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51.
This paper analyzes the average bit error probability (BEP) of the differential binary and quaternary phase-shift keying (DBPSK and DQPSK respectively) with multiple-input multiple-output (MIMO) systems employing postdetection equal gain combining (MIMO EGC) diversity reception over Rayleigh fading channels. Finite closed-form expressions for the average BEP of DBPSK and DQPSK are presented. Two approaches are introduced to analyze the error rate of DQPSK. The proposed structure for the differential phase-shift keying (DPSK) with MIMO EGC provides a reduced-complexity and low-cost receiver for MIMO systems compared to the coherent phase-shift keying system (PSK) with MIMO employing maximal ratio combining (MIMO MRC) diversity reception. Finally, a useful procedure for computing the associated Legendre functions of the second kind with half-odd-integer order and arbitrarily degree is presented.  相似文献   
52.
The concept of usage of heterogeneous networks (HetNets) is about improving the LTE system performance by increasing the capacity and coverage of the Macro cell. In this paper, a performance comparison of various packet scheduling algorithms such as Proportional Fair, Maximum Largest Weighted Delay First and Exponential/Proportional Fair is studied in detail in the HetNets environment. The key performance indicators such as throughput, packet loss ratio, delay and fairness are considered to judge the performance of the scheduling algorithms. Various strategies such as increasing the number of Pico cells in the cell edge were used in the simulation for the performance evaluation study. The results achieved through various simulations show that adding Pico cells to the existing Macros enhances the overall system performance in addition to the various scheduling algorithms implemented in Macros. For reader’s convenience, various types of graphs have been used to represent the simulation results to better understand the performance metrics of various scheduling algorithms. Simulation results shows that overall system gain has increased because of adding Picos and thereby providing better coverage in the cell edge areas and thereby increasing the capacity of the network to provide better quality of service.  相似文献   
53.
The hydrodynamic characteristics of a 10-cm reciprocating plate column used for counter-current gas-liquid contacting was investigated. The values of gas holdup, interfacial area and maximum throughputs achievable in this unit put it in a favourable position in comparison with other types of contactors.  相似文献   
54.
Relative oscillatory motion between solid particles and a fluid increases the rate of interphase mass transfer due to the establishment of secondary flows (acoustic streaming). A critical survey of published data shows that mass transfer is well correlated by a theoretically founded dimensionless relation of the form where K, a, b and d depend on the Schmidt number. The equation successfully correlates experimental data for both gases and liquids over a range of frequencies F < 1 Hz to F ? 106 Hz, provided the amplitude to diameter ratio A/D is below 0.75. At higher values of this parameter, NSh is better predicted by a quasi-steady model which no longer depends on A/D. Based on a paper presented at the 26th Canadian Chemical Engineering Conference, Montreal, Quebec, November 2–5, 1975.  相似文献   
55.
Current subsidies to residential water users in Oman are estimated at USD 314 million/y. This study estimates the demand function for residential water in Muscat, Oman, for households living in villas. A two-stage least squares econometric model with lagged average water price was used with socio-economic variables. Price elasticity for residential water in Muscat was estimated as –2.10. This high price elasticity is explained by the large proportion of water used for outdoor purposes. This study indicates that it may be possible to manage water demand in Muscat through modifying the price of water and reforming subsidies for residential water.  相似文献   
56.
57.
    
Field emission finds a vital space in numerous scientific and technological applications, including high-resolution imaging at micro- and nano-scales, conducting high-energy physics experiments, molecule ionization in spectroscopy, and electronic uses. A continuous effort exists to develop new materials for enhanced field emission applications. In the present work, two-dimensional (2D) well-aligned CdSSe flake flowers (CdSSe-FFs) were successfully grown on gold-coated silicon substrate utilizing a simple and affordable chemical bath deposition approach at ambient temperature. The time-dependent growth mechanism from nanoparticles to FFs was observed at optimized parameters such as concentration of precursors, pH (~11), deposition time, and solution temperature. The crystalline nature of CdSSe-FFs is confirmed by high-resolution transmission electron microscopy (HRTEM) results, and selected area electron diffraction (SAED) observations reveal a hexagonal crystal structure. Additionally, the CdSSe-FFs thickness was confirmed by TEM analysis and found to be ~20–30 nm. The optical, photoelectric, and field emission (FE) characteristics are thoroughly explored which shows significant enhancement due to the formation of heterojunction between the gold-coated silicon substrate and CdSSe-FFs. The UV–visible absorption spectra of CdSSe-FFs show enhanced absorption at 700 nm, corresponding to the energy band gap (Eg) of 1.77 eV. The CdSSe-FFs exhibited field emission and photosensitive field emission (PSFE) characteristics. In FE study CdSSe-FFs shows an increase in current density of 387.2 μ A cm−2 in an applied field of 4.1 V m−1 which is 4.08 fold as compared to without light illumination (95.1 μ A cm−2). Furthermore, it shows excellent emission current stability at the preset value of 1.5 μA over 3 h with a deviation of the current density of less than 5% respectively.  相似文献   
58.
    
ABSTRACT

Arabic sign language (ArSL) is method of communication between deaf communities in Arab countries; therefore, the development of systemsthat can recognize the gestures provides a means for the Deaf to easily integrate into society. In this research we implemented a computational structurefor an intelligent interpreter that automatically recognizes the isolated dynamic gestures. The proposed system recognizes and translates gesturesperformed with one or both hands. It comprises five subsystems, building dataset, video processing, feature extraction, mapping between ArSL and Arabictext, and text generation. To apply the system, 100-signs of ArSL was used, which was applied on 1500 video files. It's were divided into five classes:alphabet, numbers, \"prepositions, pronouns and question words\", Arabic life expressions, and \"nouns and verbs\". The evaluation indicated that thesystem automatically recognizes and translates isolated dynamic ArSL gestures by highly accurate manner. The results showed that the system accuracy is 95.8%.  相似文献   
59.
    
Extracellular vesicles secreted from adipose‐derived mesenchymal stem cells (ADSCs) have therapeutic effects in inflammatory diseases. However, production of extracellular vesicles (EVs) from ADSCs is costly, inefficient, and time consuming. The anti‐inflammatory properties of adipose tissue‐derived EVs and other biogenic nanoparticles have not been explored. In this study, biogenic nanoparticles are obtained directly from lipoaspirate, an easily accessible and abundant source of biological material. Compared to ADSC‐EVs, lipoaspirate nanoparticles (Lipo‐NPs) take less time to process (hours compared to months) and cost less to produce (clinical‐grade cell culture facilities are not required). The physicochemical characteristics and anti‐inflammatory properties of Lipo‐NPs are evaluated and compared to those of patient‐matched ADSC‐EVs. Moreover, guanabenz loading in Lipo‐NPs is evaluated for enhanced anti‐inflammatory effects. Apolipoprotein E and glycerolipids are enriched in Lipo‐NPs compared to ADSC‐EVs. Additionally, the uptake of Lipo‐NPs in hepatocytes and macrophages is higher. Lipo‐NPs and ADSC‐EVs have comparable protective and anti‐inflammatory effects. Specifically, Lipo‐NPs reduce toll‐like receptor 4‐induced secretion of inflammatory cytokines in macrophages. Guanabenz‐loaded Lipo‐NPs further suppress inflammatory pathways, suggesting that this combination therapy can have promising applications for inflammatory diseases.  相似文献   
60.
    
This paper presents a focused and comprehensive literature survey on the use of machine learning (ML) in antenna design and optimization. An overview of the conventional computational electromagnetics and numerical methods used to gain physical insight into the design of the antennas is first presented. The major aspects of ML are then presented, with a study of its different learning categories and frameworks. An overview and mathematical briefing of regression models built with ML algorithms is then illustrated, with a focus on those applied in antenna synthesis and analysis. An in‐depth overview on the different research papers discussing the design and optimization of antennas using ML is then reported, covering the different techniques and algorithms applied to generate antenna parameters based on desired radiation characteristics and other antenna specifications. Various investigated antennas are sorted based on antenna type and configuration to assist the readers who wish to work with a specific type of antennas using ML.  相似文献   
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