Energy efficiency in materials testing by reactive power part 2: resonance method in fatigue testing

Industrial automation is embracing wireless sensor-actuator networks (WSANs). Despite the success of WSANs for monitoring applications, feedback control poses significant challenges due to data loss and stringent energy constraints in WSANs. Holistic control adopts a cyber-physical system approach to overcome the challenges by orchestrating network reconfiguration and process control at run time. Fundamentally, it leverages self-awareness across control and wireless boundaries to enhance the resiliency of wireless control systems. In this article, we explore efficient holistic control designs to maintain control performance while reducing the communication cost. The contributions of this work are five-fold: (1) We introduce a holistic control architecture that integrates Low-power Wireless Bus (LWB) and two control strategies, rate adaptation and self-triggered control ; (2) We present heuristics-based and optimal rate selection algorithms for rate adaptation; (3) We design novel network adaptation mechanisms to support rate adaptation and self-triggered control in a multi-hop WSAN; (4) We build WCPS-RT, a real-time network-in-the-loop simulator that integrates MATLAB/Simulink and a physical WSAN testbed to evaluate wireless control systems; (5) We empirically explore the tradeoff between communication cost and control performance in holistic control approaches. Our studies show that rate adaptation and self-triggered control offer advantages in control performance and energy efficiency, respectively, in normal operating conditions. The advantage in energy efficiency of self-triggered control, however, may diminish under harsh physical and wireless conditions due to the cost of recovering from data loss and physical disturbances.

The development of actuators for flight control surfaces based on electrical technologies had a breakthrough in the last decade. Nevertheless, servo-hydraulic systems are still widely used. Servo Hydraulic Actuators (SHA) have the advantages of precise positioning, high dynamic response and being a jam-free solution in case of failures, but they present low energy efficiency. Digital hydraulics has become a topic of interest in improving energy efficiency in the fluid power community. A Digital Hydraulic Actuator (DHA) for aircraft is being developed to be used in primary flight control surfaces. The DHA concept is based on secondary control with multi-chamber cylinders and shows an energy efficiency gain with a similar response when compared to SHA. However, the opening and closing times of on/off valves are different and uncertain. These aspects may result in short circuits, bringing energy losses, or in blocked chambers, which may cause pressure peaks or cavitation. Consequently, the DHA system may have a lower energy efficiency or presents vibration due to fluid blocking. The present paper presents a solution for these issues and the reliability evaluation of the DHA. The opening and closing times issues are addressed using the synchronization between on/off valves through a method to find the correct time for valve opening control. As a result, the synchronization of pressure shifting without knowledge of the response times of on/off valves was accomplished. Moreover, when used periodically, this method can estimate future failures in valves due to a change of the required time delay. In order to evaluate the system reliability, FTA models were developed considering valve and pressure line failures, modelling how the failures affect force availability to move the control surfaces. The resulting FTAs were reduced to the minimum cut-sets that lead to force profiles that are insufficient for a safe flight and also may lead to an aircraft crash. Considering that the on/off valves have similar failure rates to those of servo valves, the results show that DHA and SHA have comparable reliability levels.

<div class="htmlview paragraph">Component fatigue test is extremely time-consuming and costly. In order to get more reliable test results in a shorter period, a computerized electrodynamic resonant fatigue test machine, named PDC model, has been developed and applied to automotive component tests at Dong Feng Motor Co. Ltd. It can be divided into two major parts: a mechanical resonant rig and a computerized electronic control system. In this paper the structure and working principle of the machine is described, the characteristic of the resonant system is analyzed and the load calibration method of the machine is also dealt with. In addition to bending fatigue test of crankshaft □ the typical applications of the PDC are torsional and bending-torsional complex fatigue tests of crankshaft, torsional fatigue test of small bars and standard material specimen, bending fatigue test of semi-axle sleeve and compressive fatigue test for valve spring. Measurement and practical application have shown that the PDC test machine does offer a lot of advantages, including high accuracy, high efficiency, full automation and low energy consumption.</div>

In January 2008 the Governor of Hawaii announced the Hawaii Clean Energy Initiative; an initiative that aims to have at least 70 percent of Hawaii’s power come from clean energy by 2030 [4]. In July 2009, the Hawaii Department of Accounting and General Services awarded NORESCO, an energy service company, a $33.9M contract to improve the energy efficiency of 10 government buildings. The avoided utility cost of the energy and water savings from the improvements is the project funding mechanism. The energy savings realized by the project will reduce carbon dioxide emissions associated with utility power generation. However, as renewable energy becomes a larger portion of the utility generation profile through the Hawaii Clean Energy Initiative, the carbon dioxide emissions reductions from specific energy efficiency measures may erode over time. This work presents a method of analysis to quantify the carbon dioxide emissions reduction over the life of a project generated by energy efficiency upgrades that accounts for both the impact of policy initiatives and climate change using DOE-2/eQUEST. The analysis is based on the fact that HVAC energy usage will vary with climate changes and that carbon dioxide emission reductions will vary with both energy savings and the corresponding utility’s power generation portfolio. The energy savings related to HVAC system energy efficiency improvements are calculated over the life of a 20 year performance contract using a calibrated DOE-2/eQUEST model of an existing building that utilizes weather data adjusted to match the predictions of the Intergovernmental Panel on Climate Change. The carbon dioxide emissions reductions are calculated using the energy savings results and a projection of the implementation of the Hawaii Clean Energy Initiative. The emissions reductions are compared with other analysis methods and discussed to establish more refined expectations of the impact of energy efficiency projects in context with climate changes and policy initiatives.

Energy and exergy utilization in transportation sector of Saudi Arabia

This paper describes a high-performance and energy-efficient online video retrieval system called Ameba. Ameba contains a number of custom reconfigurable nodes which are grouped by a novel architecture. The system aims to address the performance and energy efficiency issues for large scale dynamic concurrent query requests. The open SURF approach and a Hamming distance based matching algorithm were implemented and improved on FPGA to increase the performance and energy efficiency. A predictive algorithm is proposed to forecast the trends of online query requests. This scalability which is obtained from the dynamic reconfiguration, makes the system have ability to improve its energy efficiency with the guarantee of performance. The simulation experiments are conducted with a considerable library which consists of 4650 videos with a combined length of more than 3000 hours. The comparative results demonstrate that Ameba has performance and energy efficiency advantages when facing large scale online video retrieval requests.

The FinFET based Full Adder in various cell designs is investigated in terms of performance and energy efficiency. Additionally, the performance of the FinFET Full Adder in the subthreshold region reveals significant results in low power technology. The 1-bit FinFET based Full Adder is designed in four different cell designs, and while the average power dissipated, delays, power-delay-product (PDP) and energy-delay-product (EDP) of all four topologies were analyzed based on the types of transistors used i.e. conventional Field Oxide Transistor (MOSFET) and FinFET. Based on this study, FinFET based Full Adder shows an average of 94 % reduction in delay, 97 % reduction in power dissipation and 99 % reduction for both PDP and EDP over the conventional FET, giving FinFET advantages in energy efficiency.

This work presents a novel wireless interrogator designed to efficiently interface with passive ‎electromagnetic sensors, addressing critical challenges in energy efficiency and real-time IoT ‎connectivity. The Internet of Things (IoT) is transforming a wide range of industries, enabling real-time ‎monitoring and information collection through interconnected sensor networks. Passive electromagnetic ‎sensors, which do not require an external power source, offer significant advantages in energy efficiency ‎and maintenance-free operation. However, efficient data interrogation and communication from these ‎sensors remain a challenge, particularly in IoT-based wireless applications. The design and development of a ‎wireless IoT interrogator for passive electromagnetic sensors are described in this paper. The proposed ‎interrogator leverages advanced wireless communication protocols and energy-efficient techniques to ‎interrogate passive sensors, retrieve data, and transmit it to IoT networks for real-time monitoring and ‎analysis. We analyze the system's performance through experiments, highlighting the interrogator's ‎capability to support diverse IoT applications, such as environmental monitoring and smart agriculture. ‎The proposed system is energy-efficient, scalable, and capable of supporting real-time data transmission ‎to IoT networks, making it ideal for a wide range of IoT applications. F1 antenna gain is 3.50 dBi, and ‎mF1 antenna gain is 5.10 dBi. Output power for frequency doubling reflectenna system observed -20dB, ‎‎-89dB for distance between Tx and Rx at 100 cm, 1000cm, respectively‎.

Flaking and spalling caused by rolling contact fatigue associate with a small crack, and a special testing method and machine are required to study the small fatigue crack behavior under shear mode loading. It was found by authors that the behaviors of small shear-mode fatigue cracks from the inclusions and the artificial defects could be successfully observed by applying the fully-reversed torsion coupled with static axial compressive stress. However, the servo-hydraulic fatigue testing machine is quite expensive for purchase and maintenance, and large installation space is necessary for the hydraulic and cooling systems. Moreover, the presence of axial compression significantly lowers the frequency of torsional loading, which consequently results in low testing speed. In this study, a cost-effective, space-saving and high-speed fatigue testing method was newly proposed, and the shear-mode fatigue crack growth tests were carried out by using the developed machine. Based on the obtained experimental data, the potential of the new testing machine is discussed.

Energy harvesting (EH) endows device-to-device (D2D) communication and cellular equipment with the ability of continuous communication to provide internet-of-things (IoT) services in natural areas. While the available energy, which relies on EH, becomes an extra nonnegligible factor in resource allocation. Besides, we integrate uplink non-orthogonal multiple access (NOMA) with D2D communication to provide multiple access for D2D transmitters for more efficient IoT service and more efficient utilization of limited spectrum. In this scenario, ingenious resource allocation approach is a key focus for utilizing the advantages in energy and spectral efficiency. Aiming to investigate the inherent resource allocation issue, we set our goal as maximizing the energy efficiency for both NOMA-based D2D groups and cellular users (CUs), where the power and spectrum allocation are both considered. Then we propose a two-stage game approach, which is theoretically proved to be capable of obtaining the equilibrium and a stable result, to solve the unilateral energy efficiency maximization problems. Besides, an energy-aware screening method is proposed to reduce the computations based on the available energy of user equipment. Finally, the effectiveness of our proposed method is verified through elaborated simulation results.

A research on approaches to energy saving through energy service contract (ESC) use has been conducted in this work. It is determined that the main requirement to the content and structure of the ESC is the existence of a list of measures aimed at energy saving and energy efficiency improvement. A procedure of efficiency estimation of energy saving measures implementation is given. The factors and parameters that affect the result of energy saving measures realization are outlined. It is defined that success of any ESC critically depends on the correct calculation of savings from energy efficiency measures implementation.The need for transition to an energy efficient variant of development through strengthening the requirements for compliance with European standards in terms of energy efficiency is substantiated. Otherwise economic growth will be restrained by high prices and reduced accessibility to energy resources.It is also inferred that providing of standardized and unified norms and approaches to the energy efficiency parameters determination requires the development of appropriate methodological framework of formal methods and documented rationale for projects effectiveness evaluation, as well as implementation of procedure for organization of measurements and verification of the energy savings achieved. The procedure for energy efficiency measurement and verification involves the inspection of facilities, energy usage measuring, independent variables monitoring, calculations, including computation of target indicators values in the field of energy saving and energy efficiency improvement in comparable conditions, as well as computation of energy consumption reduction in comparable conditions. Creation of a comprehensive methodological framework, without any doubts, will make possible energy servicing market development, increase investment in energy saving and energy efficiency improvement projects, contribute to the professional growth and realization of specialists in energy saving and energy efficiency.

Electrical machines such as motor, generator, and transformer are tested to evaluate their performance characteristics such as their efficiency, voltage regulation etc. These tests requires loading of electrical machines using passive elements such as resistance, inductance and capacitance. During testing of any machine, huge amount of energy consumption take place especially when machine needs to be kept under test for a long duration of time. Hence the energy cost associated is also high for testing large rated machine. This paper proposes a pair of power electronic converter (rectifier and inverter set) that act as a load which can be resistive, inductive or capacitive in nature. The converter is also capable of regenerating the consumed power during testing of machines and feed the power back to the grid. The converter set is made to act as loader and regenerator by controlling the active and reactive power independently from machine to converter and from converter to grid. To obtain a decoupled control of active and reactive power flow, the control scheme is implemented in d-q reference frame using vector control approach. Based upon the value of active and reactive power reference, the converter is modeled to emulate any kind of resistive, inductive, capacitive or any combination of these loads. The propose model can also be used for power factor improvement.

New stopping criteria for crack detection during fatigue tests of railway axles

Electric heaters are widely used owing to their portability, fast heating, single-focus heating, and energy efficiency advantages. Manufacturers provide customers with information on the power consumption and energy efficiency classes of heaters but do not provide any information on heating patterns. Knowing the heating pattern enables users to select the correct heater, which has a significant effect on comfort, health, energy efficiency, industrial process performance, plant growth, and climate change. In previous studies, two-dimensional temperature measurements were performed using sensor arrays. However, the three-dimensional heating patterns of the heaters have not been extracted, and the deformation effect of gravity on the heating patterns has not been demonstrated. In this study, a temperature measurement system with 64 temperature sensors placed at equal intervals in the xz-plane was designed and implemented. Then, the fan heater was moved along the y-axis at intervals of 10 cm from 0 to 100 cm, and three-dimensional heating patterns were obtained for different fan voltages. As part of the research objectives, the deformation effect of gravity on the heating pattern was revealed, and the shift in the maximum temperature point on the +z-axis was measured. The mathematical formula for the maximum temperature value was derived based on the fan voltage and the distance between the heater and the sensor array. The goodness-of-fit statistical values for the derived mathematical formula for the 55 temperature measurements were calculated as the root mean square error of 1.9543 and R-squared of 99.43%, demonstrating the accuracy of the presented model.

Energy has moved to the forefront in societal and economic development. Our homes and real estate are more and more dependent on electricity. In order to reach the full potential for new consumer-oriented market mechanisms and in order to fulfil climate policy targets we need more information on consumers’ behaviour and attitudes towards energy. This paper uses a survey to examine the attitudes and behaviour of households' energy-related issues. The analytical framework used is based on ordered choice and probability models. The objective is to identify households' characteristics that affect energy consumption and savings, attitudes towards climate change and conservation of natural resources, and the importance of municipal energy-related issues. According to the results, the importance of reduction in electricity consumption is positively correlated with attitudes towards mitigation of climate change and importance of renewable energy. Heating system of residence, income, and gender affect attitude and behaviour. Interestingly, the higher the income the less important is electricity reduction. Women have changed their behaviour in order to reduce electricity consumption more than men. Utilising this information it is possible for society to build efficient mechanisms, such as real-time pricing, through which we can affect consumers' energy-related behaviour and give incentives for energy savings and efficiency. One interesting result is also that over 80% of the respondents view municipalities' energy efficiency as very important.