Types Of Insulators Research Articles

Effects of Converter Harmonic Voltages on Transformer Insulation Ageing and an Online Monitoring Method for Interlayer Insulation

Power electronic converter can produce massive voltage stresses on the connected transformer, with great effects on electrical ageing of the insulation. Such effects can be diverse upon different insulation components under different harmonic voltages, which have not been well clarified. This article aims at enhancing online monitoring of converter transformers from two aspects. First, electrical ageing evaluation models are developed for different types of transformer insulation. It is the first time to clarify the effects related to the component location and the ageing severity under differential-mode and common-mode (CM) voltages. Interlayer (IL) insulation faces a serious ageing threat and the line-lead component is aged with the severest degree. Second, CM voltages are used to build transfer function (TF) measurement for IL insulation monitoring. The key is to identify the optimal monitoring frequency with the highest sensitivity. Based on the analytical case introducing typical parameters, the TF performance is analyzed in different ageing conditions. Online experiments validate that the proposed method is effective and has good application prospect. The contributions lie in that the diverse ageing effects of converter harmonic voltages on different insulation components can be distinguished and online monitoring of IL insulation can be achieved effectively.

Influence of Nanoparticles on the Degradation Processes of Ester-Based Transformer Insulation Systems

The use of nanofluids as dielectric liquids for transformer insulation has been widely investigated during the last decade. A number of authors have performed extensive studies on liquids produced from different types of nanoparticles and base fluids, providing evidence of their good dielectric properties. Nevertheless, nanodielectric fluids are still at the research stage, and they are far from being a solution that can be applied to real transformers. One of the aspects that might be clarified is their compatibility with the rest of the materials present in the transformer and their behavior throughout the life of the equipment. This paper studies the aging process of cellulose impregnated with an ester-based nanofluid and compares it with the process that takes place when the impregnation liquid is a natural ester. Accelerated aging experiments were performed, and physical and chemical characterization of the process with several analytical techniques was carried out. The mechanical degradation of the cellulose was studied in terms of tensile strength, and the evolution of moisture in the paper and oil was monitored throughout the aging process. The study was completed with FTIR and XPS tests aimed at studying the chemical changes of the materials during the aging process. The experimental results suggest that the degradation rate of the cellulose is not significantly affected by the presence of nanoparticles. However, the XPS study revealed that the chemical reactions involved in the degradation processes of both types of insulation might differ. Several mechanisms are proposed in this work.

Multi-objective optimization of setpoint temperature of thermostats in residential buildings

Determination of the optimum setpoint temperature of thermostats in various climates is a problem in air conditioning of residential buildings. In this paper, a new method is developed to optimize the setpoint temperature of thermostats in different climates of Iran. Design variables in the optimization process are heating setpoint, cooling setpoint, thickness, and thermal conductivity of insulations in the building envelopes. The optimization goals are minimizing energy consumption and cost of insulations in addition to maximizing thermal comfort of occupants. Thus, the static payback period (SPP) and the predicted percentage dissatisfied (PPD) indices are selected as objective functions which should be minimized in the optimization process. The methods applied to attain these objectives are numerical modeling by EnergyPlus software, Grouped Method of Data Handling (GMDH) type of Artificial Neural Network (ANN), and Non-Dominated Sorting Genetic Algorithm II (NSGA-II). Therefore in this process, first, EnergyPlus is used to train the neural network. Afterward, the GMDH-type neural network is applied to derive polynomials computing the objective functions from the design variables. Then, Pareto optimal points for the objective functions are obtained through using these polynomials and NSGA-II multi-objective optimization. Finally, the optimum design point is selected for different cities. According to the results, type and thickness of insulation integrated in the building envelopes affect the static payback period and thermal comfort of occupants. For all the climates of Iran, the most appropriate insulation is XPS and the optimum heating setpoint of thermostat is 22 °C. Also, the optimum value for the cooling setpoint pertains to the type of climate, so that this value for Bandar Abbas, Yazd, Tehran, Rasht and, Tabriz is, respectively, equal to 24.5, 24.7, 25.2, 25.3, and 25.6 °C. Moreover, thermal comfort of occupants increases with thickness of insulation, except for Bandar Abbas whose PPD is almost constant. The most value of PPD reduction with insulation thickness is related to Tehran where by increasing the insulation thickness from 1 cm to 5 cm, PPD decreases up to 53%.

Charge and Lattice Dynamics in Excitonic Insulator Ta2NiSe5 Investigated Using Ultrafast Reflection Spectroscopy

An excitonic insulator, in which an optical gap is formed by exciton condensation, is expected to exhibit large photoresponses. Here, we report the results of femtosecond reflection spectroscopy covering a wide infrared region on a typical excitonic insulator, Ta2NiSe5, which gives direct information not only about a change of excitonic gap but also a metallization. With a weak excitation, the excitonic gap decreases due to the weakening of excitonic effect by photocarriers. With a strong excitation, a Drude-like high-reflection band appears, showing an excitonic-insulator-to-metal transition. Analyses of spectral and temporal changes of reflectivity revealed that the metallization is accompanied by large structural changes. This demonstrates an important role of electron–lattice interaction on the stabilization of excitonic phase.

Physical mechanism for photon emissions from group-IV-semiconductor quantum-dots in quartz-glass and thermal-oxide layers

We experimentally studied the influence of both impurity density and dangling-bond density on PL emissions from group-IV-semiconductor quantum-dots (IV-QDs) of Si and SiC fabricated by hot-ion implantation technique, to improve the PL intensity (I PL) from IV-QDs embedded in two types of insulators of quartz-glass (QZ) with low impurity density and thermal-oxide (OX) layers. First, we verified the I PL reduction in the IV-QDs in QZ. However, we demonstrated the I PL enhancement of IV-QDs in doped QZ, which is attributable to multiple-level emission owing to acceptor and donor ion implantations into QZ. Secondly, we confirmed the large I PL enhancement of IV-QDs in QZ and OX, owing to forming-gas annealing with H2/N2 mixed gas, which are attributable to the reduction of the dangling-bond density in IV-QDs. Consequently, it is possible to improve the I PL of IV-QDs by increasing impurity density and reducing dangling-bond density.

Shaking Table Test of a New Type Insulation Decorative Block Wall under Out-of-Plane Loading

In order to solve the problems of complex construction, poor weather resistance, and environmental pollution of conventional thermal insulation materials, this paper introduces a new type of insulation decorative block (IDB) filled with insulation materials. Different anchoring methods were adopted to study the influence of anchor bolts on the out-of-plane mechanical properties of IDB walls. The test results revealed that the anchor bolts could effectively prevent the appearance and development of cracks in the specimens. With the increase of anchor bolts, the acceleration and displacement of the IDB walls decreased. Compared to rectangular arrangement, the staggered pattern of anchor bolts could reduce the relative displacement and acceleration. The structural calculation of IDB walls was carried out to determine the number of anchor bolts at different heights, and design suggestions were given to improve the performance of IDB walls. The analysis and test results indicated that the IDB is suitable for application in engineering structures.

Evaluation of the dielectric strength of the insulation of innovative busbar conductors with a voltage class of 6 (10) kV

The article discusses the issue of increasing the dielectric strength of solid insulation of conduits used in various areas of the electric power industry, chemical and metallurgical industries, as well as in the agro-industrial complex. For a conductor with a voltage class of 6 (10) kV with a specially developed new type of insulating compound, electric strength tests were carried out with a full lightning impulse and one-minute power frequency voltage. As a result of the tests carried out, the functionality of the improved design and the new type of insulation was confirmed.

Triple Point Surface Discharge Photography in Atmospheric Gases Using Intensified High-Speed Camera System

In this article, investigations of surface discharges using an ultraviolet (UV) intensified high-speed camera system are presented, accompanied by high-frequency response and resolution current recordings. A needle-plane electrode configuration is employed for the generation of a strongly nonuniform electric field on the surface of disk-shaped insulator samples made of polytetrafluoroethylene (PTFE) or epoxy resin. The electrode arrangement is further insulated by a gaseous medium of either technical air (21% O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /79% N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ), nitrogen (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ), or carbon dioxide (CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). An alternating (ac) voltage waveform at power frequency (50 Hz) is maintained at levels sufficiently below the flashover voltage corresponding to each presented case. Detailed descriptions of the technical specifications of the utilized equipment are provided for both optical and electrical measurements in the experimental setup. The obtained results demonstrate the discharge propagation during the ac-cycle and its dependence on the insulator type and gaseous insulating medium. Individual surface discharges are captured in the microsecond range to describe the discharge morphology based on the generated current pulse and instantaneous applied voltage level. Back-discharges on the insulating disk are also discussed, and relevant image capture is presented.

Study on insulation defect discharge features of dry-type reactor based on audible acoustic

The audible signal (20 Hz to 20 kHz) generated during the operation of a dry-type reactor is one of the key features to evaluate its operation state. However, at present, the time/frequency domain features of the audible signal under typical insulation defects are not clear, which makes it difficult to effectively carry out the fault diagnosis of the dry-type reactor based on audible signals. Based on this, the audible signal features under typical insulation defect discharge of the dry-type reactor are studied in this paper. Three typical insulation defect discharge models (metal protrusion defect, pollution defect, and metal foreign bodies defect) are simulated; then, the discharge acoustic signals are collected under the voltage of 8 kV. Analysis of acoustic signal features shows that the acoustic signal of metal protrusion defect discharge occurs in the positive half cycle of power frequency with the cycle of 20 ms. Both pollution defect discharge and metal foreign bodies defect discharge show intermittent discharge; during the discharge, the discharge acoustic signal of pollution defect has features similar to that of metal protrusion defect, while the discharge of metal foreign bodies defect shows randomness with a larger amplitude of discharge acoustic signal (up to 110 dB). Based on the frequency domain feature vectors’ extraction, it is found that the odd harmonic component of the metal protrusion defect discharge acoustic signal accounts for more than twice the even-order harmonic, and the high-frequency energy (12.5–25 kHz) is the main component. The discharge acoustic signal of the metal foreign bodies defect is mainly low-frequency energy, and the high-frequency energy proportion of pollution defect discharge acoustic signal is similar to that of low-frequency energy. In addition, the variance of high-frequency energy ratio (Rhf) of the metal foreign bodies defect discharge acoustic signal is 5.25 and 21 times that of the metal protrusion defect and pollution defect. This study provides some technical support for further detection and assessment of the operation state of the dry-type reactor based on audible signals.

Assessment of the partial discharges impact on the new type 20 kV busbar with cast insulation

The article considers the partial discharges impact on busbars of voltage class 20 kV. The composition of a new type insulation includes a dusty inert material, which contributes to an increase in electrical strength. As a result of the tests carried out, the amplitude of partial discharges was recorded. It did not exceed the standard values. Also, areas of partial discharges high-amplitude values were recorded less than busbars without filler.

Sound insulation of lightweight external frame walls and the acoustic effect of additional thermal insulation

The sound insulation of lightweight frame façades and the acoustic effect of additional thermal insulation were examined. The research aimed to investigate the contribution of different insulating layers to the acoustic performance of an external wall. In particular, the use of ETICS (external thermal insulation composite systems) was considered. This usually reduces the sound insulation of traditional massive partitions substantially whereas for lightweight frame structures the effect was not precisely identified. The study is based on laboratory measurements, and several full-scale models were tested. Wood and metal frame walls with various claddings were considered. The application of ETICS caused the reduction of sound insulation in a certain frequency range. The effect, however, seems not as harmful as for massive partitions. Another type of thermal insulation with a venting cavity demonstrated much better acoustic performance. Conversely, internal installation cladding, when rigidly fastened to the basic structure had practically no effect on the wall properties. Significant improvement was observed when resilient spacers or separate supporting structures were applied.

A DFT study of perovskite type halides KBeBr3, RbBeBr3, and CsBeBr3 in triclinic phase for advanced optoelectronic devices

The structural, electronic, magnetic, optical, vibrational, thermodynamic and mechanical properties of beryllium based perovskite type halides KBeBr3, RbBeBr3, and CsBeBr3 in triclinic phase have been investigated by utilizing PBE + GGA functional based on density functional theory in CASTEP simulation code. The determined lattice constants for considered perovskite type halides are listed as 5.7125 Å, 5.7202 Å and 5.9533 Å for KBeBr3, RbBeBr3, and CsBeBr3, respectively. The electronic properties have been determined and it is observed that these materials show insulator type character. The observed energy band gaps are in the order of 4.0 eV, 4.2 eV, and 4.7 eV for KBeBr3, RbBeBr3, and CsBeBr3, respectively as calculated by hybrid HSE06 functional. The optical properties like dielectric function, absorption coefficient, conductivity, extinction coefficient etc. also predict that the studied perovskite type halides are the potential candidate for optoelectronic devices. Additionally, the dynamic vibrational stability has been calculated and the determined phonon energy dispersion curves predict that these compounds are dynamically stable. Also, the thermodynamic parameters including enthalpy, free energy and temperature time's entropy have been investigated. Moreover, the mechanical and elastic properties of considered materials are also calculated to check their reliability, stability and easy handling for optoelectronic applications. This first principle investigation of computational properties of the novel materials implement an advance route to the theorists and experimentalists for the new potential applications in the renewable and advanced optoelectronic devices.

Pathologies of a Different Kind: Dysfunctional Interactions between International Organizations

AbstractThis article develops the concept of “interorganizational pathologies” as an extension of Michael N. Barnett and Martha Finnemore's work on bureaucratic pathologies. Adopting an open system perspective, I argue that dysfunctional interactions may arise between international organizations (IOs) even when their cooperation is fairly institutionalized. To advance this line of reasoning, I examine interactions between the International Monetary Fund (IMF or Fund) and the World Bank (or Bank). Evidence from more than ninety stakeholder interviews indicates that the interactions have been marked by what Barnett and Finnemore call “insulation.” In particular, two opposing types of interorganizational insulation have been common in the context of Fund–Bank relations: (1) groupthink, or sustained intellectual decoupling by the two IOs from the outside world; and (2) silence, or (temporary) communicative disruption between them. This finding is partly puzzling because while we may expect IMF–World Bank interactions to produce groupthink given the organizations’ highly similar worldviews, we would expect them to prevent silence given established protocols for continuous cross-organizational information sharing. The analysis sheds fresh light on the promises and pitfalls of cogovernance by IOs as key players in regime complexes and transnational networks.

Mott\u2013Hubbard insulating state for the layered van der Waals hbox {FePX}_3 (X: S, Se) as revealed by NEXAFS and resonant photoelectron spectroscopy

A broad family of the nowadays studied low-dimensional systems, including 2D materials, demonstrate many fascinating properties, which however depend on the atomic composition as well as on the system dimensionality. Therefore, the studies of the electronic correlation effects in the new 2D materials is of paramount importance for the understanding of their transport, optical and catalytic properties. Here, by means of electron spectroscopy methods in combination with density functional theory calculations we investigate the electronic structure of a new layered van der Waals hbox {FePX}_3 (X: S, Se) materials. Using systematic resonant photoelectron spectroscopy studies we observed strong resonant behavior for the peaks associated with the 3d^{n-1} final state at low binding energies for these materials. Such observations clearly assign hbox {FePX}_3 to the class of Mott–Hubbard type insulators for which the top of the valence band is formed by the hybrid Fe-S/Se electronic states. These observations are important for the deep understanding of this new class of materials and draw perspectives for their further applications in different application areas, like (opto)spintronics and catalysis.

ADVANCED METHOD OF CALCULATING SOUND PRESSURE IN CONDUCTORS WHEN THEY ARE IDENTIFIED BY ACOUSTIC METHOD

Despite the fact that the operation of identifying conductors seems to be an easy and deeply studied topic, it can be time-consuming due to the large number of unidentified conductors (cables). A method based on the use of an acoustic signal as a carrier is proposed, which makes it easier and faster to identify conductors. Previously, a method for calculating the sound pressure in conductors during their identification was developed, but it has a number of inaccuracies. Therefore, an improved method for calculating sound pressure in conductors is proposed. According to the above method, the sound pressure level was calculated depending on the specific length of the conductor, the cross section of the conductor and the type of insulation. The calculations carried out revealed the possibility of identifying conductors by the acoustic method. (Research purpose) The research purpose is developing an improved methodology for calculating the parameters of acoustic signal propagation in electrical conductors and their insulation when identifying wires and cables by acoustic method. (Materials and methods) Analyzed literature sources and existing methods of identification of conductors. Revealed the essence of the acoustic method of wire identification. (Results and discussion) A mathematical model of sound propagation in conductors and insulation was described. Calculations were performed to determine the sound pressure level depending on the specific length of the conductor, the cross-section of the conductor and the type of insulation. (Conclusions) The shortcomings of existing methods and means for identifying conductors have been identified. A multifactorial experiment was conducted in which the controlled and controlled factors were: the cross section of the conductor, the distance of the identification point from the sound source, the frequency of the acoustic signal. The regression equation was obtained; the response surfaces of the sound pressure level in the conductors at an acoustic signal frequency of 80 Hz.

Influence of Sheath Radial Crack on Flashover Arc and Leakage Current of Roof Silicon Rubber Insulator for High-Speed Train

In this paper, three types of insulators with no crack, short crack, and long crack are taken as the research objects to evaluate the influence of the penetrating cracks on the 1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> sheath of the roof silicone rubber composite insulator of high-speed train on the flashover characteristics. The continuous voltage rising method is used to obtain the influence characteristics of the crack on the development process of the flashover arc. The constant voltage withstand method is adopted to compare the leakage current when the contamination degree is 0.1 mg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The test results demonstrate that the crack has no significant effect on the flashover voltage and flashover path, and the flashover arc can burn the edge of the crack. The peak leakage current of the three different tests ranges from 24 mA to 30 mA. Additionally, the development of leakage current can be divided into four stages: rising, continuous violence, falling, and oscillating. Moreover, the sequence of the apparent leakage current of the insulator is long crack insulator, short crack insulator, and the one with no crack. The acceleration of the rising stage of the leakage current increases with the increase in the crack length. Meanwhile, the sum of the time of the rising stage, continuous stage, and falling stage of the insulator with long crack is the smallest. The crack will distort the distribution of current density and the electric field intensity in the vicinity. The results can provide references for evaluating the influence of radial cracks at the edge of the sheath on the flashover characteristics and optimizing the design of the roof insulator sheath structure.

Topological corner states in acoustic honeycomb structure

In recent years, a new type of topological insulator, termed higher-order topological insulator, has attracted tremendous research interest. Such exotic lower-dimensional topological boundary states have been extended and reproduced in classical systems, such as optics and acoustics. In this paper, a two-dimensional acoustic honeycomb structure with a triangle resonant cavity is numerically studied. Topological phase transition is induced by gradually adjusting the intracell and intercell coupling, and then the topological phase is used to construct a second-order topological insulator. The topological properties of second-order topological insulators can be characterized by using the quantized quadrupole moments. When quantized quadrupole &lt;inline-formula&gt;&lt;tex-math id="M4"&gt;\begin{document}$ {Q_{ij}} = 0 $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20211848_M4.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20211848_M4.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, the system is trivial, while &lt;inline-formula&gt;&lt;tex-math id="M5"&gt;\begin{document}$ {Q_{ij}} = 1/2 $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20211848_M5.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20211848_M5.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, the system is topologically nontrivial. We investigate the acoustical higher-order states of triangular and hexagonal structures, respectively. The gapped zero-dimensional corner states are observed in both structures, but the robustness properties of the corner states emerge only in the hexagonal structures but not in the triangular-shaped ones. The topological corner modes will offer a new way to robustly confine the sound in a compact acoustic system.

Effects of local exchange field in different directions on spin transport of stanene

Topological insulator is a new quantum state of matter in which spin-orbit coupling gives rise to topologically protected gapless edge or surface states. The nondissipation transport properties of the edge or surface state make the topological device a promising candidate for ultra-low-power consumption electronics. Stanene is a type of two-dimensional topological insulator consisting of Sn atoms arranged similarly to graphene and silicene in a hexagonal structure. In this paper, the effects of various combinations of local exchange fields on the spin transport of stanene nanoribbons are studied theoretically by using the non-equilibrium Green's function method. The results show that the spin-dependent conductance, edge states, and bulk bands of stanene are significantly dependent on the direction and strength of the exchange field in different regions. Under the joint action of the exchange fields in [I: &lt;inline-formula&gt;&lt;tex-math id="M12"&gt;\begin{document}$ \pm Y $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M12.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M12.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, II: &lt;inline-formula&gt;&lt;tex-math id="M13"&gt;\begin{document}$ +Z $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M13.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M13.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, III: &lt;inline-formula&gt;&lt;tex-math id="M14"&gt;\begin{document}$ \pm Y $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M14.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M14.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;] direction, the edge states form a band-gap under the influence of the &lt;i&gt;Y&lt;/i&gt;-direction exchange field. The band-gap width is directly proportional to the exchange field strength &lt;i&gt;M&lt;/i&gt;, and the conductance is zero in an energy range of &lt;inline-formula&gt;&lt;tex-math id="M15"&gt;\begin{document}$ -M&lt;E&lt;M $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M15.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M15.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;. When the exchange fields in the direction of &lt;inline-formula&gt;&lt;tex-math id="M16"&gt;\begin{document}$ +Z $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M16.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M16.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; or &lt;inline-formula&gt;&lt;tex-math id="M17"&gt;\begin{document}$ -Z $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M17.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M17.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; are applied, respectively, to the upper edge region and the lower edge region at the same time, the spin-up energy band and the spin-down energy band move to a high energy region in opposite directions, and strong spin splitting occurs in the edge state and bulk bands. Increasing the strength of the exchange field, the range of spin polarization of conductance spreads from the high energy region to the low energy region. When the directions of the exchange field are [I: &lt;inline-formula&gt;&lt;tex-math id="M18"&gt;\begin{document}$ \mp Z $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M18.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M18.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, II: &lt;inline-formula&gt;&lt;tex-math id="M19"&gt;\begin{document}$ \pm Y $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M19.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M19.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, III: &lt;inline-formula&gt;&lt;tex-math id="M20"&gt;\begin{document}$ \pm Z $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M20.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M20.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;], the edge states are spin degenerate, but the weak spin splitting occurs in the bulk bands. Under the condition of different exchange field strengths, the spin-dependent conductance maintains a conductance platform of &lt;inline-formula&gt;&lt;tex-math id="M21"&gt;\begin{document}$ G_\sigma=e^2/h $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M21.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M21.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; in the same energy range of &lt;inline-formula&gt;&lt;tex-math id="M22"&gt;\begin{document}$ -\lambda_{\rm so} &lt;E&lt;\lambda_{\rm so} $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M22.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M22.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;.

Energy Efficient Thermal Comfort Control for Residential Building Based on Nonlinear EMPC

For purpose of achieving the desired thermal comfort level and reducing the economic cost of maintaining the thermal comfort of green residential building, an energy efficient thermal comfort control strategy based on economic model predictive control (EMPC) for green residential buildings which adopts household heat metering is presented. Firstly, the nonlinear thermal comfort model of heating room is analyzed and obtained. A practical nonlinear thermal comfort prediction model is obtained by using an approximation method. Then, the economic cost function and optimization problem of energy-saving under the necessary thermal comfort requirements are constructed to realize the optimal economic performance of the dynamic process. The energy efficient thermal comfort MPC (EETCMPC) is designed. Finally, the comparison and analysis between EETCMPC and Double-layer Model Predictive Control (DMPC) is simulated. The simulation results reveal that when the clothing insulation is typical, the energy efficiency of EETCMPC is 8.9% and 11.6%, respectively, in the two simulation scenarios. When the clothing insulation varies with temperature, the energy efficiency of EETCMPC is 7.29% and 9.15%, respectively, and the total energy consumption is reduced by about 1.65% and 14.6%, respectively, compared with the typical clothing insulation. The economic performance is improved in the thermal comfort dynamic process of heating room.

The reuse of discarded plastic water bottles as an insulating material for external walls in buildings

The thermal conductivity of exterior wall insulation affects the overall energy consumption of a given building. Fiberglass insulation is often used for this application. This research investigated the feasibility of replacing typical fiberglass insulation with used empty Polyethylene Terephthalate (PET) bottles. In addition to potential cost savings, replacing fiberglass insulation with PET bottles on a large scale could help alleviate the environmental impact of sending these bottles to landfills. A small 8-inch by 8-inch wall section constructed with sheet metal and drywall was used for testing, maintaining a 3-inch airspace for proposed insulation. Thermal resistance was measured with the airspace packed with empty water bottles and comparisons were made to the same wall sections void of any water bottles. Testing was conducted both with and without a 1/2-inch foam board present for comparison. Kapton heaters and temperature sensors were used for the simulation. Preliminary testing showed promise for the proposed application. The effectiveness of the plastic water bottles at providing insulation properties increased with decreasing voltage in both test setups (both with and without the foam board) and was most effective when the foam board was present. Further research is needed to determine how the use of PET bottles for exterior wall insulation can be implemented on a larger scale and how R-values can be improved.