Evaluating the Effect of Cover Materials on Greenhouse Microclimates and Thermal Performance

This study compared and analyzed changes in the microclimate and thermal environment inside single-span greenhouses covered with a single layer of plastic film, polycarbonate (PC), and glass. The results of the experiment show that the PC-covered greenhouse was the most favorable for managing the nighttime heating effect during the cold season. However, the glass-covered greenhouse was found to be the most favorable for managing the cooling effect during the hot season. Although the plastic-covered greenhouse was inexpensive and easy to install, the air temperature inside varied significantly, and it was difficult to control its indoor environment. The thermal load leveling values showed that the PC-covered greenhouse had the lowest variation, confirming its superiority in terms of environmental control and energy savings. In terms of the overall heat transfer, heat was generally transferred from the interior to the exterior of the greenhouses. In the plastic-covered greenhouse, however, heat was transferred in the opposite direction at night due to the influence of radiant cooling. The occurrence of the minimum and maximum heat transfer values had a tendency similar to that of the occurrence of the minimum and maximum air temperatures inside the greenhouses.

A Two-Level Desired Load Profile Tracking Algorithm for Electric Two-Wheeler Charging Stations

In Vietnam and in other developing countries, two-wheeled electric vehicles are potential alternatives to gasoline-powered motorbikes. The growth in the number of Electric Two-Wheelers (E2Ws) requires a large power demand of charging load. In addition, the increasing spread in the appearance and penetration of rooftop photovoltaic (PV) power systems, with their intermittence and uncertain nature, poses technical challenges that need to be addressed. The coordination of PV rooftop operation and EV charging may be an effective solution to meet the emerging load demand from EVs, increasing solar power penetration while minimizing the cost of grid reinforcement or possible upgrades. In this paper, a two-level desired load profile tracking algorithm for PV integrated electric bicycles/electric motorcycle charging stations is proposed with the purposes of load leveling, valley filling, and peak shaving. The simulation results show that the proposed algorithm is an effective solution, significantly improving the load profile, especially when compared with uncontrolled charging and constant charging power scheme.

Semi-transparent Photovoltaic Thermal Greenhouse System Combined with Earth Air Heat Exchanger for Hot Climatic Condition

Semi-transparent photovoltaic thermal (SPVT) greenhouse system combined with an earth air heat exchanger (EAHE) has been developed to make the system sustainable. The system is designed to cultivate plants in a hot climatic condition, where green net is provided which bifurcates the enclosed space of the greenhouse into zone-1 and zone-2, and this green net cuts the solar radiation incident on the plants. The influence of air changes in zone-1, mass flow rate of air flowing through EAHE, and packing factor on PV cell, air of the greenhouse, and the plant temperatures is investigated for a typical harsh summer day by using periodic model of these parameters. Further, for a holistic performance assessment of this SPVT greenhouse, exergy, thermal load leveling, and decrement factor are evaluated. Results indicate that the optimum temperature range for plant growth (30 °C- 37 °C) within the greenhouse can be achieved through a combination of ventilation in zone-1 and integration of EAHE. The temperature of plants reduced by 9 °C for 30 air changes in zone-1, and the temperature reduces further by 24 °C when EAHE having a flow rate of 0.5 kg/s is operated. The SPVT greenhouse system also generates 128 kWh of daily overall exergy that makes the system sustainable.

A Novel Method for Solving Second Kind Volterra Integral Equations with Discontinuous Kernel

Load leveling problems and energy storage systems can be modeled in the form of Volterra integral equations (VIE) with a discontinuous kernel. The Lagrange–collocation method is applied for solving the problem. Proving a theorem, we discuss the precision of the method. To control the accuracy, we apply the CESTAC (Controle et Estimation Stochastique des Arrondis de Calculs) method and the CADNA (Control of Accuracy and Debugging for Numerical Applications) library. For this aim, we apply discrete stochastic mathematics (DSA). Using this method, we can control the number of iterations, errors and accuracy. Additionally, some numerical instabilities can be identified. With the aid of this theorem, a novel condition is used instead of the traditional conditions.

Estimation Method of Greenhouse Gas Reduction for Electrical Energy Storage Based on Load-Leveling Application

In recent years, there have been several types of energy storage technologies adopted in many different areas, such as peak shaving, frequency regulation, and renewable stabilization applications. Moreover, technologies of high energy and power density are useful for load leveling, power smoothing for renewable energy systems (RESs), and peak shaving for demand management. Under these circumstances, an estimation technique for assessing environmental issues applied to electrical energy storage (EES) systems is essential in order to promote commercialization of EES systems. Therefore, this paper proposes an estimation method for CO2 emission in cases where EES systems are introduced and not introduced. It is essential to evaluate environmental issues in EES systems at operation stages of their life cycle and make an effective contribution to environmental improvement and reduce potential adverse environmental impacts. Thus, this paper deals with an evaluation method for CO2 emission based on an optimal algorithm including a successive approximation method for the best-mix solution of power sources, etc. From the simulation result based on the proposed evaluation algorithm, it is found that the output power of a coal power plant (high CO2 emission) is replaced by the output powers of the EES systems and the nuclear generator (low CO2 emission).

Production flow improvement and value stream mapping in a lean manufacturing world

The importance of lean manufacturing concepts has been discussed many times over the few decades. The most important elements in lean manufacturing practices are value stream mapping (VSM), Kaizen events, load leveling (heijunka), etc. In this case study, a real-world clock assembly simulation has been used to study the performance improvement in terms of production flow and lead time after introducing lean concepts. In each round of simulation, the lean concepts have been introduced one by one and performance metrics were recorded. After implementing the concepts, the productivity was improved enormously. So, this simulation study emphasizes the importance of continuous improvement of production flow through lean concepts in a real production setting.

Paradigm towards ensuring of energy saving in the crisis management conditions in the aspect of sustainable environmental development

The aim of the article is to develop the theoretical foundations of energy saving as a factor in achieving the goals of sustainable environmental development on the principles of crisis management. The growth in the volume of energy consumption in the world is accompanied by the increase in anthropogenic pressures on the environment and humans and actualizes the issue of achieving sustainable environmental development of the society while reducing the resources use and solving environmental problems. Based on the use of economic and mathematical methods it is substantiated the feasibility of household consumers to use three-phase meters and it is proved the need to switch to a combined electric heating system which allowed to stimulate the electricity users to use electricity economically and solve the problem of load leveling in accordance with the crisis management principles. In practice, the implementation of the proposed activities will make it possible to activate the transition of household consumers to a differentiated tariff and achieve the goals of crisis management and environmental efficiency.

Using Queue Theory and Load-Leveling Principles to Identify a Simple Metric for Resource Planning in a Pediatric Emergency Department

Increased waiting time in pediatric emergency departments is a well-recognized and complex problem in a resource-limited US health care system. Efforts to reduce emergency department wait times include modeling arrival rates, acuity, process flow, and human resource requirements. The aim of this study was to investigate queue theory and load-leveling principles to model arrival rates and to identify a simple metric for assisting with determination of optimal physical space and human resource requirements. We discovered that pediatric emergency department arrival rates vary based on time of day, day of the week, and month of the year in a predictable pattern and that the hourly change in pediatric emergency department waiting room census may be useful as a simple metric to identify target times for shifting resources to better match supply and demand at no additional cost.