Series Configuration Research Articles

Retrofitting conventional chilled-water system to a solar-assisted absorption cooling system: Modeling, polynomial regression, and grasshopper optimization

This study aims to replace the current conventional chilled-water system with solar-assisted absorption cooling in a large pharmaceutical company in Amman, Jordan. Conventional heating, ventilation, and air conditioning (HVAC) systems were used to serve the existing 9000 m2 area of the pharmaceutical facilities. Two solar absorption chiller configurations were proposed and evaluated to investigate this replacement using TRNSYS® software. The auxiliary heater and storage tank were configured in series and parallel and evaluated based on actual data from the company. The effects of the evacuated tube collector (ETC) on the solar fraction, storage tank volume (STV), auxiliary heat required (Qaux), and heat loss (Qloss) were studied. The grasshopper optimization algorithm (GOA), a newly developed optimization technique, was used to optimize the storage tank volume with solar fraction (SF), Qaux, and average heat loss (kJ/h) on an hourly basis in parallel and series configurations. Mathematical equations involving the factor such as storage tank volume and Qloss responses in parallel and series configurations were developed using regression modeling (RM) over all experimental observations. The optimal factor values were then calculated using the GOA and regression models. The confirmation findings indicated that SF was maximized, and Qloss was effectively minimized. Under the 95 % confidence level with = 0.05, the p-value for all RMs was <0.05, indicating the significance of the RM. Furthermore, the RM matched the provided data well, with a low prediction error. The GOA indicated that the parallel system configuration was the superior connection that provided optimum results for SF, and Qaux at a storage tank of 2.8 m3. According to the GOA method, the optimal STV for a series layout was 2.0 m3 and for a parallel arrangement was 2.8 m3. In terms of SF, the parallel system configuration outperformed the series system, which increased by 12.34 %. The parallel system significantly decreases Qloss and Qaux by 4.04 % and 7.39 %, respectively. To compare the GOA with other meta-heuristic optimization approaches, conventional HVAC systems were optimized using particle swarm optimization (PSO). The results indicated that the GOA surpasses the PSO technique in terms of the required convergence speed and population size. Because the movement of agents depends on the positions of each agent inside the swarm, GOA differs from other optimization algorithms. The novelty of this study demonstrates that the GOA technique provides a higher probability of convergence with less computing effort than well-liked and popular optimization methodologies such as PSO for a variety of Qloss, Qaux, and SF issues. These results have significant reverberation for the potential of the GOA to minimize Qloss and Qaux, and maximize SF in the parallel and series configurations of the auxiliary heater.

Performance Analysis of Continuous Casting System of Steel Industry

The continuous casting system is the most important to solidify the liquid steel in the steel industry. Steel is the backbone of civilization and modernization. So, there is a need to optimize the performance of continuous casting system of steel industry. Continuous casting system has six subsystems: “Pouring turret ladle”, “Tundish”, “Mold”, “Water spray chamber”, “Support roller” and “Torch cutter”. Series configuration is used to arrange these subsystems. The subsystem “Pouring turret ladle” is having three similar units. These units are operating in parallel. The subsystems “Tundish”, “Mold”, “Water spray chamber” and “Support roller” have a single unit. The subsystem “Torch cutter” contains two identical units: one is operative and other keep in cold standby. For all subsystems, the distribution of repair rates and failure rates of continuous casting system are taken as arbitrary distributions. Analysis of continuous casting system has been done by using supplementary variable technique. The numerical results of reliability measure of continuous casting system in terms of availability and profit have been computed by assuming exponential, Rayleigh and Weibull distributions.

Towards a full design of a super-wide band slotted antenna array using graphene material for future 6G applications

Sixth-generation (6G) wireless communication systems have been developed in response to the growing demand for higher data rates and ultra-high-speed communication. It is expected to emerge around the year 2030. In order to fulfill this need, the 6G wireless communication system will exploit the terahertz (THz) frequency spectrum (0.1–10 THz). In the same framework, the current study seeks to design and analyze various antenna and antenna array configurations across the whole THz range. Initially, by integrating graphene material into various patch and feedline combinations for a single antenna. The return loss, VSWR (Voltage Standing Wave Ratio), gain, and directivity of the antenna were the four key features that were analyzed. Furthermore, a parametric investigation of substrate thicknesses was carried out for three distinct materials: Rogers RT5880, silicon, and polymide. In order to increase the directivity and gain of the optimized graphene antenna, we used five different antenna array architectures (1*2, 1*4, 2*2, 2*4, and 4*2) in both serial and parallel configurations. Finally, a further enhancement of the structure—a sixteen-antenna array (2*8 array)—was implemented by doubling the arrays' structural dimensions to meet the requirements of the sixth generation of telecommunication systems in terms of gain and directivity.

A New Single-Leg Lower-Limb Rehabilitation Robot: Design, Analysis and Experimental Evaluation

Conventional lower-limb rehabilitation robots are large, complicated to wear, and require moving the patient to a designated position. To solve these problems, a new single-legged lower-limb rehabilitation robot (S-LLRR) that is easy to move and suitable for different height carriers was proposed. The mechanical leg has a variable working space, and its rotating joints are designed with mechanical limiters. The series configuration of the S-LLRR was analyzed, and trajectory planning was performed based on continuous linear motion training. Meanwhile, an active training control method based on the sand model was proposed to enhance the motion sensation of patients, and an active participation degree evaluation model was designed based on human physiological information. The simulation and experimental results showed that S-LLRR had a large workspace and good motion accuracy, and the accuracy of the active participation degree evaluation model could reach more than 85%. This research could provide a theoretical basis for improving the standardization and compliance of lower-limb robot rehabilitation training.

Stochastic Assessment of k Operational State System with k-out-of-n:G Working Scheme with Employing Copula Repair Approach

This paper is a probabilistic performance study of a repairable complex system with three subsystems coupled in a series configuration. All three subsystems have been differently configured and also have different operational schemes. The first subsystem has [Formula: see text] units and works under the [Formula: see text]-out-of-[Formula: see text]:G scheme, the second subsystem has four identical units and associates with a defined work scheme 2-out-of-4:G, however, the third subsystem has two indistinguishable units and works under the 1-out-of-2:G policy. The units’ failure rates of the subsystems are different but constant and follow an exponential distribution, however, there are two types of repair facilities available for repair general and copula repair. Under the consideration of the system with the operational duration, the failed unit was replaced with a new one and it was assigned for repair. In the complete shutdown condition, a copula repair has been employed to repair the system. Traditional reliability measures have been studied for different values of failure and repair through supplementary variable and copula approaches. The numerical computations for securing different values of [Formula: see text] and [Formula: see text] have been exhibited and tables and graphs predict the future behavior of the system performance. In the conclusion section, the effect of reliability measures has been highlighted.

Physico-chemical characteristics and biodegradability of primary effluent and particulate matter removed by microscreens.

In this study, the physical, chemical, and biological characteristics of raw wastewater were compared with the liquid and solid streams generated by a primary clarifier (PC), a rotating belt filter (RBF, 350 μm), and a drum filter (DF, 60 μm) and series (SER) combination of an RBF with a PC or a DF using pilot-scale primary treatment units. The RBF removed about 36% of the influent total suspended solids. The DF and PC yielded an influent total suspended solid removal of 47% to 55% in both individual (parallel) and SER configurations. The size fractionation and chemical characterizations of the liquid fractions indicated a significant change in the wastewater composition in both filter configurations with no variation in the biodegradability of liquid fractions. The solids recovered by RBF had a higher total solids (TS) concentration and a higher volatile solids (VS) content (0.92 g VS/g TS) than that of DF and PC treatments (0.58 to 0.84 g VS/g TS). DF and PC sludge demonstrated a higher biodegradability rate (k1 ; 0.11 d-1 < k1 < 0.20 d-1 ) than solids recovered by RBF (0.09 d-1 ). The retained solids in the SER configuration demonstrated a significantly lower theoretical biochemical methane potential than the parallel configuration, likely due to the presence of smaller particles with a significantly higher ratio of particulate chemical oxygen demand over volatile suspended solids (1.86 to 2.40 g chemical oxygen demand/g volatile suspended solids). These results indicated that the physical, chemical, and biological characteristics of liquid and solids from different filter configurations are required to determine design criteria to upgrade or retrofit water resource recovery facilities using an RBF or a DF. PRACTITIONER POINTS: A rotating belt filter (RBF) removed less solids than a drum filter (DF) or a primary clarifier (PC). A series configuration of an RBF with either a DF or PC resulted in an effluent with a lower proportion of slowly biodegradable organic matter than in a parallel configuration. Solids from an RBF, a DF, or a PC had similar theoretical biochemical methane potential.

A Burst Mode and Variable Frequency Voltage Sharing Control Mechanism for an Adjustable High Voltage Pulsed Converter

This article presents a modular adjustable high-voltage pulse (MAHVP) generation system. The proposed MAHVP generation system uses a combination of full-bridge LLC resonant converters whose input terminals are connected in parallel and whose output terminals are in series to boost the output voltage; input parallel output series configuration efficiently increases the power holding capabilities of the overall system. The MAHVP generation system uses a novel burst mode and variable frequency voltage sharing (BMVFVS) control mechanism, the BMVFVS control mechanism senses the type of load if the MAHVP generation system needs to operate at a heavy load, it uses the variable frequency voltage sharing method to divide the power equally between the modules to enhance the overall performance. For light load conditions, the MAHVP generation system operates in burst mode, and the BMVFVS control mechanism combined with the frequency modulation technique is used to control the amplitude and pulsewidth of the output voltage smoothly and efficiently. A hardware prototype of 2.4 kW is developed, and experimental results are taken to verify the feasibility and validity of the proposed system, the maximum output voltage of the developed two-module prototype is tested up to 6 kV at the high efficiency of 97%.

Parameteric Estimation for Reliability Function of Phased Mission Systems with Series Network

In this paper, we consider a phased mission system consisting of [Formula: see text] phases (subsystems) wherein the control flows sequentially. The mission is successful if tasks associated with every phase are successful. Density and reliability functions of the lifetime of such a system are worked out when the lifetimes of components of the subsystems follow exponential distribution. It is assumed that components in different subsystems are in series configuration and function independently. The subsystems are assumed to operate independently. A simulation study is conducted to find bias of the estimates of the parameters and the reliability function. The Root Mean Square Error (RMSE) of the estimates is also calculated.

Utilising a novel multi-electrode approach for improving micro-resistance spot welding productivity for electric-mobility battery interconnects

The micro-resistance spot welding is widely used for low-to-medium-volume applications due to its low cost, especially for cylindrical Lithium-ion cell-based modules. Using typical micro-resistance spot welding electrodes in a series configuration, two nuggets/welds are created in a single welding operation. As it is a contact joining process, productivity is limited. This paper developed a novel approach to enhance the productivity of micro-resistance spot welding, where four nuggets were produced instead of two nuggets in a single operation. The critical-to-quality criteria, including joint strength, microstructure, electrical resistance and temperature rise at joints, were demonstrated by comparing the existing and proposed approaches. A reduction in cycle time by up to 57% can be achieved by adopting the proposed approach while maintaining the weld quality.

Pose accuracy improvement in robotic machining by visually-guided method and experimental investigation

Industrial robots have been widely used in the industries of automotive, machining, electrical and electronic, rubber and plastics, aerospace, food, etc., owing to their high efficiency and flexibility in contrast to large scaled machining centers. However, the poor accuracy resulted from the serial configuration of industrial robots has restricted their applications to high-precision machining for several decades. In this paper, an error compensation technique is proposed using the visual guidance to effectively improve the pose accuracy of industrial robots. Firstly, the effect of the establishment method of tracking coordinate system for a visual sensor on the pose measurement error is analyzed and the establishment method is optimized. Next, a fuzzy PID controller is designed and integrated with a KUKA robot controller KRC via the KUKA robot sensor interface to guide the robot to the desired pose in real-time. Finally, experimental tests are implemented to validate the effectiveness of the proposed approach.

A Descriptor System Approach for the Nonlinear State Estimation of Li-Ion Battery Series/Parallel Arrangements

The nonlinear state estimation for a series/parallel arrangement of lithium-ion (Li-ion) battery cells is addressed in this article assuming limited information. First, a unified model for series/parallel arrangements in terms of a nonlinear descriptor model is proposed in order to account for Kirchhoff’s laws characterizing the interconnection. It relies on a simplified electrochemical model of the individual cells, the so-called equivalent-hydraulic model. Then, assuming that the system and output equation nonlinearities locally satisfy Lipschitz-like constraints, a linear matrix inequality (LMI)-based technique is proposed for designing a nonlinear state observer, which estimates the state of each individual cell (such as the state-of-charge and inner temperature) as well as the algebraic variables (currents or voltages for respectively parallel or series configurations). The proposed design conditions also provide an estimate of the region of guaranteed convergence while ensuring a peak-to-peak performance with respect to exogenous inputs and model uncertainties. The effectiveness of the approach is demonstrated on a detailed battery electrochemical simulator (based on the Doyle–Fuller–Newman model) for a series arrangement of two cells. Comparisons with a standard extended Kalman filter demonstrate the superior performance of the proposed approach.

Predictive Energy Management for Hybrid Electric Aircraft Propulsion Systems

We present a model predictive control (MPC) algorithm for energy management in aircraft with hybrid electric propulsion systems consisting of gas turbine and electric motor components. Series and parallel configurations are considered. By combining a point-mass aircraft dynamical model with models of electrical losses and losses in the gas turbine, the fuel consumed over a given future flight path is minimized subject to constraints on the battery, electric motor, and gas turbine. The optimization is formulated as a convex problem under mild assumptions and its solution is used to define a predictive energy management control law that takes into account the variation in aircraft mass during flight. We investigate the performance of algorithms for solving this problem. An alternating direction method of multipliers (ADMM) algorithm is proposed and compared with a general purpose convex interior point solver. We also show that the ADMM implementation reduces the required computation time by orders of magnitude in comparison with a general purpose nonlinear programming solver, making it suitable for real-time supervisory energy management control.

A Novel Non-Isolated High-Gain Non-Inverting Interleaved DC–DC Converter

High-gain DC-DC converters are being drastically utilized in renewable energy generation systems, such as photovoltaic (PV) and fuel cells (FC). Renewable energy sources (RES) persist with low-level output voltage; therefore, high-gain DC-DC converters are essentially integrated with RES for satisfactory performance. This paper proposes a non-isolated high-gain non-inverting interleaved DC-DC boost converter. The proposed DC-DC converter topology is comprised of two inductors and these are charging and discharging in series and parallel circuit configurations. The voltage multiplier technique is being utilized to produce high gain. The proposed topology is designed to operate in three modes of operation. Three switches are operated utilizing two distinct duty ratios to avoid the extreme duty ratio while having high voltage gain. Owing to its intelligent design, the voltage stress on the switches is also significantly reduced where the maximum stress is only 50% of the output voltage. The proposed converter's steady-state analysis with two distinct duty ratios is thoroughly explored. Furthermore, a 160 W 20/400 V prototype is developed for performance analysis and validation. The converter topology can generate output voltage with a very high voltage gain of 20, which is verified by the prototype. Moreover, a high efficiency of 93.2% is attained by the proposed converter's hardware prototype.

Modelling and Characterization Piezoelectric Transducer for Sound Wave Energy Harvesting

Energy harvesting system is using ambient energy conversion in the environment. The environmental energy will be converted into usable electrical energy that can be used in controlling wireless electronic devices. The available mechanical vibration from the sound energy will then be converted to electrical energy by using a piezoelectric transducer. The size of the piezoelectric represents the surface area of the electrode on the piezoelectric model. A smaller size piezoelectric transducer is unable to produce a good vibration due to the smaller surface area. The bigger dimension of the piezoelectric model would be able to harvest more electrical energy output because the vibration from the bigger piezoelectric model which would able to produce more sound wave energy. The piezoelectric material Lead Zirconate Titanate (PZT-5H) vibration is focused on the resonance frequency at below 1 kHz with sound level decibel is between the range of 35-100 dB. This research is to concentrate on rectangular and trapezium-shaped cantilever. The trapezium shaped cantilever produces higher energy output due to its shape which has better in terms of stress and strain distribution. In addition, researchers have modelled and validated energy harvesters with different proof masses shapes. The improved piezoelectric vibrational energy harvester has a trapezoidal beam and an added triangular proof mass. The arrangement of the piezoelectric tested in parallel, series, combination series and parallel configuration to investigate the performance of the output power generated from the sound wave. The rectangular and trapezium shaped cantilever are resulted in a resonant frequency of 269.4 Hz and 269.88 Hz, respectively. The rectangular and trapezium shaped cantilever produced a maximum output voltage of 3.105 V and 3.635 V respectively. The piezoelectric output during the parallel array configuration, which is 5.636 V, 0.497 mA and 2.803 mW. The output power produced by parallel is 81 % higher than compare in series array configuration and 35.8 % higher than combination of series and parallel. Thus, the produced energy output 5 V would be able to apply at several low power supply applications such as mobile phones, power bank or wireless sensor networks (WSN).

An improved technique for quantifying PD activity in cross-linked polyethylene (XLPE) power cables

The presence of air-filled cavities within the insulation of active power cables affects the electric field distribution in the insulation bulk and increases the electrical stress inside and around the cavities. This causes accelerated ageing of the materials and creates regions for partial discharge (PD) development that may subsequently result in cable failure. In this paper, an improved PD quantifying technique applied for insulated power cables is first presented. Its effectiveness is demonstrated through an in-depth study of electric field distribution across a defective cross-linked polyethylene (XLPE) power cable with practical dimensions for HV applications and by analysing the PD behaviour under different ageing conditions. In realizing the aforementioned, the cable model with different arrangements, in series and parallel, of two discharging air-filled cavities was implemented in COMSOL software. The simulated cable fields are analysed for different separations and positions of the cavities before and after PD activity. The cavity fields are extracted in MATLAB and utilized for PD pattern characterization under three ageing conditions. Through the PD patterns and statistical quantities measured from simulated PD behaviour, the severity of PD in the cable model was quantified over the different ageing periods. It was found that the series configuration of the cavities was the most harmful configuration due to its high-field magnitude and greater tendency to initiate a PD propagation. Furthermore, the PD behaviour changes during ageing and the highest PD activity, greater PD magnitude and rate, were recorded at the most advanced ageing stage. Thus, indicating that PD characteristics can be used for inferring the ageing stage.

Geothermal trigeneration systems with Organic Rankine Cycles: Evaluation of different plant configurations considering part load behaviour

Due to the increasing importance of cooling applications, geothermal trigeneration systems might be of high interest in the future. This work aims at evaluating different plant layouts against the background of more advanced plant configurations and part load behaviour. Five different plant configurations are analysed for geothermal heat source temperatures between 110 and 150 °C. The highest net power output is achieved by an advanced serial-parallel configuration (ASPC), but in case of high heating and cooling demand, a standard serial-parallel configuration is more favourable. For the considered base demand scenario of 130 °C, the ASPC results in an annual net power generation of 20.94 GWh, which is 6.9% higher than the second favourable configuration. The application of a recuperator within the ORC system has a significant impact on the serial concepts, but only marginally increases the power output of the parallel layouts. Comparing two exergetic efficiencies highlights that the assumed definition can result in a different ranking of the plant layouts. Considering the exergy that is transferred from the brine to the trigeneration system reveals the highest exergetic efficiency for a serial configuration, while the focus on the available exergy flow reveals the highest efficiency for the ASPC layout. Considering a brine temperature of 130 °C results in a maximal achievable second law efficiency of 34.1% if evaluating the available exergy flow. The evaluation of the pay-back period reveals that the ASPC results in the shortest pay-back period of 13.8 years.

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro-Harvesters.

Semiconductor nanowires have demonstrated fascinating properties with applications in a wide range of fields, including energy and information technologies. Particularly, increasing attention has focused on SiGe nanowires for applications in a thermoelectric generation. In this work, a bottom-up vapour-liquid-solid chemical vapour Deposition methodology is employed to integrate heavily boron-doped SiGe nanowires on thermoelectric generators. Thermoelectrical properties -, i.e., electrical and thermal conductivities and Seebeck coefficient - of grown nanowires are fully characterized at temperatures ranging from 300 to 600 K, allowing the complete determination of the Figure-of-merit, zT, with obtained values of 0.4 at 600 K for optimally doped nanowires. A correlation between doping level, thermoelectric performance, and elemental distribution is established employing advanced elemental mapping (synchrotron-based nano-X-ray fluorescence). Moreover, the operation of p-doped SiGe NWs integrated into silicon micromachined thermoelectrical generators is shown over standalone and series- and parallel-connected arrays. Maximum open circuit voltage of 13.8mV and power output as high as 15.6 µW cm-2 are reached in series and parallel configurations, respectively, operating upon thermal gradients generated with hot sources at 200 °C and air flows of 1.5 m s-1 . These results pave the way for direct application of SiGe nanowire-based micro-thermoelectric generators in the field of the Internet of Things.

Investigation of inerter-based suspension systems for heavy vehicles.

The inerter is a two-terminal component that can be added to the spring-and-damper configuration of a suspension system. It has the property that the force exerted is proportional to the relative acceleration at its terminals. Studies have demonstrated the inerter's benefit of providing superior vibration isolation when it is used in the vehicle suspension of passenger cars. However, similar benefit on another common vehicle class on the roads, namely heavy vehicles, remain to be shown, as these vehicles have vastly different parameter values than passenger cars. This study is an investigation on the performance improvement brought by an inerter in the suspension of common heavy vehicles. In the study, the parameter values of a truck and a bus were adopted in the quarter vehicle model with two different spring-damper-inerter configurations (parallel and serial inerter), and the improvements in vibration isolation and road holding capability were determined by optimization of inertance. Results show that the inerter is similarly effective in providing the said improvements when implemented on heavy vehicles instead of on passenger cars, judging from reductions in sprung mass acceleration and dynamic tire load. It is also observed that the performance benefit is associated with larger optimum inertance than that for passenger cars. Overall, the inerter has been shown to be beneficial in the parallel and serial configurations, both of which are common and can be practically implemented in the suspension of heavy vehicles.

Development of a dual-mode electro-hydrostatic actuator with serial-parallel hybrid configured piezoelectric pumps

Smart materials-based electro-hydrostatic actuator (EHA) plays an important role in the power-by-wire technology for the next generation of more electric aircraft. However, the output flow of a smart materials-based EHA is relatively low to narrow down its practical applications. To address this issue, a piezoelectric material-based dual-mode electro-hydrostatic actuator (DMEHA) is proposed in this work. The output flow can be improved by adopting two piezoelectric pumps without sacrificing the carrying capacity. In addition, a hybrid serial and parallel configuration for the two pumps is realized for the adaptability of different actuation requirements. Mathematical modeling and parameter identification are conducted and presented in detail for the designers. A physical prototype is fabricated and a series of experiments are carried out to investigate its characteristics. Results indicated that the DMEHA achieves a maximum output flow of 1.17 l min−1 at 360 Hz under the serial mode and the blocking load up to 40 kg. The corresponding maximum output flow in the parallel mode can reach 1.96 l min−1 at 420 Hz, and the blocking load is 20 kg.

Generalized modelling of PV module and different PV array configurations under partial shading condition

This paper proposes generalized modelling of photovoltaic(PV) module and different PV array configurations - (i) conventional configurations: Series, Parallel, Series-Parallel, Total-Cross-Tied, Bridge-Linked, Honey-Comb and (ii) hybrid configurations: SeriesParallel-TotalCrossTied, BridgeLinked-TotalCrossTied, HoneyComb-TotalCrossTied, BridgeLinked-HoneyComb under partialshadingcondition. The projected modelling is fully efficient in determining the detailed output graphs of PV module and different PV array configurations of whichever rating, synthesized of any class of PV cell or module, and for every probable real-time partially shaded situation. The presented modelling can accomplish this objective by merely exploiting the information given in the catalogue released by manufacturers. The results obtained by the execution of MATLAB codes of the proposed equations for the module and the aforesaid array configurations under uniformirradiancecondition and partialshadingcondition in presence and absence of bypass diodes have been investigated on the basis of their maximumpower, fill-factor, thermalvoltage, and relativepowerloss and authenticated by MATLAB simulation. The proposed modelling has also been practically verified on the ZONHAN PV module and array made of four WS-330 PV modules.