Nanoscale Continuous Directional Motion Driven by a Cyclic Thermal Field

Directional motion plays a crucial role in various mechanical systems. Although mechanisms for nanoscale directional motion have been widely used in many aspects of nanotechnology, it remains a great challenge to generate continuous and controllable motion at the nanoscale. Herein we propose a nanoscale continuous directional motion in cyclic thermal fields by using a double-walled system which consists of an outer BN/C heterojunction nanotube and a concentric inner carbon nanotube (CNT). By manipulating the heating region of the outer BN/C heterojunction tube, the continuous motion of the inner CNT can be realized with ease. The inner CNT demonstrates three distinct movements due to the joint actions of the asymmetric thermal gradient forces and interlayer attraction forces caused by the presence of the outer BN/C heterojunction nanotube. The mechanism revealed in the present study may be useful in designing novel devices for energy conversion and directional transportation.

Homeowners’ Participation in Energy Efficient Renovation Projects in China’s Northern Heating Region

In China’s government-led energy efficient renovation of residential buildings, homeowners’ participation refers to their involvement and engagement throughout the process. Lacking homeowners’ participation has brought difficulties in the execution and financing of the projects. This paper explores the current situation of homeowners’ participation and provides suggestions for optimization from three perspectives: the steps and procedures of the participation process, the composition of the working group responsible for contacting the homeowners, and the contents to be discussed during the process. The semi-structured interview and questionnaire results show that homeowners’ participation is not adequate, and the current arrangement deviates from their expectations. Although most homeowners are positive towards government-led renovation and are enthusiastic about being involved, the process setup is not well-designed to let them fully participate. Moreover, their expectations and preferences are related to several factors. It can be concluded that relevant laws and regulations should be introduced to provide a basis for solving problems at the executive level, and homeowner associations should be established to serve as a channel of communication between homeowners and the working group. Designing targeted renovation and participation strategy is a necessity to minimize the communication efforts.

Cooling–heating phase transition of the Euler–Heisenberg-AdS black hole

We investigate the cooling–heating phase transition of the Euler–Heisenberg-AdS black hole. First, the black hole thermodynamic quantities and the state equation are reviewed. Then, we research cooling–heating phase transition and further plot the inversion and isenthalpic curves in the T–P plane. Meanwhile, we find that the inversion temperature gradually decreases with the increase of Euler–Heisenberg parameter a for the inversion curves, while this parameter has no effect in the cooling region, and the isenthalpic curves gradually move to the positive direction of X-axis with the increase of Euler–Heisenberg parameter a in the heating region. In particular, the inversion temperature and pressure of this black hole are negative, we deem that this case is caused by the vacuum polarization and the quantum electrodynamics corrections, which makes the electromagnetic energy (repulsion force) produced by the black hole shield the gravity produced by the black hole mass. In addition, this explanation has been mentioned in previous studies [M. Daniela and B. Nora, Phys. Rev. D 102, 084011 (2020); R. Ruffini, Y. B. Wu and S. S. Xue, Phys. Rev. D 88, 085004 (2013)].

Влияние локального нагрева набегающего потока на уровень звукового удара от тонкого тела, находящегося в аэродинамической тени за диском

Calculations are performed for a sonic boom generated by two bodies (a disk and a thin body of revolution) in the case of local heating of the incident air flow. The bodies are in a heat trail behind the heating region. The thin body is in an aerodynamic shadow behind the disk. The Mach number of the cold air flow is 2. The calculations are carried out using the combined method of "phantom bodies". It is concluded on the basis of the calculations that the level of a sonic boom can be effectively suppressed by simultaneously using the heating of the incident flow and the aerodynamic shadow behind the disk.

Validation of MEMS Based New MicroLPCVD Technique for Thin Films Deposition

In this work we present and optimized a new microCVD technique to produce thin films for microelectronics devices. The technique was first presented in a recent work and here we successfully utilize to produce microcrystalline Silicon films at 1 Torr and temperatures of 740 oC, utilizing SiH4 as precursor gas. The technique is based on a MEMS micro- heater and presents 3 main advantages: (1) the heating region is very localized, (2) allows to attain easily temperatures as high as 1000 oC) and (3) present very short heating and cooling time. In addition to the fabrication process of MEMS micro-heater, we also present a multiphysics computer simulation study to understand its thermal response of MESM micro-heater and to predicting the final temperatures attainable with the technique.

Interaction between Sound and Thermal Influences on Patient Comfort in the Hospitals of China’s Northern Heating Region

Previous studies have found that hospitals are often inadequately ventilated in the heating region of China, which causes an increased risk of negative impacts on patients. The complex interaction between thermal comfort and acoustics presents considerable challenges for designers. There is a wide range of literature covering the area of the interaction between the sound–thermal, sound–odor, and acoustic–visual influences, but a focused research on the sound –thermal influence on comfort in hospitals has not been published yet. This paper describes a series of field measurements and subjective evaluations that investigate the thermal comfort and acoustic performance of eighteen hospitals in China. The results showed that the thermal comfort in the monitored wards was mostly acceptable, but the temperatures tended to be much higher and the humidity much lower, in practice than they were designed to be in the heating season. The most significant conclusion is that a positive thermal stimulus can create a comfortable thermal environment, which can improve patients’ evaluation of the acoustics, while a negative stimulus has the opposite effect. A comfortable acoustic environment also caused patients to positively evaluate thermal comfort. Moreover, the relationship between thermal and sound effects in the overall evaluation showed that they are almost equal.

Multi-scale modeling and thermal transfer properties of electric heating fabrics system

Purpose The purpose of this paper is to investigate the thermal transfer properties of electric heating fabric system which contains heating units or conductive yarns by numerical simulation, in order to optimize and evaluate the thermal performance of heating clothing. Design/methodology/approach Two kinds of FEM models are created by ANSYS system: macro-scale models of the fabrics system with heating units and air layer; and meso-scale models of the plain-woven fabrics were established embedded with the stainless yarns. In the macro-scale model, the interior and surface temperature field distribution were simulated and analyzed based on different heating unit size, heating power, heating region, air layer thickness and ambient temperature. For meso-scale models, the effects of the conductive yarns temperature, covering fabrics and pore-filling material on the temperature field distribution were simulated and analyzed. Findings With the increasing of the air layer thickness or the effective conductivity, the heat transfer along the direction of fabric thickness decreases gradually. The heat transfer along the fabric plane can be increased by dispersing the heating region. With the increasing of the conductive yarns’ temperature or the covering fabrics’ conductivity, the heat transfer distance along the fabric warp direction can be increased. Filling the internal pores of the fabric with 10 wt% SiC/TPU hybrid materials can effectively increase the in-plane heat transfer and improve the temperature uniformity on the surface of heated fabrics. Originality/value The finite element method was used to establish the simulation models of the heating fabric systems. The influence of several parameters on the thermal performance was analyzed and discussed, as well as the internal and external temperature distribution in the macro and micro scales models.