In this paper, advanced DC-Link (DCL) based reversing voltage type Multilevel Inverter (MLI) topologies by compensating the difficulties in the conventional MLIs are reviewed. These topologies consist of less switching components and driver circuits when compared with conventional MLIs predominantly in higher levels. Consequently, installation area, total cost and hardware difficulties are reduced by increasing the voltage levels. The unipolar based Pulse Width Modulation Schemes (PWMS) will improve DCL inverters performance. This paper presents unipolar Multi-Reference (MR) based sine and space vector PWMS with single triangular carrier wave for generating required levels in output voltage. Comparison between UMR sine and space vector PWMS for DCL inverter topologies is presented in terms of Fundamental Output Voltage (FOV) and Total Harmonic Distortion (THD). The research tries to establish the survey analysis for single-phase 7-level DCL based reversing voltage type MLI topologies with UMR based sine and space vector PWMs. Finally, to confirm the feasibility of proposed DCL-MLIs in terms of FOV and THD the simulation results are incorporated. Further, the prototype model is developed for single-phase 7-level DCL inverter with Field Programmable Gate Array (FPGA) based UMR sine and space vector PWMS to authenticate simulation results. The efficiency of the proposed cascaded MLI achieves the value of 99.003%.
Public green spaces are very important in the urban structure, both on environmental and social level. Renovation may be necessary, but the process must involve complexity.
The objective of this research is to define the main criteria of a successful renovation process, using two case studies - the Lucius-Burckhardt-Platz in Kassel, Germany, and the ‘Parku i lodrave’ in the city of Peja, Kosovo, where the recent intervention had rather negative effects. The paper considered aspects as community activity, key functions, visual elements, accessibility, safety, well-being and maintenance.
The transformation of these spontaneously developed, liveable spaces into renewed but abandoned parks was explained by the lack of correlation between the analysis of function, public needs, and the dominance of aesthetics.
Carbon-dioxide-based trans-critical power cycle is a novel technology for waste heat recovery. This technology can handle the high-temperature exhaust gas and can be built in a compact size, which is an important feature for the auxiliary equipment for an internal combustion engine. To obtain the best output, four configurations were constructed: the basic system; one with preheater, another with regenerator and a fourth with preheater and regenerator. Special features of supercritical CO2 make these cycles able to recover more energy than the traditional organic Rankine cycle. According to this study, heat regeneration increases thermal efficiency while preheating influences the net power output. Thus, it is beneficial to add both regenerator and preheater to the basic cycle.
This work aims to highlight gravity segmental retaining walls with their varied advantages. The paper investigates the dynamic behavior analysis of segmental retaining walls. The stability analysis is conducted on the basis of a pseudo-static Mononobe-Okabe theory that provides safety factors against sliding and overturning failure. The results demonstrate that the crucial safety factor of internal stability is the safety factor against overturning. Moreover, the positive wall inclination angle contributes to an improvement in the stability of the segmental retaining walls and the effect of the vertical seismic coefficient on the stability can be disregarding. Finally, a new equation is proposed for the elementary design of the segmental retaining walls.
The analysis of the world experience in the design, construction, and operation of penitentiary complexes revealed an urgent need to modernize the architectural environment of correctional institutions in post-Soviet countries. Several problems of the life of modern correctional institutions have been identified, namely: the inconsistency of the quality of their architectural environment with the modern needs of the penitentiary system; low level of adaptability and flexibility of urban planning, functional planning, and subject-spatial forms; morally outdated, emotionally negative, unaesthetic architectural and artistic image of penitentiary buildings and complexes. The purpose of this study was to identify traditional and innovative methods and means of forming an architectural and artistic image of penitentiary complexes for their further use in the field, covering their design and modernization. Based on the functional-typological and socio-psychological requirements, the criteria for harmonizing the architectural environment were determined and the patterns, methods, and means of creating a humane aesthetic architectural and artistic image of such complexes.
This study focuses on exploring the impact of urban forms and vegetation combination patterns on the microclimate in a complex urban environment. Results shown that the closed urban form has higher air temperature resulting in pedestrians are easier to feel heat stress; instead, the open urban form usually has higher wind speed. Vegetation can effectively reduce wind speed while reducing the change rate of the mean radiant temperature. However, the effect on air temperature and humidity are most distinct in the morning. Trees and shrubs could improve the surrounding thermal comfort conditions by reducing heat stress, but this effect depends on the density of the leaf area. More importantly, study has not found that the ground cover plants contribute to the improvement of thermal comfort.
This paper classifies the architecture, engineering, and construction enterprises in the South Transdanubia Region, Hungary, according to the size and function of the firms. It is a primary step for later investigation about the implementation of building information modeling in small and medium-sized enterprises within the region. It introduces digital construction in the sector, includes most construction firms based in the region, and systematically gathers data. It analyzes the data to introduce a new sorting method based on the local construction market, unlike the international classification, which leans on the global perspective.
This paper focuses on the relationship between the composition of foam glass and its thermal conductivity and density. In this experimental research, three levels of glass particle size and foaming agent (SiC) quantity were tested. The results showed that the thermal conductivity increased by increasing the ratio of fine glass particles. On the contrary, the thermal conductivity was not affected by changing the foaming agent weight ratio. The density of foam glass increased by decreasing the foaming agent ratio, and there was no linear relation between the size of glass particles and the density of foam glass.
Scour is the leading cause of bridge collapse beneath any bridge pier located within the waterway. A numerical-based hydraulic model named the Hydrologic Engineering Centre River Analysis System and a mathematical model of the Florida Department of Transport were implemented to investigate their performance and accuracy in estimating the maximum scour depth beneath bridge piers where large and small-scale physical prototypes are used as a benchmark. The main findings are that a hydraulic model is an effective tool when employing the Colorado State University equation, which compares well with physical prototypes irrespective of the variation in piers' size and shape. Also, it has achieved more consistent results than the Froehlich and the Florida Department of Transport methodologies.
In the present study, a comparison has been conducted to investigate the efficiency of using the near-surface mounted steel bars technique for strengthening and repairing the damaged reinforced concrete corbels. Three configurations for installing the steel bars have been considered; horizontal, diagonal, and combined. Results revealed that is better to use this technique within the early stages of loading. Moreover, results proved that the strengthening by the diagonal scheme yielded a better response in terms of cracking and failure loads with values of 166 and 95% relative to the control specimen. Also, it is found that for damage of 45%, the horizontal arrangement yielded the highest failure load of 99% whereas for damage of 65%, the diagonal system yielded the optimum value of 50% relative to the control specimen.