Small-scale Operations Research Articles

An overview of work productivity evaluation of farm tractors in timber skidding operations

Farm tractors have been applied in forest operations to carry out several tasks such as tree/felling/process-ing, forwarding, loading, skidding and cable yarding. Farm tractors can be equipped with special logging equipment that allows for their safe and efficient work in the harvesting of forest stands. This research is aimed to collect and review available literary sources on the productivity of farm tractors during skidding operations. The study results showed that work productivity of farm tractors for timber skidding has been studied by several researchers around the world. According to the results, the reported work productivity of skidding with farm tractors varied from 1.2 m3/PMH0 to 15.8 m3/PMH0 among international studies. Main variables impacting the work productivity of skidding included skidding distance, load volume, number of pieces per turn, tree diameter, tree length, slope of skid trails and engine power. Proper skid trail planning, applying suitable skidding equipment (e.g. winches, sulkies etc.), considering suitable engine size and prop-er safety standards can all help improving the work efficiency of the farm tractors during timber extracting. The information provided in this research can help the forest industry users and researchers gain proper knowledge on the work productivity of farm tractors applied for timber skidding. The study results can be also useful for planning and development purposes within small-scale forest operations.

Optimising small-scale electronic commerce supply chain operations: a dynamic cost-sharing contract approach

For small-scale electronic commerce supply chains, designing effective strategies to improve operational effectiveness, market share and long-term survival are essential aspects. However, researchers have given less attention in addressing these issues. This study proposes a dynamic cost-sharing contract for an e-tailer supply chain to address the issues of asymmetric information, long-term integration, and ineffective costs. We include consistency constraints to obtain stable incentives over time and eliminate the need for re-negotiation. The findings emphasise that the dynamic contract significantly reduces the overall supply chain costs. The consistency constraints guarantee high incentives, thus assuring the players remain in the total contract period and enable long-term integration.

Economic viability of a small scale low-cost aquaponic system in South Africa

ABSTRACT Aquaponics provides a sustainable means of converting aquaculture effluent to nutrients for growing plant. This unconventional, but synergistic system of food production has been documented to be economically feasible and sustainable, particularly in areas with limited land and water resources availability. This study assessed the economic feasibility of a low-cost small-scale aquaponics system using production output and economic data. Price trends, cost, revenue, return on investment (ROI), net present value (NPV) using a 10-year period, internal rate of return (IRR) and profitability analyses were modeled to determine the financial performance of the aquaponic system. The result indicated that this small-scale aquaponic operation is not economically viable (Gross profit: 42%, net profit: – 22%, ROI: – 8%, NPV: R81,466, IRR: 13% and Profitability Index: 0.35) by adopting conventional aquaponics cultural practice (fish: plant revenue model 59% to 41%) due to higher operating cost of producing a kg of fish (R55) vis-à-vis the market price, compared to plant production. A revenue model of 42% to 58% fish-to-plant ratio was marginally feasible (Gross profit: 59%, net profit: 13%, ROI: 7%, NPV: R92,445, IRR: 19% and Profitability Index: 0.50). A minimum revenue model of 30% to 70% fish-to-plant ratio by adopting optimized plant yield cultural techniques to attain economies of scale and viability, is suggested. This study serves as a model for promoting viable and sustainable unconventional food production system to attain food security and local economic development in South Africa.

The Betrayed Fish: Reply to Oldfield

Abstract Empirical evidence suggests that fishes, as a whole, are emotional and possess intelligence comparable to that of mammals. Furthermore, although data are sparse, recent studies suggest that representatives from the two major “fish” taxa—bony fish (e.g., groupers and cleaner wrasses) and cartilaginous fish (e.g., giant mantas)—may possess self-awareness and a theory of mind. These capacities indicate that a fish could be capable of the emotion of betrayal. Modern, small-scale aquaculture operations present preconditions in which betrayal might be felt by a fish.

Impact of COVID 19 on the Production of Sardines in Bulan, Sorsogon, Southern Luzon, Philippines

Sardine fishery is a multimillion industry in Bulan, Sorsogon. It provides opportunity of the smallholders catching fish but also through various interventions across supply chain that include boat and net repairman, traders, brokers, wholesalers, retailers and labors, transportation, processing and canning. The study recorded that sardine’s production in Bulan, Sorsogon was not significantly affected by COVID 19 pandemics with a monthly average production of 16mt and an estimated annual production of 1,887mt but this had reduced income of small-scale sardine fishermen and operators around 40%. Income reduction was attributed mostly to strict implementation of movement and mass gatherings. The research team also identified that limited transport mechanism to local markets and Metro Manila and suburbs along with the social distancing contributed much to the drop of farm gate price of sardine. It was estimated that PhP 11M lost occurred to the total annual income of sardine fishers and operators due to the pandemic.

‘This is where all the white farmers come to die’: Exploring the Roles and Narratives of Former Tobacco Farmers in Contemporary Zimbabwe

Throughout the pre-independence era, commercial tobacco growing remained an exclusively white enterprise in Zimbabwe. The situation did not substantially change with the advent of majority rule in 1980. Commercial agriculture in general, and tobacco growing in particular, continued to be dominated by a few large-scale white farmers. However, the situation was to change drastically following the adoption by the Robert Mugabe regime of the fast-track land reform programme (FTLRP) in 2000. This resulted in nearly all white farmers losing their farms, leading to a near collapse of the tobacco farming industry in Zimbabwe. The country’s tobacco farming industry has now been resuscitated, in part due to the successes of contract farming operations, both small-scale and commercial. The collapse of white farming in Zimbabwe following the FTLRP resulted in the movement of white farmers and their families into other areas of the tobacco industry. This article seeks to explore what happened to white tobacco farmers after the FTLRP. Many ex-farmers and their children are now working in the subsidiaries of the large leaf buying companies, on tobacco auction floors, and in small-scale contract farming operations. This article explores the history of the white farming community in Zimbabwe as a background to understand the new roles and positions that former farmers occupy as part of the new boom in tobacco production in Zimbabwe, and southern Africa in general.

Trammel net size selectivity and determination of a minimum legal size (MLS) for the haffara seabream, Rhabdosargus haffara in the Gulf of Suez

The size selectivity of trammel nets used in the Suez Bay in small-scale fishing operations was calculated for the haffara seabream Rhabdosargus haffara using length-frequency distributions of the catch from three different mesh sizes (34, 37 and 40 mm) of the inner layer of the trammel net. Three experimental fishing trials were conducted in the Suez Bay during October 2018, andJanuary and September 2019. The SELECT method has been used to estimate selectivity parameters using five major models (log-normal model, normal location model, normal scale model, gamma model, and bi-normal model). The bi-normal was assessed as the most appropriate model for the haffara seabream. Modal sizes were estimated as 11.8, 12.1, 16.1 cm for 34, 37 and 40 mm mesh sizes, respectively. The calculated lengths at first maturity (Lm) were 13.67 cm for males and 14.15 cm for females. Our findings revealed that the fish lengths caught by the inner layer 34 and 37 mm mesh sizes were less than the length at first maturity, while, those caught with 40 mm were more than the length at first maturity. The minimum legal size (MLS) for R. haffara was fixed at 14.15 cm. Finally, the results revealed that increasing the mesh size of the trammel nets, especially the inner layer mesh, can lead to significant improvements in size selectivity and allow the protection of this valuable fish resource.

Beyond the doom: Sustainable water management practices of small-scale mining operations

Artisanal and Small-scale Mining (ASM) is often implicated as a source of pollution to water systems. In this paper, we explore the water management systems of a formalised small-scale mining operator in Ghana to explicate how its operational activities and organising routines contribute to sustainable water management in practice. Emphasizing how sustainable management of water bodies play out in organising, our study highlights the underpinning mechanisms shaping the shift to environmentally sustainable operations. By unpacking the complex practices of water management in ASM operations, the study extends understanding of how sustainability driven practices emerge and comes to be identified and labelled in the context of an industry historically tagged as an ‘enemy of the environment’, and the consequences that follow. Thus, contrary to the dominant logic of stigmatizing ASM as water polluting champions, our study suggests that ASM operators could be caretakers of water bodies and the environment. We conclude by highlighting implications for policy on sustainable water management.

Flight Scheduling and Fleet Sizing for an Airport Shuttle Air Taxi Service

A multicommodity network flow framework for optimal flight scheduling for an envisioned airport shuttle air taxi service is presented. The framework includes a trip generation model that simulates requests from individuals who travel to and from the airport and are willing to pay for the travel time savings associated with an airport shuttle air taxi service. The framework can be used to determine the fleet size required to satisfy a given user demand and to assess how an operator’s profitability can be influenced by multiple factors, including the population density and income distribution in a metropolitan area, fleet size, ticket price, and air taxi operating costs. The results for an example business airport shuttle service to and from Atlanta Hartsfield Jackson International Airport suggest that a viable business case is possible using electric vertical take-off and landing aircraft. For example, the results for this Atlanta case study indicate that it is possible to have profitable business use case with positive cash flow with a four-seat aircraft with a 60-mile design range and a 150 mph cruise speed using a fleet size of five aircraft at a price point of $5 per passenger-mile during near-term small-scale operations.

How has the 'customary nature' of Japanese fisheries reacted to Covid-19? An interdisciplinary study examining the impacts of the pandemic in 2020

Like many other countries, the economy and society of Japan have been deeply affected by the Covid-19 outbreak, and the fishery sector is no exception. This study takes an interdisciplinary approach to analyze the economic and social impacts of the pandemic on Japanese fisheries, gauging the extent and nature of the damages incurred from Covid-19 while helping to provide tailored post-recovery recommendations for the industry. Using results from an online survey questionnaire (N = 429) and compiling additional economic information from public sources, this study revealed the overwhelmingly negative changes in sales figures and overall financial security that survey participants experienced when compared to a year earlier. High-value and fresh fish species were also significantly affected in 2020 across Japan, in line with similar trends across the developed world. Aquaculture businesses were shown to be more vulnerable to the spread of Covid-19 than small-scale fishing operations, which tend to be more diverse and flexible. Bonding social capital was also shown to be important for mutual help and human well-being, especially among small-scale fishers. This “customary nature” of Japanese fisheries, at the same time, can be seen as a barrier to the transformation of the industry. Given these results, several policy implications are discussed to help fisheries stakeholders and their communities build back better from the Covid-19 pandemic.

Predicting the peak particle velocity from rock blasting operations using Bayesian approach

Measuring the blast-induced ground vibration at blasting sites is very important, to plan and avoid adverse effects of blasting in terms of the peak particle velocity (PPV). However, the measurement of PPV often requires time, cost, and logistic commitment, which may not be economical for small-scale mining operations. This has prompted the development of numerous regression equations in the literature to estimate PPV from a relatively easier to estimate scaled distance (SD) measurement. With numerous regression equations available in the literature, there is a challenge of how to select the appropriate model for a specific blasting site, more so that rocks behave differently from site to site because of different geological processes that rocks are subjected to. This study develops a method that selects appropriate models for specific blasting sites by comparing the evidence and occurrence probability of different regression models. The appropriate model is the model with the highest evidence and occurrence probability given the available blasting site SD data. The selected model is then integrated with prior knowledge and available blasting SD data in Bayesian framework for probabilistic characterization of PPV. The SD and PPV data at the opencast coal mine, Jharia coalfield in the Dhanbad district of Jharkhand, India, is used to illustrate and validate the approach. The mean and standard deviation of simulated PPV samples from the proposed approach are 12.38 mm/s and 7.36 mm/s, respectively, which are close to the mean of 12.03 mm/s and standard deviation of 9.24 mm/s estimated from the measured PPV at the site. In addition, the probability distribution of the simulated PPV samples is consistent with the probability distribution of the measured PPV at the blasting site.

Marine aquaculture in the pacific coast of Costa Rica: Identifying the optimum areas for a sustainable development

Sustainable marine aquaculture requires the definition of adequate areas for its development, where the productive activity has a lower impact on the environment and avoid conflicts with other coastal activities. The aim of this research is to identify the potential areas for marine aquaculture operations in the central and northern Pacific coast of Costa Rica, considering five fish species of commercial interest and three operation scale scenarios (large, medium and small scale). The mapping procedure considers the biological suitability for the species to have an optimum development, the structural suitability for the fish cages to endure the environmental conditions (mainly waves and currents), and the operational suitability for operation and maintenance activities associated to the fish production (e.g. feeding, harvesting, maintenance). Sea surface temperature, salinity, water clarity, wind speed and currents in open coasts regions were obtained from global models and satellite data. Currents and wave data in the Gulf of Nicoya, one of the main estuaries of the country, were modeled numerically. Available docking sites, marine protected areas and tourism sites were used and obtained from the corresponding national official entities. Results show a high potential for marine aquaculture projects, specifically for large and medium scale operations. Three out of five study species present high suitability in most of the study site, and the other two species present promising results in the Gulf of Nicoya. Small scale operations have several areas with high suitability for marine aquaculture projects, with extensions ranging from 101 km2 to 2 118 km2 depending on the species. At a regional scale, the Pacific coast of Costa Rica presents high potential for fish aquaculture, being a promising development medium for coastal communities as long as it is environmentally sustainable and compatible with other coastal activities such as tourism.

Consideration Of Beef Cattle Barn Projects With Manure Management Planning: Çanakkale/Ayvacik Case Study

Livestock barns are built without taking into account animal welfare, productivity and effective use of labor in cattle breeding enterprises. These problems can be eliminated by following the design principles. However, considering the small family businesses in our country, it is seen that there are quite large design errors in the cattle barns. Another issue that is not taken into account in livestock enterprises is the processes related to the collection, transmission, storage and disposal of animal wastes that will arise during production. This makes management difficult, causes some environmental problems, and wastes manure, which is a very valuable plant food source. In this study, a small scale (50 head beef) operation is designed considering the above mentioned design criteria and possible manure management options. Annual manure production capacity of 575 t is calculated. However based on the soil analysis results and various plants this operation will need to apply 76 to 902 tons of manure annualy. This shows that a detailed plant production plan should be conducted based on the manure management plans. For alternative plantations land requirement to dispose of manure vary between 13 – 91 da. The land available for manure application is about 20 da for this operation. Therefore, additional land should be managed to manage manure. Results of the study showed that commercial value of manure produced annualy is about 874 $. This value aslo demonstrates the importance of manure management based on soil/manure nutrient contents and plan needs.

Pesticide toxicity assessment and geographic information system (GIS) application in small-scale rice farming operations, Thailand

The objectives of the study were to evaluate the impact of pesticide exposure on farmer health during non-active rice farming and active rice farming periods and present the change in the individual cholinesterase activities (%reduction) on the geographic information system (GIS) mapping in Nakhon Ratchasima Province, Thailand. Acetyl- and butyryl-cholinesterase (AChE and BuChE) activities were monitored during both study periods using Test-mate ChE (Model 400). The location of paddy fields was specified using Garmin geographic positioning system MAP 62s. Fifty-eight farmers who participated in this study had an average age of 49.2 ± 6.9 years. Higher prevalence of all health symptoms was observed among farmer participants during the active rice farming period comparing to the non-active rice farming period (p < 0.01). Furthermore, farmers had significantly lower activities of AChE and BuChE during the active rice farming period comparing to the non-active rice farming period (p < 0.01). Our findings indicate that the GIS mapping indicate that the cases with a significant enzyme inhibition have dispersed across the agricultural and the nearby residential areas. This, investigation can be used to promote safer use of pesticides among farmers and mitigate pesticide exposure among residents living in close proximity to a rice field.

Applying the agent-based modeling approach to evaluate future communication strategies in dispersed operations in a complex environment

Future conflicts will increasingly take place in complex, urban environments. This calls for a change from operating in large formations and from static encampments to dispersed, networked, decentralized and small-scale operations. Concept development for dispersed operations and their accompanying strategies has only just begun. To aid in this early phase of concept development, this study presents (i) a framework for modeling the effects of communication strategies during dispersed land operations in a complex environment using the Agent-Based Modeling method, and (ii) a case study to illustrate the framework using the research question ‘What are the effects of communication strategies that make use of either a cloud or bundling on the shared Situational Awareness of units in dispersed operations in a complex environment?’, using a peace enforcement scenario in an urban area.

Cooperation between the UN and ECOWAS in the field of peacekeeping

Recently, the UN has been increasingly cooperating with regional organizations in solving African security problems. Among the most reliable partners in this area is the Economic Community of West African States (ECOWAS). The purpose of this work is to analyze the dynamics of cooperation between these organizations and to identify the factors that determine the effectiveness of their joint work. This study presents an analysis of the joint peacekeeping experience of ECOWAS and the UN in Liberia, Sierra Leone, Côte d&amp;apos;Ivoire and Guinea-Bissau. In each case, special attention is paid to the format of interaction between the regional mission and the “Blue helmets” one. In particular, the author aims at identifying the most commonly used scheme of cooperation. The author states that over the past three decades, the UN has moved from small-scale operations implemented in parallel with ECOWAS efforts to full-fledged missions deployed after the ECOWAS forces have paved the way for peacekeeping. This scheme allows full use of the comparative advantages of the two organizations. ECOWAS forces are efficient at the initial stage of the conflict, when prompt intervention is needed to minimize humanitarian losses. “Blue helmets”, in turn, are most useful when the parties to the conflict manage to reach an agreement on a ceasefire. Particular attention in the study is paid to the role of the leader among the contributing countries. It seems that further studies of the driving forces of regional operations will be useful in terms of strategic planning of UN peacekeeping activities.

Manipulator Motion Planning for Part Pickup and Transport Operations From a Moving Base

Mobile manipulators are being deployed for transporting parts between machines and work stations in warehouses and shop floors. To increase the efficiency of operations, these mobile manipulators are required to complete the tasks as fast as possible. Picking up parts with the manipulator while the mobile base is moving decreases the time required to complete the transportation task and increases the efficiency of operations. However, motions of the manipulator on a moving platform can be risky, and hence, it is desired that the manipulator starts and ends its motions as close as possible to the part being picked up. In this article, we present a bidirectional sampling-based scheme for generating such manipulator trajectories for a given mobile base trajectory for pickup and transportation. Our approach implicitly determines the location of the mobile base where the manipulator motion starts and ends as well as where grasping happens. It also determines which grasping pose to use for picking up the part. Furthermore, we have presented the techniques to reduce the manipulator motion time (span time) and the computation time. Our approach enables us to reduce span time on average by 35% with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16\times $ </tex-math></inline-formula> reduction in the computation time compared to the RRT-based baseline methods. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —Transportation of objects is a crucial application in industrial and warehouse environments. Conveyor belts and AGVs are typically used for such applications as they provide an efficient mode of transportation of a large number of objects. However, they may not provide the flexibility which mobile manipulators bring in for small-scale operations. The method presented in this article provides a way to increase the efficiency of operation for mobile manipulators for transportation tasks. We attempt to reduce the risks of the manipulator colliding with expensive equipment and moving obstacles by making sure that the manipulator moves only when needed for picking up objects. Moreover, the method can be used to pick up and transport a variety of parts in different ways using a two-fingered gripper. The method can also easily incorporate different types of grippers and mobile platforms.

COVID-19 and Tactical Urbanism

This work sought to reflect on urgent adjustments in public space in times of crisis from tactical urban interventions. For this, it elucidates protective measures related to the control of the COVID-19 pandemic, in particular under the aspects of urban mobility and civil engagement, using for this the case study of the implementation of temporary cycle lanes in the municipality of Belo Horizonte, Minas Gerais, Brazil. The methodology of this research was based on official publications made available electronically by the Municipality of Belo Horizonte and by the Company responsible for the transport and transit sector of Belo Horizonte (BHTRANS). In addition, this work was supported by publications available electronically from the Association of Urban Cyclists of Belo Horizonte (BH in Cycle) from 2012 to 2021. Based on the correlation between the material collected and the theoretical basis available on topics of interest to this research, the study aimed to discuss temporary and small-scale operations of the Tactical Urbanism type, implemented from the partnership between public authorities and civil society to ensure a safer urban mobility in the midst of the COVID-19 pandemic during the year 2020 to date. The work highlights that the inclusion of Tactical Urbanism as a formal tool in urban planning can foster new local possibilities and immediate action strategies in the face of crises such as COVID-19, in addition to fostering citizen participation in decision-making processes about the city and its importance , guaranteeing basic rights such as moving safely.

Decentralized high-strength wastewater treatment using a compact aerobic baffled bioreactor

Decentralized wastewater treatment is a potential solution to the economic and sustainability issues associated with current wastewater infrastructure requirements for rural and expanding urban settings. However, wastewater produced from small-scale operations (domestic, industrial, agricultural, defense, etc.) are often found to have higher pollution concentrations than municipal wastewater and is referred to as “blackwater” in the study. A baffled bioreactor (BBR) was employed to carry out blackwater treatment. The results of this study showed the removal of organic content and inorganic nitrogen was high in all of the feed amounts tested and increased corresponding to an increase in feed amount. Microbial diversity results supported that the feed amount was the most important factor in treatment performance. The microbial community was more diverse at higher feed amounts than lower feed amounts. A non-metric multidimensional scaling (NMDS) analysis revealed that higher feed amounts enriched Verrucomicrobiaceae, unclassified Sphingomonadales, unclassified Burkholderiales in the microbial community, and facilitated the removal of total solids, total nitrogen, and NO3−. The energy and exergy analyses showed the consumption of 5.02 Wh/L wastewater energy with a universal exergy efficiency of 61% at the feed amount of 3750 LPD. An economic analysis further delineated the treatment cost profiles of the decentralized unit under four different energy case scenarios of electricity from the grid, propane gas engine for remote rural communities, diesel engine (I) using standard U.S. market diesel fuel costs for remote rural communities and scientific research bases, and diesel engine (II) using the fully burdened cost of diesel fuel for military contingency bases and other extreme environmental scenarios.

Peanut crisp: A protein-rich snack

Peanut processed products sold in the local market are still limited but the potential is great. There is a need therefore to explore more diversified peanut products that are acceptable, nutritious, and within the buying capacity of the general consumers. This study aimed to produce crisp; a very popular snack food utilizing rice and peanut at various levels applying some appropriate technologies. The products were analyzed and evaluated to determine their sensory qualities, nutritive value, and profitability. The treatments of the study were different proportions of rice and peanut. Replication was done three times and Completely Randomized Design (CRD) was used. The crisp products were rated and results showed that these had good sensory qualities. Peanut significantly improved the taste and crispiness acceptability as well as the protein quality. Based on cost and return analysis, the commercial processing of the products either in a household or small-scale operation indicates good economic profitability.