Reliable Layout Research Articles

Optimization of spatial layouts for underground facilities to achieve carbon neutrality in cities: A multi-agent system model

Subways, underground logistics systems and underground parking, as the primary facilities types of underground, contribute significantly to the achievement of carbon–neutral cities by moving surface transportation to underground, thereby releasing surface space for the creation of more urban blue-green space for carbon sink. Therefore, in-depth studies on carbon neutrality strategies as well as reliable layout optimization solutions of these three types of underground facilities are required. This study proposes a spatial layout optimization strategy for carbon neutrality using underground hydrogen storage and geothermal energy for these three types of underground facilities employing a multi-agent system model. First, three spatial layout relationships, competition, coordination, and followership, between five underground facilities that contribute to emission reduction were investigated. Second, the implementation steps for optimizing the spatial layout of underground facilities were determined by defining the behavioral guidelines for spatial environment, underground facility, and synergistic agent. Finally, using the Tianfu New District in Chengdu City, China, as a case study, layouts of underground facilities under three different underground space development scenarios were simulated to verify the model. The findings of this study address the gap in the research on underground spatial facilities and their layout optimization in response to emission reduction. This study provided a significant reference for the study of underground space and underground resources at the planning level to aid in achieving carbon–neutral cities.

Wind-driven smoke dispersion in rooftop photovoltaic fires: An experimental investigation with helium smoke

In 2022, global photovoltaic (PV) deployed capacity increased by 240 GW, reaching a cumulative capacity 1.185 of terawatts, accompanied by anticipated 34,247 PV-inducted fires. The dispersion of fire smoke from rooftops with PVs raises significant safety concerns regarding residents’ exposure. Therefore, it is essential to investigate the phenomenon of smoke dispersion generated by rooftop PV fires, particularly through rooftop openings such as skylights. However, there are limited studies on this topic in the literature. This study conducts small-scale tests in a wind tunnel to examine rooftop PV fire smoke dispersion using a novel smoke-helium similarity and scaling law. A parametric analysis is carried out, aiming to guide the fire protection design of the building. It examines the smoke dispersion generated from rooftop PV fires, considering a variety of rooftop angles, incoming wind velocities, as well as heat release rates (HRR). According to the findings, residents exposed to rooftop PV fire smoke must evacuate within 4 min. Moreover, descending to lower levels may not be a safe means of escape. The scenario with a 15° rooftop angle is deemed fatal. Conversely, rooftop angles of 45° and 60° are considered the most reliable layout for rooftop PV. As incoming wind velocity decreases from 7.75 m/s (full-scale 30 m/s) to 2.58 m/s (full-scale 10 m/s), smoke dispersion increases across the rooftop opening (e.g., skylight) as the rooftop angle increases from 0° to 30°. Smaller HRRs of rooftop PV fires correspond to more reliable fire protection.

Tunable elastic metasurface based on adjustable impedances for Gaussian beam manipulation

Different from the common tunable elastic metasurface (TEM), like piezoelectric active metasurface, in this paper, we propose a TEM composed of impedance-adjustable subunits (IASs) to realize tunable manipulations of flexural waves. Based on the impedance theory, the adjustable mechanism of the phase shift of the IAS is clarified according to the derivations for the relationship between the force/moment interface impedances and complex reflection coefficients. The boundary effect is considered, and the difference between the impedances of the flexural and acoustic waves is demonstrated for the subunits with free and clamped boundary conditions. By using the diffraction theory and coupled-mode theory, an analytical model is established for the metasurface subjected to a Gaussian flexural beam incidence, based on which, the total wavefield consisting of all propagating diffraction orders is solved. Its accuracy and the modulation function adjustability of the TEM are demonstrated by the finite element (FE) simulations and experiments. The proposed IAS possesses a flexible and reliable layout for TEM design and has potential engineering applications in vibration control, health monitoring, etc.

Performance analysis of pinnate horizontal well in enhanced geothermal system

• Feasibility of enhanced geothermal system with pinnate horizontal wells is studied. • Total heat production is improved by 21.4% with pinnate horizontal wells. • Effect of wells structure on heat extraction performance is evaluated. • Reliable layout of pinnate horizontal well is presented. The well layout is crucial for improving the utilization of hot dry rock geothermal resources. In present work, a three-dimensional enhanced geothermal system (EGS) with pinnate horizontal well is proposed. Furthermore, the effect of pinnate horizontal well structure on the heat extraction performance of present EGS is numerically investigated. For scCO 2 -based EGS and water-based EGS, the stable heat extraction state and a competitive heat production can be obtained by present EGS. Compared with the conventional EGS with doublet system, the production temperature and the total heat production of EGS with pinnate horizontal well increase by 21.54 K and 21.4 %, respectively. The heat extraction performance of EGS with pinnate horizontal well is positively correlated with the main well bore number and length. In comparison, the branch well structure and number have less effect on the heat extraction performance. Consequently, main wellbore number with 3 or main wellbore length with 300 m can be taken as criterion for the design of the main wellbore. Besides, the branch well with staggered pattern, inclination angel of 60° and the number of 4, is proved to be the optimum arrangement.

Integration and evaluation of a meander-shaped fibre-optical sensor in a GFRP leaf spring

Fibre-reinforced plastics experience an increasing attention also in the non-aerospace sector. However, the detection of possible internal damage of safety-relevant components remains a challenge. In previous work, a meander-shaped sensor layout with a single fibre-optical sensor was proposed as a particularly efficient and reliable layout and its suitability was demonstrated in coupon tests. In the present work, the approach was transferred to a leaf spring made of glass fibre reinforced plastics and investigated in an extensive test campaign with a realistic test setup. The investigations show the particular suitability of the proposed meander-shaped sensor layout for simultaneous loads monitoring and structural health monitoring.

A New Bi-Level Planning Approach to Find Economic and Reliable Layout for Large-Scale Wind Farm

This paper presents a bi-level planning approach to find an optimal layout for a large-scale wind farm (WF) from economic and reliability perspectives. The upper level of the planning approach is formulated as constrained multi-objective optimization (MOO) to obtain the optimal WF layout, where two conflicting objectives are optimized simultaneously. Two objectives for MOO are i) yearly gross energy production and ii) annual loan repayment (for cable and land area of the WF), where the first objective is maximized and the second objective is minimized. Jensen's wake model is used to calculate the wake effect, and to evaluate the multiple wake effect within a WF, a coordinate-transformation-based approach has been adopted in this study. An efficient hybrid multi-objective metaheuristic algorithm, which is based on nondominated sorting multi-objective particle swarm optimization and improved archive multi-objective simulated annealing, has been proposed to find the optimized WF layout. The superiority of the Pareto front obtained by the proposed algorithm for the large-scale WF layout is supported by its comparison with different powerful and well-established MOO algorithms. In the lower level of the proposed approach, economic and reliability analyses of the solutions (WF layout), obtained in the Pareto front by the proposed hybrid algorithm, have been done. In this context, two performance metrics, a) generation economy index and b) expected wind energy generation (EWEG), have been considered. A sequential Monte Carlo simulation has been developed to calculate the EWEG considering random failure of both wind turbines and cables in this paper. The most suitable WF layout is selected by trading off between economy and reliability using a fuzzy decision-making approach.

Characterization of levitation force for a superconducting magnetic levitation vehicle

Background: In Superconducting Magnetic Levitation (SML) transportation systems, such as the MagLev-Cobra prototype, the levitation force plays an important role, both for efficiency and safety reasons.
 Aim: Determination of the maximum load on the magnetic suspension.
 Methods: To determine how much load the magnetic suspension system supports, numerical simulations, based on computational models, and laboratory experimental tests are normally used.
 The most commonly way for characterization of a SML bearing is the measurement of the levitation force as a function of distance between a Superconductor (YBCO) [1, 2] and a Permanent Magnet Guideway (PMG). The measurement of levitation as a function of distance, the banana curve, has a hysteretic behavior with the results depending of the history of measurement: whether the distance between the superconductor and the PMG is decreasing the force is higher than when the distance is increasing, the force is higher with faster movements and so on. A different approach of levitation force test will be proposed as an alternative to the hysteresis curve. This method, applied to characterize the levitation dynamics of the Maglev-Cobra vehicle, provided more reliable and consistent data with the levitation dynamics observed during the operation of the real scale prototype in the transportation of passengers.
 The bench-top levitation test emulates the behavior of the vehicle along its operation, regardless of the position history between the magnets and the superconductor materials. The test consists in placing the superconductor, refrigerated inside cryostats, in a predetermined Field Cooling (FC) position, and slowly move the cryostat above the PMG to a lower high, for example 15 mm, and wait 10 minutes. After that, the high is decreased 1 mm and again hold there for 10 minutes. The procedure is repeated until a high of 10 mm is reached. The hole process is repeated at least 5 times. This routine replicates the load condition during the vehicle operation when passengers board the train and the load stay constant until the end of the journey. After that, another group of passengers takes place inside the vehicle and is carried to the next station.
 This kind of test shows the creep of the levitation force over time with slow dynamics and gives the average load over height of levitation along the given time of operation, helping engineers to predict the load capacity of the vehicle and design a more reliable layout.
 Results: Three FC positions were investigated. The position currently used by the MagLev-Cobra (35 mm) and other 2 positions (45 mm and 55 mm) of initial height between the superconductor and the permanent magnet guideway.
 Conclusion: All these results contribute to an improvement in the criticality index and a safe application of this system on transportation of persons.

Layout Criteria for Enhancing Indonesian SMEs Production’s Performance

A reliable layout will improve the process effectiveness and lead the production performance at an excellent level. Unfortunately, SMEs in Indonesia have not realized how important it is, and put layout decisions just as an alternative operating decision to improve company’s performance. This study aims to identify reliable layout criteria that should be applied by SMEs production managers in Indonesia to improve their production performance. This research used quantitative methods by investigating 276 SMEs in West Java – Indonesia. The result found that related to the layout design; technology, process, facilities, and product type are the most important factors affecting company's production performance. The four factors are then derived into appropriate criteria that can be applied to Indonesian SMEs. Two kinds of further research can be continued by deepening each of the generated criteria and their application in the specific SME so that the results will better reflect the conditions of SME’s production layout in Indonesia.

Analyzing the effects of converter and DC line outages due to Distributed Voltage Control in AC-MTDC Distribution Network

Technological advancements in power electronics devices in recent years and the increase in the integration of distributed energy resources (DER) due to green energy awareness has transformed the conventional power network into a sophisticated and smart network. With the large-scale integration of sensitive DC load along with AC, and availability of DER with AC and DC type outputs results in an inevitable shift to develop an efficient and reliable layout for a distribution network known as AC-MTDC distribution network. In this paper, an AC-MTDC distribution network is realized to perform the load flow analysis, employing voltage source converter (VSC). A distributed DC voltage control technique is also implemented on VSC based AC-MTDC distribution network, and its effects are analyzed considering the converter and DC line outages for various network scenarious. A modified IEEE 33-bus AC-MTDC distribution network with VSC is considered for this study, and results are analyzed according to power sharing requirement and operational efficiency using MATPOWER, an open source power flow package.

Risk Index Approach for the Optimal Layout of Chemical Processes Minimizing Risk to Humans

Chemical processes are constructed within very compact areas in the consideration of limited resources, including land, although many of their units are dangerous and vulnerable to accidents. Even the safety among units is secured by modifying the layout of process to ensure the safety distance, this situation can get worse if the process site is near residential areas or the workspace of employees because of the risk to humans from the process. In this study, such risk to humans as well as the risk to the equipment itself are quantitatively considered to give more reliable layout of chemical processes. Modified individual risk index has been adopted, counting for the direct risk that a person near the dangerous equipment can take. With this index, optimal process layout is designed by minimization of cost and land area to consider the limitation of resources. The proposed methodology can provide a guideline to designing safe layout of a chemical process concerning the various safety distance measures inc...

EMC Issues in High-Power Grid-Connected Photovoltaic Plants

This paper outlines the main electromagnetic compatibility issues frequently encountered in high-power grid-connected photovoltaic (PV) systems, and proposes several guidelines that allow to obtain an effective and highly efficient layout of the plant. At first, with reference to a 1-MWp PV plant of Sorgenia Solar, Italy, the paper focuses on the peculiar aspects concerning the radio-frequency behavior of a large-size PV plant: the great extent of the direct-current cabling, the capacitance toward earth of the PV source, the common-mode (CM) disturbance generated by inverters, the galvanic isolation ensured by dedicated low-voltage power transformers, and the presence of resonant circuits for CM leakage currents. The dominant electromagnetic phenomena and coupling mechanisms are pointed out by means of an equivalent circuit and through measurements. In the light of the matured experience, several guidelines are proposed and a new reliable layout is implemented on a second 1-MWp PV plant. New measurements confirm the validity of the proposed design strategy.

Electrothermal model of GaAs FET devices for fast PC implementation

An electrothermal model of GaAs FET devices is proposed for an easy, fast and reliable layout design using a personal computer. The contributions to the temperature increase and total thermal resistance of the attachment layer, mounting, metallisations and coating layers, and convection effect are taken into account. The feedback between FET current and channel temperature has also been considered. The simulation can evaluate the thermal field, current distribution, thermal resistance, and the minimum distance between two contiguous devices to minimise the mutual thermal coupling. A comparison has been carried out with the finite-difference technique and experimental results for a wide range of dissipated power in a MESFET device, and good agreement has been observed.

Electrothermal modelling of GaAs MESFETs

In this paper a new analytic electrothermal model of a GaAs FET is proposed in order to evaluate the thermal field in the semiconductor body for an easy, fast and reliable layout design using a personal computer. The contribution to the thermal resistance of all the top and bottom layers of a typical chip and the interaction of the channel temperature with the drain current are taken into account. A comparison with a three-dimensional finite-difference simulator and experimental data confirms the accuracy of the model. The CAD tool in which the mathematical model has been implemented can be used for the layout design since it is able to calculate the optimal spacing between contiguous devices to minimize the mutual thermal coupling and also the optimal number of gate fingers and gate-to-gate spacing of a single power device with a multigate layout. The proposed technique is general and can be applied to silicon as well as to heterojunction FET devices.

Managing information systems’ contingencies in banks: a case study

As information systems (IS) become indispensable, EDP disaster recovery has to become an essential IS function. In this paper, after discussing the criticality of sound planning for information systems disaster recovery in banks, the approach to contingency planning adopted by Banca Commerciale Italiana, one of the largest banks of Italy, is presented. The most crucial point of the whole decision‐making process was the selection of the most reliable layout configuration. Hence, the steps and the simulation methodology followed to such a purpose are illustrated. Finally the benefits and pitfalls of the solution adopted in Banca Commerciale Italiana are discussed.

Topological optimization of a reliable communication network

This paper considers backbone network design under the constraints: minimal total link cost, and 1-FT (fault-tolerant to 1 link-failure). As networks become huge, the backbone layout design is essential to network performance and reliability. A 1-FT backbone can survive any 1-link failure. On the other hand, the total cost of the links in backbone layout is a practical concern. Therefore, the problem is to find a network topology for a set of nodes whose total link cost is minimized, subject to the condition that the backbone network can accommodate 1 link failure. The problem is NP-hard, and methods based on heuristic search are desired to obtain optimal or sub-optimal solutions. This paper proposes an efficient method based on genetic algorithms to solve the problem. The representation of a backbone layout is based on a list of ordered links. The genetic operators attempt to generate a more cost-effective or reliable layout. Simulation shows that the proposed algorithm can efficiently find a sub-optimal solution for most cases.

Shaft spillways combined with a water intake

1. Under confined conditions the combination of a spillway and intake in the same structure makes it possible to discharge floods during construction and operation of the hydrostation, to empty the reservoir, to create favorable conditions for its flushing, and also to withdraw water for consumers. 2. The combination of spillway and intake in one structure often reduces their total cost and provides an optimal and reliable layout of the hydrostation. 3. The use of an inclined shaft on a spillway provides a free-flow hydraulic regime on the structure, which in turn improves the hydraulic and static conditions of its operation, facilitates construction, and increases operational reliability. 4. Under certain conditions — presence of strong rocks in the lower pool, removal of the outlet part of the spillway to some distance from the dam — the flow in the lower pool should be joined with the river by means of a ski-jump bucket.