Waveform requirements for a ground penetration ultra-wideband exciter (UWBE) include generating a frequency spectrum over a wide bandwidth, with a low-start frequency. A scripted ...linear-frequency-modulated waveform is used for the frequency coverage, with the added ability of arbitrarily notching-out portions of the transmitting spectrum in which radio frequency interference (RFI) exists. This exciter uses an arbitrary waveform generator (AWG), which scripts waveform packets with notches in the spectrum. The AWG is coupled to a frequency synthesizing architecture (FSA) device for waveform packet placement to create a phase-continuous broad-band response.
A test target simulator (TTS) based on a fiber-optic delay line (FODL) has been designed for realistic testing and characterizing of wideband pulsed Doppler radars. The TTS can simulate one or two ...targets at different radar cross sections (RCS's), different Doppler, and different ranges in the presence of uncorrelated noise or interference. With one target, clutter and multipath effects can also be simulated. In a closed-loop test of a pulsed Doppler radar transceiver, the variable control of the RCS can be used to test the radar's dynamic range. Simulating two targets and varying the range and Doppler of each target in the closed-loop test can evaluate the radar's range and Doppler resolution, respectively.< >
碩士
義守大學
管理科學研究所
102
Theoretically, human resource management has been becoming critical task and directly to help the firms enhance their competitive advantage in the market. It is worth to denote ...that firms can obtain higher productivity and profitability through quality of human resource. Thus, almost firms today have establish HRM Department as stand-alone entity in order to take into account current performance of their HRM as well as providing necessary mechanism in order to foster the quality of their HRM to higher level. In this study, the author would like to focus on current performance of HRM in TQPC with interest is set toward managerial level of the firm. The study is conducted with conceptual research model adopted from top 5 qualities of successful managers in 2013 provided by Archer (2013), including (1) commercial or organization purpose awareness, (2) performance, (3) development of people, (4) leadership, and (5) motivation. Then, the author establishes survey with 35 managers of TQPC and methodology that is applied in this study includes quantitative and qualitative methods. The author utilizes descriptive statistics, graphs and frequency analysis tables in order to analyze how managers of TQPC qualify 5 qualities of successful managers in 2013. The survey and interview are applied for this study with sample of survey is about 100 employees and sample of interview is about 34 managers of TQPC. The result of survey is that commercial or organization purpose awareness, development of people, leadership, and motivation are statistical significant to quality of managers of TQPC. Performance factor, however, is not statistical significant to quality of managers of TQPC
A test target simulator (TTS) based on a fiber-optic delay line (FODL) has been designed for realistic testing and characterizing of wideband pulsed Doppler radars. The TTS can simulate one or two ...targets at different radar cross sections (RCSs), different Doppler, and different ranges in the presence of uncorrelated noise or interference. With one target, clutter and multipath effects can also be simulated. In a closed-loop test of a pulsed Doppler radar transceiver, the variable control of the RCS can be used to test the radar's dynamic range. Simulating two targets and varying the range and Doppler of each target in the closed-loop test can evaluate the radar's range and Doppler resolution, respectively.
Nghiên cứu này tìm hiểu các yếu tố ảnh hưởng đến sự hài lòng của hành khách đối với nhà ga quốc nội, cảng hàng không quốc tế Tân Sơn Nhất (TSN). Sử dụng mô hình cấu trúc tuyến tính (PLS-SEM) nhằm ...kiểm định các mối quan hệ giữa các giả thuyết, áp dụng phương pháp khảo sát mẫu chặn được thu thập từ 230 ở phòng chờ nhà ga quốc nội. Kết quả nghiên cứu cho thấy chất lượng dịch vụ, giá trị cảm nhận và hình ảnh sân bay có tác động đến sự hài lòng của hành khách. Trong đó, chất lượng dịch vụ là một khái niệm bậc hai bao gồm các thành phần: hiệu quả, hiệu suất, tương tác và trang trí, ảnh hưởng trực tiếp và gián tiếp đến sự hài lòng. Đối với tác động gián tiếp, giá trị cảm nhận và hình ảnh sân bay đóng vai trò trung gian trong mối quan hệ giữa chất lượng dịch vụ và sự hài lòng. Giá trị cảm nhận có tác động lớn nhất đến sự hài lòng so với chất lượng dịch vụ và hình ảnh sân bay. Nghiên cứu này cung cấp các hàm ý quản trị đối với sân bay TSN nhằm thiết lập các chiến lược nhằm góp phần vào sự phát triển bền vững cũng như tạo ra hình ảnh sân bay tích cực, gia tăng giá trị cảm nhận và nâng cao mức độ hài lòng.
Low-cost technology for multimode radar Adler, E.; Clark, J.; Conn, M. ...
IEEE aerospace and electronic systems magazine,
06/1999, Letnik:
14, Številka:
6
Magazine Article
A flexible test bed radar architecture is described which includes an integrated RF electronics package that can support multiple radar applications, including surveillance, fire control, target ...acquisition, and tracking. This type of architecture can significantly reduce the cost, power, size, and weight of electronics on future weapon delivery platforms. The Army Research Laboratory (ARL) is developing technology to support multimode radar requirements. These requirements include the detection and location of moving or stationary low radar cross section targets in heavy ground clutter and the classification and/or recognition of these targets. We address these requirements with commercial-off-the-shelf (COTS) products and the integration of several enabling technologies. The test bed radar includes a direct digital synthesizer (DDS) for frequency-diverse waveform generation, a flexible wideband transceiver for bandwidth extension and frequency translation, and an open architecture signal processor with embedded wideband analog-to-digital converters for real-time acquisition and processing. Efficient signal processing algorithms have been developed to demonstrate multimode radar capability. This paper discusses the various subassemblies, algorithm efficiency, and field experiment results.
Low-cost enabling technology for multimode radar requirements Adler, E.; Clark, J.; Conn, M. ...
Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197),
1998
Conference Proceeding
A flexible test bed radar architecture is described which includes an integrated RF electronics package that can support multiple radar applications, including surveillance, fire control, target ...acquisition, and tracking. This type of architecture can significantly reduce the cost, power, size, and weight of electronics on future weapon delivery platforms. The Army Research Laboratory (ARL) is developing technology to support multimode radar requirements. These requirements include the detection and location of moving or stationary low radar cross section targets in heavy ground clutter and the classification and/or recognition of these targets. We address these requirements with commercial-off-the-shelf (COTS) products and the integration of several enabling technologies. The test bed radar includes a direct digital synthesizer (DDS) for frequency-diverse waveform generation, a flexible wideband transceiver for bandwidth extension and frequency translation, and an open architecture signal processor with embedded wideband analog-to-digital converters for real-time acquisition and processing. Efficient signal processing algorithms have been developed to demonstrate multimode radar capability. This paper discusses the various subassemblies, algorithm efficiency, and field experiment results.
A wide-bandwidth electronic scanning antenna (ESA), based on a Rotman lens beam-former, has been developed for shared aperture applications. The key feature of the Rotman lens is that it allows ...multiple simultaneous beams to be transmitted in different directions and at different frequencies. Since the Rotman lens is a true time-delay element, it is inherently wide-bandwidth and other components of the antenna were designed to support a bandwidth of 8 to 18 GHz. In the ESA, the input signal to the Rotman lens is controlled by a PIN diode beamswitching network, and the outputs are fed to a two-dimensional array of Vivaldi notches. The ESA performance is characterized, and the results is presented.
Abstract
Background
Little is known about the natural history of asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
Methods
We conducted a prospective study at a ...quarantine center for coronavirus disease 2019 in Ho Chi Minh City, Vietnam. We enrolled quarantined people with reverse-transcription polymerase chain reaction (RT-PCR)–confirmed SARS-CoV-2 infection, collecting clinical data, travel and contact history, and saliva at enrollment and daily nasopharyngeal/throat swabs (NTSs) for RT-PCR testing. We compared the natural history and transmission potential of asymptomatic and symptomatic individuals.
Results
Between 10 March and 4 April 2020, 14 000 quarantined people were tested for SARS-CoV-2; 49 were positive. Of these, 30 participated in the study: 13 (43%) never had symptoms and 17 (57%) were symptomatic. Seventeen (57%) participants imported cases. Compared with symptomatic individuals, asymptomatic people were less likely to have detectable SARS-CoV-2 in NTS collected at enrollment (8/13 62% vs 17/17 100%; P = .02). SARS-CoV-2 RNA was detected in 20 of 27 (74%) available saliva samples (7 of 11 64% in the asymptomatic group and 13 of 16 81% in the symptomatic group; P = .56). Analysis of RT-PCR positivity probability showed that asymptomatic participants had faster viral clearance than symptomatic participants (P < .001 for difference over the first 19 days). This difference was most pronounced during the first week of follow-up. Two of the asymptomatic individuals appeared to transmit SARS-CoV-2 to 4 contacts.
Conclusions
Asymptomatic SARS-CoV-2 infection is common and can be detected by analysis of saliva or NTSs. The NTS viral loads fall faster in asymptomatic individuals, but these individuals appear able to transmit the virus to others.
Forty-three percent (13/30) of confirmed SARS-CoV-2–infected individuals were asymptomatic, with the virus detected in both saliva and nasopharyngeal/throat swabs. Viral clearance was faster in asymptomatic individuals, but they still appeared able to pass the infection to others.
Synbiotics, a conjunction between prebiotics and probiotics, have been used in aquaculture for over 10 years. However, the mechanisms of how synbiotics work as growth and immunity promoters are far ...from being unraveled. Here, we show that a prebiotic as part of a synbiotic is hydrolyzed to mono- or disaccharides as the sole carbon source with diverse mechanisms, thereby increasing biomass and colonization that is established by specific crosstalk between probiotic bacteria and the surface of intestinal epithelial cells of the host. Synbiotics may indirectly and directly promote the growth of aquatic animals through releasing extracellular bacterial enzymes and bioactive products from synbiotic metabolic processes. These compounds may activate precursors of digestive enzymes of the host and augment the nutritional absorptive ability that contributes to the efficacy of food utilization. In fish immune systems, synbiotics cause intestinal epithelial cells to secrete cytokines which modulate immune functional cells as of dendritic cells, T cells, and B cells, and induce the ability of lipopolysaccharides to trigger tumor necrosis factor-α and Toll-like receptor 2 gene transcription leading to increased respiratory burst activity, phagocytosis, and nitric oxide production. In shellfish, synbiotics stimulate the proliferation and degranulation of hemocytes of shrimp due to the presence of bacterial cell walls. Pathogen-associated molecular patterns are subsequently recognized and bound by specific pattern-recognition proteins, triggering melanization and phagocytosis processes.
•Current applications of synbiotics in aquaculture.•Steps for establishing a synergistic synbiotic.•Synbiotic metabolism and molecular crosstalk with host.•Mechanisms of actions in improving growth and immune responses of host.•Highlight notes for further investigations.
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