-Shin

2014-02-10

The enhancement of color saturation and color gamut has been demonstrated, by taking advantage of a dual-band color filter based on a subwavelength rectangular metal-dielectric resonant grating, which exhibits an adjustable spectral response with respect to its relative transmittances at the two bands of green and red, thereby producing any color in between green and red, through the adjustment of incoming light polarization. Also, the prominent features of the spectral response of the filter, namely the bandwidth and resonant wavelength, can be readily adjusted by varying the dielectric layer thickness and the grating pitch, respectively. The dependence of chromaticity coordinates of the filter in the CIE (International Commission on Illumination) 1931 chromaticity diagram upon the parameters of the spectral response, including the center wavelength, spectral bandwidth and sideband level, has been rigorously examined, and their influence on the color gamut and the excitation purity, which is a colorimetric measure of saturation, has been analytically explored at the same time, in order to optimize the color performance of the filters. In particular, a device with wider spectral bandwidth was observed to efficiently extend the color gamut and enhance the color saturation, i.e. the excitation purity for a given sideband level. Two dual-band green-red filters, exhibiting different bandwidths of about 17 and 36 nm, were specifically designed and fabricated. As compared with the case with narrower bandwidth, the device with wider bandwidth was observed to provide both higher excitation purity leading to better color saturation and greater separation of the chromaticity coordinates for the filter output for different incident polarizations, which provides extended color gamut. The proposed device structure may permit the color tuning span to encompass all primary color bands, by adjusting the grating pitch.

Adiabatic and fast passage ultra-wideband inversion in pulsed EPR.

PubMed

Doll, Andrin; Pribitzer, Stephan; Tschaggelar, René; Jeschke, Gunnar

2013-05-01

We demonstrate that adiabatic and fast passage ultra-wideband (UWB) pulses can achieve inversion over several hundreds of MHz and thus enhance the measurement sensitivity, as shown by two selected experiments. Technically, frequency-swept pulses are generated by a 12 GS/s arbitrary waveform generator and upconverted to X-band frequencies. This pulsed UWB source is utilized as an incoherent channel in an ordinary pulsed EPR spectrometer. We discuss experimental methodologies and modeling techniques to account for the response of the resonator, which can strongly limit the excitation bandwidth of the entire non-linear excitation chain. Aided by these procedures, pulses compensated for bandwidth or variations in group delay reveal enhanced inversion efficiency. The degree of bandwidth compensation is shown to depend critically on the time available for excitation. As a result, we demonstrate optimized inversion recovery and double electron electron resonance (DEER) experiments. First, virtually complete inversion of the nitroxide spectrum with an adiabatic pulse of 128ns length is achieved. Consequently, spectral diffusion between inverted and non-inverted spins is largely suppressed and the observation bandwidth can be increased to increase measurement sensitivity. Second, DEER is performed on a terpyridine-based copper (II) complex with a nitroxide-copper distance of 2.5nm. As previously demonstrated on this complex, when pumping copper spins and observing nitroxide spins, the modulation depth is severely limited by the excitation bandwidth of the pump pulse. By using fast passage UWB pulses with a maximum length of 64ns, we achieve up to threefold enhancement of the modulation depth. Associated artifacts in distance distributions when increasing the bandwidth of the pump pulse are shown to be small. Copyright © 2013 Elsevier Inc. All rights reserved.

An analysis of stock market efficiency: Developed vs Islamic stock markets using MF-DFA

NASA Astrophysics Data System (ADS)

Rizvi, Syed Aun R.; Dewandaru, Ginanjar; Bacha, Obiyathulla I.; Masih, Mansur

An efficient market has been theoretically proven to be a key component for effective and efficient resource allocation in an economy. This paper incorporates econophysics with Efficient Market Hypothesis to undertake a comparative analysis of Islamic and developed countries’ markets by extending the understanding of their multifractal nature. By applying the Multifractal Detrended Fluctuation Analysis (MFDFA) we calculated the generalized Hurst exponents, multifractal scaling exponents and generalized multifractal dimensions for 22 broad market indices. The findings provide a deeper understanding of the markets in Islamic countries, where they have traces of highly efficient performance particularly in crisis periods. A key finding is the empirical evidence of the impact of the ‘stage of market development’ on the efficiency of the market. If Islamic countries aim to improve the efficiency of resource allocation, an important area to address is to focus, among others, on enhancing the stage of market development.

T1 weighted fat/water separated PROPELLER acquired with dual bandwidths.

PubMed

Rydén, Henric; Berglund, Johan; Norbeck, Ola; Avventi, Enrico; Skare, Stefan

2018-04-24

To describe a fat/water separated dual receiver bandwidth (rBW) spin echo PROPELLER sequence that eliminates the dead time associated with single rBW sequences. A nonuniform noise whitening by regularization of the fat/water inverse problem is proposed, to enable dual rBW reconstructions. Bipolar, flyback, and dual spin echo sequences were developed. All sequences acquire two echoes with different rBW without dead time. Chemical shift displacement was corrected by performing the fat/water separation in k-space, prior to gridding. The proposed sequences were compared to fat saturation, and single rBW sequences, in terms of SNR and CNR efficiency, using clinically relevant acquisition parameters. The impact of motion was investigated. Chemical shift correction greatly improved the image quality, especially at high resolution acquired with low rBW, and also improved motion estimates. SNR efficiency of the dual spin echo sequence was up to 20% higher than the single rBW acquisition, while CNR efficiency was 50% higher for the bipolar acquisition. Noise whitening was deemed necessary for all dual rBW acquisitions, rendering high image quality with strong and homogenous fat suppression. Dual rBW sequences eliminate the dead time present in single rBW sequences, which improves SNR efficiency. In combination with the proposed regularization, this enables highly efficient T1-weighted PROPELLER images without chemical shift displacement. © 2018 International Society for Magnetic Resonance in Medicine.

Multimedia transmission in MC-CDMA using adaptive subcarrier power allocation and CFO compensation

NASA Astrophysics Data System (ADS)

Chitra, S.; Kumaratharan, N.

2018-02-01

Multicarrier code division multiple access (MC-CDMA) system is one of the most effective techniques in fourth-generation (4G) wireless technology, due to its high data rate, high spectral efficiency and resistance to multipath fading. However, MC-CDMA systems are greatly deteriorated by carrier frequency offset (CFO) which is due to Doppler shift and oscillator instabilities. It leads to loss of orthogonality among the subcarriers and causes intercarrier interference (ICI). Water filling algorithm (WFA) is an efficient resource allocation algorithm to solve the power utilisation problems among the subcarriers in time-dispersive channels. The conventional WFA fails to consider the effect of CFO. To perform subcarrier power allocation with reduced CFO and to improve the capacity of MC-CDMA system, residual CFO compensated adaptive subcarrier power allocation algorithm is proposed in this paper. The proposed technique allocates power only to subcarriers with high channel to noise power ratio. The performance of the proposed method is evaluated using random binary data and image as source inputs. Simulation results depict that the bit error rate performance and ICI reduction capability of the proposed modified WFA offered superior performance in both power allocation and image compression for high-quality multimedia transmission in the presence of CFO and imperfect channel state information conditions.

Light energy partitioning, photosynthetic efficiency and biomass allocation in invasive Prunus serotina and native Quercus petraea in relation to light environment, competition and allelopathy.

PubMed

Robakowski, Piotr; Bielinis, Ernest; Sendall, Kerrie

2018-05-01

This study addressed whether competition under different light environments was reflected by changes in leaf absorbed light energy partitioning, photosynthetic efficiency, relative growth rate and biomass allocation in invasive and native competitors. Additionally, a potential allelopathic effect of mulching with invasive Prunus serotina leaves on native Quercus petraea growth and photosynthesis was tested. The effect of light environment on leaf absorbed light energy partitioning and photosynthetic characteristics was more pronounced than the effects of interspecific competition and allelopathy. The quantum yield of PSII of invasive P. serotina increased in the presence of a competitor, indicating a higher plasticity in energy partitioning for the invasive over the native Q. petraea, giving it a competitive advantage. The most striking difference between the two study species was the higher crown-level net CO 2 assimilation rates (A crown ) of P. serotina compared with Q. petraea. At the juvenile life stage, higher relative growth rate and higher biomass allocation to foliage allowed P. serotina to absorb and use light energy for photosynthesis more efficiently than Q. petraea. Species-specific strategies of growth, biomass allocation, light energy partitioning and photosynthetic efficiency varied with the light environment and gave an advantage to the invader over its native competitor in competition for light. However, higher biomass allocation to roots in Q. petraea allows for greater belowground competition for water and nutrients as compared to P. serotina. This niche differentiation may compensate for the lower aboveground competitiveness of the native species and explain its ability to co-occur with the invasive competitor in natural forest settings.

Water resources planning and management : A stochastic dual dynamic programming approach

NASA Astrophysics Data System (ADS)

Goor, Q.; Pinte, D.; Tilmant, A.

2008-12-01

Allocating water between different users and uses, including the environment, is one of the most challenging task facing water resources managers and has always been at the heart of Integrated Water Resources Management (IWRM). As water scarcity is expected to increase over time, allocation decisions among the different uses will have to be found taking into account the complex interactions between water and the economy. Hydro-economic optimization models can capture those interactions while prescribing efficient allocation policies. Many hydro-economic models found in the literature are formulated as large-scale non linear optimization problems (NLP), seeking to maximize net benefits from the system operation while meeting operational and/or institutional constraints, and describing the main hydrological processes. However, those models rarely incorporate the uncertainty inherent to the availability of water, essentially because of the computational difficulties associated stochastic formulations. The purpose of this presentation is to present a stochastic programming model that can identify economically efficient allocation policies in large-scale multipurpose multireservoir systems. The model is based on stochastic dual dynamic programming (SDDP), an extension of traditional SDP that is not affected by the curse of dimensionality. SDDP identify efficient allocation policies while considering the hydrologic uncertainty. The objective function includes the net benefits from the hydropower and irrigation sectors, as well as penalties for not meeting operational and/or institutional constraints. To be able to implement the efficient decomposition scheme that remove the computational burden, the one-stage SDDP problem has to be a linear program. Recent developments improve the representation of the non-linear and mildly non- convex hydropower function through a convex hull approximation of the true hydropower function. This model is illustrated on a cascade of 14 reservoirs on the Nile river basin.

Makalu: fast recoverable allocation of non-volatile memory

DOE PAGES

Bhandari, Kumud; Chakrabarti, Dhruva R.; Boehm, Hans-J.

2016-10-19

Byte addressable non-volatile memory (NVRAM) is likely to supplement, and perhaps eventually replace, DRAM. Applications can then persist data structures directly in memory instead of serializing them and storing them onto a durable block device. However, failures during execution can leave data structures in NVRAM unreachable or corrupt. In this paper, we present Makalu, a system that addresses non-volatile memory management. Makalu offers an integrated allocator and recovery-time garbage collector that maintains internal consistency, avoids NVRAM memory leaks, and is efficient, all in the face of failures. We show that a careful allocator design can support a less restrictive andmore » a much more familiar programming model than existing persistent memory allocators. Our allocator significantly reduces the per allocation persistence overhead by lazily persisting non-essential metadata and by employing a post-failure recovery-time garbage collector. Experimental results show that the resulting online speed and scalability of our allocator are comparable to well-known transient allocators, and significantly better than state-of-the-art persistent allocators.« less

Makalu: fast recoverable allocation of non-volatile memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhandari, Kumud; Chakrabarti, Dhruva R.; Boehm, Hans-J.

Byte addressable non-volatile memory (NVRAM) is likely to supplement, and perhaps eventually replace, DRAM. Applications can then persist data structures directly in memory instead of serializing them and storing them onto a durable block device. However, failures during execution can leave data structures in NVRAM unreachable or corrupt. In this paper, we present Makalu, a system that addresses non-volatile memory management. Makalu offers an integrated allocator and recovery-time garbage collector that maintains internal consistency, avoids NVRAM memory leaks, and is efficient, all in the face of failures. We show that a careful allocator design can support a less restrictive andmore » a much more familiar programming model than existing persistent memory allocators. Our allocator significantly reduces the per allocation persistence overhead by lazily persisting non-essential metadata and by employing a post-failure recovery-time garbage collector. Experimental results show that the resulting online speed and scalability of our allocator are comparable to well-known transient allocators, and significantly better than state-of-the-art persistent allocators.« less

Advanced technology satellite demodulator development

NASA Technical Reports Server (NTRS)

Ames, Stephen A.

1989-01-01

Ford Aerospace has developed a proof-of-concept satellite 8 phase shift keying (PSK) modulation and coding system operating in the Time Division Multiple Access (TDMA) mode at a data range of 200 Mbps using rate 5/6 forward error correction coding. The 80 Msps 8 PSK modem was developed in a mostly digital form and is amenable to an ASIC realization in the next phase of development. The codec was developed as a paper design only. The power efficiency goal was to be within 2 dB of theoretical at a bit error rate (BER) of 5x10(exp 7) while the measured implementation loss was 4.5 dB. The bandwidth efficiency goal was 2 bits/sec/Hz while the realized bandwidth efficiency was 1.8 bits/sec/Hz. The burst format used a preamble of only 40 8 PSK symbol times including 32 symbols of all zeros and an eight symbol unique word. The modem and associated special test equipment (STE) were fabricated mostly on a specially designed stitch-weld board although a few of the highest rate circuits were built on printed circuit cards. All the digital circuits were ECL to support the clock rates of from 80 MHz to 360 MHz. The transmitter and receiver matched filters were square-root Nyquist bandpass filters realized at the 3.37 GHz i.f. The modem operated as a coherent system although no analog phase locked (PLL) loop was employed. Within the budgetary constraints of the program, the approach to the demodulator has been proven and is eligible to proceed to the next phase of development of a satellite demodulator engineering model. This would entail the development of an ASIC version of the digital portion of the demodulator, and MMIC version of the quadrature detector, and SAW Nyquist filters to realize the bandwidth efficiency.

Performance Optimization of Priority Assisted CSMA/CA Mechanism of 802.15.6 under Saturation Regime

PubMed Central

Shakir, Mustafa; Rehman, Obaid Ur; Rahim, Mudassir; Alrajeh, Nabil; Khan, Zahoor Ali; Khan, Mahmood Ashraf; Niaz, Iftikhar Azim; Javaid, Nadeem

2016-01-01

Due to the recent development in the field of Wireless Sensor Networks (WSNs), the Wireless Body Area Networks (WBANs) have become a major area of interest for the developers and researchers. Human body exhibits postural mobility due to which distance variation occurs and the status of connections amongst sensors change time to time. One of the major requirements of WBAN is to prolong the network lifetime without compromising on other performance measures, i.e., delay, throughput and bandwidth efficiency. Node prioritization is one of the possible solutions to obtain optimum performance in WBAN. IEEE 802.15.6 CSMA/CA standard splits the nodes with different user priorities based on Contention Window (CW) size. Smaller CW size is assigned to higher priority nodes. This standard helps to reduce delay, however, it is not energy efficient. In this paper, we propose a hybrid node prioritization scheme based on IEEE 802.15.6 CSMA/CA to reduce energy consumption and maximize network lifetime. In this scheme, optimum performance is achieved by node prioritization based on CW size as well as power in respective user priority. Our proposed scheme reduces the average back off time for channel access due to CW based prioritization. Additionally, power based prioritization for a respective user priority helps to minimize required number of retransmissions. Furthermore, we also compare our scheme with IEEE 802.15.6 CSMA/CA standard (CW assisted node prioritization) and power assisted node prioritization under postural mobility in WBAN. Mathematical expressions are derived to determine the accurate analytical model for throughput, delay, bandwidth efficiency, energy consumption and life time for each node prioritization scheme. With the intention of analytical model validation, we have performed the simulations in OMNET++/MIXIM framework. Analytical and simulation results show that our proposed hybrid node prioritization scheme outperforms other node prioritization schemes in terms of average network delay, average throughput, average bandwidth efficiency and network lifetime. PMID:27598167

Efficient Hybrid Watermarking Scheme for Security and Transmission Bit Rate Enhancement of 3D Color-Plus-Depth Video Communication

NASA Astrophysics Data System (ADS)

El-Shafai, W.; El-Rabaie, S.; El-Halawany, M.; Abd El-Samie, F. E.

2018-03-01

Three-Dimensional Video-plus-Depth (3DV + D) comprises diverse video streams captured by different cameras around an object. Therefore, there is a great need to fulfill efficient compression to transmit and store the 3DV + D content in compressed form to attain future resource bounds whilst preserving a decisive reception quality. Also, the security of the transmitted 3DV + D is a critical issue for protecting its copyright content. This paper proposes an efficient hybrid watermarking scheme for securing the 3DV + D transmission, which is the homomorphic transform based Singular Value Decomposition (SVD) in Discrete Wavelet Transform (DWT) domain. The objective of the proposed watermarking scheme is to increase the immunity of the watermarked 3DV + D to attacks and achieve adequate perceptual quality. Moreover, the proposed watermarking scheme reduces the transmission-bandwidth requirements for transmitting the color-plus-depth 3DV over limited-bandwidth wireless networks through embedding the depth frames into the color frames of the transmitted 3DV + D. Thus, it saves the transmission bit rate and subsequently it enhances the channel bandwidth-efficiency. The performance of the proposed watermarking scheme is compared with those of the state-of-the-art hybrid watermarking schemes. The comparisons depend on both the subjective visual results and the objective results; the Peak Signal-to-Noise Ratio (PSNR) of the watermarked frames and the Normalized Correlation (NC) of the extracted watermark frames. Extensive simulation results on standard 3DV + D sequences have been conducted in the presence of attacks. The obtained results confirm that the proposed hybrid watermarking scheme is robust in the presence of attacks. It achieves not only very good perceptual quality with appreciated PSNR values and saving in the transmission bit rate, but also high correlation coefficient values in the presence of attacks compared to the existing hybrid watermarking schemes.

Tracking historical increases in nitrogen-driven crop production possibilities

NASA Astrophysics Data System (ADS)

Mueller, N. D.; Lassaletta, L.; Billen, G.; Garnier, J.; Gerber, J. S.

2015-12-01

The environmental costs of nitrogen use have prompted a focus on improving the efficiency of nitrogen use in the global food system, the primary source of nitrogen pollution. Typical approaches to improving agricultural nitrogen use efficiency include more targeted field-level use (timing, placement, and rate) and modification of the crop mix. However, global efficiency gains can also be achieved by improving the spatial allocation of nitrogen between regions or countries, due to consistent diminishing returns at high nitrogen use. This concept is examined by constructing a tradeoff frontier (or production possibilities frontier) describing global crop protein yield as a function of applied nitrogen from all sources, given optimal spatial allocation. Yearly variation in country-level input-output nitrogen budgets are utilized to parameterize country-specific hyperbolic yield-response models. Response functions are further characterized for three ~15-year eras beginning in 1961, and series of calculations uses these curves to simulate optimal spatial allocation in each era and determine the frontier. The analyses reveal that excess nitrogen (in recent years) could be reduced by ~40% given optimal spatial allocation. Over time, we find that gains in yield potential and in-country nitrogen use efficiency have led to increases in the global nitrogen production possibilities frontier. However, this promising shift has been accompanied by an actual spatial distribution of nitrogen use that has become less optimal, in an absolute sense, relative to the frontier. We conclude that examination of global production possibilities is a promising approach to understanding production constraints and efficiency opportunities in the global food system.

Optimization of an Offset Receiver Optics for Radio Telescopes

NASA Astrophysics Data System (ADS)

Yeap, Kim Ho; Tham, Choy Yoong

2018-01-01

The latest generation of Cassegrain radio astronomy antennas is designed for multiple frequency bands with receivers for individual bands offset from the antenna axis. The offset feed arrangement typically has two focusing elements in the form of ellipsoidal mirrors in the optical path between the feed horn and the antenna focus. This arrangement aligns the beam from the offset feed horn to illuminate the subreflector. The additional focusing elements increase the number of design variables, namely the distances between the horn aperture and the first mirror and that between the two mirrors, and their focal lengths. There are a huge number of possible combinations of these four variables in which the optics system can take on. The design aim is to seek the combination that will give the optimum antenna efficiency, not only at the centre frequency of the particular band but also across its bandwidth. To pick the optimum combination of the variables, it requires working through, by computational mean, a continuum range of variable values at different frequencies which will fit the optics system within the allocated physical space. Physical optics (PO) is a common technique used in optics design. However, due to the repeated iteration of the huge number of computation involved, the use of PO is not feasible. We present a procedure based on using multimode Gaussian optics to pick the optimum design and using PO for final verification of the system performance. The best antenna efficiency is achieved when the beam illuminating the subreflector is truncated with the optimum edge taper. The optimization procedure uses the beam's edge taper at the subreflector as the iteration target. The band 6 receiver optics design for the Atacama Large Millimetre Array (ALMA) antenna is used to illustrate the optimization procedure.

Double mushroom 1.55-μm waveguide photodetectors for integrated E-band (60-90 GHz) wireless transmitter modules

NASA Astrophysics Data System (ADS)

Rymanov, Vitaly; Tekin, Tolga; Stöhr, Andreas

2012-03-01

High data rate photonic wireless systems operating at millimeter wave carrier frequencies are considered as a disruptive technology e.g. for reach extension in optical access networks and for mobile backhauling. Recently, we demonstrated 60 GHz photonic wireless systems with record data rates up to 27 Gbit/s. Because of the oxygen absorption at 60 GHz, it is beneficial for fixed wireless systems with spans exceeding 1 km to operate at even higher frequencies. Here, the recently regulated 10 GHz bandwidth within the E-band (60-90 GHz) is of particular interest, covering the 71-76 GHz and 81-86 GHz allocations for multi-gigabit wireless transmission. For this purpose, wideband waveguide photodetectors with high external quantum efficiency are required. Here, we report on double mushroom 1.55 μm waveguide photodetectors for integration in an E-band wireless transmitter module. The developed photodetector consists of a partially p-doped, partly non-intentionally doped absorbing layer centered in a mushroom-type optical waveguide, overcoming the compromise between the junction capacitance and the series resistance. For efficient fiber-chip coupling, a second mushroom-type passive optical waveguide is used. In contrast to the conventional shallow ridge waveguide approach, the mushroom-type passive waveguide allows to shift the center of the optical mode further away from the top surface, thus reducing waveguide losses due to the surface roughness. Experimentally, a very flat frequency response with a deviation up to +/-1 dB in the entire E-band has been found together with an output power level of -15.7 dBm at 10 mA photocurrent and at a frequency of 73 GHz.

Single-electron pulses for ultrafast diffraction

PubMed Central

Aidelsburger, M.; Kirchner, F. O.; Krausz, F.; Baum, P.

2010-01-01

Visualization of atomic-scale structural motion by ultrafast electron diffraction and microscopy requires electron packets of shortest duration and highest coherence. We report on the generation and application of single-electron pulses for this purpose. Photoelectric emission from metal surfaces is studied with tunable ultraviolet pulses in the femtosecond regime. The bandwidth, efficiency, coherence, and electron pulse duration are investigated in dependence on excitation wavelength, intensity, and laser bandwidth. At photon energies close to the cathode’s work function, the electron pulse duration shortens significantly and approaches a threshold that is determined by interplay of the optical pulse width and the acceleration field. An optimized choice of laser wavelength and bandwidth results in sub-100-fs electron pulses. We demonstrate single-electron diffraction from polycrystalline diamond films and reveal the favorable influences of matched photon energies on the coherence volume of single-electron wave packets. We discuss the consequences of our findings for the physics of the photoelectric effect and for applications of single-electron pulses in ultrafast 4D imaging of structural dynamics. PMID:21041681

APHiD: Hierarchical Task Placement to Enable a Tapered Fat Tree Topology for Lower Power and Cost in HPC Networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michelogiannakis, George; Ibrahim, Khaled Z.; Shalf, John

The power and procurement cost of bandwidth in system-wide networks has forced a steady drop in the byte/flop ratio. This trend of computation becoming faster relative to the network is expected to hold. In this paper, we explore how cost-oriented task placement enables reducing the cost of system-wide networks by enabling high performance even on tapered topologies where more bandwidth is provisioned at lower levels. We describe APHiD, an efficient hierarchical placement algorithm that uses new techniques to improve the quality of heuristic solutions and reduces the demand on high-level, expensive bandwidth in hierarchical topologies. We apply APHiD to amore » tapered fat-tree, demonstrating that APHiD maintains application scalability even for severely tapered network configurations. Using simulation, we show that for tapered networks APHiD improves performance by more than 50% over random placement and even 15% in some cases over costlier, state-of-the-art placement algorithms.« less

Pushing Memory Bandwidth Limitations Through Efficient Implementations of Block-Krylov Space Solvers on GPUs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, M. A.; Strelchenko, Alexei; Vaquero, Alejandro

Lattice quantum chromodynamics simulations in nuclear physics have benefited from a tremendous number of algorithmic advances such as multigrid and eigenvector deflation. These improve the time to solution but do not alleviate the intrinsic memory-bandwidth constraints of the matrix-vector operation dominating iterative solvers. Batching this operation for multiple vectors and exploiting cache and register blocking can yield a super-linear speed up. Block-Krylov solvers can naturally take advantage of such batched matrix-vector operations, further reducing the iterations to solution by sharing the Krylov space between solves. However, practical implementations typically suffer from the quadratic scaling in the number of vector-vector operations.more » Using the QUDA library, we present an implementation of a block-CG solver on NVIDIA GPUs which reduces the memory-bandwidth complexity of vector-vector operations from quadratic to linear. We present results for the HISQ discretization, showing a 5x speedup compared to highly-optimized independent Krylov solves on NVIDIA's SaturnV cluster.« less

Terabit optical OFDM superchannel transmission via coherent carriers of a hybrid chip-scale soliton frequency comb

NASA Astrophysics Data System (ADS)

Geng, Yong; Huang, Xiatao; Cui, Wenwen; Ling, Yun; Xu, Bo; Zhang, Jin; Yi, Xingwen; Wu, Baojian; Huang, Shu-Wei; Qiu, Kun; Wong, Chee Wei; Zhou, Heng

2018-05-01

We demonstrate seamless channel multiplexing and high bitrate superchannel transmission of coherent optical orthogonal-frequency-division-multiplexing (CO-OFDM) data signals utilizing a dissipative Kerr soliton (DKS) frequency comb generated in an on-chip microcavity. Aided by comb line multiplication through Nyquist pulse modulation, the high stability and mutual coherence among mode-locked Kerr comb lines are exploited for the first time to eliminate the guard intervals between communication channels and achieve full spectral density bandwidth utilization. Spectral efficiency as high as 2.625 bit/Hz/s is obtained for 180 CO-OFDM bands encoded with 12.75 Gbaud 8-QAM data, adding up to total bitrate of 6.885 Tb/s within 2.295 THz frequency comb bandwidth. Our study confirms that high coherence is the key superiority of Kerr soliton frequency combs over independent laser diodes, as a multi-spectral coherent laser source for high-bandwidth high-spectral-density transmission networks.

ASIC-based architecture for the real-time computation of 2D convolution with large kernel size

NASA Astrophysics Data System (ADS)

Shao, Rui; Zhong, Sheng; Yan, Luxin

2015-12-01

Bidimensional convolution is a low-level processing algorithm of interest in many areas, but its high computational cost constrains the size of the kernels, especially in real-time embedded systems. This paper presents a hardware architecture for the ASIC-based implementation of 2-D convolution with medium-large kernels. Aiming to improve the efficiency of storage resources on-chip, reducing off-chip bandwidth of these two issues, proposed construction of a data cache reuse. Multi-block SPRAM to cross cached images and the on-chip ping-pong operation takes full advantage of the data convolution calculation reuse, design a new ASIC data scheduling scheme and overall architecture. Experimental results show that the structure can achieve 40× 32 size of template real-time convolution operations, and improve the utilization of on-chip memory bandwidth and on-chip memory resources, the experimental results show that the structure satisfies the conditions to maximize data throughput output , reducing the need for off-chip memory bandwidth.

Vertically integrated visible and near-infrared metasurfaces enabling an ultra-broadband and highly angle-resolved anomalous reflection.

PubMed

Gao, Song; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

2018-06-21

An optical device with minimized dimensions, which is capable of efficiently resolving an ultra-broad spectrum into a wide splitting angle but incurring no spectrum overlap, is of importance in advancing the development of spectroscopy. Unfortunately, this challenging task cannot be easily addressed through conventional geometrical or diffractive optical elements. Herein, we propose and demonstrate vertically integrated visible and near-infrared metasurfaces which render an ultra-broadband and highly angle-resolved anomalous reflection. The proposed metasurface capitalizes on a supercell that comprises two vertically concatenated trapezoid-shaped aluminum antennae, which are paired with a metallic ground plane via a dielectric layer. Under normal incidence, reflected light within a spectral bandwidth of 1000 nm ranging from λ = 456 nm to 1456 nm is efficiently angle-resolved to a single diffraction order with no spectrum overlap via the anomalous reflection, exhibiting an average reflection efficiency over 70% and a substantial angular splitting of 58°. In light of a supercell pitch of 1500 nm, to the best of our knowledge, the micron-scale bandwidth is the largest ever reported. It is noted that the substantially wide bandwidth has been accomplished by taking advantage of spectral selective vertical coupling effects between antennae and ground plane. In the visible regime, the upper antenna primarily renders an anomalous reflection by cooperating with the lower antenna, which in turn cooperates with the ground plane and produces phase variations leading to an anomalous reflection in the near-infrared regime. Misalignments between the two antennae have been particularly inspected to not adversely affect the anomalous reflection, thus guaranteeing enhanced structural tolerance of the proposed metasurface.

ACTS 118x Final Report High-Speed TCP Interoperability Testing

NASA Technical Reports Server (NTRS)

Ivancic, William D.; Zernic, Mike; Hoder, Douglas J.; Brooks, David E.; Beering, Dave R.; Welch, Arun

1999-01-01

With the recent explosion of the Internet and the enormous business opportunities available to communication system providers, great interest has developed in improving the efficiency of data transfer using the Transmission Control Protocol (TCP) of the Internet Protocol (IP) suite. The satellite system providers are interested in solving TCP efficiency problems associated with long delays and error-prone links. Similarly, the terrestrial community is interested in solving TCP problems over high-bandwidth links. Whereas the wireless community is interested in improving TCP performance over bandwidth constrained, error-prone links. NASA realized that solutions had already been proposed for most of the problems associated with efficient data transfer over large bandwidth-delay links (which include satellite links). The solutions are detailed in various Internet Engineering Task Force (IETF) Request for Comments (RFCs). Unfortunately, most of these solutions had not been tested at high-speed (155+ Mbps). Therefore, the NASA's ACTS experiments program initiated a series of TCP experiments to demonstrate scalability of TCP/IP and determine how far the protocol can be optimized over a 622 Mbps satellite link. These experiments were known as the 118i and 118j experiments. During the 118i and 118j experiments, NASA worked closely with SUN Microsystems and FORE Systems to improve the operating system, TCP stacks. and network interface cards and drivers. We were able to obtain instantaneous data throughput rates of greater than 520 Mbps and average throughput rates of 470 Mbps using TCP over Asynchronous Transfer Mode (ATM) over a 622 Mbps Synchronous Optical Network (SONET) OC12 link. Following the success of these experiments and the successful government/industry collaboration, a new series of experiments. the 118x experiments. were developed.

Optimization Model for cooperative water allocation and valuation in large river basins regarding environmental constraints

NASA Astrophysics Data System (ADS)

Pournazeri, S.

2011-12-01

A comprehensive optimization model named Cooperative Water Allocation Model (CWAM) is developed for equitable and efficient water allocation and valuation of Zab river basin in order to solve the draught problems of Orumieh Lake in North West of Iran. The model's methodology consists of three phases. The first represents an initial water rights allocation among competing users. The second comprises the water reallocation process for complete usage by consumers. The third phase performs an allocation of the net benefit of the stakeholders participating in a coalition by applying cooperative game theory. The environmental constraints are accounted for in the water allocation model by entering probable environmental damage in a target function, and inputting the minimum water requirement of users. The potential of underground water usage is evaluated in order to compensate for the variation in the amount of surface water. This is conducted by applying an integrated economic- hydrologic river basin model. A node-link river basin network is utilized in CWAM which consists of two major blocks. The first indicates the internal water rights allocation and the second is associated to water and net benefit reallocation. System control, loss in links by evaporation or seepage, modification of inflow into the node, loss in nodes and loss in outflow are considered in this model. Water valuation is calculated for environmental, industrial, municipal and agricultural usage by net benefit function. It can be seen that the water rights are allocated efficiently and incomes are distributed appropriately based on quality and quantity limitations.

Impact of water allocation strategies to manage groundwater resources in Western Australia: Equity and efficiency considerations

NASA Astrophysics Data System (ADS)

Iftekhar, Md Sayed; Fogarty, James

2017-05-01

In many parts of the world groundwater is being depleting at an alarming rate. Where groundwater extraction is licenced, regulators often respond to resource depletion by reducing all individual licences by a fixed proportion. This approach can be effective in achieving a reduction in the volume of water extracted, but the approach is not efficient. In water resource management the issue of the equity-efficiency trade-off has been explored in a number of contexts, but not in the context of allocation from a groundwater system. To contribute to this knowledge gap we conduct an empirical case study for Western Australia's most important groundwater system: the Gnangara Groundwater System (GGS). Resource depletion is a serious issue for the GGS, and substantial reductions in groundwater extraction are required to stabilise the system. Using an individual-based farm optimization model we study both the overall impact and the distributional impact of a fixed percentage water allocation cut to horticulture sector licence holders. The model is parameterised using water licence specific data on farm area and water allocation. The modelling shows that much of the impact of water allocation reductions can be mitigated through changing the cropping mix and the irrigation technology used. The modelling also shows that the scope for gains through the aggregation of holdings into larger farms is much greater than the potential losses due to water allocation reductions. The impact of water allocation cuts is also shown to impact large farms more than small farms. For example, the expected loss in net revenue per ha for a 10-ha farm is around three times the expected loss per ha for a 1-ha farm; and the expected loss per ha for a 25-ha farm is around five times the expected loss per ha for a 1-ha farm.

Waste management: how reducing partiality can promote efficient resource allocation.

PubMed

Choshen-Hillel, Shoham; Shaw, Alex; Caruso, Eugene M

2015-08-01

Two central principles that guide resource-allocation decisions are equity (providing equal pay for equal work) and efficiency (not wasting resources). When these two principles conflict with one another, people will often waste resources to avoid inequity. We suggest that people wish to avoid inequity not because they find it inherently unfair, but because they want to avoid the appearance of partiality associated with it. We explore one way to reduce waste by reducing the perceived partiality of inequitable allocations. Specifically, we hypothesize that people will be more likely to favor an efficient (albeit inequitable) allocation if it puts them in a disadvantaged position than if it puts others in a disadvantaged position. To test this hypothesis, we asked participants to choose between giving some extra resource to one person (thereby creating inequity between this person and equally deserving others) and not giving the resource to anyone (thereby wasting the resource). Six studies, using realistic scenarios and behavioral paradigms, provide robust evidence for a self-disadvantaging effect: Allocators were consistently more likely to create inequity to avoid wasting resources when the resulting inequity would put them at a relative disadvantage than when it would put others at a relative disadvantage. We further find that this self-disadvantaging effect is a direct result of people's concern about appearing partial. Our findings suggest the importance of impartiality even in distributive justice, thereby bridging a gap between the distributive and procedural justice literatures. (c) 2015 APA, all rights reserved.

Improving Efficiency with Work Sampling.

ERIC Educational Resources Information Center

Friedman, Mark; Hertz, Paul

1982-01-01

Work sampling is a managerial accounting technique which provides information about the efficiency of an operation. This analysis determines what tasks are being performed durinq a period of time to ascertain if time and effort are being allocated efficiently. (SK)

Interactive Land-Use Optimization Using Laguerre Voronoi Diagram with Dynamic Generating Point Allocation

NASA Astrophysics Data System (ADS)

Chaidee, S.; Pakawanwong, P.; Suppakitpaisarn, V.; Teerasawat, P.

2017-09-01

In this work, we devise an efficient method for the land-use optimization problem based on Laguerre Voronoi diagram. Previous Voronoi diagram-based methods are more efficient and more suitable for interactive design than discrete optimization-based method, but, in many cases, their outputs do not satisfy area constraints. To cope with the problem, we propose a force-directed graph drawing algorithm, which automatically allocates generating points of Voronoi diagram to appropriate positions. Then, we construct a Laguerre Voronoi diagram based on these generating points, use linear programs to adjust each cell, and reconstruct the diagram based on the adjustment. We adopt the proposed method to the practical case study of Chiang Mai University's allocated land for a mixed-use complex. For this case study, compared to other Voronoi diagram-based method, we decrease the land allocation error by 62.557 %. Although our computation time is larger than the previous Voronoi-diagram-based method, it is still suitable for interactive design.

Eavesdropping-aware routing and spectrum allocation based on multi-flow virtual concatenation for confidential information service in elastic optical networks

NASA Astrophysics Data System (ADS)

Bai, Wei; Yang, Hui; Yu, Ao; Xiao, Hongyun; He, Linkuan; Feng, Lei; Zhang, Jie

2018-01-01

The leakage of confidential information is one of important issues in the network security area. Elastic Optical Networks (EON) as a promising technology in the optical transport network is under threat from eavesdropping attacks. It is a great demand to support confidential information service (CIS) and design efficient security strategy against the eavesdropping attacks. In this paper, we propose a solution to cope with the eavesdropping attacks in routing and spectrum allocation. Firstly, we introduce probability theory to describe eavesdropping issue and achieve awareness of eavesdropping attacks. Then we propose an eavesdropping-aware routing and spectrum allocation (ES-RSA) algorithm to guarantee information security. For further improving security and network performance, we employ multi-flow virtual concatenation (MFVC) and propose an eavesdropping-aware MFVC-based secure routing and spectrum allocation (MES-RSA) algorithm. The presented simulation results show that the proposed two RSA algorithms can both achieve greater security against the eavesdropping attacks and MES-RSA can also improve the network performance efficiently.

End-to-End Network QoS via Scheduling of Flexible Resource Reservation Requests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, S.; Katramatos, D.; Yu, D.

2011-11-14

Modern data-intensive applications move vast amounts of data between multiple locations around the world. To enable predictable and reliable data transfer, next generation networks allow such applications to reserve network resources for exclusive use. In this paper, we solve an important problem (called SMR3) to accommodate multiple and concurrent network reservation requests between a pair of end-sites. Given the varying availability of bandwidth within the network, our goal is to accommodate as many reservation requests as possible while minimizing the total time needed to complete the data transfers. We first prove that SMR3 is an NP-hard problem. Then we solvemore » it by developing a polynomial-time heuristic, called RRA. The RRA algorithm hinges on an efficient mechanism to accommodate large number of requests by minimizing the bandwidth wastage. Finally, via numerical results, we show that RRA constructs schedules that accommodate significantly larger number of requests compared to other, seemingly efficient, heuristics.« less

Tunable, Highly Stable Lasers for Coherent Lidar

NASA Technical Reports Server (NTRS)

Henderson, Sammy W.; Hale, Charley P.; EEpagnier, David M.

2006-01-01

Practical space-based coherent laser radar systems envisioned for global winds measurement must be very efficient and must contend with unique problems associated with the large platform velocities that the instruments experience in orbit. To compensate for these large platform-induced Doppler shifts in space-based applications, agile-frequency offset-locking of two single-frequency Doppler reference lasers was thoroughly investigated. Such techniques involve actively locking a frequency-agile master oscillator (MO) source to a comparatively static local oscillator (LO) laser, and effectively producing an offset between MO (the lidar slave oscillator seed source, typically) and heterodyne signal receiver LO that lowers the bandwidth of the receiver data-collection system and permits use of very high-quantum-efficiency, reasonably- low-bandwidth heterodyne photoreceiver detectors and circuits. Recent work on MO/LO offset locking has focused on increasing the offset locking range, improving the graded-InGaAs photoreceiver performance, and advancing the maturity of the offset locking electronics. A figure provides a schematic diagram of the offset-locking system.

Real-time motion-based H.263+ frame rate control

NASA Astrophysics Data System (ADS)

Song, Hwangjun; Kim, JongWon; Kuo, C.-C. Jay

1998-12-01

Most existing H.263+ rate control algorithms, e.g. the one adopted in the test model of the near-term (TMN8), focus on the macroblock layer rate control and low latency under the assumptions of with a constant frame rate and through a constant bit rate (CBR) channel. These algorithms do not accommodate the transmission bandwidth fluctuation efficiently, and the resulting video quality can be degraded. In this work, we propose a new H.263+ rate control scheme which supports the variable bit rate (VBR) channel through the adjustment of the encoding frame rate and quantization parameter. A fast algorithm for the encoding frame rate control based on the inherent motion information within a sliding window in the underlying video is developed to efficiently pursue a good tradeoff between spatial and temporal quality. The proposed rate control algorithm also takes the time-varying bandwidth characteristic of the Internet into account and is able to accommodate the change accordingly. Experimental results are provided to demonstrate the superior performance of the proposed scheme.

Broadband and Wide Field-of-view Plasmonic Metasurface-enabled Waveplates

PubMed Central

Jiang, Zhi Hao; Lin, Lan; Ma, Ding; Yun, Seokho; Werner, Douglas H.; Liu, Zhiwen; Mayer, Theresa S.

2014-01-01

Quasi two-dimensional metasurfaces composed of subwavelength nanoresonator arrays can dramatically alter the properties of light in an ultra-thin planar geometry, enabling new optical functions such as anomalous reflection and refraction, polarization filtering, and wavefront modulation. However, previous metasurface-based nanostructures suffer from low efficiency, narrow bandwidth and/or limited field-of-view due to their operation near the plasmonic resonance. Here we demonstrate plasmonic metasurface-based nanostructures for high-efficiency, angle-insensitive polarization transformation over a broad octave-spanning bandwidth. The structures are realized by optimizing the anisotropic response of an array of strongly coupled nanorod resonators to tailor the interference of light at the subwavelength scale. Nanofabricated reflective half-wave and quarter-wave plates designed using this approach have measured polarization conversion ratios and reflection magnitudes greater than 92% over a broad wavelength range from 640 to 1290 nm and a wide field-of-view up to ±40°. This work outlines a versatile strategy to create metasurface-based photonics with diverse optical functionalities. PMID:25524830

Performance investigation of optical multicast overlay system using orthogonal modulation format

NASA Astrophysics Data System (ADS)

Singh, Simranjit; Singh, Sukhbir; Kaur, Ramandeep; Kaler, R. S.

2015-03-01

We proposed a bandwidth efficient wavelength division multiplexed-passive optical network (WDM-PON) to simultaneously transmit 60 Gb/s unicast and 10 Gb/s multicast services with 10 Gb/s upstream. The differential phase shift keying (DPSK) multicast signal is superimposed onto multiplexed non-return to zero/polarization shift keying (NRZ/PolSK) orthogonal modulated data signals. Upstream amplitude shift keying (ASK) signals formed without use of any additional light source and superimposed onto received unicast NRZ/PolSK signal before being transmitted back to optical line terminal (OLT). We also investigated the proposed WDM-PON system for variable optical input power, transmission distance of single mode fiber in multicast enable and disable mode. The measured Quality factor for all unicast and multicast signal is in acceptable range (>6). The original contribution of this paper is to propose a bandwidth efficient WDM-PON system that could be projected even in high speed scenario at reduced channel spacing and expected to be more technical viable due to use of optical orthogonal modulation formats.

Graphene-silicon phase modulators with gigahertz bandwidth

NASA Astrophysics Data System (ADS)

Sorianello, V.; Midrio, M.; Contestabile, G.; Asselberghs, I.; Van Campenhout, J.; Huyghebaert, C.; Goykhman, I.; Ott, A. K.; Ferrari, A. C.; Romagnoli, M.

2018-01-01

The modulator is a key component in optical communications. Several graphene-based amplitude modulators have been reported based on electro-absorption. However, graphene phase modulators (GPMs) are necessary for functions such as applying complex modulation formats or making switches or phased arrays. Here, we present a 10 Gb s-1 GPM integrated in a Mach-Zehnder interferometer configuration. This is a compact device based on a graphene-insulator-silicon capacitor, with a phase-shifter length of 300 μm and extinction ratio of 35 dB. The GPM has a modulation efficiency of 0.28 V cm at 1,550 nm. It has 5 GHz electro-optical bandwidth and operates at 10 Gb s-1 with 2 V peak-to-peak driving voltage in a push-pull configuration for binary transmission of a non-return-to-zero data stream over 50 km of single-mode fibre. This device is the key building block for graphene-based integrated photonics, enabling compact and energy-efficient hybrid graphene-silicon modulators for telecom, datacom and other applications.

A broadband gyrotron backward-wave oscillator with tapered interaction structure and magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, G. D.; Chang, P. C.; Chiang, W. Y.

2015-11-15

The gyro-monotron and gyrotron backward-wave oscillator (gyro-BWO) are the two oscillator versions of gyrotrons. While serving different functions, they are also radically different in the RF field formation mechanisms. The gyro-monotron RF field profile is essentially fixed by the resonant interaction structure, while the gyro-BWO possesses an extra degree of freedom in that the axial RF field profile is self-determined by the beam-wave interaction in a waveguide structure. The present study examines ways to utilize the latter feature for bandwidth broadening with a tapered magnetic field, while also employing a tapered waveguide to enhance the interaction efficiency. We begin withmore » a mode competition analysis, which suggests the theoretical feasibility of broadband frequency tuning in single-mode operation. It is then shown in theory that, by controlling the RF field profile with an up- or down-tapered magnetic field, the gyro-BWO is capable of efficient operation with a much improved tunable bandwidth.« less

High rate concatenated coding systems using bandwidth efficient trellis inner codes

NASA Technical Reports Server (NTRS)

Deng, Robert H.; Costello, Daniel J., Jr.

1989-01-01

High-rate concatenated coding systems with bandwidth-efficient trellis inner codes and Reed-Solomon (RS) outer codes are investigated for application in high-speed satellite communication systems. Two concatenated coding schemes are proposed. In one the inner code is decoded with soft-decision Viterbi decoding, and the outer RS code performs error-correction-only decoding (decoding without side information). In the other, the inner code is decoded with a modified Viterbi algorithm, which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, whereas branch metrics are used to provide reliability information on the decoded sequence. This information is used to erase unreliable bits in the decoded output. An errors-and-erasures RS decoder is then used for the outer code. The two schemes have been proposed for high-speed data communication on NASA satellite channels. The rates considered are at least double those used in current NASA systems, and the results indicate that high system reliability can still be achieved.

Optimal allocation of conservation effort among subpopulations of a threatened species: how important is patch quality?

PubMed

Chauvenet, Aliénor L M; Baxter, Peter W J; McDonald-Madden, Eve; Possingham, Hugh P

2010-04-01

Money is often a limiting factor in conservation, and attempting to conserve endangered species can be costly. Consequently, a framework for optimizing fiscally constrained conservation decisions for a single species is needed. In this paper we find the optimal budget allocation among isolated subpopulations of a threatened species to minimize local extinction probability. We solve the problem using stochastic dynamic programming, derive a useful and simple alternative guideline for allocating funds, and test its performance using forward simulation. The model considers subpopulations that persist in habitat patches of differing quality, which in our model is reflected in different relationships between money invested and extinction risk. We discover that, in most cases, subpopulations that are less efficient to manage should receive more money than those that are more efficient to manage, due to higher investment needed to reduce extinction risk. Our simple investment guideline performs almost as well as the exact optimal strategy. We illustrate our approach with a case study of the management of the Sumatran tiger, Panthera tigris sumatrae, in Kerinci Seblat National Park (KSNP), Indonesia. We find that different budgets should be allocated to the separate tiger subpopulations in KSNP. The subpopulation that is not at risk of extinction does not require any management investment. Based on the combination of risks of extinction and habitat quality, the optimal allocation for these particular tiger subpopulations is an unusual case: subpopulations that occur in higher-quality habitat (more efficient to manage) should receive more funds than the remaining subpopulation that is in lower-quality habitat. Because the yearly budget allocated to the KSNP for tiger conservation is small, to guarantee the persistence of all the subpopulations that are currently under threat we need to prioritize those that are easier to save. When allocating resources among subpopulations of a threatened species, the combined effects of differences in habitat quality, cost of action, and current subpopulation probability of extinction need to be integrated. We provide a useful guideline for allocating resources among isolated subpopulations of any threatened species.

An Efficient Interactive Model for On-Demand Sensing-As-A-Servicesof Sensor-Cloud

PubMed Central

Dinh, Thanh; Kim, Younghan

2016-01-01

This paper proposes an efficient interactive model for the sensor-cloud to enable the sensor-cloud to efficiently provide on-demand sensing services for multiple applications with different requirements at the same time. The interactive model is designed for both the cloud and sensor nodes to optimize the resource consumption of physical sensors, as well as the bandwidth consumption of sensing traffic. In the model, the sensor-cloud plays a key role in aggregating application requests to minimize the workloads required for constrained physical nodes while guaranteeing that the requirements of all applications are satisfied. Physical sensor nodes perform their sensing under the guidance of the sensor-cloud. Based on the interactions with the sensor-cloud, physical sensor nodes adapt their scheduling accordingly to minimize their energy consumption. Comprehensive experimental results show that our proposed system achieves a significant improvement in terms of the energy consumption of physical sensors, the bandwidth consumption from the sink node to the sensor-cloud, the packet delivery latency, reliability and scalability, compared to current approaches. Based on the obtained results, we discuss the economical benefits and how the proposed system enables a win-win model in the sensor-cloud. PMID:27367689

An Efficient Interactive Model for On-Demand Sensing-As-A-Servicesof Sensor-Cloud.

PubMed

Dinh, Thanh; Kim, Younghan

2016-06-28

This paper proposes an efficient interactive model for the sensor-cloud to enable the sensor-cloud to efficiently provide on-demand sensing services for multiple applications with different requirements at the same time. The interactive model is designed for both the cloud and sensor nodes to optimize the resource consumption of physical sensors, as well as the bandwidth consumption of sensing traffic. In the model, the sensor-cloud plays a key role in aggregating application requests to minimize the workloads required for constrained physical nodes while guaranteeing that the requirements of all applications are satisfied. Physical sensor nodes perform their sensing under the guidance of the sensor-cloud. Based on the interactions with the sensor-cloud, physical sensor nodes adapt their scheduling accordingly to minimize their energy consumption. Comprehensive experimental results show that our proposed system achieves a significant improvement in terms of the energy consumption of physical sensors, the bandwidth consumption from the sink node to the sensor-cloud, the packet delivery latency, reliability and scalability, compared to current approaches. Based on the obtained results, we discuss the economical benefits and how the proposed system enables a win-win model in the sensor-cloud.

The 20 GHz spacecraft IMPATT solid state transmitter

NASA Technical Reports Server (NTRS)

Best, T.; Ngan, Y. C.

1986-01-01

The engineering development of a solid-state transmitter amplifier operating in the 20-GHz frequency range is described. This effort involved a multitude of disciplines including IMPATT device development, circulator design, multiple-diode circuit design, and amplifier integration and test. The objective was to develop a transmitter amplifier demonstrating the feasibility of providing an efficient, reliable, lightweight solid-state transmitter to be flown on a 30 to 20 GHz communication demonstration satellite. The work was done under contract from NASA/Lewis Research Center for a period of three years. The result was the development of a GaAs IMPACT diode amplifier capable of an 11-W CW output power and a 2-dB bandwidth of 300 MHz. GaAs IMPATT diodes incorporating diamond heatsink and double-Read doping profile capable of 5.3-W CW oscillator output power and 15.5% efficiency were developed. Up to 19% efficiency was also observed for an output power level of 4.4 W. High performance circulators with a 0.2 dB inserting loss and bandwidth of 5 GHz have also been developed. These represent a significant advance in both device and power combiner circuit technologies in K-band frequencies.

Evaluation of Efficient XML Interchange (EXI) for Large Datasets and as an Alternative to Binary JSON Encodings

DTIC Science & Technology

2015-03-01

fall in the lossy category (Gonzalez, Woods , & Eddins, 2009, p. 420). For the textual or numeric data in XML, however, lossy compression is...7/1,337 > Professional Notes Being Efficient with Bandwidth By Lieutenant Commander Steve Debich, Lieutenant Bruce Hill, Captain Scot Miller (Retired...2005). XML Binary Characterization. Retrieved from http://www.w3.org/TR/xbc-characterization/ Gonzalez, R., Woods , R., & Eddins, S. (2009

Multiple access capacity trade-offs for a Ka-band personal access satellite system

NASA Technical Reports Server (NTRS)

Dessouky, Khaled; Motamedi, Masoud

1990-01-01

System capability is critical to the economic viability of a personal satellite communication system. Ka band has significant potential to support a high capacity multiple access system because of the availability of bandwidth. System design tradeoffs are performed and multiple access schemes are compared with the design goal of achieving the highest capacity and efficiency. Conclusions regarding the efficiency of the different schemes and the achievable capacities are given.

Technology Assessment for Future MILSATCOM Systems: The EHF Bands

DTIC Science & Technology

1979-04-01

improvements must be pursued to provide long life (7 to 10 years), higher efficiencies and higher power. 1. Current Availability A 4-watt helix TWT ... helix TWT ), adequate bandwidth for communications applications and efficiencies of 40-50%. An example is the 200-watt tube operating at 12 GHz with an...costly than its helix counterpart. In addition, experience with coupled-cavity tubes in space is rare. Consequently, coupled-cavity TWTs will only be

Flexible and evolutionary optical access networks

NASA Astrophysics Data System (ADS)

Hsueh, Yu-Li

Passive optical networks (PONs) are promising solutions that will open the first-mile bottleneck. Current PONs employ time division multiplexing (TDM) to share bandwidth among users, leading to low cost but limited capacity. In the future, wavelength division multiplexing (WDM) technologies will be deployed to achieve high performance. This dissertation describes several advanced technologies to enhance PON systems. A spectral shaping line coding scheme is developed to allow a simple and cost-effective overlay of high data-rate services in existing PONs, leaving field-deployed fibers and existing services untouched. Spectral shapes of coded signals can be manipulated to adapt to different systems. For a specific tolerable interference level, the optimal line code can be found which maximizes the data throughput. Experiments are conducted to demonstrate and compare several optimized line codes. A novel PON employing dynamic wavelength allocation to provide bandwidth sharing across multiple physical PONs is designed and experimentally demonstrated. Tunable lasers, arrayed waveguide gratings, and coarse/fine filtering combine to create a flexible optical access solution. The network's excellent scalability can bridge the gap between conventional TDM PONs and WDM PONs. Scheduling algorithms with quality of service support are also investigated. Simulation results show that the proposed architecture exhibits significant performance gain over conventional PON systems. Streaming video transmission is demonstrated on the prototype experimental testbed. The powerful architecture is a promising candidate for next-generation optical access networks. A new CDR circuit for receiving the bursty traffic in PONs is designed and analyzed. It detects data transition edges upon arrival of the data burst and quickly selects the best clock phase by a control logic circuit. Then, an analog delay-locked loop (DLL) keeps track of data transitions and removes phase errors throughout the burst. The combination of the fast phase detection mechanism and a feedback loop based on DLL allows both fast response and manageable jitter performance in the burst-mode application. A new efficient numerical algorithm is developed to analyze holey optical fibers. The algorithm has been verified against experimental data, and is exploited to design holey optical fibers optimized for the discrete Raman amplification.

Design of transmissive lens with nearly 100% efficiency by using Huygens metasurface

NASA Astrophysics Data System (ADS)

Lin, B. C.; Wang, G. M.; Cai, T.; Hou, H. S.; Guo, W. L.; Xie, P.; Shuai, S. Y.; Liao, Z. H.; Li, K.; Zhu, L.; Gao, X. J.

2018-01-01

We proposed a high-efficiency meta-surface with a parabolic phase distribution that can focus a plane wave to a point image in transmission geometry. For realizing the predicted effects, we use the meta-atoms with 100% transmission to make it. Then we operate the simulation in the CST Microwave Studio to perform the focusing characteristic. The results show that the maximum efficiency is up to 90.6% at 10GHz and the half-power bandwidth is 31.8%, which is better than other previous works.

Mode conversion efficiency to Laguerre-Gaussian OAM modes using spiral phase optics.

PubMed

Longman, Andrew; Fedosejevs, Robert

2017-07-24

An analytical model for the conversion efficiency from a TEM 00 mode to an arbitrary Laguerre-Gaussian (LG) mode with null radial index spiral phase optics is presented. We extend this model to include the effects of stepped spiral phase optics, spiral phase optics of non-integer topological charge, and the reduction in conversion efficiency due to broad laser bandwidth. We find that through optimization, an optimal beam waist ratio of the input and output modes exists and is dependent upon the output azimuthal mode number.

Cross-Layer Scheme to Control Contention Window for Per-Flow in Asymmetric Multi-Hop Networks

NASA Astrophysics Data System (ADS)

Giang, Pham Thanh; Nakagawa, Kenji

The IEEE 802.11 MAC standard for wireless ad hoc networks adopts Binary Exponential Back-off (BEB) mechanism to resolve bandwidth contention between stations. BEB mechanism controls the bandwidth allocation for each station by choosing a back-off value from one to CW according to the uniform random distribution, where CW is the contention window size. However, in asymmetric multi-hop networks, some stations are disadvantaged in opportunity of access to the shared channel and may suffer severe throughput degradation when the traffic load is large. Then, the network performance is degraded in terms of throughput and fairness. In this paper, we propose a new cross-layer scheme aiming to solve the per-flow unfairness problem and achieve good throughput performance in IEEE 802.11 multi-hop ad hoc networks. Our cross-layer scheme collects useful information from the physical, MAC and link layers of own station. This information is used to determine the optimal Contention Window (CW) size for per-station fairness. We also use this information to adjust CW size for each flow in the station in order to achieve per-flow fairness. Performance of our cross-layer scheme is examined on various asymmetric multi-hop network topologies by using Network Simulator (NS-2).

Combining spatial domain multiplexing and orbital angular momentum of photon-based multiplexing to increase the bandwidth of optical fiber communication systems

NASA Astrophysics Data System (ADS)

Murshid, Syed; Alanzi, Saud; Hridoy, Arnob; Lovell, Gregory L.; Parhar, Gurinder; Chakravarty, Abhijit; Chowdhury, Bilas

2016-06-01

Spatial domain multiplexing/space division multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple single-mode pigtail laser sources of the same wavelength into a carrier multimode fiber at different angles. The launching angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. We launch light from five different single-mode pigtail laser sources (of same wavelength) at different angles (with respect to the axis of the carrier fiber) into the carrier fiber. Owing to helical propagation, five distinct concentric donut-shaped rings with negligible crosstalk at the output end of the fiber were obtained. These SDM channels also exhibit orbital angular momentum (OAM), thereby adding an extradegree of photon freedom. We present the experimental data of five spatially multiplexed channels and compare them with simulated results to show that this technique can potentially improve the data capacity of optical fibers by an order of magnitude: A factor of five using SDM and another factor of two using OAM.

An order of magnitude improvement in optical fiber bandwidth using spatial domain multiplexing/space division multiplexing (SDM) in conjunction with orbital angular momentum (OAM)

NASA Astrophysics Data System (ADS)

Murshid, Syed; Alanzi, Saud; Hridoy, Arnob; Lovell, Greg; Parhar, Gurinder; Chakravarty, Abhijit; Chowdhury, Bilas

2014-09-01

Spatial Domain Multiplexing/Space Division Multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple single mode pigtail laser sources of same wavelength into a carrier fiber at different angles. The launching angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. In this endeavor we launch light from five different single mode pigtail laser sources at different angles (with respect to the axis of the carrier fiber) into the carrier fiber. Owing to helical propagation we get five distinct concentric donut shaped rings with negligible crosstalk at the output end of the fiber. These SDM channels also exhibit Orbital Angular Momentum (OAM), thereby adding an extra degree of photon freedom. We present the experimental data of five spatially multiplexed channels and compare them with simulated results to show that this technique can potentially improve the data capacity of optical fibers by an order of magnitude: A factor of five using SDM and another factor of two using OAM.

Comparing spatial tuning curves, spectral ripple resolution, and speech perception in cochlear implant users.

PubMed

Anderson, Elizabeth S; Nelson, David A; Kreft, Heather; Nelson, Peggy B; Oxenham, Andrew J

2011-07-01

Spectral ripple discrimination thresholds were measured in 15 cochlear-implant users with broadband (350-5600 Hz) and octave-band noise stimuli. The results were compared with spatial tuning curve (STC) bandwidths previously obtained from the same subjects. Spatial tuning curve bandwidths did not correlate significantly with broadband spectral ripple discrimination thresholds but did correlate significantly with ripple discrimination thresholds when the rippled noise was confined to an octave-wide passband, centered on the STC's probe electrode frequency allocation. Ripple discrimination thresholds were also measured for octave-band stimuli in four contiguous octaves, with center frequencies from 500 Hz to 4000 Hz. Substantial variations in thresholds with center frequency were found in individuals, but no general trends of increasing or decreasing resolution from apex to base were observed in the pooled data. Neither ripple nor STC measures correlated consistently with speech measures in noise and quiet in the sample of subjects in this study. Overall, the results suggest that spectral ripple discrimination measures provide a reasonable measure of spectral resolution that correlates well with more direct, but more time-consuming, measures of spectral resolution, but that such measures do not always provide a clear and robust predictor of performance in speech perception tasks. © 2011 Acoustical Society of America

Comparing spatial tuning curves, spectral ripple resolution, and speech perception in cochlear implant users

PubMed Central

Anderson, Elizabeth S.; Nelson, David A.; Kreft, Heather; Nelson, Peggy B.; Oxenham, Andrew J.

2011-01-01

Spectral ripple discrimination thresholds were measured in 15 cochlear-implant users with broadband (350–5600 Hz) and octave-band noise stimuli. The results were compared with spatial tuning curve (STC) bandwidths previously obtained from the same subjects. Spatial tuning curve bandwidths did not correlate significantly with broadband spectral ripple discrimination thresholds but did correlate significantly with ripple discrimination thresholds when the rippled noise was confined to an octave-wide passband, centered on the STC’s probe electrode frequency allocation. Ripple discrimination thresholds were also measured for octave-band stimuli in four contiguous octaves, with center frequencies from 500 Hz to 4000 Hz. Substantial variations in thresholds with center frequency were found in individuals, but no general trends of increasing or decreasing resolution from apex to base were observed in the pooled data. Neither ripple nor STC measures correlated consistently with speech measures in noise and quiet in the sample of subjects in this study. Overall, the results suggest that spectral ripple discrimination measures provide a reasonable measure of spectral resolution that correlates well with more direct, but more time-consuming, measures of spectral resolution, but that such measures do not always provide a clear and robust predictor of performance in speech perception tasks. PMID:21786905

An OKQPSK modem incorporating numerically controlled carrier synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oetken, R.E.

1988-04-04

The feasibility of incorporating numerically controlled oscillators (NCO) in communication related applications is evaluated. NCO generation of sinusoids may prove useful in systems requiring precise frequency control, tuning linearity, and orthogonality versus frequency. An OKQPSK modem operating at a data rate of 200 kb/s was fabricated. The modem operates in a back to back hardwired channel and thus does not incorporate carrier or symbol timing recovery. Spectra of the NCO generated sinusoids are presented along with waveforms from the modulation and demodulation process. Generation of sinusoids in the digital domain is a viable alternative to analog oscillators. Implementation of anmore » NCO should be considered when frequency allocation, tuning bandwidth, or frequency hopped transmission requires precise frequency synthesis. 24 figs.« less

Design of modified pentagonal patch antenna on defective ground for Wi-Max/WLAN application

NASA Astrophysics Data System (ADS)

Rawat, Sanyog; Sharma, K. K.

2016-04-01

This paper presents the design and performance of a modified pentagonal patch antenna with defective ground plane. A pentagonal slot is inserted in the pentagonal patch and slot loaded ground through optimized dimensions is used in the antenna to resonate it at dual frequency. The geometry operates at two resonant frequencies (2.5 GHz and 5.58 GHz) and offers impedance bandwidth of 864 MHz and 554 MHz in the two bands of interest. The proposed antenna covers the lower band (2.45 to 2.484/2.495 to 2.695 GHz) and upper band (5.15 to 5.825 GHz/5.25 to 5.85 GHz) allocated for Wi-Max and WLAN communication systems.

MASM: a market architecture for sensor management in distributed sensor networks

NASA Astrophysics Data System (ADS)

Viswanath, Avasarala; Mullen, Tracy; Hall, David; Garga, Amulya

2005-03-01

Rapid developments in sensor technology and its applications have energized research efforts towards devising a firm theoretical foundation for sensor management. Ubiquitous sensing, wide bandwidth communications and distributed processing provide both opportunities and challenges for sensor and process control and optimization. Traditional optimization techniques do not have the ability to simultaneously consider the wildly non-commensurate measures involved in sensor management in a single optimization routine. Market-oriented programming provides a valuable and principled paradigm to designing systems to solve this dynamic and distributed resource allocation problem. We have modeled the sensor management scenario as a competitive market, wherein the sensor manager holds a combinatorial auction to sell the various items produced by the sensors and the communication channels. However, standard auction mechanisms have been found not to be directly applicable to the sensor management domain. For this purpose, we have developed a specialized market architecture MASM (Market architecture for Sensor Management). In MASM, the mission manager is responsible for deciding task allocations to the consumers and their corresponding budgets and the sensor manager is responsible for resource allocation to the various consumers. In addition to having a modified combinatorial winner determination algorithm, MASM has specialized sensor network modules that address commensurability issues between consumers and producers in the sensor network domain. A preliminary multi-sensor, multi-target simulation environment has been implemented to test the performance of the proposed system. MASM outperformed the information theoretic sensor manager in meeting the mission objectives in the simulation experiments.

FIBER AND INTEGRATED OPTICS. OTHER TOPICS IN QUANTUM ELECTRONICS: Increase of the bandwidth and of the efficiency of integrated optical traveling-wave modulators

NASA Astrophysics Data System (ADS)

Zolotov, Evgenii M.; Pelekhatyĭ, V. M.; Tavlykaev, R. F.

1990-05-01

A simultaneous increase in the frequency bandwidth and a reduction in the control (drive) power of integrated optical traveling-wave modulators can be achieved as a result of the electrooptic interaction in accordance with a linear frequency-modulated oscillatory law derived by inverse Fourier transformation of a rectangular amplitude-frequency characteristic and a quadratic phase-frequency characteristic of a modulator. This oscillatory law is realized using planar electrode structures with triangular or trapezoidal toothed edges. The tooth repetition frequency is governed by the linearly frequency-modulated oscillations and it rises on increase in the light modulation frequency.

Packets Distributing Evolutionary Algorithm Based on PSO for Ad Hoc Network

NASA Astrophysics Data System (ADS)

Xu, Xiao-Feng

2018-03-01

Wireless communication network has such features as limited bandwidth, changeful channel and dynamic topology, etc. Ad hoc network has lots of difficulties in accessing control, bandwidth distribution, resource assign and congestion control. Therefore, a wireless packets distributing Evolutionary algorithm based on PSO (DPSO)for Ad Hoc Network is proposed. Firstly, parameters impact on performance of network are analyzed and researched to obtain network performance effective function. Secondly, the improved PSO Evolutionary Algorithm is used to solve the optimization problem from local to global in the process of network packets distributing. The simulation results show that the algorithm can ensure fairness and timeliness of network transmission, as well as improve ad hoc network resource integrated utilization efficiency.

Compression of CCD raw images for digital still cameras

NASA Astrophysics Data System (ADS)

Sriram, Parthasarathy; Sudharsanan, Subramania

2005-03-01

Lossless compression of raw CCD images captured using color filter arrays has several benefits. The benefits include improved storage capacity, reduced memory bandwidth, and lower power consumption for digital still camera processors. The paper discusses the benefits in detail and proposes the use of a computationally efficient block adaptive scheme for lossless compression. Experimental results are provided that indicate that the scheme performs well for CCD raw images attaining compression factors of more than two. The block adaptive method also compares favorably with JPEG-LS. A discussion is provided indicating how the proposed lossless coding scheme can be incorporated into digital still camera processors enabling lower memory bandwidth and storage requirements.

Tactically Extensible and Modular Communications X-Band TEMCOM-X

NASA Technical Reports Server (NTRS)

Sims, William H.

2015-01-01

This paper will discuss a CubeSat size (3U) telemetry system concept being developed at Marshall Space Flight Center (MSFC) in cooperation with the U.S. Department of the Army and Dynetics Corporation. This telemetry system incorporates efficient, high-bandwidth communications by developing flight-ready, low-cost, Proto-flight software defined radio (SDR) and Electronically Steerable Patch Array (ESPA) antenna subsystems for use on platforms as small as CubeSats and unmanned aircraft systems (UASs). Higher bandwidth capacity will enable high-volume, low error-rate data transfer to and from tactical forces or sensors operating in austere locations (e.g., direct imagery download, unattended ground sensor data exfiltration, interlink communications).

The effects of limited bandwidth and noise on verbal processing time and word recall in normal-hearing children.

PubMed

McCreery, Ryan W; Stelmachowicz, Patricia G

2013-09-01

Understanding speech in acoustically degraded environments can place significant cognitive demands on school-age children who are developing the cognitive and linguistic skills needed to support this process. Previous studies suggest the speech understanding, word learning, and academic performance can be negatively impacted by background noise, but the effect of limited audibility on cognitive processes in children has not been directly studied. The aim of the present study was to evaluate the impact of limited audibility on speech understanding and working memory tasks in school-age children with normal hearing. Seventeen children with normal hearing between 6 and 12 years of age participated in the present study. Repetition of nonword consonant-vowel-consonant stimuli was measured under conditions with combinations of two different signal to noise ratios (SNRs; 3 and 9 dB) and two low-pass filter settings (3.2 and 5.6 kHz). Verbal processing time was calculated based on the time from the onset of the stimulus to the onset of the child's response. Monosyllabic word repetition and recall were also measured in conditions with a full bandwidth and 5.6 kHz low-pass cutoff. Nonword repetition scores decreased as audibility decreased. Verbal processing time increased as audibility decreased, consistent with predictions based on increased listening effort. Although monosyllabic word repetition did not vary between the full bandwidth and 5.6 kHz low-pass filter condition, recall was significantly poorer in the condition with limited bandwidth (low pass at 5.6 kHz). Age and expressive language scores predicted performance on word recall tasks, but did not predict nonword repetition accuracy or verbal processing time. Decreased audibility was associated with reduced accuracy for nonword repetition and increased verbal processing time in children with normal hearing. Deficits in free recall were observed even under conditions where word repetition was not affected. The negative effects of reduced audibility may occur even under conditions where speech repetition is not impacted. Limited stimulus audibility may result in greater cognitive effort for verbal rehearsal in working memory and may limit the availability of cognitive resources to allocate to working memory and other processes.

Sample allocation balancing overall representativeness and stratum precision.

PubMed

Diaz-Quijano, Fredi Alexander

2018-05-07

In large-scale surveys, it is often necessary to distribute a preset sample size among a number of strata. Researchers must make a decision between prioritizing overall representativeness or precision of stratum estimates. Hence, I evaluated different sample allocation strategies based on stratum size. The strategies evaluated herein included allocation proportional to stratum population; equal sample for all strata; and proportional to the natural logarithm, cubic root, and square root of the stratum population. This study considered the fact that, from a preset sample size, the dispersion index of stratum sampling fractions is correlated with the population estimator error and the dispersion index of stratum-specific sampling errors would measure the inequality in precision distribution. Identification of a balanced and efficient strategy was based on comparing those both dispersion indices. Balance and efficiency of the strategies changed depending on overall sample size. As the sample to be distributed increased, the most efficient allocation strategies were equal sample for each stratum; proportional to the logarithm, to the cubic root, to square root; and that proportional to the stratum population, respectively. Depending on sample size, each of the strategies evaluated could be considered in optimizing the sample to keep both overall representativeness and stratum-specific precision. Copyright © 2018 Elsevier Inc. All rights reserved.

Optimal Computing Budget Allocation for Particle Swarm Optimization in Stochastic Optimization.

PubMed

Zhang, Si; Xu, Jie; Lee, Loo Hay; Chew, Ek Peng; Wong, Wai Peng; Chen, Chun-Hung

2017-04-01

Particle Swarm Optimization (PSO) is a popular metaheuristic for deterministic optimization. Originated in the interpretations of the movement of individuals in a bird flock or fish school, PSO introduces the concept of personal best and global best to simulate the pattern of searching for food by flocking and successfully translate the natural phenomena to the optimization of complex functions. Many real-life applications of PSO cope with stochastic problems. To solve a stochastic problem using PSO, a straightforward approach is to equally allocate computational effort among all particles and obtain the same number of samples of fitness values. This is not an efficient use of computational budget and leaves considerable room for improvement. This paper proposes a seamless integration of the concept of optimal computing budget allocation (OCBA) into PSO to improve the computational efficiency of PSO for stochastic optimization problems. We derive an asymptotically optimal allocation rule to intelligently determine the number of samples for all particles such that the PSO algorithm can efficiently select the personal best and global best when there is stochastic estimation noise in fitness values. We also propose an easy-to-implement sequential procedure. Numerical tests show that our new approach can obtain much better results using the same amount of computational effort.

A generalized fuzzy credibility-constrained linear fractional programming approach for optimal irrigation water allocation under uncertainty

NASA Astrophysics Data System (ADS)

Zhang, Chenglong; Guo, Ping

2017-10-01

The vague and fuzzy parametric information is a challenging issue in irrigation water management problems. In response to this problem, a generalized fuzzy credibility-constrained linear fractional programming (GFCCFP) model is developed for optimal irrigation water allocation under uncertainty. The model can be derived from integrating generalized fuzzy credibility-constrained programming (GFCCP) into a linear fractional programming (LFP) optimization framework. Therefore, it can solve ratio optimization problems associated with fuzzy parameters, and examine the variation of results under different credibility levels and weight coefficients of possibility and necessary. It has advantages in: (1) balancing the economic and resources objectives directly; (2) analyzing system efficiency; (3) generating more flexible decision solutions by giving different credibility levels and weight coefficients of possibility and (4) supporting in-depth analysis of the interrelationships among system efficiency, credibility level and weight coefficient. The model is applied to a case study of irrigation water allocation in the middle reaches of Heihe River Basin, northwest China. Therefore, optimal irrigation water allocation solutions from the GFCCFP model can be obtained. Moreover, factorial analysis on the two parameters (i.e. λ and γ) indicates that the weight coefficient is a main factor compared with credibility level for system efficiency. These results can be effective for support reasonable irrigation water resources management and agricultural production.

Optimal Computing Budget Allocation for Particle Swarm Optimization in Stochastic Optimization

PubMed Central

Zhang, Si; Xu, Jie; Lee, Loo Hay; Chew, Ek Peng; Chen, Chun-Hung

2017-01-01

Particle Swarm Optimization (PSO) is a popular metaheuristic for deterministic optimization. Originated in the interpretations of the movement of individuals in a bird flock or fish school, PSO introduces the concept of personal best and global best to simulate the pattern of searching for food by flocking and successfully translate the natural phenomena to the optimization of complex functions. Many real-life applications of PSO cope with stochastic problems. To solve a stochastic problem using PSO, a straightforward approach is to equally allocate computational effort among all particles and obtain the same number of samples of fitness values. This is not an efficient use of computational budget and leaves considerable room for improvement. This paper proposes a seamless integration of the concept of optimal computing budget allocation (OCBA) into PSO to improve the computational efficiency of PSO for stochastic optimization problems. We derive an asymptotically optimal allocation rule to intelligently determine the number of samples for all particles such that the PSO algorithm can efficiently select the personal best and global best when there is stochastic estimation noise in fitness values. We also propose an easy-to-implement sequential procedure. Numerical tests show that our new approach can obtain much better results using the same amount of computational effort. PMID:29170617

Design and performance verification of advanced multistage depressed collectors. [traveling wave tubes for ECM

NASA Technical Reports Server (NTRS)

Kosmahl, H.; Ramins, P.

1975-01-01

Design and performance of a small size, 4-stage depressed collector are discussed. The collector and a spent beam refocusing section preceding it are intended for efficiency enhancement of octave bandwidth, high CW power traveling wave tubes for use in ECM.

Digital pre-compensation techniques enabling high-capacity bandwidth variable transponders

NASA Astrophysics Data System (ADS)

Napoli, Antonio; Berenguer, Pablo Wilke; Rahman, Talha; Khanna, Ginni; Mezghanni, Mahdi M.; Gardian, Lennart; Riccardi, Emilio; Piat, Anna Chiadò; Calabrò, Stefano; Dris, Stefanos; Richter, André; Fischer, Johannes Karl; Sommerkorn-Krombholz, Bernd; Spinnler, Bernhard

2018-02-01

Digital pre-compensation techniques are among the enablers for cost-efficient high-capacity transponders. In this paper we describe various methods to mitigate the impairments introduced by state-of-the-art components within modern optical transceivers. Numerical and experimental results validate their performance and benefits.

The impact of service-specific staffing, case scheduling, turnovers, and first-case starts on anesthesia group and operating room productivity: a tutorial using data from an Australian hospital.

PubMed

McIntosh, Catherine; Dexter, Franklin; Epstein, Richard H

2006-12-01

In this tutorial, we consider the impact of operating room (OR) management on anesthesia group and OR labor productivity and costs. Most of the tutorial focuses on the steps required for each facility to refine its OR allocations using its own data collected during patient care. Data from a hospital in Australia are used throughout to illustrate the methods. OR allocation is a two-stage process. During the initial tactical stage of allocating OR time, OR capacity ("block time") is adjusted. For operational decision-making on a shorter-term basis, the existing workload can be considered fixed. Staffing is matched to that workload based on maximizing the efficiency of use of OR time. Scheduling cases and making decisions on the day of surgery to increase OR efficiency are worthwhile interventions to increase anesthesia group productivity. However, by far, the most important step is the appropriate refinement of OR allocations (i.e., planning service-specific staffing) 2-3 mo before the day of surgery. Reducing surgical and/or turnover times and delays in first-case-of-the-day starts generally provides small reductions in OR labor costs. Results vary widely because they are highly sensitive both to the OR allocations (i.e., staffing) and to the appropriateness of those OR allocations.

Biomass Allocation Patterns Are Linked to Genotypic Differences in Whole-Plant Transpiration Efficiency in Sunflower

PubMed Central

Velázquez, Luciano; Alberdi, Ignacio; Paz, Cosme; Aguirrezábal, Luis

2017-01-01

Increased transpiration efficiency (the ratio of biomass to water transpired, TE) could lead to increased drought tolerance under some water deficit scenarios. Intrinsic (i.e., leaf-level) TE is usually considered as the primary source of variation in whole-plant TE, but empirical data usually contradict this assumption. Sunflower has a significant variability in TE, but a better knowledge of the effect of leaf and plant-level traits could be helpful to obtain more efficient genotypes for water use. The objective of this study was, therefore, to assess if genotypic variation in whole-plant TE is better related to leaf- or plant-level traits. Three experiments were conducted, aimed at verifying the existence of variability in whole-plant TE and whole-plant and leaf-level traits, and to assess their correlation. Sunflower public inbred lines and a segregating population of recombinant inbred lines were grown under controlled conditions and subjected to well-watered and water-deficit treatments. Significant genotypic variation was found for TE and related traits. These differences in whole-plant transpiration efficiency, both between genotypes and between plants within each genotype, showed no association to leaf-level traits, but were significantly and negatively correlated to biomass allocation to leaves and to the ratio of leaf area to total biomass. These associations are likely of a physiological origin, and not only a consequence of genetic linkage in the studied population. These results suggest that genotypic variation for biomass allocation could be potentially exploited as a source for increased transpiration efficiency in sunflower breeding programmes. It is also suggested that phenotyping for TE in this species should not be restricted to leaf-level measurements, but also include measurements of plant-level traits, especially those related to biomass allocation between photosynthetic and non-photosynthetic organs. PMID:29204153

Biomass Allocation Patterns Are Linked to Genotypic Differences in Whole-Plant Transpiration Efficiency in Sunflower.

PubMed

Velázquez, Luciano; Alberdi, Ignacio; Paz, Cosme; Aguirrezábal, Luis; Pereyra Irujo, Gustavo

2017-01-01

Increased transpiration efficiency (the ratio of biomass to water transpired, TE) could lead to increased drought tolerance under some water deficit scenarios. Intrinsic (i.e., leaf-level) TE is usually considered as the primary source of variation in whole-plant TE, but empirical data usually contradict this assumption. Sunflower has a significant variability in TE, but a better knowledge of the effect of leaf and plant-level traits could be helpful to obtain more efficient genotypes for water use. The objective of this study was, therefore, to assess if genotypic variation in whole-plant TE is better related to leaf- or plant-level traits. Three experiments were conducted, aimed at verifying the existence of variability in whole-plant TE and whole-plant and leaf-level traits, and to assess their correlation. Sunflower public inbred lines and a segregating population of recombinant inbred lines were grown under controlled conditions and subjected to well-watered and water-deficit treatments. Significant genotypic variation was found for TE and related traits. These differences in whole-plant transpiration efficiency, both between genotypes and between plants within each genotype, showed no association to leaf-level traits, but were significantly and negatively correlated to biomass allocation to leaves and to the ratio of leaf area to total biomass. These associations are likely of a physiological origin, and not only a consequence of genetic linkage in the studied population. These results suggest that genotypic variation for biomass allocation could be potentially exploited as a source for increased transpiration efficiency in sunflower breeding programmes. It is also suggested that phenotyping for TE in this species should not be restricted to leaf-level measurements, but also include measurements of plant-level traits, especially those related to biomass allocation between photosynthetic and non-photosynthetic organs.

Study on Equity and Efficiency of Health Resources and Services Based on Key Indicators in China

PubMed Central

Zhang, Xinyu; Zhao, Lin; Cui, Zhuang; Wang, Yaogang

2015-01-01

Background This study aims to evaluate the dialectical relationship between equity and efficiency of health resource allocation and health service utilization in China. Methods We analyzed the inequity of health resource allocation and health service utilization based on concentration index (CI) and Gini coefficient. Data envelopment analysis (DEA) was used to evaluate the inefficiency of resource allocation and service utilization. Factor Analysis (FA) was used to determine input/output indicators. Results The CI of Health Institutions, Beds in Health Institutions, Health Professionals and Outpatient Visits were -0.116, -0.012, 0.038, and 0.111, respectively. Gini coefficient for the 31 provinces varied between 0.05 and 0.43; out of these 23 (742%) were observed to be technically efficient constituting the “best practice frontier”. The other 8 (25.8%) provinces were technically inefficient. Conclusions Health professionals and outpatient services are focused on higher income levels, while the Health Institutions and Beds in Health Institutions were concentrated on lower income levels. In China, a few provinces attained a basic balance in both equity and efficiency in terms of current health resource and service utilization, thus serving as a reference standard for other provinces. PMID:26679187

Study on Equity and Efficiency of Health Resources and Services Based on Key Indicators in China.

PubMed

Zhang, Xinyu; Zhao, Lin; Cui, Zhuang; Wang, Yaogang

2015-01-01

This study aims to evaluate the dialectical relationship between equity and efficiency of health resource allocation and health service utilization in China. We analyzed the inequity of health resource allocation and health service utilization based on concentration index (CI) and Gini coefficient. Data envelopment analysis (DEA) was used to evaluate the inefficiency of resource allocation and service utilization. Factor Analysis (FA) was used to determine input/output indicators. The CI of Health Institutions, Beds in Health Institutions, Health Professionals and Outpatient Visits were -0.116, -0.012, 0.038, and 0.111, respectively. Gini coefficient for the 31 provinces varied between 0.05 and 0.43; out of these 23 (742%) were observed to be technically efficient constituting the "best practice frontier". The other 8 (25.8%) provinces were technically inefficient. Health professionals and outpatient services are focused on higher income levels, while the Health Institutions and Beds in Health Institutions were concentrated on lower income levels. In China, a few provinces attained a basic balance in both equity and efficiency in terms of current health resource and service utilization, thus serving as a reference standard for other provinces.

Efficiency measurement and the operationalization of hospital production.

PubMed

Magnussen, J

1996-04-01

To discuss the usefulness of efficiency measures as instruments of monitoring and resource allocation by analyzing their invariance to changes in the operationalization of hospital production. Norwegian hospitals over the three-year period 1989-1991. Efficiency is measured using Data Envelopment Analysis (DEA). The distribution of efficiency and the ranking of hospitals is compared across models using various distribution-free tests. Input and output data are collected by the Norwegian Central Bureau of Statistics. The distribution of efficiency is found to be unaffected by changes in the specification of hospital output. Both the ranking of hospitals and the scale properties of the technology, however, are found to depend on the choice of output specification. Extreme care should be taken before resource allocation is based on DEA-type efficiency measures alone. Both the identification of efficient and inefficient hospitals and the cardinal measure of inefficiency will depend on the specification of output. Since the scale properties of the technology also vary with the specification of output, the search for an optimal hospital size may be futile.

Technical efficiency and resources allocation in university hospitals in Tehran, 2009-2012.

PubMed

Rezapour, Aziz; Ebadifard Azar, Farbod; Yousef Zadeh, Negar; Roumiani, YarAllah; Bagheri Faradonbeh, Saeed

2015-01-01

Assessment of hospitals' performance in achieving its goals is a basic necessity. Measuring the efficiency of hospitals in order to boost resource productivity in healthcare organizations is extremely important. The aim of this study was to measure technical efficiency and determining status of resource allocation in some university hospitals, in Tehran, Iran. This study was conducted in 2012; the research population consisted of all hospitals affiliated to Iran and Tehran medical sciences universities of. Required data, such as human and capital resources information and also production variables (hospital outputs) were collected from data centers of studied hospitals. Data were analyzed using data envelopment analysis (DEA) method, Deap2,1 software; and the stochastic frontier analysis (SFA) method, Frontier 4,1 software. According to DEA method, average of technical, management (pure) and scale efficiency of the studied hospitals during the study period were calculated 0.87, 0.971, and 0.907, respectively. All kinds of efficiency did not follow a fixed trend over the study time and were constantly changing. In the stochastic frontier's production function analysis, the technical efficiency of the studied industry during the study period was estimated to be 0.389. This study represented hospitals with the highest and lowest efficiency. Reference hospitals (more efficient states) were indicated for the inefficient centers. According to the findings, it was found that in the hospitals that do not operate efficiently, there is a capacity to improve the technical efficiency by removing excess inputs without changes in the level of outputs. However, by the optimal allocation of resources in most studied hospitals, very important economy of scale can be achieved.

Technical efficiency and resources allocation in university hospitals in Tehran, 2009-2012

PubMed Central

Rezapour, Aziz; Ebadifard Azar, Farbod; Yousef Zadeh, Negar; Roumiani, YarAllah; Bagheri Faradonbeh, Saeed

2015-01-01

Background: Assessment of hospitals’ performance in achieving its goals is a basic necessity. Measuring the efficiency of hospitals in order to boost resource productivity in healthcare organizations is extremely important. The aim of this study was to measure technical efficiency and determining status of resource allocation in some university hospitals, in Tehran, Iran. Methods: This study was conducted in 2012; the research population consisted of all hospitals affiliated to Iran and Tehran medical sciences universities of. Required data, such as human and capital resources information and also production variables (hospital outputs) were collected from data centers of studied hospitals. Data were analyzed using data envelopment analysis (DEA) method, Deap2,1 software; and the stochastic frontier analysis (SFA) method, Frontier 4,1 software. Results: According to DEA method, average of technical, management (pure) and scale efficiency of the studied hospitals during the study period were calculated 0.87, 0.971, and 0.907, respectively. All kinds of efficiency did not follow a fixed trend over the study time and were constantly changing. In the stochastic frontier's production function analysis, the technical efficiency of the studied industry during the study period was estimated to be 0.389. Conclusion: This study represented hospitals with the highest and lowest efficiency. Reference hospitals (more efficient states) were indicated for the inefficient centers. According to the findings, it was found that in the hospitals that do not operate efficiently, there is a capacity to improve the technical efficiency by removing excess inputs without changes in the level of outputs. However, by the optimal allocation of resources in most studied hospitals, very important economy of scale can be achieved. PMID:26793657

Money, Time and Learning. Final Report.

ERIC Educational Resources Information Center

Thomas, J. Alan; Kemmerer, Frances

Chapter 1 of this study discusses sources of educational inequality in terms of criteria for resource allocation, definitions of educational equity, and equity and efficiency in the classroom. Following the second chapter's review of literature on how resources affect learning, chapter 3 offers a theory of resource allocation education. The fourth…

50 CFR 600.325 - National Standard 4-Allocations.

Code of Federal Regulations, 2012 CFR

2012-10-01

... communities, efficiency of various types of gear used in the fishery, transferability of effort to and impact... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false National Standard 4-Allocations. 600.325 Section 600.325 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND...

50 CFR 600.325 - National Standard 4-Allocations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... communities, efficiency of various types of gear used in the fishery, transferability of effort to and impact... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false National Standard 4-Allocations. 600.325 Section 600.325 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND...

50 CFR 600.325 - National Standard 4-Allocations.

Code of Federal Regulations, 2014 CFR

2014-10-01

... communities, efficiency of various types of gear used in the fishery, transferability of effort to and impact... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false National Standard 4-Allocations. 600.325 Section 600.325 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND...

Aggregation of Heterogeneous Time Preferences

ERIC Educational Resources Information Center

Gollier, Christian; Zeckhauser, Richard

2005-01-01

We examine an economy whose consumers have different discount factors for utility, possibly not exponential. We characterize the properties of efficient allocations of resources and of the shadow prices that would decentralize such allocations. We show in particular that the representative agent has a decreasing discount rate when, as is usually…

The Frozen Price Game

ERIC Educational Resources Information Center

Alden, Lori

2003-01-01

In this article, the author discusses the educational frozen price game she developed to teach the basic economic principle of price allocation. In addition to demonstrating the advantages of price allocation, the game also illustrates such concepts as opportunity costs, cost benefit comparisons, and the trade-off between efficiency and equity.…

Coalition Game-Based Secure and Effective Clustering Communication in Vehicular Cyber-Physical System (VCPS)

PubMed Central

Huo, Yan; Dong, Wei; Qian, Jin; Jing, Tao

2017-01-01

In this paper, we address the low efficiency of cluster-based communication for the crossroad scenario in the Vehicular Cyber-Physical System (VCPS), which is due to the overload of the cluster head resulting from a large number of transmission bandwidth requirements. After formulating the issue as a coalition formation game, a coalition-based clustering strategy is proposed, which could converge into a Nash-stable partition to accomplish the clustering formation process. In the proposed strategy, the coalition utility is formulated by the relative velocity, relative position and the bandwidth availability ratio of vehicles among the cluster. Employing the coalition utility, the vehicles are denoted as the nodes that make the decision whether to switch to a new coalition or stay in the current coalition. Based on this, we can make full use of the bandwidth provided by cluster head under the requirement of clustering stability. Nevertheless, there exist selfish nodes during the clustering formation, so as to intend to benefit from networks. This behavior may degrade the communication quality and even destroy the cluster. Thus, we also present a reputation-based incentive and penalty mechanism to stop the selfish nodes from entering clusters. Numerical simulation results show that our strategy, CG-SECC, takes on a better performance for the tradeoff between the stability and efficiency of clustering communication. Besides, a case study demonstrates that the proposed incentive and penalty mechanism can play an important role in discovering and removing malicious nodes. PMID:28264469

43 CFR 418.12 - Project efficiency.

Code of Federal Regulations, 2012 CFR

2012-10-01

... delivery level including droughts or allocations, automatically adjusts to changes during the year and... (except in a real drought), it allows for future planning and averaging over time. (3) Efficiency targets...

43 CFR 418.12 - Project efficiency.

Code of Federal Regulations, 2014 CFR

2014-10-01

... delivery level including droughts or allocations, automatically adjusts to changes during the year and... (except in a real drought), it allows for future planning and averaging over time. (3) Efficiency targets...

43 CFR 418.12 - Project efficiency.

Code of Federal Regulations, 2013 CFR

2013-10-01

... delivery level including droughts or allocations, automatically adjusts to changes during the year and... (except in a real drought), it allows for future planning and averaging over time. (3) Efficiency targets...

Maximizing the impact of malaria funding through allocative efficiency: using the right interventions in the right locations.

PubMed

Scott, Nick; Hussain, S Azfar; Martin-Hughes, Rowan; Fowkes, Freya J I; Kerr, Cliff C; Pearson, Ruth; Kedziora, David J; Killedar, Madhura; Stuart, Robyn M; Wilson, David P

2017-09-12

The high burden of malaria and limited funding means there is a necessity to maximize the allocative efficiency of malaria control programmes. Quantitative tools are urgently needed to guide budget allocation decisions. A geospatial epidemic model was coupled with costing data and an optimization algorithm to estimate the optimal allocation of budgeted and projected funds across all malaria intervention approaches. Interventions included long-lasting insecticide-treated nets (LLINs), indoor residual spraying (IRS), intermittent presumptive treatment during pregnancy (IPTp), seasonal mass chemoprevention in children (SMC), larval source management (LSM), mass drug administration (MDA), and behavioural change communication (BCC). The model was applied to six geopolitical regions of Nigeria in isolation and also the nation as a whole to minimize incidence and malaria-attributable mortality. Allocative efficiency gains could avert approximately 84,000 deaths or 15.7 million cases of malaria in Nigeria over 5 years. With an additional US$300 million available, approximately 134,000 deaths or 37.3 million cases of malaria could be prevented over 5 years. Priority funding should go to LLINs, IPTp and BCC programmes, and SMC should be expanded in seasonal areas. To minimize mortality, treatment expansion is critical and prioritized over some LLIN funding, while to minimize incidence, LLIN funding remained a priority. For areas with lower rainfall, LSM is prioritized over IRS but MDA is not recommended unless all other programmes are established. Substantial reductions in malaria morbidity and mortality can be made by optimal targeting of investments to the right malaria interventions in the right areas.

Cascaded chirped photon acceleration for efficient frequency conversion

NASA Astrophysics Data System (ADS)

Edwards, Matthew R.; Qu, Kenan; Jia, Qing; Mikhailova, Julia M.; Fisch, Nathaniel J.

2018-05-01

A cascaded sequence of photon acceleration stages using the instantaneous creation of a plasma density gradient by flash ionization allows the generation of coherent and chirped ultraviolet and x-ray pulses with independently tunable frequency and bandwidth. The efficiency of the cascaded process scales with 1/ω in energy, and multiple stages produce significant frequency up-conversion with gas-density plasmas. Chirping permits subsequent pulse compression to few-cycle durations, and output frequencies are not limited to integer harmonics.

Efficient optical injection locking of electronic oscillators

NASA Astrophysics Data System (ADS)

Cochran, S. R.; Wang, S. Y.

1989-05-01

The paper presents techniques for direct optical injection locking of electronic oscillators and analyzes the problem of direct optical injection locking of a common-source FET oscillator using a high impedance optoelectronic transducer. A figure-of-merit for optically injection locked oscillators is defined, and an experimental oscillator based on the design criteria was fabricated. The oscillator achieved efficient, high power operation and moderate locking bandwidth with small locking signal magnitude. The experimental results are consistent with the theoretical model.

High-efficiency broadband excitation and propagation of second-mode spoof surface plasmon polaritons by a complementary structure.

PubMed

Zhang, Dawei; Zhang, Kuang; Wu, Qun; Yang, Guohui; Sha, Xuejun

2017-07-15

A complementary structure based on coplanar waveguides (CPWs) with periodical etching slots is proposed to support spoof surface plasmon polaritons (SSPPs). In contrast to the traditional slotline-based complementary SSPP structure, a dispersion curve of the second mode by the proposed structure has a much lower starting point from the origin which exhibits greatly improved operating bandwidth. Moreover, tighter confinements of SSPPs in the region of small wave vectors corresponding to lower frequencies can be predicted from the dispersion analysis, which means enhancement of transmission efficiency. Then a simple and efficient transition structure with tapered CPWs and gradient slots is proposed to realize high-efficiency and broadband excitation of the second mode of SSPPs for the first time, to the best of our knowledge. Based on the proposed structure, a seamless connection between CPWs and the SSPP structure can be achieved. The measured insertion loss and return loss below 6.6 GHz is better than -0.86 and -13.62  dB, respectively. Furthermore, it can be seen from the measurement results that a 3 dB bandwidth ranges from 0 to 10.57 GHz, and the return loss is better than -10  dB from 0 to 8.96 GHz. The proposed structure can promote the development of plasmonic integrate circuits and functional devices at microwave frequencies.

Opto-microwave Butler matrixes based front-end for a multi-beam large direct radiating array antenna

NASA Astrophysics Data System (ADS)

Piqueras, M. A.; Mengual, T.; Navasquillo, O.; Sotom, M.; Caille, G.

2017-09-01

The evolution of broadband communication satellites shows a clear trend towards beam forming and beam-switching systems with efficient multiple access schemes with wide bandwidths, for which to be economically viable, the communication price shall be as low as possible.

Engineering the Ideal Array (BRIEFING CHARTS)

DTIC Science & Technology

2007-03-05

48 V, f = 10 GHz GaN HEMT Transistor i t Dramatically higher: • Output power • Efficiency • Bandwidth GaN HEMT Power Amplifier lifi ...functions – RF amplifiers – 4-bit phase shifters – Amplitude controllers – Summing network – Power control – Latches for phase state – Address

Elymus repens biomass allocation and acquisition as affected by light and nutrient supply and companion crop competition

PubMed Central

Ringselle, Björn; Prieto-Ruiz, Inés; Andersson, Lars; Aronsson, Helena; Bergkvist, Göran

2017-01-01

Background and Aims Competitive crops are a central component of resource-efficient weed control, especially for problematic perennial weeds such as Elymus repens. Competition not only reduces total weed biomass, but denial of resources can also change the allocation pattern – potentially away from the underground storage organs that make perennial weeds difficult to control. Thus, the competition mode of crops may be an important component in the design of resource-efficient cropping systems. Our aim was to determine how competition from companion crops with different modes of competition affect E. repens biomass acquisition and allocation and discuss that in relation to how E. repens responds to different levels of light and nutrient supply. Methods Greenhouse experiments were conducted with E. repens growing in interspecific competition with increasing density of perennial ryegrass or red clover, or growing at three levels of both light and nutrient supply. Key Results Elymus repens total biomass decreased with increasing biomass of the companion crop and the rate of decrease was higher with red clover than with perennial ryegrass, particularly for E. repens rhizome biomass. A reduced nutrient supply shifted E. repens allocation towards below-ground biomass while a reduced light supply shifted it towards shoot biomass. Red clover caused no change in E. repens allocation pattern, while ryegrass mostly shifted the allocation towards below-ground biomass, but the change was not correlated with ryegrass biomass. Conclusions The companion crop mode of competition influences both the suppression rate of E. repens biomass acquisition and the likelihood of shifts in E. repens biomass allocation. PMID:28025285

Effects of space allocations and energy levels on growth performance and nutrient digestibility in growing and finishing pigs.

PubMed

Lei, X J; Yan, L; Kim, Y M; Kim, I H

2018-02-01

Two experiments were conducted to investigate effects of different space allocations and different dietary metabolizable energy (ME) levels on growth performance and nutrient digestibility in growing and finishing pigs. In experiment 1, a total of 84 growing pigs [(Yorkshire × Landrace) × Duroc] with an initial body weight (BW) of 27.10 ± 1.60 kg were used in a 5-week trial. Pigs were blocked based on initial BW into a 2 × 2 factorial design with the following factors: (i) 0.60 or 0.80 m 2 /pig space allocations; and (ii) 3,400 or 3,550 kcal/kg ME of diets. In experiment 2, a total of 84 finishing pigs with an initial BW of 67.43 ± 1.97 kg were used in a 10-week trial. Pigs were allotted based on initial BW into a 2 × 2 factorial design with the following factors: (i) 0.81 or 1.08 m 2 /pig space allocations; and (ii) 3,300 or 3,450 kcal/kg ME of diet. In experiment 1, high ME diet improved gain-to-feed ratio (G:F) in pigs with low space allocation but not in pigs in high space allocation (p < .05). Additionally, high ME diet increased apparent total tract digestibility (ATTD) of nitrogen in low space allocation but decreased ATTD of nitrogen in high space allocation (p < .05). In experiment 2, high ME diet improved average daily gain (ADG) and G:F in early-finishing pigs with low space allocation but not in pigs with high space allocation (p < .05). In conclusion, the provision of high ME diets was not enough to overcome the reduction in growth performance due to low space allocation but can improve feed efficiency in growing pigs and daily gain and feed efficiency early-finishing pigs. © 2017 Blackwell Verlag GmbH.

Automatic recognition of postural allocations.

PubMed

Sazonov, Edward; Krishnamurthy, Vidya; Makeyev, Oleksandr; Browning, Ray; Schutz, Yves; Hill, James

2007-01-01

A significant part of daily energy expenditure may be attributed to non-exercise activity thermogenesis and exercise activity thermogenesis. Automatic recognition of postural allocations such as standing or sitting can be used in behavioral modification programs aimed at minimizing static postures. In this paper we propose a shoe-based device and related pattern recognition methodology for recognition of postural allocations. Inexpensive technology allows implementation of this methodology as a part of footwear. The experimental results suggest high efficiency and reliability of the proposed approach.

Improving the Success of Strategic Management Using Big Data.

PubMed

Desai, Sapan S; Wilkerson, James; Roberts, Todd

2016-01-01

Strategic management involves determining organizational goals, implementing a strategic plan, and properly allocating resources. Poor access to pertinent and timely data misidentifies clinical goals, prevents effective resource allocation, and generates waste from inaccurate forecasting. Loss of operational efficiency diminishes the value stream, adversely impacts the quality of patient care, and hampers effective strategic management. We have pioneered an approach using big data to create competitive advantage by identifying trends in clinical practice, accurately anticipating future needs, and strategically allocating resources for maximum impact.

Strategic costs and preferences revelation in the allocation of resources for health care.

PubMed

Levaggi, Laura; Levaggi, Rosella

2010-09-01

This article examines the resources allocation process in the internal market for health care in an environment characterised by asymmetry of information. We analyse the strategic behaviour of the provider and show how, by misreporting its cost function and reservation utility, it might shift the allocation of resources away from the purchaser's objectives. Although the fundamental importance of equity, efficiency and risk aversion considerations which have been the traditional focus of the literature on allocation of resources should not be denied, this paper shows that contracts and internal markets are not neutral instruments and more research should be devoted to studying their effects.

Data envelopment analysis for estimating efficiency of intensive care units: a case study in Iran.

PubMed

Bahrami, Mohammad Amin; Rafiei, Sima; Abedi, Mahdieh; Askari, Roohollah

2018-05-14

Purpose As hospitals are the most costly service providers in every healthcare systems, special attention should be given to their performance in terms of resource allocation and consumption. The purpose of this paper is to evaluate technical, allocative and economic efficiency in intensive care units (ICUs) of hospitals affiliated by Yazd University of Medical Sciences (YUMS) in 2015. Design/methodology/approach This was a descriptive, analytical study conducted in ICUs of seven training hospitals affiliated by YUMS using data envelopment analysis (DEA) in 2015. The number of physicians, nurses, active beds and equipment were regarded as input variables and bed occupancy rate, the number of discharged patients, economic information such as bed price and physicians' fees were mentioned as output variables of the study. Available data from study variables were retrospectively gathered and analyzed through the Deap 2.1 software using the variable returns to scale methodology. Findings The study findings revealed the average scores of allocative, economic, technical, managerial and scale efficiency to be relatively 0.956, 0.866, 0.883, 0.89 and 0.913. Regarding to latter three types of efficiency, five hospitals had desirable performance. Practical implications Given that additional costs due to an extra number of manpower or unnecessary capital resources impose economic pressure on hospitals also the fact that reduction of surplus production plays a major role in reducing such expenditures in hospitals, it is suggested that departments with low efficiency reduce their input surpluses to achieve the optimal level of performance. Originality/value The authors applied a DEA approach to measure allocative, economic, technical, managerial and scale efficiency of under-study hospitals. This is a helpful linear programming method which acts as a powerful and understandable approach for comparative performance assessment in healthcare settings and a guidance for healthcare managers to improve their departments' performance.

Computer architecture for efficient algorithmic executions in real-time systems: New technology for avionics systems and advanced space vehicles

NASA Technical Reports Server (NTRS)

Carroll, Chester C.; Youngblood, John N.; Saha, Aindam

1987-01-01

Improvements and advances in the development of computer architecture now provide innovative technology for the recasting of traditional sequential solutions into high-performance, low-cost, parallel system to increase system performance. Research conducted in development of specialized computer architecture for the algorithmic execution of an avionics system, guidance and control problem in real time is described. A comprehensive treatment of both the hardware and software structures of a customized computer which performs real-time computation of guidance commands with updated estimates of target motion and time-to-go is presented. An optimal, real-time allocation algorithm was developed which maps the algorithmic tasks onto the processing elements. This allocation is based on the critical path analysis. The final stage is the design and development of the hardware structures suitable for the efficient execution of the allocated task graph. The processing element is designed for rapid execution of the allocated tasks. Fault tolerance is a key feature of the overall architecture. Parallel numerical integration techniques, tasks definitions, and allocation algorithms are discussed. The parallel implementation is analytically verified and the experimental results are presented. The design of the data-driven computer architecture, customized for the execution of the particular algorithm, is discussed.

Computer architecture for efficient algorithmic executions in real-time systems: new technology for avionics systems and advanced space vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carroll, C.C.; Youngblood, J.N.; Saha, A.

1987-12-01

Improvements and advances in the development of computer architecture now provide innovative technology for the recasting of traditional sequential solutions into high-performance, low-cost, parallel system to increase system performance. Research conducted in development of specialized computer architecture for the algorithmic execution of an avionics system, guidance and control problem in real time is described. A comprehensive treatment of both the hardware and software structures of a customized computer which performs real-time computation of guidance commands with updated estimates of target motion and time-to-go is presented. An optimal, real-time allocation algorithm was developed which maps the algorithmic tasks onto the processingmore » elements. This allocation is based on the critical path analysis. The final stage is the design and development of the hardware structures suitable for the efficient execution of the allocated task graph. The processing element is designed for rapid execution of the allocated tasks. Fault tolerance is a key feature of the overall architecture. Parallel numerical integration techniques, tasks definitions, and allocation algorithms are discussed. The parallel implementation is analytically verified and the experimental results are presented. The design of the data-driven computer architecture, customized for the execution of the particular algorithm, is discussed.« less

Market power in auction and efficiency in emission permits allocation.

PubMed

Jiang, Min Xing; Yang, Dong Xiao; Chen, Zi Yue; Nie, Pu Yan

2016-12-01

This paper analyzes how to achieve the cost-effectiveness by initial allocation of CO 2 emission permits when a single dominant firm in production market has market power in auction, and compare two prevalent allocation patterns, mixed allocation and single auction. We show how the firm with market power may manipulate the auction price, thereby this leads to fail to achieve cost-effective solution by auction unless the total permits for allocation equal to the effective emissions cap. Provided that the market power firm receives strictly positive free permits, the effective emissions cap of mixed allocation is larger than that of single auction. The production market share of dominant firm is increasing with the free permits it holds. Finally, we examine the compliance costs and welfare of mixed allocation and single auction, the result show that the former is preferred to the later when policy makers consider economic welfare without welfare cost due to CO 2 emissions. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Efficiency-Equity Trade-off of Schooling Outcomes: Public Education Expenditures and Welfare in Mexico.

ERIC Educational Resources Information Center

Gershberg, Alec Ian; Schuermann, Til

2001-01-01

Performs empirical tests of the Mexican federal government's state-level education expenditures and examines changes in allocation patterns by comparing 1980 and 1990 cross-sections. Unlike other Latin American countries, where formulated grants are made to subnational jurisdictions, the Mexican allocation pattern seems neither rational nor…

Implementation and Incentive of Education Policies: Experience from the High School Admissions Quota Allocation Policy

ERIC Educational Resources Information Center

Shiyue, Wang

2017-01-01

Improving administrative efficiency is the core problem in administrative governance. This case study of quota allocation policy implementation in City A reveals that a set of education policy implementation and incentive mechanisms revolving around responsibility contracts and target evaluations has already taken shape, to guarantee effective…

University and Polytechnic Objectives, Resource Allocation and Performance Indices in the Central Services. Program on Institutional Management in Higher Education.

ERIC Educational Resources Information Center

Norris, Graeme, Ed.

Research progress by member institutions is reviewed with regard to university administration, computing, committees, libraries, and student welfare. Consideration is given to effectiveness and efficiency, management information, management by objectives, periodic review of objectives, strategy, and analytic resource allocation. Two research…

Resource Allocation Procedure at Queensland University: A Dynamic Modelling Project.

ERIC Educational Resources Information Center

Galbraith, Peter L.; Carss, Brian W.

A structural reorganization of the University of Queensland, Australia, was undertaken to promote efficient resource management, and a resource allocation model was developed to aid in policy evaluation and planning. The operation of the restructured system was based on creating five resource groups to manage the distribution of academic resources…