System In Different Configurations Research Articles

Mathematical model for selecting the auxiliary equipment parameters of aerodynamic deorbit systems

The goal of this work is to develop a model for selecting the design parameters of auxiliary equipment for aerodynamic deorbit systems. For normal operation, an aerodynamic deorbit system, according to its class, is equipped with the following support systems: for deployment, inflation, аnd storage onboard the space object to be deorbited. The deployment system consists of two components: a mast deployment system, in which four rolled-up masts are stored and deployed, and an airfoil storage spindle, on which four quadrants of a film material are wound. Aerodynamic systems can be inflated in several ways: using a system of gas storage and supply to the shell, using the residual pressure, or using the sublimation of a powder substance. The characteristics of sublimable substances and inert gases for inflation are given. The paper presents a methodology for determining the inflating gas parameters taking into account the exposure of the aerodynamic system to space debris fragments. The following requirements are imposed on the storage system materials: resistance to space factors, resistance to dynamic loads in orbital injection, and resistance to thermal deformations. A mathematical model for selecting the auxiliary system parameters of aerodynamic deorbit systems is presented. This model includes deployment system mass estimation, relationships for determining the inflation system mass for aerodynamic systems of various configurations, wall thickness estimation for gas cylinders of different configurations, and relationships for determining the storage system mass for aerodynamic deorbit systems of different configurations.

Performance analysis of dual-evaporator ejector refrigeration system in different configurations: Experimental investigation

This study aimed to assess the effectiveness of an ejector refrigeration cycle, using a laboratory-scale experimental system operating in different configurations. The investigated configurations consisted of a conventional vapour compression refrigeration (CVCR) system and a dual evaporator ejector system (DEES) operated in two modes: DEES with a single thermal expansion valve (DEESA) and DEES with dual thermal expansion valves (DEESB). The findings revealed that the utilization of the ejector enhanced the refrigerant's mass flow rate. Additionally, the DEESA configuration achieved higher cooling capacities compared to the CVCR. Moreover, the DEESA configuration achieved up to 21% higher coefficient of performance (COP) values. On the other hand, when the system was operated in the DEESB configuration, it yielded lower evaporation temperatures and higher superheating degrees in comparison to DEESA. Based on the evaluations, it can be concluded that the ejector operates more efficiently in systems with dual evaporators, thereby making positive contributions to overall system performance.

Techno-Economic Analysis and Multi-Objective Optimization of Cross-Flow Wind Turbines for Smart Building Energy Systems.

This work reports a technical, economic, and environmental investigation of the possibility of using a recently developed smallscale crossflow wind turbine (CFWT) to supply the energy demand of buildings for different integration scenarios. For this purpose, three CFWT-assisted building energy system configurations with heat pumps, with and without batteries, and two-way interaction with the local grid in two residential building models in Iran and Germany are investigated. Triobjective optimization with a Nondominated Sorting Genetic Algorithm (NSGA-II) is performed for finding the optimal configuration of the energy system in different configurations. For economic assessment, the Capital Budgeting Analysis method is used with four indicators, namely, payback period (PP), net present value (NPV), internal rate of return (IRR), and profitability index (PI). The results show that due to different energy market regulations and prices, different integration scenarios and system configurations can outperform others in Germany and Iran. Overall, due to the exchange rate instability and low energy tariff in Iran, in order for the project to be feasible, either the CFWT cost must fall to below 30% of its current cost or the local electricity price should increase significantly to get a Levelized cost of energy of as low as 0.6 $ kWh-1.

Evaluation of the Audibility Boundaries of Multirotor Systems of Different Configurations

The paper proposes a method for calculating the limits of audibility of multirotor systems such as quad- and hexacopters. The components of the proposed methodology are data on the noise of the device and the ambient noise, as well as the criterion of the audibility of the device. The acoustic-vortex method is used to simulate the tonal noise of multirotor systems. A trailing edge noise model is used to calculate the broadband noise of propellers.

A novel mechanism - smart morphing façade system - to mitigate wind-induced vibration of tall buildings

Wind-induced vibration plays a significant role in the design of tall buildings, primarily due to serviceability requirements for occupant comfort and structural safety. As a result, several approaches have been developed to address this concern. This paper describes a novel control mechanism, a smart-morphing-façade (Smorphacade) system, using the concept of an aerodynamically modified building façade to mitigate wind-induced vibration of tall buildings. Compared to a fixed-façade system, since a Smorphacade can be dynamically modified in real time based on rapidly-changing wind speed and wind direction during a windstorm, it can be further developed into an active control system. The Smorphacade is comprised of a set of circular ducts embedded in a flat plate and arranged in a matrix formation that is fixed on the original façade but with a gap between the two facades. Each circular-shaped duct is comprised of two parts, a fixed base with alternate open and closed surfaces shaped like a fan-blade and a rotating part similar in shape like the fixed one but placed inside the fixed one and capable of rotation by a protruding fin. By rotating the fin, the porosity of the duct and the fin inclination angle can be simultaneously changed, enabling flow control through the duct. The performance of a Smorphacade system in different configurations was studied using the CAARC standard tall-building model under atmospheric boundary layer wind; its effectiveness in reducing building response was examined by comparing the results of a building with a Smorphacade system to those from one without it. It was found that the effectiveness of the Smorphacade system in reducing the average combined vibration among all three directions (2 transverse and 1 torsional) varied between 16.7 and 18.6%, with a maximum reduction of 32% and 59.7% in across-wind direction and torsional direction, respectively, depending on factors such as Smorphacade configuration, wind speed, and angle of attack.

TRNSYS simulation of desiccant integrated hybrid cooling and dehumidification system

The traditional air conditioners suffer from performance degradation especially in humid conditions. This is due to fact that the excess moisture level in ventilation air considerably increases latent cooling load of the space to be conditioned. The use of desiccant integrated sensible cooling system can alleviate this problem by controlling the temperature and humidity separately. It also reduces energy consumption for obtaining desired thermal comfort. In the present study, TRNSYS simulation studio project has been developed to perform the simulations of the desiccant dehumidifier coupled HVAC system for different configurations in summer cooling season. Measurements are also carried out to observe the influence of operating parameters on system performance. The obtained results show that the proposed system has ensured a substantial reduction in process air humidity at dehumidifier exit while maintaining the conditioned room comfort.

Operation and Performance Assessment of a Hybrid Solar Heating and Cooling System for Different Configurations and Climatic Conditions

Energy needs of air conditioning systems are constantly growing worldwide, due to climate change and growing standards of buildings. Among the possible systems, solar heating and cooling based on reversible heat pumps and thermally driven chillers are a viable option for ensuring space heating and cooling for different users. The high installation costs are a limit to their diffusion, however, under specific circumstances (climate, type of the building, type of the user, etc.), the investment in this technology can be profitable in a long term. The presented paper describes an energy-economic assessment of a solar heating and cooling system integrating a solar dish concentrator with thermal collectors coupled with a reversible heat pump and an absorption or adsorption chiller. The system integrated with a household building is developed and dynamically simulated in the Transient System Simulation (TRNSYS) environment under different circumstances –adoption of absorption or adsorption chiller, use of auxiliary thermal energy to drive the sorption chillers, and locality. The results show that space cooling demand in Cracow is matched by solar energy, in a range between 49.0 and 97.6%, while for Naples the space cooling demand is provided by solar heat from 46.1 to 99.1% depending on the adopted sorption chiller and or the use of auxiliary heat for a natural gas boiler. The proposed system is not profitable in case Cracow, since a Simple Pay Back period of about 20 years is achieved. Conversely, case of Naples, the same index achieves a value between 8 and 12 years showing that the proposed system may be a viable solution for heating and cooling installation.

CFD Modelling and Optimization Procedure of an Adhesive System for a Modular Climbing Robot

Adhesion systems are very important in robots for infrastructure inspection (especially in vertical walls). They present the challenge of optimizing the ratio vacuum/power consumption in battery-powered robots. In this paper, a CFD (computer fluid dynamics) modelling and optimization process of a robot adhesion system is carried out to determine the best performing configuration in terms of vacuum and power consumption. Analytical and numerical models were developed to predict the behaviour of the system for different configurations. The models were validated, using test rig measurements, by calibrating an arbitrary defined inlet height that simulates the leakage flow. Then, different geometric parameters were varied to determine the best performing configuration based on the vacuum/power consumption ratio value. The model presented in the paper was capable of predicting the behaviour of the system for different configurations, with a margin of error of 15% for the vacuum prediction and 25% for the motor power calculation. Finally, the model was used to optimize parameters of the system, like the number of blades of the impeller. The adhesion system was conceived for the modular autonomous climbing legged robot ROMERIN.

Trends in the development of the Smart home system and its integration into modern society

The stages of development of smart home systems and integration of these systems into the city infrastructure are considered. The main advantages and disadvantages of these solutions are identified, and problems associated with their installation and use are identified. The research on the volume of markets and target audience is analyzed, and the trends of recent years in the areas of both "smart home" and "smart city in General" are considered. Priority directions of development of the entire field of solutions are indicated. Specific examples of using smart systems in different configurations and with different functions are considered. Conclusions are drawn about the current situation on the market, as well as about the future prospects for implementing smart home systems in the lives of users.

Ultrasonic Deicing Efficiency Prediction and Validation for a Flat Deicing System

An effective deicing system is needed to be designed to conveniently remove ice from the surfaces of structures. In this paper, an ultrasonic deicing system for different configurations was estimated and verified based on finite element simulations. The research focused on deicing efficiency factor (DEF) discussions, prediction, and validations. Firstly, seven different configurations of Lead zirconate titanate (PZT) disk actuators with the same volume but different radius and thickness were adopted to conduct harmonic analysis. The effects of PZT shape on shear stresses and optimal frequencies were obtained. Simultaneously, the average shear stresses at the ice/substrate interface and total energy density needed for deicing were calculated. Then, a coefficient named deicing efficiency factor (DEF) was proposed to estimate deicing efficiency. Based on these results, the optimized configuration and deicing frequency are given. Furthermore, four different icing cases for the optimize configuration were studied to further verify the rationality of DEF. The effects of shear stress distributions on deicing efficiency were also analyzed. At same time, a cohesive zone model (CZM) was introduced to describe interface behavior of the plate and ice layer. Standard-explicit co-simulation was utilized to model the wave propagation and ice layer delamination process. Finally, the deicing experiments were carried out to validate the feasibility and correctness of the deicing system.

Optimization of the TEGs Configuration (Series/Parallel) in Energy Harvesting Systems with Low-Voltage Thermoelectric Generators Connected to Ultra-Low Voltage DC–DC Converters

Solar radiation and human activity generate ubiquitous temperature gradients that could be harvested by thermoelectric generators (TEGs). However, most of these temperature gradients are in the range of very few degrees and, while TEGs are able to harvest them, the resulting output voltages are extremely small (a few hundreds of mV), and DC–DC converters are necessary to boost them to usable levels. Impedance matching between TEGs and DC–DC converter plays a fundamental role in the energy harvesting efficiency. Therefore, it is essential to determine the output power of the system in different configurations, in order to decide on the optimum TEG connection. Here, we present an electronic circuit to measure the maximum power that can be harvested with low-voltage TEGs connected to a DC–DC converter. The developed circuit is an electronic controlled load that drains the maximum current from the output of the DC–DC converter while maintaining its output voltage at the maximum allowed value. Using a mechanical set-up able to apply precise low temperature gradients between the hot and cold side of the TEGs, experimental data using different configurations of TEGs are obtained. The measured results show that, for ultra-low voltages, the TEG ensemble’s output impedance plays an important role not only in the amount of the energy scavenged, but also in the onset temperature of the energy harvesting.

Reshaping the activated sludge process: has the time come or passed?

AbstractDespite the amazing achievements over the years, the activated sludge (AS) process still maintains inherent drawbacks, namely gravity settling, high sludge ages, low excess sludge generation, etc., which hinder its successful operation and sometimes disrupt system performance. Substantial research on the subject has provided clear scientific evidence that time has come – or even passed – for reshaping the AS process. In the novel AS process, gravity settling will be replaced by membrane filtration, which will convert the system configuration into a membrane activated sludge (MAS) reactor; this configuration will be operated at an extremely low sludge age range of 2 to 4 days, which will maximize sludge generation and it will abandon the traditional anaerobic sludge digestion for optimizing energy recovery. It is suggested that super‐fast membrane activated sludge (SFMAS) reactor be the new face of the AS process. SFMAS reactor will be the core unit of the AS process essentially limited to organic carbon (chemical oxygen demand) removal and energy recovery. The core SFMAS unit will also enable to benefit from all the assets of the AS process, such as nutrient removal, biopolymer recovery, etc., by means of hybrid systems in different configurations, i.e. by reactors with various functions that will be attached to the core unit. © 2019 Society of Chemical Industry

Hardware in the loop framework proposal for a semi-autonomous car architecture in a closed route environment

The development of intelligent vehicles has been increasing at great speed in recent years, which has allowed to improve their capabilities in autonomous driving systems. Many of these features are related to advanced driving assistance systems and autonomous driving systems. This capability improvement, has been achieved because of recent developments of automation oriented software and hardware. Such improvements, allowed the vehicle to achieve a more precise perception of it’s working environment. For this improvement it is important the integration and simulation of the systems in different configurations, such as hardware-in-the-loop, software-in-the-loop and model-in-the-loop. In this paper, we present a framework proposal that allows the design and testing of computer vision and control systems for the partial automation of a vehicle, with the use of hardware and software systems in the loop. This proposal is focused on the rapid experimental development of these systems for the implementation by autonomous vehicle designers and engineers. Our proposal allows faster data capture, either in a real or simulated environment, to improve and optimize data training with machine learning algorithms; this proposal integrates several open source systems and hardware with the necessary capacity for real-time implementation.

Free cooling potential of a PCM-based heat exchanger coupled with a novel HVAC system for simultaneous heating and cooling of buildings

This article presents a simulation-based study that estimates the primary energy use of a novel HVAC system for different configurations of a thermal plant. The main characteristic of the system is its ability to provide simultaneous heating and cooling to buildings by using a single hydronic circuit with water temperatures of about 22 °C all year round. Four different configurations of the thermal plant were analyzed. A district heating-cooling network was considered as baseline. Other configurations included the use of a reversible air-to-water heat pump coupled with free cooling devices. In particular, a model of a PCM-based heat exchanger was developed in this work by using the programming language Modelica. This device was designed to store cold energy during night-time and release it during daytime through the water circuit. Results for a typical office building model showed that the integration of free cooling devices can significantly reduce the primary energy use of the novel HVAC system. In particular, the thermal plant configuration including the PCM-based heat exchanger made it possible to almost completely avoid the use of mechanical cooling, leading to annual primary energy savings of about 67% when compared with the baseline thermal plant configuration.

Performance analysis of a solid desiccant assisted hybrid space cooling system using TRNSYS

The traditional air conditioners suffer from performance degradation especially in humid conditions. This is due to fact that the excess moisture level in ventilation air considerably increases latent cooling load of the space to be conditioned. The use of desiccant integrated vapor compression hybrid cooling system can alleviate this problem by controlling the temperature and humidity separately. It also reduces energy consumption for obtaining desired thermal comfort. In the present study, TRNSYS simulation studio project has been developed to perform the simulations of the desiccant dehumidifier coupled vapor compression hybrid system for different configurations in summer cooling season. Experimental measurements are also carried out to observe the influence of operating parameters on system performance. The obtained results show that the proposed system has ensured a substantial reduction in process air humidity at dehumidifier exit while maintaining the conditioned room comfort.

Reliability analysis of software with three types of errors and imperfect debugging using Markov model

In this analysis, we consider a Markovian software reliability model (SRM) with imperfect debugging (ID) wherein software may fail due to three types of errors called error generation (EG). For developing the governing differential equations of SRM with three types of errors, an irreducible Markov process is used. Further, we have applied the method namely 'Runge-Kutta' (R-K) under transient condition for obtaining reliability of concerned system in different configurations. Moreover, we suggest various software reliability indices like reliability, failure frequency and mean time to failure (MTTF). By taking a numerical illustration, the sensitivity analysis is done to demonstrate the validity of analytical outcomes and to explore the effects of various parameters. Moreover, the analytical results are also compared with adaptive neuro-fuzzy inference system (ANFIS). At last, conclusions are given.

Reliability analysis of software with three types of errors and imperfect debugging using Markov model

In this analysis, we consider a Markovian software reliability model (SRM) with imperfect debugging (ID) wherein software may fail due to three types of errors called error generation (EG). For developing the governing differential equations of SRM with three types of errors, an irreducible Markov process is used. Further, we have applied the method namely 'Runge-Kutta' (R-K) under transient condition for obtaining reliability of concerned system in different configurations. Moreover, we suggest various software reliability indices like reliability, failure frequency and mean time to failure (MTTF). By taking a numerical illustration, the sensitivity analysis is done to demonstrate the validity of analytical outcomes and to explore the effects of various parameters. Moreover, the analytical results are also compared with adaptive neuro-fuzzy inference system (ANFIS). At last, conclusions are given.

Using Markov Chains and Multi-Objective Optimization for Energy-Efficient Context Recognition.

The recognition of the user’s context with wearable sensing systems is a common problem in ubiquitous computing. However, the typically small battery of such systems often makes continuous recognition impractical. The strain on the battery can be reduced if the sensor setting is adapted to each context. We propose a method that efficiently finds near-optimal sensor settings for each context. It uses Markov chains to simulate the behavior of the system in different configurations and the multi-objective genetic algorithm to find a set of good non-dominated configurations. The method was evaluated on three real-life datasets and found good trade-offs between the system’s energy expenditure and the system’s accuracy. One of the solutions, for example, consumed five-times less energy than the default one, while sacrificing only two percentage points of accuracy.

Dynamic analysis of the tether transportation system using absolute nodal coordinate formulation

Long space tethers are becoming a rising concern as an alternate way for transportation in space. It benefits from fuel economizing. This paper focuses on the dynamics of the tether transportation system, which consists of two end satellites connected by a flexible tether, and a movable vehicle driven by the actuator carried by itself. The Absolute Nodal Coordinate Formulation is applied to the establishment of the equation of motion, so that the influence caused by the distributed mass and elasticity of the tether is introduced. Moreover, an approximated method for accelerating the calculation of the generalized gravitational forces on the tether is proposed by substituting the volume integral every step into summation of finite terms. Afterwards, dynamic evolutions of such a system in different configurations are illustrated using numerical simulations. The deflection of the tether and the trajectory of the crawler during the transportation is investigated. Finally, the effect on the orbit of the system due to the crawler is revealed.

3-Rooted Maxillary First Premolars: An Ex Vivo Study of External and Internal Morphologies

IntroductionThis study aimed to analyze the external and internal morphologies of 3-rooted maxillary first premolars using cone-beam computed tomographic (CBCT) imaging. MethodsFifty-six three-rooted maxillary first premolars were imaged by CBCT imaging and classified into 4 groups on the basis of external root morphology. Internal morphologic features, including the shapes of the buccal and palatal orifices and distances of bifurcation of the buccal-palatal and mesiobuccal-distobuccal root canals from the cementoenamel junction (CEJ), were measured. ResultsThe teeth were classified into 4 groups on the basis of external morphology: group A, separation of the buccal and palatal roots with bifurcation of the former into the mesiobuccal and distobuccal roots (n = 22); group B, fusion of 2 buccal roots with the palatal root being separate (n = 19); group C, complete or partial fusion of the distobuccal and palatal roots (n = 9); and group D, fusion of all 3 roots (n = 6). The buccal orifice was mainly triangular/heart shaped. The distance of bifurcation of the buccal-palatal root canals from the CEJ in group A differed significantly from those in groups B and C (P < .05). There were significant differences in the distance of bifurcation of the mesiobuccal-distobuccal root canals from the CEJ among groups A, B, and C (P < .05). Four teeth exhibited C-shaped root canal systems of different configurations. ConclusionsThe external and internal morphologies of 3-rooted maxillary first premolars vary considerably.