Automotive Science and Engineering
Volume:13 Issue: 4, Autumn 2023

The general public considers auto service operators to be experts in their work, and they use their advice and guidance when changing the oil. Therefore, due to the importance of this issue, during applied research conducted in a mixed (quantitative and qualitative) manner, an attempt was made to identify and prioritize factors affecting the offer of motor oil brands by Iranian auto services using the fuzzy Delphi technique. In terms of the research method, this research is considered descriptive-survey research, and its statistical population includes all the operators of Iranian auto services. The statistical sample of the research consists of 36 Iranian auto service operators who were selected as a cluster from all over Iran. In the following, after collecting data through semi-structured interviews and questionnaires and analyzing the information, it was determined that the engine oil quality factor is the most important in introducing the engine oil brand by the auto services, according to the experts present. Also, after the quality of the engine oil, the two factors of matching the engine oil with the technical specifications of the car and the timely delivery of orders from the manufacturing companies were placed in the second and third ranks of importance, respectively.

This paper presents a single layer circularly polarized (CP) antenna array based on gap waveguide (GW) technology for automotive radar applications. The antenna element is a curved slot that is cut into the top wall of a groove gap waveguide (GGW) structure. An 8×8 slot array antenna is constructed by combining eight sub-arrays of linearly arranged slots, using an 8-way power divider as the feeding network. The power divider and the transition from WR12 to GGW are also designed based on GW technology. The proposed antenna array operates in the frequency band from 76 GHz to 81 GHz, covering the automotive radar working bandwidth. The antenna has a maximum gain of 23.8 dBi and a minimum axial ratio of 0.5 dB. The antenna performance is verified by simulation using CST Microwave Studio.

The utilization of adhesively bonded square sections (ABSS) serves to enhance energy absorption and specific energy absorption (SEA) when subjected to oblique loading. Finite element models utilizing LS-DYNA were constructed in order to examine the deformation mode and load-displacement characteristics of ABSS and hybrid aluminum/carbon fiber reinforced polymer models. Subsequently, an evaluation was conducted on the general parameter pertaining to crashworthiness and the capacity for absorption of energy. The results reveal that an increase in the quantity of Carbon Fiber Reinforced Polymer (CFRP) layers within the stacking sequence of [0,90] affords enhanced potential for energy absorption. Conversely, the stacking sequence of [90] exhibits an incongruity with this trend, and achieves superior energy absorption capacity with a count of 4 CFRP layers rather than 8.The present study indicates that carbon fiber reinforced polymer (CFRP) possessing a stacking sequence of [90] exhibits superior energy absorption capacity under both axial and oblique loading conditions at an inclination angle of 10 degrees. In contrast, the use of eight layers of CFRP with a stacking sequence of [0, 90] is found to yield better performance in achieving both axial and oblique loading up to 10 degrees.

Portfolio optimization is the process of distributing a specific amount of wealth across various available assets, with the aim of achieving the highest possible returns while minimizing investment risks. There are a large number of studies on portfolio optimization in various cases, covering numerous applications; however, none have focused exclusively on the automotive industry as one of the largest manufacturing sectors in the global economy. Since the economic activity of this industry has a coherent pattern with that of the global economy, the automotive industry is very sensitive to the booms and busts of business cycles. Due to the volatile global economic environment and significant inter-industry implications, providing an appropriate approach to investing in this sector is essential. Thus, this paper aims to provide an appropriate approach to investing in this sector. In this study, an extended Conditional Drawdown at Risk (CDaR) model with cardinality and threshold constraints for portfolio optimization problems is proposed, which is highly beneficial in practical portfolio management. The feature of this risk management technique is that it admits the formulation of a portfolio optimization model as a linear programming problem. The CDaR risk functions family also enables a risk manager to control the worst ( 1-α)×100%  drawdowns. In order to demonstrate the effectiveness of the proposed model, a real-world empirical case study from the annual financial statements of automotive companies and their suppliers in the Tehran Stock Exchange (TSE) database is utilized.

In this article, the effect of the usage of variable speed electric water pump on the cooling system of a type of passenger car engine has been investigated. The engine water circulation in most of today's cars uses a mechanical method, the power required for its circulation is provided by a belt with a ratio of 1:1 from the crankshaft. This action makes the changes of the water pump speed a function of the engine speed and there is no control over it. One way to solve this problem is to use an intelligent thermal management system. In this method, some components of the cooling system, including the electric water pump, are controlled based on the working conditions and engine temperature. In this research, GT Suite and Simulink software were used simultaneously, and for this purpose, the engine cooling circuit with a mechanical water pump was simulated in GT Suite software and the accuracy of laboratory values was verified in terms of heat transfer. Then the mechanical connection of the water pump was disconnected and the water pump circuit was controlled with an electric motor. In the next step, in order to obtain the control pattern, the electric water pump was replaced with the mechanical water pump in the simulation pattern. The results of the software and experimental simulations of the intelligent cooling system showed a 13.4% reduction in engine warm-up time.

Protection of Armor Vehicles and military truck Occupants Against Explosion Mine and IED is the most important Parameter for comprehensive performance evaluation of armored vehicle. Armored Vehicle components Specifically Hull Floor Must be Able to Disperse Blast Shock Waves and Resist Against the structural Fracture. Analysis of the War Documents proves that flat hulls with thin-walled steel cannot resist against Anti-Tank Mines. In Recent years, development of V-shape Hull configurations Consider as an efficient Approach to improve Safety of armored vehicles. In the new generation of Armor Vehicle, Monocoque chassis combined with V-shape hull, But Replacement of All of the Old Armor Vehicle in the Defense Industry is not cost effective. So, there is an urgent need to develop the efficient strategy for enhancing the protection level of old armor vehicle. Since most of the armored vehicles used in the armies of different countries were designed and built in the past years, it is very likely that the safety standards have not been fully observed in them. Therefore, it is of great importance to provide a simple and low-cost plan for the reliable upgrade of such armored and logistics vehicles. In this article, by investigating the effect of placing V-shaped composite panels in three case studies, we were able to reduce the acceleration of the center of mass of the passenger compartment by approximately 7 times, in addition to reducing displacement by 50% on average. In addition, the explosion products were not able to penetrate into the cabin.