2E (Energy and Exergy) Analysis of ET-CPC Solar Collector Integrated with Different Configuration of Thermal Storage System

The intermittency of solar thermal energy warrants the integration/utilization of thermal energy storage system for efficient operation. Effective utilization of solar water heating (SWH) system can reduce nearly 70 - 90 % of the energy cost incurred for water heating applications. In this study, a compound parabolic concentrator (CPC) solar collector is paired with thermal energy storage (TES) system for the improvement of thermal performance of the collector through enhanced heat transfer rate and minimizing the heat losses. Effects of varying mass flow rate and different arrangement of phase change materials (PCMs) on the performance of the CPC solar collector are investigated. A study of the influence of PCMs configurations in TES systems viz three PCMs (Case 1) and five PCMs (Case 2) on the energy efficiency, exergy efficiency and overall loss coefficient of the solar collector and TES system is made and compared with sensible TES system. The results show the attainment of maximum thermal efficiency of 70 % for ‘Case 2’. Comparison with ‘Case 1’, ‘Case 2’ exhibited a reduction heat loss of 4 % from the TES system. Results of exergy study reveal a superior performance in Case 2 over other configurations.

Rebalancing Autonomous Vehicles using Deep Reinforcement Learning

The shared autonomous mobility-on-demand (AMoD) system is a promising business model in the coming future which provides a more efficient and affordable urban travel mode. However, to maintain the efficient operation of AMoD and address the demand and supply mismatching, a good rebalancing strategy is required. This paper proposes a reinforcement learning-based rebalancing strategy to minimize passengers’ waiting in a shared AMoD system. The state is defined as the nearby supply and demand information of a vehicle. The action is defined as moving to a nearby area with eight different directions or staying idle. A 4.6 4.4 km2 region in Cambridge, Massachusetts, is used as the case study. We trained and tested the rebalancing strategy in two different demand patterns: random and first-mile. Results show the proposed method can reduce passenger’s waiting time by 7% for random demand patterns and 10% for first-mile demand patterns.

Performance and Sensitivity of Individual Tree Segmentation Methods for UAV-LiDAR in Multiple Forest Types

Using unmanned aerial vehicles (UAV) as platforms for light detection and ranging (LiDAR) sensors offers the efficient operation and advantages of active remote sensing; hence, UAV-LiDAR plays an important role in forest resource investigations. However, high-precision individual tree segmentation, in which the most appropriate individual tree segmentation method and the optimal algorithm parameter settings must be determined, remains highly challenging when applied to multiple forest types. This article compared the applicability of methods based on a canopy height model (CHM) and a normalized point cloud (NPC) obtained from UAV-LiDAR point cloud data. The watershed algorithm, local maximum method, point cloud-based cluster segmentation, and layer stacking were used to segment individual trees and extract the tree height parameters from nine plots of three forest types. The individual tree segmentation results were evaluated based on experimental field data, and the sensitivity of the parameter settings in the segmentation methods was analyzed. Among all plots, the overall accuracy F of individual tree segmentation was between 0.621 and 1, the average RMSE of tree height extraction was 1.175 m, and the RMSE% was 12.54%. The results indicated that compared with the CHM-based methods, the NPC-based methods exhibited better performance in individual tree segmentation; additionally, the type and complexity of a forest influence the accuracy of individual tree segmentation, and point cloud-based cluster segmentation is the preferred scheme for individual tree segmentation, while layer stacking should be used as a supplement in multilayer forests and extremely complex heterogeneous forests. This research provides important guidance for the use of UAV-LiDAR to accurately obtain forest structure parameters and perform forest resource investigations. In addition, the methods compared in this paper can be employed to extract vegetation indices, such as the canopy height, leaf area index, and vegetation coverage.

Operating Characteristic Analysis and Verification of Short-Stroke Linear Oscillating Actuators Considering Mechanical Load

Linear oscillating machines are electric devices that reciprocate at a specific frequency and at a specific stroke. Because of their linear motion, they are used in special applications, such as refrigerators for home appliances and medical devices. In this paper, the structure and electromagnetic characteristics of these linear oscillating machines are investigated, and the stroke is calculated according to voltage and motion equations. In addition, static and transient behavior analysis is performed, considering mechanical systems such as springs, damping systems, and mover mass. Furthermore, in this study, the magnetic force is analyzed, experiments are conducted according to the input power, and the current magnitude and stroke characteristics are analyzed according to the input frequency. Finally, the study confirmed that the most efficient operation is possible when the electrical resonance frequency matches the resonance frequency of the linear oscillating machines.

A Study on the Efficiency Analysis of Global Terminal Operators Based on the Operation Characteristics

Shipping and port industries are undergoing rapid environmental changes because of the reorganization of carrier alliances, enlargement of ships, and an increase in global uncertainty. Thus, the sustainable operation of container terminals requires a new assessment of port efficiency and measures to enhance efficient operation. Hence, we classified 21 global terminal operators (GTOs) into stevedore, carrier, and hybrid GTOs based on their operation characteristics and derived a sustainable container terminal operation method using data envelopment analysis efficiency and Malmquist productivity index analysis. The results showed that stevedore GTOs exhibited improved efficiency when the terminal infrastructure was expanded. However, the returns to scale and technical change factors in the productivity change trend decreased. Meanwhile, the objective of carrier GTOs is cost reduction, unlike stevedore and hybrid GTOs, which focus on generating profits. Consequently, carrier GTOs were the most inefficient with little intention to improve efficiency. A systematic efficiency improvement strategy through the acquisition of a terminal share was effective for hybrid GTOs. However, similar to stevedore GTOs, investment in technical change was insufficient for hybrid GTOs. The efficiency analysis we conducted for each operation characteristic is expected to provide useful basic data for establishing efficiency improvement strategies for every GTO.

Assessment of Building Automation and Control Systems in Danish Healthcare Facilities in the COVID-19 Era

A well-designed and properly operated building automation and control system (BACS) is key to attaining energy-efficient operation and optimal indoor conditions. In this study, three healthcare facilities of a different type, age, and use are considered as case studies to investigate the functionalities of BACS in providing optimal air quality and thermal comfort. IBACSA, the first-of-its-kind instrument for BACS assessment and smartness evaluation, is used to evaluate the current systems and their control functionalities. The BACS assessment is reported and analyzed. Then, three packages of improvements were implemented in the three cases, focusing on (1) technical systems enhancement, (2) indoor air quality and comfort, and (3) energy efficiency. It was found that the ventilation system domain is the best performer in the three considered cases with an overall score of 52%, 89% and 91% in Case A, B, and C,, respectively. On the other hand, domestic hot water domain scores are relatively low, indicating that this is an area where Danish healthcare facilities need to provide more concentration on. A key finding indicated by the assessment performed is that the three buildings score relatively very low when it comes to the impact criteria of energy flexibility and storage.

Determination of the Area of Energy-efficient Working Equipment Position and Effective Digging Radius of Hydraulic Excavators in Open-pit Mining

Since the end of the last century, a significant number of hydraulic excavators have arrived on Russian quarries. Most of these excavators are equipped with backhoe operating equipment. The widespread use of such excavators in open-pit mining proves their exceptional efficiency. However, at the same time there is no clear understanding of the conditions under which a hydraulic excavator will be most effective: a theory of the face block of hydraulic shovels has not yet been developed. The available scientific studies are limited to determining the rational height of the excavation layer for efficient operation. If to take the quality of preparation of rock mass and the scheme of its loading into dump trucks as external parameters, i.e. not depending on the features of excavator design, then the position of its working equipment relative to the rock block has a decisive influence on operation of the hydraulic drive and fuel consumption. This is due to the changing value of digging force at various points of the bucket teeth position in the range of their possible positions at constant power of the hydraulic drive. Thus, application of optimal position of hydraulic excavator working equipment elements (bucket, arm, and boom) relative to the rotary platform and the rock massive during the digging cycle allows both to reduce fuel consumption and to increase the digging force. The application of the developed methodology is promising in terms of improving the energy efficiency of both individual excavation and loading units and the enterprise as a whole.

Simulation on adjacent line mutual interference of high-speed railway track circuit

As the density of the high-speed railway network continues to increase, the problem of electromagnetic interference on adjacent lines has become increasingly prominent. This paper focuses on the electromagnetic interference of adjacent lines caused by rail and line in the signal transmission process of the high-speed rail track circuit. Firstly, complete the establishment of the four-terminal network model of the ZPW-2000A track circuit system and the cab signal entry current crosstalk model, calculation of interference voltage under different parallel length of signal frequency. Then the interference factors and coupling mechanism of adjacent lines are analysed to realize calculation of interference amount. Finally, according to the sensitivity index of the cab signal, the maximum parallel length of adjacent sections is given respect, and the interference protection suggestions of adjacent lines are put forward. The research work of this paper provides a theoretical basis for suppressing the interference of adjacent lines and guarantees the safe and efficient operation of high-speed trains.

Influence of natural production conditions on efficient operation of wheel tractors

For the zones of “risky farming” characteristic of the Far East of the Russian Federation, the natural production conditions of the region are an important problem in preparing the soil for further basic agricultural work. So, when carrying out early spring agricultural work, due to presence of a solid underlying layer in the form of permafrost, they shall be completed in operational terms no more than 10 days, until the permafrost base thaws and the soil has not lost its bearing capacity. In addition, due to the peculiarities of the relief, the soil does not thaw equally in depth everywhere, which reduces the quality of field work and harrowing, as the most common operation, namely. This article provides theoretical and experimental studies on the adaptation of a wheeled tractor as part of a machine-tractor unit (MTU) used in harrowing to natural production conditions by installing a device that automatically regulates the load on the working body of the disc harrow or on the propellers of the energy device, depending on the conditions of use or the state of the motion surface.