Performance Characteristics Of System Research Articles

Spatial Linear Coding in Joint Radar and Multicast Communication Systems

Introduction. This paper presents optimization methods for the amplitude-phase distribution in a transmitting antenna array in a system with a common signal for multicast data transmission and radar sensing in a given sector of space. Two approaches are considered for the choice of an objective function for the optimization problem. The first approach involves minimizing the transmitted power for a given quality of user service and radar surveillance. The second approach involves optimizing the quality of service for the worst radar and communication channel under a given power budget. The value that determines the quality of service is the signal-to-noise ratio, for both communication and radar.Aim. Тo solve the optimization problem of spatial linear coding of signals in a joint multicast radar and communication system, which shares a common signal.Materials and methods. Optimization of spatial linear coding in a joint radio radar and communication system was carried out by the methods of statistical theory and optimization theory using the numerical solution of optimization problems. The performance characteristics of the system were analyzed by Monte Carlo simulation. Statistical simulation was performed in the MATLAB environment using standard tools, as well as the CVX package for the numerical solution of convex optimization problems.Results. Optimization problems were formulated based on the criteria of the minimum radiated power and the maximum signal-to-noise ratio in the worst channel. A limitation on the radiated power of individual antenna channels was used for both cases. Optimization problems were approximately reduced to convex problems with semidefinite constraints, which could be solved using the wellknown interior point algorithm with polynomial complexity. The performed statistical simulation produced optimal performance characteristics of a joint system, including the total power versus the threshold signal-to-noise ratio and the signal-to-noise ratio for the worst channel versus the power budget.Conclusion. The proposed numerical optimization methods for spatial linear coding in a transmitting antenna array can be recommended when designing joint radar communication systems.

A hierarchical model for analyzing multisite individual-level disease surveillance data from multiple systems.

Passive surveillance systems are widely used to monitor diseases occurrence over wide spatial areas due to their cost-effectiveness and integration into broadly distributed healthcare systems. However, such systems are generally associated with imperfect ascertainment of disease cases and with heterogeneous capture probabilities arising from factors such as differential access to care. Augmenting passive surveillance systems with other surveillance efforts provides a way to estimate the true number of incident cases. We develop a hierarchical modeling framework for analyzing data from multiple surveillance systems that allows for individual-level covariate-dependent heterogeneous capture probabilities, and borrows information across surveillance sites to improve estimation of the true number of incident cases. Inference is carried out via a two-stage Bayesian procedure. Simulation studies illustrated superior performance of the proposed approach with respect to bias, root mean square error, and coverage compared to a model that does not borrow information across sites. We applied the proposed model to data from three surveillance systems reporting pulmonary tuberculosis (PTB) cases in a major center of ongoing transmission in China. The analysis yielded bias-corrected estimates of PTB cases from the passive system and led to the identification of risk factors associated with PTB rates, as well as factors influencing the operating characteristics of the implemented surveillance systems.

Drying of tomato pomace in daylight simulated photovoltaic‐assisted drying system: Effects of daylight intensity and application mode

AbstractIt was aimed to dry a by‐product of tomato paste production (tomato pomace) by minimizing the losses valuable components and reducing energy consumption. In this concept, a daylight simulated photovoltaic‐assisted dryer (DPVD) applying the daylight in different modes and intensities during drying was custom‐designed. The effects of daylight applications on the change of some quality characteristics of tomato pomace and system performance characteristics were investigated, and the optimum drying condition was determined. The process conditions included the combination of three different daylight application modes (UV‐blocked daylight via solar tube‐DLST, DLST + LED, and LED) and three different daylight intensities (2,500, 7,500, and 10,000 lux). The drying was applied for 240 min at constant air temperature (60°C) with an air velocity of 2 m/s. The moisture content and the water activity values of dried tomato pomace were 8.86 ± 2.00% and 0.57 ± 0.10%, respectively. The lycopene and β‐carotene losses after drying were determined as 68.36 ± 4.32% and 65.66 ± 4.33%, respectively. The energy and exergy efficiencies of the system were in the range of 19.56%–35.73% and 5.10%–17.05%, respectively. The optimum condition meeting the criteria of superior quality and high‐performance characteristics was obtained by applying DLST at 7,500 lux (desirability 0.728). In the performance improvement studies, it has been concluded that all the energy required for the process could have been fulfilled as 100% from solar energy with the support of photovoltaic panels. In other words, it was demonstrated that the developed DPVD system could be used to dry the tomato pomace not only in terms of providing high food quality and safety, but also in terms of having high energy efficiency.Practical applicationsExposure to the daylight is important to dry some foods. Especially in north countries, products are dried in artificial dryers, but it requires high energy consumption. In this study, the daylight transfer system was integrated into the artificial dryer for the purpose of using daylight effect in addition to the photovoltaic (PV) assistance for using solar energy. During periods when the solar thermal effect is not intense or in countries where the sun effect is limited, it will be possible to dry food products with the daylight effects via using the DPVD system in suitable microbiological conditions.In this study, tomato pomace samples, which are the byproduct of tomato paste production, could be dried in daylight simulated PV‐assisted drying system in high quality and with low energy consumption. It is concluded that it can be possible to obtain valuable components from a byproduct having no economical value.

Research on Dual-LCC MCRWPT system based on controlled rectifier

Among many types of Wireless Power Transfer (WPT) technology, Magnetically Coupled Resonance Wireless Power Transfer (MCRWPT) technology has been studied more and more due to its stable transmission Power and strong anti-interference ability. In this paper, the operating characteristics of the Dual-LCC MCRWPT system based on the secondary side controlled rectifier are analyzed, and the variation of the system current with D, the phase relationship between the input voltage and current of the resonant network, the phase relationship between the output voltage and current of the resonant network, and the variation of the input and output load of the system are studied in depth. Through the simulation analysis of inverter MOSFET switching state, verify the effectiveness of the controlled rectifier control mode and the rationality of theoretical analysis, provide a solid theoretical basis for the optimization of the controlled rectifier control mode.

Energy, economic and environmental dynamic response characteristics of organic Rankine cycle (ORC) system under different driving cycles

Internal combustion (IC) engine as the main power source of vehicle, its energy saving and emission reduction is of great significance to alleviate the energy crisis. Organic Rankine cycle (ORC) system has a good prospect in the field of waste heat recovery of IC engine. However, in the actual operation of the vehicle, the hysteresis time, time-varying and uncertainty of ORC system are more obvious. Moreover, under the influence of the fluctuation of IC engine and the hysteresis time of ORC system, the performance of the system is heavily dependent on the change of operating parameters. This paper firstly constructs four key models of power system, waste heat recovery system, chassis and driving cycle. Then, the driving cycle-based vehicle-ORC combined system model is proposed. From the perspective of thermodynamic performance, economic performance and environmental impact, the dynamic response characteristics of ORC system performance and operating parameters under real driving cycles are systematically evaluated. The performance of ORC system can be improved by 9.25–17.72% with the increase of the large speed gradient. The hysteresis time of ORC system is 16.6–144.3 s. Hysteresis time and performance degradation will become more serious with the superposition of decrease of the large speed gradient, low speed and idle speed. The hysteresis time under the influence of superposition is up to 150.4–295.3 s. There is also a 39.59–62.45% decline in performance. The analysis of dynamic characteristics of ORC system under complex real driving cycles can provide useful guidance for practical engineering application of vehicle ORC system.

Applications of solar PV tree systems with different design aspects and performance assessment

ABSTRACT Solar energy is deemed as the most abundant, reliable, eco-friendly and totally free resource of energy. There is a wide range of techniques to harness solar energy for different purposes. Among all the available methods, direct conversion of sunlight into electricity through photovoltaic (PV) phenomenon is the most mature and popular process. Progress of PV technology in market is perspicuous; however, it has still some drawbacks such as notable land requirement in cities, energy conversion efficiencies that already reached the theoretical limits and social acceptance issues due to aesthetic details. To overcome the aforesaid challenges, solar PV tree concept has been recently developed, and the simplicity, compact structure and elegance of this novel technology have been in the focus of researchers. Within the scope of this review, the concept of solar PV tree has been extensively investigated in terms of various design aspects and potential applications. Current performance characteristics of solar PV tree systems and power management strategies in real applications have been discussed. Challenges involved with the solar PV tree technology have also been addressed as well as suggestions on the direction of further works.

Application of fuzzy-logic for design assessment of complex engineering systems in the early design stages

Performance characteristics of production-logistic systems arestrongly dependent on their initial design. Hence, it is crucial to employ proper performance assessment approaches at their early design stages. Existing approaches mostly use optimisation for quantitative performance assessment. However, qualitative aspects of such systems considerably impact their lifetime performance. Uncertainty is significant in assessing the qualitative performance of a system. Fuzzy-logic is a useful approach in addressing uncertainty. This paper investigates the application of fuzzy-logic for design assessment of such systems against qualitative criteria. The proposed approach can be utilised as a decision-supporting framework at early design stages of such systems. The framework allows design assessment by modelling the subjective opinion of domain experts. The framework has a hybrid-hierarchical structure, embodying the complex structure of a system to fuzzy-models in a hierarchical manner and allocates related knowledge to fuzzy-models in different hierarchy levels. The framework is applied to a real case to demonstrate its application.

Operating characteristics and performance evaluation of carbon dioxide heat pump driven liquid desiccant dehumidification systems: A comparative study

Carbon dioxide heat pump driven liquid desiccant dehumidification takes perfect advantage of the eco-friendly and excellent heating performance of the carbon dioxide heat pump, making regeneration performance significantly improved, being a possible green and efficient air conditioning method. However, the system's operating characteristics and performance are not yet fully clear, hindering practical applications. Given this, a comparative study is conducted in terms of both refrigerants and system configurations. The mathematical models are developed and validated. The results suggested that the power consumption and dehumidification performance of the carbon dioxide heat pump driven liquid desiccant dehumidification systems are reduced and improved by a maximum of 51.67% and 106.89%, respectively, compared with condensing dehumidification. The carbon dioxide heat pump driven liquid desiccant dehumidification systems provide better performance at high dehumidification needs than R134a while offering comparable or even better seasonal performance. The total power consumption and seasonal dehumidification performance are reduced and enhanced by a maximum of 18.84% and 23.21%, respectively. However, owing to the special characteristics and performance of the carbon dioxide heat pump, it is not applicable to the liquid desiccant dehumidification system with solution self-circulation while being less sensitive to the solution-solution heat exchanger. Hence, more efficient systems should be tailored in the future. This study lays the foundation for the optimization and practical applications of the carbon dioxide heat pump driven liquid desiccant dehumidification systems.

On the use of thermal energy storage in solar-aided power generation systems

The solar-aided power generation (SAPG) technology has been proven to be one of the most efficient ways to integrate solar thermal energy into coal-fired power plants. An open question is whether to integrate the SAPG plant with a thermal energy storage system (TES). Conventionally, most SAPG plants are not designed to include TESs due to high costs and challenges related to the intermittent nature of solar energy. To address this question, a realistic case study utilizing a 330MWe SAPG plant is investigated in this paper. The simulation shows that when the SAPG plant uses a TES with a proper regulation strategy, the energy efficiency of the SAPG can be increased by 2.5% and the levelized cost of electric energy (LCOE) can be reduced by 0.27 cents/kWh. A well-regulated TES does not deteriorate the economic performance of the SAPG plant here and has a positive impact on its operational safety (especially under sudden irradiance change). To the best of authors’ knowledge, this is the first time to study the operational strategies of TES (based on the operating characteristics of the SAPG systems) and to combine them with the TES’s size optimization to maximize the techno-economic performance of the SAPG plant.

Performance of integrated sequencing batch reactor (SBR) and reverse osmosis (RO) process for leachate treatment: effect of pH

PurposeIn this paper the performance and effectiveness of the reverse osmosis (RO) process for the biologically pretreated leachate was investigated. The RO process was carried out separately for two different pH: 8.0 and 9.3.MethodsA general pollution parameters as well as organic and inorganic indicators were determined in raw, biologically pretreated and RO treated leachate. The performance characteristics of the reverse osmosis system were made on the basis of permeate flux, electroconductivity removal rate, concentration factor and efficiency in removal of analyzed parameters.ResultsThe use of SBR pretreatment had very good efficiency in BOD (97.3%) and ammonia nitrogen (95.4%) removal. The lowest effectivity was observed for chloride (11.6%), boron (3.9%) and TDS (1.2%). Pretreated leachate was subjected to RO system. The normalized average flux was 0.53 (42.3 L/m2·h) for pH = 8.0 and 0.68 (33.5 L/m2·h) for pH = 9.3. The lower membrane fouling at higher pH can be explained by electrostatic repulsion between the negatively charged membrane surface and organic substances. Independently of the process pH, a two-step membrane fouling was observed. The greatest differences in removal rates were observed for boron, which had a higher retention rate at higher pH, and ammonia nitrogen, whose removal rate decreased at higher pH. The obtained permeate pH after RO process was lower than the feed pH in two analyzed value of pH.ConclusionsThe higher flux value at pH = 9.3 is result of high content of organic matter in leachate, which is better rejected at higher pH because of higher electrostatic repulsion between organic matter and membrane surface. This indicates that the organic matter content should be taken into account when determining the operating parameters (pH values) of the RO system.

In Vitro Simulation of Shoulder Motion Driven by Three-Dimensional Scapular and Humeral Kinematics.

In vitro simulation of three-dimensional (3D) shoulder motion using in vivo kinematics obtained from human subjects allows investigation of clinical conditions in the context of physiologically relevant biomechanics. Herein, we present a framework for laboratory simulation of subject-specific kinematics that combines individual 3D scapular and humeral control in cadavers. The objectives were to: (1) robotically simulate seven healthy subject-specific 3D scapulothoracic and glenohumeral kinematic trajectories in six cadavers, (2) characterize system performance using kinematic orientation accuracy and repeatability, and muscle force repeatability metrics, and (3) analyze effects of input kinematics and cadaver specimen variability. Using an industrial robot to orient the scapula range of motion (ROM), errors with repeatability of ±0.1 mm and <0.5 deg were achieved. Using a custom robot and a trajectory prediction algorithm to orient the humerus relative to the scapula, orientation accuracy for glenohumeral elevation, plane of elevation, and axial rotation of <3 deg mean absolute error (MAE) was achieved. Kinematic accuracy was not affected by varying input kinematics or cadaver specimens. Muscle forces over five repeated setups showed variability typically <33% relative to the overall simulations. Varying cadaver specimens and subject-specific human motions showed effects on muscle forces, illustrating that the system was capable of differentiating changes in forces due to input conditions. The anterior and middle deltoid, specifically, showed notable variations in patterns across the ROM that were affected by subject-specific motion. This machine provides a platform for future laboratory studies to investigate shoulder biomechanics and consider the impacts of variable input kinematics from populations of interest, as they can significantly impact study outputs and resultant conclusions.

ПРИМЕНЕНИЕ ПЕРСПЕКТИВНОГО МНОГОФУНКЦИОНАЛЬНОГО ЭШЕЛОНИРОВАННОГО ВОЗДУШНОГО КОМПЛЕКСА НА БАЗЕ ЛЕТАТЕЛЬНЫХ АППАРАТОВ ЛЕГЧЕ ВОЗДУХА В ОРГАНАХ ВНУТРЕННИХ ДЕЛ

Introduction: The paper substantiates a justification for the use of Lighter-Than-Air aircrafts in the interests of the internal affairs bodies of the Russian Federation. Purpose: Аnalysis of existing Heavier-Than-Air unmanned aircrafts and Lighter-Than-Air aircrafts capabilities, as well as review of a wide range of payloads with the aim of synthesis of the multilevel aerial complex destined for the internal affairs bodies. Results: Based on the analysis of existing unmanned aerial vehicles and Lighter-Than-Air aircrafts, the article proposes the composition and further use of multifunctional echeloned air complex based on lighter-than-air aircrafts designed for the internal affairs bodies. Taking into consideration the internal affairs bodies tasks specificity, various options of an air complex construction scheme, as well as its equipment with designed and existing payload modules, are proposed. Practical relevance: Practical recommendations for the construction of a two-tier scheme air complex for internal affairs bodies based on Lighter-Than-Air aircrafts have been developed. The first tier is built on well-known samples of tethered balloon complexes (stationary component) and medium-altitude unmanned airships (mobile component), as well as perspective small (up to 50 kilograms of payload) and ultra-small (up to 20 kilograms of payload) tethered and unmanned aerial vehicles (stationary and mobile components) proposed in this article. The second tier comprises the unmanned high-altitude aerostatic platforms (mobile component). Discussion: the results obtained in the article are proposed to be used for the calculation of the individual modules performance characteristics, of the performance characteristics of a repeater system built on the basis of airships and for developing an algorithm for the coordination control of the interoperable Lighter-Than-Air aircrafts and Heavier-Than-Air unmanned aircrafts.

Experimental Study on the Influence of Inclination on Operating Characteristics of Secondary Side Passive Residual Heat Removal System

Experimental Study on the Influence of Inclination on Operating Characteristics of Secondary Side Passive Residual Heat Removal System

The On-site Verification of Key Technologies for Kunbei-Liuzhou-Longmen Hybrid Multi-terminal Ultra HVDC Project

Hybrid high voltage direct current transmission (Hybrid HVDC) is a new type of HVDC technology developed in recent years. It combines the characteristics of large-capacity and low cost of the line commutated converters (LCC) and non-commutation failure and dynamic reactive power support of voltage sourced converters (VSCs) in one HVDC system. It has technical advantages in the fields of unidirectional power transmission and in the application of improving the stability of multi-infeed HVDCs, giving it broad application prospects. The Kunbei-Liuzhou-Longmen (KBL) project is the first hybrid ultra HVDC project. It was put into service on Dec. 27 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> , 2020. This paper introduces the KBL project, analyzes the operation characteristics of hybrid HVDC system, and provides on-site verification of KBL project, including operation of LCC-VSC hybrid system, ultra-high voltage VSC technology using the series of two valve groups, the DC fault ride-though of hybrid VSC without using DC breaker, the connection and disconnection of a third station, and etc.

Simulation research on heat recovery system of heat pump composite pump-driven loop heat pipe

To promote energy-saving potentials of the energy recovery unit under all-year conditions, a composite system combining pump-driven loop heat pipe with heat pump was firstly proposed, and the mathematical models were established. The operating characteristics of the composite system were studied in the whole year and compared with the traditional heat pump heat recovery system. The results show that the heating capacity of the composite system is in line with the heating load in winter. Compared with the traditional heat pump system, the composite system has higher energy efficiency ratio and lower deviation degree of temperature effectiveness in the whole year. The heat pump composite pump-driven loop heat pipe heat recovery system is generally superior to similar system reported in literatures, which indicates that it can replace heat pump system in buildings ventilation.

Simulatiomn of BHE fresh air air conditioning system based on TRNSYS-CFD Hybrid Simulation

In order to solve the problem of input fresh air overheating (cooling) in the cold supply (heating) season in severe cold regions, a soil source (BHE) combined with fresh air preheating (cooling) air conditioning system was studied in a net-zero energy building in Shenyang. Firstly, a hybrid TRNSYS-CFD simulation model based on TRNSYS and Fluent simulation software was established to simulate the operation and indoor temperature distribution of the air conditioning system in the building during a typical day in the summer (winter) season. The TRNSYS-CFD hybrid simulation allows simultaneous analysis of the operating characteristics of the air conditioning system and the real-time indoor temperature distribution. The results show that the accuracy of the hybrid simulation is compared with that of the TRNSYS stand-alone simulation by monitoring the temperature changes in each room. The room temperature from the TRNSYS stand-alone simulation is the average temperature of the room return air, while the room temperature from the hybrid simulation has a stratification effect and the simulation data is more valuable for reference.

Development of Computational Fluid Dynamics (Cfd) Methodology for Characterization of Exhalation Delivery System (Eds) Performance

Development of Computational Fluid Dynamics (Cfd) Methodology for Characterization of Exhalation Delivery System (Eds) Performance

Effects of working conditions on the operating characteristics of an injection system applied on CNG fueled vehicles

A model-based study is conducted to examine the operating characteristics of an injection system applied on CNG fueled vehicles. This injection system is a combination of an electric pressure regulator, a rail tube, and a solenoid injector. The electric pressure regulator has a great potential to be widely used in injection systems of natural gas-fueled engines due to its flexible operation, which can help to improve the engine performance and reduce emission. This paper presents a simulation study using mathematical models to describe and analyze the operating characteristics of the gaseous fuel injection system, in which models of electric pressure regulator, solenoid fuel injector, and control model for electric pressure regulator are presented. The simulation results are compared with experimental data to validate the simulation models. Effects of working conditions, including coil resistance of the electric pressure regulator, inlet gas pressure, and set pressure in the rail tube, on the operating characteristics of the gaseous fuel injection system are investigated. Simulation results show that when the coil resistance of the electric pressure regulator is increased from 3.1 Ω to 4.1 Ω, the maximum fluctuation of the controlled gas pressure in the rail tube is reduced from 0.017 to 0.012 MPa, respectively. By decreasing the inlet gas pressure of the electric pressure regulator from 2.5 to 2.3 MPa, the controlled gas pressure in the rail tube is more stable with the maximum fluctuation significantly reduced from 0.012 to 0.002 MPa, respectively, which leads to stability in injection flow rate. The increase of set pressure in the rail tube from 0.5 to 0.7 MPa can help to improve the stability of the controlled gas pressure in the rail tube with the maximum fluctuation respectively reduced from 0.002 to 0.001 MPa.

Tuning of a control compensator from the first generation with comparison with compensators from the second compensator generation

The paper investigates the tuning of a second order compensator from the first compensators generation when used to control a highly oscillating second order process. It compares the performance characteristics of the control system comprising this compensator to control the highly oscillating second order process with those resulting from the use of five compensators from the second compensators generation. The comparison covers three time-based characteristics: maximum percentage overshoot, settling time and steady-state error. All the compensators are tuned and the analysis results help control engineers to select appropriate compensators according to the desired performance characteristic for a specific application.

Optimization of Computer Communication Monitoring System for Wind Turbine Speed

This article first studies the operating principles of wind turbines, focusing on the analysis of the structure and working principles of permanent magnet direct-drive wind turbines. According to the actual needs of the wind power system, the monitoring objects of the monitoring system are determined, and the overall monitoring plan for wind power generation is proposed to realize real-time analysis of the operating characteristics of the wind power system. At the same time, it pointed out the great significance of the wind power generation simulation experiment system and focused on the wind speed modeling. In terms of hardware research and analysis, relevant sensors, high-speed data acquisition cards, etc., were selected, and relevant signal conditioning circuits were designed, and a permanent magnet direct-drive wind power generation system simulation monitoring platform was constructed. In terms of software, LabVIEW was chosen as the design language of the monitoring system, and it pointed out the advantages of using LabVIEW in this monitoring system. Finally, the system uses the laboratory permanent magnet direct-drive wind turbine as the monitoring object. The practicality and accuracy of the system are verified through experiments such as permanent magnet motor power test, motor speed test, database system test, and remote monitoring test. The experimental results show that the monitoring system has a friendly interface and perfect functions and has important practicability and reference in the field of wind power monitoring.