In the two-sided mixed-model assembly line, there is a process of installing two single stations

in each position left and right of the assembly line with the combining of the product model.

The main aim of this paper is to develop a new mathematical model for the mixed model

two-sided assembly line balancing (MTALB) generally occurs in plants producing large-sized

high-volume products such as buses or trucks.

According to the literature review, authors focus on research gap that indicate in MTALB

problem, minimize the length of the line play crucial role in industry space optimization.In

this paper, the proposed mathematical model is applied to solve benchmark problems of

two-sided mixed-model assembly line balancing problem to maximize the workload on each

workstation which tends to increase the compactness in the beginning workstations which

also helps to minimize the length of the line.

Since the problem is well known as np-hard problem benchmark problem is solved using

a branch and bound algorithm on lingo 17.0 solver and based on the computational results,

station line effectiveness and efficiency that is obtained by reducing the length of the line in

mated stations of the assembly line is increased.

Shell and tube heat exchangers are commonly used in a wide range of practical engineering. The key issue in such a system is the heat exchange between the hot and cold working media. An increased cost of production of these devices has forced all manufacturing companies to reduce the total amount of used materials by better optimizing their construction. Numerous studies on the heat exchanger design codes have been carried out, basically focusing on the use of fully time-dependent partial differential equations for mass, momentum, and energy balance. They are very complex and time-consuming, especially when the designers want to have full information in a full 3D system. The paper presents the 1D mathematical model for analysis of the thermal performance of the counter-current heat exchanger comprised of mixed time-dependent and time-independent equations, solved by the upwind numerical solution method, which allows for a reduction in the CPU time for obtaining the proper solution. The comparison of numerical results obtained from an in-house program called Upwind Heat Exchanger Solver written in a Fortran code, with those derived using commercial software package ASPEN, and those obtained experimentally, shows very good agreement in terms of the temperature and pressure distribution predictions. The proposed method for fast designing calculations appears beneficial for other tube shapes and types of heat exchangers.

This paper aims to explore the relationship between the Air Quality Index (AQI), COVID-19 incidence rates, and population density within Malaysia’s ten most populous cities from January 2018 to December 2021. Data were sourced from the Department of Statistics Malaysia, the World Air Quality Index Project, and Our World in Statistics. The methodology integrated population-based city classification and AQI assessment, cluster analysis through SPSS, and Generalized Additive Mixed Model (GAMM) analysis using R Studio despite encountering a data gap in AQI for five months in 2019. Cities were organized into three clusters based on their AQI: Cluster One included Ipoh, Penang, Kuala Lumpur, and Melaka, Cluster Two comprised Kuantan, Seremban, Johor Bahru, and Kota Bharu, Cluster Three featured Kota Kinabalu and Kuching. GAMM analysis revealed prediction accuracies for AQI variations of 58%, 60%, and 41% for the respective clusters, indicating a notable impact of population density on air quality. AQI variations remained unaffected by COVID-19, with a forecasted improvement in air quality across all clusters. The paper presents novel insights into the negligible impact of COVID-19 on AQI variations and underscores the predictive power of population dynamics on urban air quality, offering valuable perspectives for environmental and urban planning.