Journal Articles - Engineering - 2021

This article presents a novel concept for an Origami-inspired shading device based on dynamic daylight that can be used to improve the daylight performance of a target building and reduce the energy consumption for the building. The daylight performance is evaluated based on the Leed v4 (Leadership in Energy and Environmental Design) daylight criterion. The proposed shading device is experimented in an office located in Ho Chi Minh City, Vietnam, where there is a tropical monsoon climate being hot and humid by the year. To investigate the effectiveness of the proposed design in acting as a sun shading system for the office, we consider eight cases corresponding to eight directions which are South, North, East, West, South-East, North-East, South-West, and North-West. An automatic simulation optimization procedure is developed by combining a daylight simulation tool called DIVA and an optimization method called Balancing Composite Motion Optimization (BCMO). BCMO is used to find the optimal design for the proposed kinetic shading device which will help the building to improve daylight performance. It must be noted that the proposed framework is not necessarily tied to any particular optimization tool or type of building. The results show that the proposed kinetic device has outstanding performance as it helps the building to achieve 2, 3 points in Leed v4 for four different directions, including North, North-East, South, North-West.

Lò đốt nhiên liệu đóng vai trò quan trọng trong việc cung cấp nhiệt năng cho các quá trình sản xuất công nghiệp. Bên cạnh việc tiêu thụ nhiên liệu, đa phần hiện nay là nhiên liệu hóa thạch, các hệ thống lò đốt còn phát sinh tro đáy (xỉ) và tro bay có khả năng tận dụng. Mục tiêu của nghiên cứu này nhằm đánh giá hiện trạng phát sinh và quản lý tro, xỉ tại nguồn để đề xuất phương án quản lý phù hợp. Dựa trên dữ liệu của HEPZA, nhóm nghiên cứu đã thực hiện điều tra khảo sát bằng phiếu câu hỏi tại 179 cơ sở sản xuất. Dữ liệu kết quả khảo sát được phân tích bằng phương pháp thống kê mô tả. Kết quả cho thấy tổng khối lượng tro xỉ phát sinh khoảng 1.606,22 tấn/tháng. Phần lớn tro và xỉ được thu gom chung. 33 đơn vị tham gia công tác thu gom, vận chuyển, xử lý và tái chế tro xỉ tại 61 cơ sở sản xuất, cho thấy nguồn lực này rất phân tán, khó kiểm soát việc thu hồi triệt để tro, xỉ để tái chế và tái sử dụng. Bài báo đề xuất một số giải pháp nhằm thúc đẩy việc tận dụng tro xỉ thông qua quản lý tại nguồn và kiểm soát các đơn vị thu gom, xử lý và tái chế.

Reconfigurable intelligent surface (RIS)-aided communication is considered as an exciting research topic in academic and industrial communities since it provides an emerging affordable solution to achieve high quality and secure next-generation wireless systems. Especially, the deployment of RIS in multi-user wireless networks promises to reduce system hardware costs, signal processing complexity, as well as energy consumption due to small size, lightweight and ability to actively shape the wireless propagation environment. Further, by realizing a cost-effective radio environment, RIS-aided communication can be implemented to be an appealing technology for future integration with other emerging wireless applications and communication systems.

Trong nghiên cứu này, chúng tôi trình bày những kết quả nghiên cứu tổng hợp vật liệu composite ZIF-67/Fe2O3/g-C3N4 và ứng dụng biến tính điện cực để xác định phẩm màu vàng ô (AO) trong thực phẩm. Vật liệu được tổng hợp thành công bằng phương pháp siêu âm và đặc trưng cấu trúc bằng các phương pháp hiển vi điện tử quét (SEM), nhiễu xạ tia X (XRD), phổ tán xạ năng lượng (EDX) và đẳng nhiệt nhiệt hấp phụ và giải hấp phụ nitơ (BET). Điện cực than thủy tinh biến tính bằng vật liệu ZIF-67/Fe2O3/g-C3N4 được sử dụng để phát triển phương pháp volt-ampere hòa tan xác định phẩm màu AO. Các kết quả cho thấy vật liệu ZIF-67/Fe2O3/g-C3N4 có kích thước và hình thái tinh thể khá đồng nhất với diện tích bề mặt riêng lớn, lên đến 1037,61 m2/g. Vật liệu ZIF-67/Fe2O3/g-C3N4 là một chất biến tính điện cực có thể xác định AO trong mẫu thực phẩm. Cường độ dòng đỉnh tỉ lệ tuyến tính với nồng độ từ 1,9.10-6 M đến 18.10-6 M, giới hạn phát hiện của AO là 6,5. 10-7 M và giới hạn định lượng là 1,9. 10-6 M – 2,6. 10-6 M.

Solar chimneys can be employed in buildings for natural ventilation, cooling, or heating of the building envelope, hence saving energy. In open double-skin facades, the air channel's thermal effects between the two layers of a façade are similar to those in a solar chimney. Most studies about solar chimney in the literature have been focusing on heating one air channel wall. In this study, the performance of a solar chimney under different distributions of the heat source on both walls of the air channel was studied numerically by the Computational Fluid Dynamics method. Induced flow rate, temperature rise, and thermal efficiency of the chimney were investigated. Chimneys with practical dimensions with the height ranging from 0.5 m to 1.5 m and the gaptoheight ratio ranging from 0.025 to 0.15 were examined. The results showed that together with the chimney's dimensions, location, and distribution of the heat source on the channel's walls strongly affect the performance of the chimney. While heating the whole left wall induced more flowrate than heating the whole right wall, heating part of the left and the right walls resulted in peak performance at specific portions of the right wall heated from the bottom or the top of the channel. The peak values of the investigated parameters and the specific portions of the heated wall to achieve those peaks also changed with the channel's gap–to–height ratio

Solar chimneys can be employed in buildings for natural ventilation, cooling, or heating of the building envelope, hence saving energy. In open double-skin facades, the air channel's thermal effects between the two layers of a façade are similar to those in a solar chimney. Most studies about solar chimney in the literature have been focusing on heating one air channel wall. In this study, the performance of a solar chimney under different distributions of the heat source on both walls of the air channel was studied numerically by the Computational Fluid Dynamics method. Induced flow rate, temperature rise, and thermal efficiency of the chimney were investigated. Chimneys with practical dimensions with the height ranging from 0.5 m to 1.5 m and the gaptoheight ratio ranging from 0.025 to 0.15 were examined. The results showed that together with the chimney's dimensions, location, and distribution of the heat source on the channel's walls strongly affect the performance of the chimney. While heating the whole left wall induced more flowrate than heating the whole right wall, heating part of the left and the right walls resulted in peak performance at specific portions of the right wall heated from the bottom or the top of the channel. The peak values of the investigated parameters and the specific portions of the heated wall to achieve those peaks also changed with the channel's gap–to–height ratio

In this paper, we propose a joint spectrum and power optimisation (SPO) for multi-hop multi-path (MHMP) device-to-device (D2D) video delivery in beyond 5G (B5G/6G) networks, where the system resources such as spectrum, energy, storage, and content of mobile users (MUs), are taken into account. Particularly, the downlink spectrum resources of the sharing users (SUs) are reused by the transmitters (TXs) of D2D hops and the energy resources of the TXs are utilised for D2D communications. We further exploit the videos stored in the caching users (CUs) located more than one D2D hop far away from the requesting users (RUs) to establish MHMP D2D video delivery sessions from the CUs to the RUs. Then, the SPO problem is formulated for the optimal spectrum sharing pairs of SUs and TXs and the optimal transmission powers allocated to the TXs. Genetic algorithms (GAs) are developed to solve the SPO problem with respect to both binary variable (spectrum sharing) and real variable (power allocation). The SPO solution allows the RUs to alternately request the videos not only from the macro base station over conventional cellular networks but also from the CUs over MHMP D2D communications at the highest quality of service, i.e., maximum video delivery capacity and low power consumption. Simulation results are analysed to demonstrate the feasibility of GAs and the benefits of the proposed SPO solution in comparison with other conventional schemes