Investigation of a Novel Thermoelectric Cooler for Building/Infrastructure Application

With the enormous building/infrastructure construction in advanced and emerging economies, the energy demand and carbon emissions from building/infrasturcture continues to rise. Buildings/infrastructure construction sectors contributed to 30% of global energy consumption and 27% of total energy emissions. To align with the carbon net zero scenario, carbon footprint from building need to more than halve by 2030, which requiring significant efforts on adopting clean and efficient technologies applicable to all end-uses. For energy consumption of modern building, heating, ventilation, and air-conditioning (HVAC) system play a critical role, which accounts for 40% of total building consumption and 70% of landlord consumption.Thermoelectric coolers (TECs) are highly dependable, scalable, and noiseless devices. Beyond their conventional use, TECs have been investigated for a wide range of applications, including waste heat energy harvesting, electronics cooling, wearable device technology, power generation, and more. Numerous researches have unveiled their substantial potential in both domestic and industrial sectors, particularly in distributed building air conditioning. However, the cooling/energy performance of the TECs faces challenges in terms of building structures embedding, which limits its application. In particular, the integrated structure of TEC makes it difficult to dissipate heat to outside of building.To overcome these challenges, the proposed research aims to investigate a novel TEC air cooler which has a number of distinguished innovations: (1) First-of-its-kind trial in separating hot and cold ends enabling placement of one side of TEC to outside of the building and another side of TEC to inside of building, thus creating an increased temperature gradient between the ends and increased cooling capacity. Furthermore, separated TEC makes it possible to be integrated with the building façade. (2) Initiative optimization of the TEC geometries enables the enhanced energy performance and cooling capacity that makes the TEC more building applicable; (3) Pioneering full-day case studies of TEC performance illustrates the applicability and adaptation of the coolers across different climatic conditions of the world.This thesis employs a fundamental approach that integrates both theoretical and experimental analyses. The methodology comprises an exhaustive literature review, a conceptual design phase, mathematical analysis, model development, validation, and an in-depth examination of performance and thermal characteristics for thermoelectric geometry optimization. Furthermore, the thesis includes a conceptual design phase, mathematical analysis, model development, experimental testing, model validation, performance analysis, and real-climatic condition case studies.Trials on the separated configuration TEC indicate that the specialist TEC, when applying 10 K temperature difference and 5A of current, led to reduction in cooling capacity by 5.6% compared to the integrated TEC, varying from 7.13 W to 6.76 W. However, the TEC device height will be doubled. While sacrificing a small portion of cooling capacity, the TEC’s application scenarios have been significantly broadened. It is noteworthy that separated-TEC configuration exhibits excellent cooling power density. The cooling capacity per unit area could exceed 15 kW/m2 under high current (I=5A), even at low current (I=0.5A), it is up to 500 W/m2.Geometry optimization of the TEC reveals that the proposed design excels in both cooling performance and thermal-mechanical characteristics. The study demonstrates that under specified conditions, the truncated cone-shaped module (g) exhibits a noteworthy improvement in cooling capacity. In comparison to a traditional TEC, the cooling capacity from 0.1429 W increases to 0.1557 W, when operating at a temperature difference of 50 K, marking an 8.9% enhancement. This translates to a rise in the overall TEC device's cooling capacity from 18.15 W to 19.78 W. Additionally, the 'g' module, characterized by its absence of corners or edges, effectively reduces the peak von Mises stress.A number of case studies were undertaken. The results show that, by introducing the separated-configuration structure, the unit cooling capacity of TEC system increases from 16.66 W/m2 to 18.82 W/m2 by 13%, while the cooling surface temperature is reduced by 0.2 °C.This research shows that the TEC geometry optimization and separated TEC configuration create an opportunity to allow the TEC to be well integrated into a building. The cooling performance of the TEC could be improved by establishing the optimal geometry and its proper connection and configuration

InGVIO: A Consistent Invariant Filter for Fast and High-Accuracy GNSS-Visual-Inertial Odometry

Combining Global Navigation Satellite System (GNSS) with visual and inertial sensors can give smooth pose estimation without drifting in geographical coordinates. The fusion system gradually degrades to Visual-Inertial Odometry (VIO) with the number of satellites decreasing, which guarantees robust global navigation in GNSS unfriendly environments. In this letter, we propose an open-sourced invariant filter-based platform, InGVIO, to tightly fuse monocular/stereo visual-inertial measurements, along with raw data from GNSS, i.e. pseudo ranges and Doppler shifts. InGVIO gives highly competitive results in terms of accuracy and computational load compared to current graph-based and `naive' EKF-based algorithms. Thanks to our proposed key-frame marginalization strategies, the baseline for triangulation is large although only a few cloned poses are kept. Besides, landmarks are anchored to a single cloned pose to fit the nonlinear log-error form of the invariant filter while achieving decoupled propagation with IMU states. Moreover, we exploit the infinitesimal symmetries of the system, which gives equivalent results for the pattern of degenerate motions and the structure of unobservable subspaces compared to our previous work using observability analysis. We show that the properly-chosen invariant error captures such symmetries and has intrinsic consistency properties. InGVIO is tested on both open datasets and our proposed fixed-wing datasets with variable levels of difficulty. The latter, to the best of our knowledge, are the first datasets open-sourced to the community on a fixed-wing aircraft with raw GNSS.Comment: 8 pages, 8 figures; manuscript will be submitted to IEEE RA-L for possible publicatio

Xi Jinping’s Political Strategy for Developing Multilateral Security Diplomacy

The purpose of the article is to analyze the implementation of the multilateral diplomatic policy in the feld of security by the current head of the People’s Republic of China, Xi Jinping. To achieve this goal, the article uses the method of content analysis of the public speeches of the leader of the Chinese state, followed by a generalization and inductive analysis of the main directions of the implementation of China’s modern foreign policy. The article discusses the current directions of the foreign policy strategy of the head of the People’s Republic of China, Xi Jinping, which allows to ensure the achievement of the state’s national interests in the feld of global security. The main vectors of multilateral diplomacy of modern China and its positioning in the world community as a leading state are considered. The role of China in security issues and UN peacekeeping missions is noted. The analysis resulted in the vectors of China’s foreign policy outlined in the article to ensure global security and develop multilateral diplomatic ties from the standpoint of Chinese President Xi Jinping. Conclusions are drawn about the correspondence of the main foreign policy discourse of Xi Jinping to the values of peaceful development, and its focus on the positions of multilateralism, cooperation and mutually benefcial relations of China on a global scale

N 2,N 2′-Bis(3-nitro­benzyl­idene)pyridine-2,6-dicarbohydrazide dimethyl­formamide disolvate trihydrate

In the title compound, C21H15N7O6·2C3H7NO·3H2O, the N 2,N 2′-bis­(3-nitro­benzyl­idene)pyridine-2,6-dicarbohydrazide and one water mol­ecule are located on a twofold rotation axis. The mol­ecules are connected by hydrogen bonds. One dimethylformamide molecule is disordered over two positions; the site occupancy factors are ca 0.8 and 0.2

Focusing light through scattering media by transmission matrix inversion

Focusing light through scattering media has broad applications in optical imaging, manipulation and therapy. The contrast of the focus can be quantified by peak-to-background intensity ratio (PBR). Here, we theoretically and numerically show that by using a transmission matrix inversion method to achieve focusing, within a limited field of view and under a low noise condition in transmission matrix measurements, the PBR of the focus can be higher than that achieved by conventional methods such as optical phase conjugation or feedback-based wavefront shaping. Experimentally, using a phase-modulation spatial light modulator, we increase the PBR by 66% over that achieved by conventional methods based on phase conjugation. In addition, we demonstrate that, within a limited field of view and under a low noise condition in transmission matrix measurements, our matrix inversion method enables light focusing to multiple foci with greater fidelity than those of conventional methods