جستجوی مقالات مرتبط با کلیدواژه "کرونا" در نشریات گروه "عمران"

The COVID-19 pandemic has caused numerous damages and challenges in the construction industry, in addition to taking a significant number of human lives and imposing heavy costs in the healthcare sector. These damages and challenges have undoubtedly resulted in extensive economic and social consequences for countries worldwide. Therefore, examining these challenges and providing appropriate solutions during times of crisis and widespread virus transmission is of utmost importance. In this research, a list of damages and challenges associated with COVID-19's spread on active construction projects was first compiled through library studies. Then, using a Likert-scale questionnaire, the opinions of project management experts in Kerman city were collected and analyzed in the SPSS software. The triangular fuzzy number comparison matrix was completed and the prioritization of indicators and sub-indicators was performed using the Super Decision software. Finally, the decision matrix was formed based on the multi-criteria TOPSIS fuzzy method using the criteria of "impact level," "importance degree," and "preventability of damage." The identified damages were ranked using the relevant questionnaire, and ultimately, risk management solutions were provided through appropriate responses. Based on the research findings, damages related to "financial challenges," "health challenges," "work and organizational challenges," and "time and scheduling challenges" had the most significant impact on active construction projects, respectively.

Nowadays, Internet taxis has become an important mode for people's daily activities and it can even be considered as a separate mode of transportation. In this research, the impact of internet taxi and personal car under Covid-19 is discussed. This study is done by designing the data collection process through questionnaire. This questionnaire was designed in the form of four parts and after collecting the questionnaires which was done online, 598 data were used for modeling out of 681 data after data validation and refinement. To investigate the effects of internet taxi on people's use of private cars under Covid-19, the multinomial logit discrete choice model (MNL) was used by the principal component analysis (PCA) method to reduce the dimension of attitudinal variables. Then the marginal effects were also calculated by simulation method. The results showed that under Covid-19, people use private cars more than internet taxis. In addition, people who have a PHD education degree use Internet taxi more than others under Covid-19 than private cars. In addition, the results of marginal effects showed that with the change of the city of residence from the small town of Birjand to the metropolis of Tehran, the tendency to use an internet taxi increases and the tendency to use a private car decreases.

Traffic accidents are one of the main causes of death in the world and the resulting damages have an important effect on the economy of any country that the need to identify factors affecting accidents that lead to a reduction in the frequency or severity of accidents is understandable. Since the outbreak of Covid-19, travel restriction policies have been widely adopted by cities around the world that it played a profound role in changing the shape of urban travel patterns. One of the factors that influenced traffic behavior in recent years was the epidemic of Corona disease in the world. Therefore, new driving rules and regulations were established for urban and suburban traffic, and traffic behaviors were affected by those rules. It is possible to investigate the effect of each factor on the severity of accidents by using accident severity models according to the effective parameters. In this article, urban accidents due to lack of attention during the corona epidemic were analyzed using logistic regression and information related to intra-urban accidents in Rasht city. The final model shows that the independent variables of working day, at-fault male drivers over 60 years of age, front-to-front collision and the at-fault vehicle Pride increase the probability of a fatal or injury accident compared to a damage accident. Variables with negative coefficients (6:00 a.m. to 9:00 p.m., dry road surface conditions, clear weather, and daylight conditions) reduce the probability of fatal or injury accidents compared to damage accidents.

Given the continuity of Covid-19, the urban transportation system has undergone remarkable changes. Besides, increased risks related to crowded places together with social distancing measures in public and shared transportation probably affect the usual choices of vehicles by passengers. In the present article, by using questionnaire design and online questionnaire in Tehran, attempts have been made to estimate the use of internet taxis by people during the pandemic. To this end, in order to specify the factors affecting the use of internet taxis, ordered and dual logit models were established using 233 data obtained from online inquiries and based on the amount of use and changes in using them before and after Covid-19. The results indicate that Covid-19 pandemic has had a negative effect on the use of internet taxis. Increasing the petrol prices and the lack of parking places at the destination have positively encouraged the use of internet taxis. Moreover, people who own a car use internet taxi less than those who do not. The number of these people not using internet taxis has been also reduced after the pandemic.

Today, coronavirus (COVID-19) has become a major global threat. A lot of programs are proposed to prevent and estimate its associated processes due to the high risk of its transmitting among humans and the lack of drugs and vaccines to stop it. COVID-19 was first reported on 31 December 2019 in Wuhan, China. After a short time, the disease spread to other countries and became a global disease. According to the lives of most people, the transportation system has a significant impact on controlling or spreading the disease. Therefore, this subsystem is considered as an element of a proposed system dynamics model in this article. This model examines two different scenarios for infected people, mortality rates, and recovery rates. The system is designed according to various subsystems such as health care systems, transportation, public contact, and the capacity of food and drug networks. In the proposed model of this paper, a flow structure is utilized to show the effects of different sections of systems and subsystems depend on the COVID-19 outbreak over a long time. The results of the proposed model show that different parts of the main system and its related subsystems have different sensitivities and effects. Analyzing this model will be useful for government decision-making based on the results of the two scenarios examined. It is assumed that there is no effective vaccine or drug in the next 6 months. The results of the proposed model show that different changes in subsystems could increase COVID-19 mortality in six months from 10,500 to more than 1.6 million. Therefore, the mortality rate of this disease depends on the policies and behaviors of the factors influencing the model. Consequently, the mortality rate can be reduced based on proper planning against each scenario.