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This paper reports on laboratory studies into the ac impedance spectra of nickel–metal hydride and nickel–cadmium batteries, aiming at finding out possible correlation between electrical parameters, extracted directly from the high frequency region, and the battery state-of-charge (SoC). Impedance diagrams were recorded immediately after interrupting the dc charge, or discharge, current. The study revealed that the series resonance frequency, at which the dynamic cell behavior switches from an inductive character (Z″>0) to a capacitive one (Z″<0), varied monotonously as a function of state-of-charge. This behavior was reproducible after intermittent charge and discharge. Half-cell measurements were also conducted to associate the cell impedance with either processes occurring at the positive or negative plates.

Abstract Every day and innumerably, road vehicles of different types pass flat roadside-placed elements like stable or temporary traffic signs, noise barriers, charge devices, etc. The elements are exposed to a vehicle-specific flow and pressure field, i.e. to transient loads. In order to quantify the involved phenomena, full-scale experiments were performed for six different vehicle types and three sizes of square plates, which were aligned in three different configurations with respect to the vehicle׳s track. For the measurement of loads effecting the plate, the pressure multi-tapping technique was implemented with high temporal and spatial resolution. The experiments delivered a broad database for the proper quantification of vehicle induced loads on flat elements as a function of vehicle type, vehicle velocity and passing distance to the plate, element size as well as spatial plate alignment with respect to the vehicle.

In this paper the low frequency shielding behavior of shielded high voltage cables for electric vehicles is analyzed using analytical methods. First the basic theory on the operational modes and modeling of cables is presented. Measurements and numerical simulations are done to verify the models. The powertrain of an electric vehicle is investigated using the simulation models. A parametrical study determines the influence of parameters such as height and distance of the cables and gives information for an EMC compliant layout. The magnetic fields for different cable setups are calculated and compared with values from health protection standards.

Abstract A variety of novel, recyclable and reusable, construction materials has already been studied within literature during the past years, aiming at improving the overall energy efficiency ranking of the building envelope. However, several studies show that a delicate control of indoor climating elements can lead to a significant performance improvement by exploiting the building’s savings potential via smart adaptive HVAC regulation to exogenous uncertain disturbances (e.g. weather, occupancy). Building Optimization and Control (BOC) systems can be categorized into two different groups: centralized (requiring high data transmission rates at a central node from every corner of the overall system) and decentralized 1 (assuming an intercommunication among neighboring constituent systems). Moreover, both approaches can be further divided into two subcategories, respectively: model-assisted (usually introducing modeling oversimplifications) and model-free (typically presenting poor stability and very slow convergence rates). This paper presents the application of a novel, decentralized, agent-based , model-free BOC methodology (abbreviated as L4GPCAO) to a modern non-residential building (E.ON. Energy Research Center’s main building), equipped with controllable HVAC systems and renewable energy sources by utilizing the existing Building Management System (BES). The building testbed is located inside the RWTH Aachen University campus in Aachen, Germany. A combined rule criterion composed of the non-renewable energy consumption (NREC) and the thermal comfort index – aligned to international comfort standards – was adopted in all cases presented herein. Besides the limited availability of the specified building testbed, real-life experiments demonstrated operational effectiveness of the proposed approach in BOC applications with complex, emerging dynamics arising from the building’s occupancy and thermal characteristics. L4GPCAO outperformed the control strategy that was designed by the planers and system provider, in a conventional manner, requiring no more than five test days.

The mixing process of hot primary zone gases with secondary air must be rapid and intense for an advanced low NOX gas turbine based on a rich-burn/quick-mix/lean-burn (RQL) combustor. The injection of multiple jets normal into a confined crossflow is a key technology for this combustion concept. Therefore, an experimental investigation of a nonreacting mixing process of jets in a crossflow was conducted. The jets were injected through one stage of opposed rows of circular orifices into a slightly heated crossflow within a rectangular duct with no annular bypass. All geometries were tested with in-line and staggered arrangements of the centerlines of the opposed jets. Using the analogy of heat and mass transfer the temperature distribution was measured, and from that the mixing rate was determined for parametric variation of flow and geometric conditions. In accordance with the application to RQL combustion, emphasis was put on high momentum-flux ratios with high mass flow addition. The mixing process was found to be minimally affected by mainstream Reynolds number and mainstream turbulence, but significantly influenced by the addition of swirl to the mainstream. Correlations based on the experimental data were developed describing best mixing depending as a function of geometric conditions (duct height to hole diameter ratio, relative spacing of adjacent jets) and jet to crossflow momentum-flux ratio.

The article deals with the issues of engineering arrangement of the territory for the nursery and the mother plant garden of common hazel - the layout of the nursery, the choice of the irrigation method, the calculation of the reservoir volume, irrigation rates, and production efficiency.

This paper presents experimental data of three different prototype valves with cone-, ball-, and slide-valve geometries that have been tested using R-744 and two reference media, ARAL 4005 and R-729, under one-phase flow conditions. Three different test rigs were used to carry out the tests using boundary conditions with the objective to achieve more or less similarity regarding the Reynolds number and the Mach number. One aim was to find physical-based flow correlations to describe the flow behavior of the three investigated valve geometries with carbon dioxide (R-744), hydrocarbon-based low-viscosity fluid (ARAL 4005), and air (R-729) as the fluid. The main goal of this research was to find a correlation between the flow coefficients of both (a) R-744 and ARAL 4005 and (b) R-744 and R-729 to enable the transfer of a flow coefficient measured for ARAL 4005 or R-729 into a flow coefficient for R-744.

This paper presents an open standards-based information system supporting the democratization and consumer empowerment through flexibility activation. The paper describes a functional technical reference infrastructure: a secure, standard-based and viable communication backbone for flexibility activation. The infrastructure allows connection, registering, activation and reporting for different types of granular consumer flexibility. The flexibility sources can be directly controllable set points of chargers and stationary batteries, as well as controllable loads. The proposed communication system sees all these flexibility provisions as distributed energy resources in a wider sense, and the architecture allows consumer-level integration of different energy systems. This makes new flexibility sources fully available to the balancing responsible entities in a viable and realistically implementable manner. The proposed reference architecture, as implemented in the FLEXCoop project, relies on established open standards as it is based on the OpenADR and OAuth2 / OpenID standards and the corresponding IEC 62746-10 standard, and it covers interfacing towards other relevant standards. The security and access implications are addressed by the OpenID security layer built on top of the OAuth2 and integrated with the OpenADR standard. To address the data protection and privacy aspects, the architecture is designed on the least knowledge principle.

Special linking circuits are required for the design of safe railway automation and remote control of trackside objects. They are usually based on devices with an asymmetrical failure rate, mainly first reliability class electromagnetic relays. The development of railway automation and remote control devices requires the use of state-of-the-art contactless semiconductor components. In this case, the use of functional converters or periodic testing of semiconductor switches and disconnection of the power supply from control objects in case of faults are needed. This article describes the use of a three-phase induction motor as the solution of the problem. They are used for the design of functional converters for railway automation electric motors control. It is proposed to use the low-frequency mode of power switch operation (switch frequency is 50 Hz) and to abandon the pulse-width modulation. The suggested technical solution is used in a CBI-MPC system for train traffic control at stations developed at the Center for Computer Railway Technologies of St. Petersburg State Transport University.