Search Results (22)

In this paper, we study the regular sensory data collection of Points of Interest (PoIs) with multiple Unmanned Aerial Vehicles (UAVs) during an extended monitoring period, where each PoI is visited multiple times before its data update deadline to keep the data fresh. We observe that most existing studies ignored the important differences in the data stored in the PoIs, scheduled a plan that dispatched UAVs to visit all PoIs before the same deadline, and simply repeated the plan during the monitoring period, which undoubtedly increased the service cost of the UAVs. Considering the specific data update deadline of each PoI, we formulate a novel UAV cost minimization problem to collect the data stored in each PoI before its deadline by finding a series of plans for UAVs such that the service cost of the UAVs during the monitoring period is minimized; the service cost of the UAVs is composed of the consumed energy of the UAVs utilized for hovering for data collection and the consumed energy of the UAVs utilized for flying. To deal with the above NP-hard problem, we devise an approximation algorithm by grouping the PoIs and accessing them in batches. Then, we analyze the proposed algorithm and evaluate the performance of the algorithm through experimental simulations. The experimental results show that the proposed algorithm is very promising. Full article

Complex concrete elements are typically produced with lost formwork made out of timber or plastic. After usage, these timber or plastic panels are disposed of. This makes complex lost formwork a polluting and high-cost-inducing aspect of concrete construction. A possible solution for this problem could be 3D printing of concrete. This high degree of freedom construction process could easily be used to produce complex formwork. As the formwork stays in place, it has a function during and after the hardening of the inner concrete. Before hardening, the formwork keeps the fresh concrete in place. After hardening, the printed formwork takes the function of a concrete cover. The concrete cover protects the steel reinforcement against aggressive environmental substances such as chlorides and carbon dioxide. To properly execute this function, the printed material and the transition between printed material and inner concrete need to perform at least as well as the inner material. This experimental research investigates the usability of a 3D printed concrete mixture as a concrete cover in a combined concrete structure. The effect of the curing condition as well as two different surface finishing techniques of the printed formwork are taken into account. The effect of the different parameters is compared based on existing service life models. Results indicate that proper curing of the printed formwork is of key importance in order to obtain significant resistance against carbonation- and chloride-induced corrosion. Adjusting the nozzle with side trowels improves the resistance of the printed material against chloride intrusion and carbonation but has only a limited effect on the service life extension. Full article

Today, consumers are increasingly demanding higher quality in fresh agricultural products. The issues that need to be addressed now are how to keep fresh products fresh and how to coordinate the operations of supply chain participants. Three decision models are developed in this paper using the Stackelberg model: supplier-led decision making, retailer-led decision making, and centralized decision making. The comparative model analysis shows the following: (1) Regardless of the decision model, the supply chain system under centralized decision-making is always more profitable than the supplier-led or retailer-led one. (2) The optimal profit and freshness preservation strategy of the supply chain system depends on the sensitivity coefficient of consumers to price and freshness. (3) Suppliers and retailers can coordinate the costs of freshness inputs according to how the cost-sharing coordination contract is structured. (4) Finally, the numerical analysis is applied to demonstrate the correction of the model. Full article

To solve freshness-keeping problems and analyse a retailer’s information sharing strategies in the fresh agricultural product supply chain (FAPSC), often confronted with challenges in keeping agri-products fresh in an uncertain market, we study an FAPSC via a decentralized mode in which the supplier or retailer exerts the freshness-keeping effort while the retailer decides its information sharing strategies regarding private demand forecasting. We consider a contract coordination mode including three incentive contracts, cost-sharing (cs), revenue-sharing (re) and revenue-and-cost-sharing (rc), to facilitate supply chain coordination. The results show that, as opposed to the case where the supplier takes on the freshness-keeping effort, the optimal freshness-keeping effort level, wholesale price and retail price are not only affected by the retailer’s information sharing strategy but also the freshness-keeping efficiency as the retailer exerts the freshness-keeping effort. Regarding the information sharing strategy, when the freshness-keeping effort is undertaken by the retailer, sharing information sometimes benefits the supplier; however, information sharing is never preferable for the retailer. Consequently, it is necessary to explore the supply chain coordination mode via effective incentive contracts which can improve the supplier and retailer’s profit. We also numerically analyze the effects of freshness-keeping efficiency on equilibrium decisions and expected profits in the decentralized mode, and the effects of the three contract parameters on the expected profits in equilibrium in the coordination mode. Full article

The seasonal nature of fruits and vegetables has an immense impact on the process of seeking methods that allow extending the shelf life in this category of food. It is observed that through continuous technological changes, it is also possible to notice changes in the methods used to examine and study food and its microbiological aspects. It should be added that a new trend of bioactive ingredient consumption is also on the increase, which translates into numerous attempts that are made to keep the high quality of those products for a longer time. New and modern methods are being sought in this area, where the main aim is to support drying processes and quality control during food processing. This review provides deep insight into the application of artificial intelligence (AI) using a multi-layer perceptron network (MLPN) and other machine learning algorithms to evaluate the effective prediction and classification of the obtained vegetables and fruits during convection as well as spray drying. AI in food drying, especially for entrepreneurs and researchers, can be a huge chance to speed up development, lower production costs, effective quality control and higher production efficiency. Current scientific findings confirm that the selection of appropriate parameters, among others, such as color, shape, texture, sound, initial volume, drying time, air temperature, airflow velocity, area difference, moisture content and final thickness, have an influence on the yield as well as the quality of the obtained dried vegetables and fruits. Moreover, scientific discoveries prove that the technology of drying fruits and vegetables supported by artificial intelligence offers an alternative in process optimization and quality control and, even in an indirect way, can prolong the freshness of food rich in various nutrients. In the future, the main challenge will be the application of artificial intelligence in most production lines in real time in order to control the parameters of the process or control the quality of raw materials obtained in the process of drying. Full article

Low-temperature storage has become the most common way for fresh meat storage because of its lower cost and better preservation effect. Traditional low-temperature preservation includes frozen storage and refrigeration storage. The refrigeration storage has a good fresh-keeping effect, but the shelf life is short. Frozen storage has a long shelf life, but it has a great impact on the quality of meat structure and other qualities, and cannot achieve a complete “fresh-keeping” effect. With the development of food processing storage and freezing technology, two new storage methods, ice temperature storage and micro-frozen storage, have attracted more attention. In this paper, the effects of different low-temperature storage methods on the sensory, physicochemical properties, myofibrillar protein oxidation, microstructure, and processing characteristics of fresh beef were studied. The optimal storage methods under different storage requirements were analyzed to reveal the mechanism and efficacy of ice temperature storage and micro-frozen storage technology, as well as the advantages compared with traditional low-temperature refrigeration. It has practical significance for guiding the application of low-temperature storage of fresh meat. Finally, this study concluded that the longest shelf life could be achieved by frozen storage, and the best preservation effect was achieved during the shelf life of ice temperature storage, and the effect of micro-frozen storage on the myofibrillar protein oxidation and microstructure was the best. Full article

To solve the problems of the impact of carbon emission reduction and low-carbon advertising on the supply chain of fresh agricultural products, a three-level low-carbon supply chain system composed of a manufacturer, a retailer and a third-party logistics service provider is taken as the research object. The profit functions of each party under the three contracts of the manufacturer bearing, the retailer bearing and the two parties jointly bearing the advertising cost are, respectively, established to solve the optimal pricing, advertising level preservation efforts, service levels and carbon emission reduction decisions. The numerical analysis shows that, with the increase in wholesale price and the decrease in fresh-keeping price coefficient and low-carbon cost coefficient, manufacturers will choose better fresh-keeping effort level and low-carbon service level. When the proportion of advertising cost borne by the supplier increases, the benefits of all parties in the supply chain will decrease; however, when the retailer bears the advertising cost alone, the profit of the supply chain system is the largest. Full article

The deterioration rate is a significant aspect of perishable goods. Since perishable items will always deteriorate, there are effective methods for reducing the rate of deterioration. Furthermore, in the existing inventory control literature, the deterioration rate is often viewed as an exogenous component. Keeping this problem in mind, this article develops the perishable inventory control system from the retailer’s perspective in which: (i) the deterioration rate is a controllable factor and suggests a new fresh quality technology (FQT) indicator, (ii) demand is determined by the perishable product’s quality, that is controlled by its rate of deterioration, (iii) the credit duration is predefined, and (iv) shortages are expected. The key goal is to demonstrate that there is an ideal quantity of the order that minimizes the retailer’s overall cost in terms of cycle time and deterioration rate. Finally, theoretical results are validated by solving two numerical illustrations and conducting a sensitivity analysis of the main factors resulting from the following managerial implications: (i) if the range of deterioration is between zero and one then the retailer should invest in the preservation factor to preserve the perishable product and if greater than one the retailer should not invest in the preservation factor, (ii) credit period significantly reduces the total cost. Hence, this trade credit strategy is more beneficial to the model. Full article

Cement is one of the most valuable materials in today’s society, as it is used in most construction developments known to mankind. However, the energy intensive process and significant environmental impacts related to the production of Ordinary Portland Cement have shown the importance of searching for more sustainable materials. Concrete uses different aggregates added to the cement binder to lower, not only cost, but other factors like environmental burden, while maintaining good mechanical properties. This study analyzes the properties of fresh and hardened concrete incorporating recycled rubber to replace fine aggregate. Locally sourced 2 mm diameter rubber was incorporated in a regular strength concrete matrix into three different replacement levels, i.e., 3%, 5%, and 10%. Compression, tensile, flexural, and modulus of elasticity of hardened concrete were carried out in specimens aged 7, 14, and 28 days. In addition, non-destructive ultrasonic pulse velocity and rebound number tests were only performed on specimens aged 28 days. Once the tests were carried out, the fresh and hardened concrete properties were obtained. Similarly, the compressive and flexural strengths had the exact relationship between the values obtained. On the other hand, the modulus of elasticity tends to decrease due to the presence of the rubber. Consequently, it is recommended not to develop mix designs with more than 5% rubber because it is not meaningfully affected. The fine aggregate can be partially replaced by the rubber, keeping almost the same performance compared with sand-only counterparts. In addition, the life cycle assessment showed a reduction of up to 40% in the global warming potential. In fact, the 15% recycled rubber concrete mix has a climate change indicator of approximately 245 kg of CO₂ eq. Full article

Maintaining mechanical ventilation has been identified as a potential strategy for reducing the risk of virus infections. However, in hot and humid climatic conditions, delivering fresh air to a building comes at an energy cost and could impact occupant comfort due to the persistent need for simultaneous cooling and dehumidification. In this paper, the performance of a novel hybrid air conditioning system that handles fresh air is studied. In this system, dehumidification is accomplished by a solid desiccant dehumidifier coupled with a cooling coil integrated with the cooling tower of an existing chiller system. Using the data available from an operational desiccant cooling system, a system-level model has been developed and validated to study the potential application of the system in hot and humid climates. The study found that such a system is effective in delivering sensible cooling in all types of climates; thanks to the two-stage cooling in cooling coil and chilled water coils, respectively. However, the system is effective in delivering thermal comfort in regions where the climate has a relatively moderate ambient humidity. For the tropical cities of Darwin, Kuala Lumpur and Bangkok, the system can provide comfortable temperatures, but faces challenges in keeping the humidity within the comfort zone. The system electrical coefficient of performance (COP) is higher than that of refrigerative systems. This system also has the benefit over the refrigerative system of the supply air, which is entirely fresh ambient air and is expected to improve the indoor environmental quality largely. Full article

Background: Despite efforts to control neglected tropical diseases (NTDs) using preventive chemotherapy (PC), soil-transmitted helminthiases and schistosomiasis remain widely prevalent in sub-Saharan Africa. The current PC regimen in endemic settings is defined based on health district-level prevalence. This work aims to highlight the need for high-resolution data when elimination, rather than morbidity control, is the targeted goal. Methodology: Cross-sectional parasitological surveys were conducted from July to August 2019 and from September to October 2019, respectively, across the entire Dabou and Jacqueville health districts in southern Côte d’Ivoire. From every village, 60 school-aged children (6–15 years) were randomly selected and invited to provide one fresh stool sample, whereof duplicate Kato–Katz thick smears were prepared and read by two independent technicians. Principal Findings: 4338 school-aged children from 77 villages were screened from the Dabou (n = 2174; 50.12%, 39 villages) and Jacqueville (n = 2164; 49.88%, 38 villages) health districts. The prevalence of any soil-transmitted helminth (STH) infection was 12.47% and 11.09% in the Dabou and Jacqueville health districts, respectively. Species-specific district-level prevalence remained below 10%, varying between 0.51% (hookworm in Jacqueville) and 9.06% (Trichuris trichiura in Dabou). However, when considering sub-districts or villages only, several STH infection hotspots (five sub-districts with ≥20% and four villages with more than 50% infected) were observed. Schistosoma mansoni infection was found in less than 1% of the examined children in each health district. Conclusions/Significance: We conclude that keeping health district-level prevalence as a reference for PC implementation leaves many high-risk sub-districts or villages requiring PC (≥20% prevalence) untreated. To avoid maintaining those high-risk villages as STH reservoirs by skipping control interventions and jeopardizing the successes already achieved in STH control through PC during the past two decades, precision mapping is required. Further investigation is needed to assess cost-efficient approaches to implement small-scale disease surveillance. Full article

Factors and motivations that drive individuals’ decisions on seafood consumption vary by population group and geographical locations. These factors may differ from one particular species to the other. The purpose of this study is to understand fish/shrimp consumption frequency and consumers’ willingness to pay (WTP) more for shrimp locally farmed in Togo. We used a Poisson model to investigate the socioeconomic factors determining fish/shrimp consumption frequency, and a Heckman Selection model to analyze the extent to which consumers are willing to pay extra for locally produced shrimp. To this end, data on fish consumption were collected through a cross-sectional study that analyzed a quantitative survey of consumers (N = 308). Our results show that the populations sampled attach great importance to the quality of fish they consume. The econometric results indicate that the quality of the fish is positively related to fish consumption frequency while the monthly income and proximity of the sea show negative relationships with the outcome variable. In addition, the factors that influence the WTP for shrimp were consuming shrimp and the amount for expenditure on fish/shrimp consumption. Moreover, consumers are willing to pay, on average, 1.2 U.S Dollars (USD) as an extra amount relative to the average price per kilogram, and the extent of their WTP is positively related to the quality of the fish. However, the age of the respondents shows a negative relationship with the value they are willing to pay. In order to fulfill consumers’ needs and preferences, these findings jointly suggest that exceptional steps by the government are needed to value fish/shrimp in a way that persuades and encourages consumers to consume seafood at any age. More importantly, promoting the consumption of fish and shrimp requires action to help improve their quality. Government should: (a) be communicating and raising awareness more among the population on the nutritional value and health benefits of fish/shrimp consumption; (b) support fish/shrimp production through cost reduction actions for the fishermen who in turn can supply fish/shrimp at reasonable prices that encourage fish and shrimp consumption; (c) take appropriate measures to develop a logistics system as an effort to support fish, especially shrimp, supply in a timely way that might help to keep their good appearance and freshness for the consumers’ benefit. Full article

The need to reduce carbon emission to cope with climate change has gradually become a global consensus, which also poses a great challenge to cold-chain logistics companies. It forces them to implement green distribution strategies. To help the distribution companies reduce carbon emission, this paper studies two aspects—carbon tax value and investing in the freshness-keeping cost—and proposes corresponding solutions. A new green vehicle-routing model for fresh agricultural products with the goal of minimizing the total cost is proposed. To solve the model proposed, an improved ant-colony optimization (IACO) is designed specifically. On one hand, the experimental results show that the increase in carbon tax will restrict the carbon emission behaviors of the distribution companies, but it will also reduce their economic benefits to a certain extent, at the same time. On the other hand, investing in the freshness-keeping cost can help actively achieve the carbon emission reduction target, reduce the loss of fresh agricultural products in the distribution process, improve the company’s economic benefits and satisfy customers. The comparison results of different algorithms prove that the IACO proposed in this paper is more effective in solving the model, which can help increase the economic benefits of the companies and reduce carbon emission. This study provides a new solution for cold-chain logistics distribution companies to reduce carbon emission in the distribution process, and also provides a reference for government departments to formulate carbon tax policies. Full article

This paper investigated the effects of the informational asymmetry phenomenon that occurs in the direct sale of fresh agricultural products (FAP) in an e-commerce environment. A three-level FAP supply chain was proposed, which was composed of a FAP supplier, a logistics service provider, and a large e-commerce platform. Considering the perishable nature of FAP, this paper analyzed the effects of logistics spatio-temporal costs and the freshness of FAP on the profit of each stakeholder in the supply chain. Three scenarios were considered: (1) complete information, (2) partial information, and (3) considering logistics spatio-temporal cost. Analytical models were developed based on the principal-agent theory and the supply chain coordination contract theory to depict the effects of a profit-sharing contract on the operations of the FAP supply chain. Modeling results indicated that under a complete information condition, an increase in the loss rate of FAP correlated to a decrease in the profit of the FAP supply chain. Under a partial information condition, considering the loss rate of FAP and the potential compensation costs to suppliers, when the loss rate of FAP was fixed, the profit of each stakeholder in the FAP supply chain displayed a decreasing trend in relation to compensation ratio. In comparison, when the compensation ratio was fixed, the total profit decreased as the freshness of the FAP degraded. To improve customer satisfaction, this paper recommends adding a front warehouse to improve the freshness of FAP. Although this option increases the logistics costs, it has the potential of increasing the overall profit of the FAP supply chain. Findings from this research have the potential to help the e-commerce platform with coordinating the various stakeholders on the supply chain to determine the optimal quality and quantity of FAPs, eventually improving the operational efficiency of the FAP direct sales supply chain by reducing the logistics costs of FAP. Full article

The performance of fruit surface defect detection is easily affected by factors such as noisy background and foliage occlusion. In this study, we choose lychee as a fruit type to investigate its surface quality. Lychees are hard to preserve and have to be stored at low temperatures to keep fresh. Additionally, the surface of lychees is subject to scratches and cracks during harvesting/processing. To explore the feasibility of the automation of defective surface detection for lychees, we build a dataset with 3743 samples divided into three categories, namely, mature, defects, and rot. The original dataset suffers an imbalanced distribution issue. To address it, we adopt a transformer-based generative adversarial network (GAN) as a means of data augmentation that can effectively enhance the original training set with more and diverse samples to rebalance the three categories. In addition, we investigate three deep convolutional neural network (DCNN) models, including SSD-MobileNet V2, Faster RCNN-ResNet50, and Faster RCNN-Inception-ResNet V2, trained under different settings for an extensive comparison study. The results show that all three models demonstrate consistent performance gains in mean average precision (mAP), with the application of GAN-based augmentation. The rebalanced dataset also reduces the inter-category discrepancy, allowing a DCNN model to be trained equally across categories. In addition, the qualitative results show that models trained under the augmented setting can better identify the critical regions and the object boundary, leading to gains in mAP. Lastly, we conclude that the most cost-effective model, SSD-MobileNet V2, presents a comparable mAP (91.81%) and a superior inference speed (102 FPS), suitable for real-time detection in industrial-level applications. Full article