The manufacture, transportation and on-site assembly sectors of precast construction projects are often considered separately and managed by rule of thumb, causing an inefficient use of resources and ...postponed delivery. This study views these sectors as a whole from the perspective of a single machine batch-scheduling problem. A dynamic programming algorithm, which aims to search for solutions that entail maximum production efficiency, was developed accordingly with the constraints of changeover costs and production deadlines. We tested the method’s ability by processing as many products as possible simultaneously using real data collected from a precast factory in a simulation and compared the effect with a previous study. We found that our method possesses great potential to improve the efficiency of precast production.
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•A single machine batch scheduling model considering the manufacturing, transportation and on-site assembly of precast construction project simultaneously is proposed.•The proposed model can potentially reduce total production cost by processing as many products as possible in the same period.•A quicker algorithm based on the schema of existing dynamic programming algorithm is developed to solve the proposed problem.
Just in Time (JIT) and Lean manufacturing are concepts that originated in the automotive industry and were then adopted by pharmaceutical and biopharmaceutical companies during the 1990s. However, ...the Covid-19 pandemic and the urgent demand for pharmaceutical treatment challenged JIT and Lean manufacturing processes. Production of Covid-19-related medicines increased, putting pressure on global supply chains and operations. This also hindered the production of medicines using the same or similar materials. Thus, questions are raised concerning JIT and Lean supply chains in the pharmaceutical industry.
The present study aimed to explore (1) if material and supply constraints occurred due to the Covid-19 pandemic, (2) how companies were impacted and managed and (3) if changes are required to future proof the JIT supply chain approach for future global events.
A mixed-method cross-sectional survey design was used and focused on material supply, qualification and validation in Irish pharmaceutical manufacturing sites.
Employees working in the Irish pharmaceutical manufacturing industry were recruited using convenience sampling through online advertisement using the social media platform 'LinkedIn'. Quantitative data was analysed using percentages and qualitative data from free-text responses were used to add context to the quantitative survey questions.
A total of 41 participants were recruited. The results suggested that the pandemic had a negative effect on material availability according to 81% of participants. This translated to delays or stoppage of production activity and was mainly handled by sourcing new materials (70%). To cope with future global crises, 60% of participants recommended more flexibility in future validation processes while 78% of participants acknowledged the importance of validating additional suppliers. A hybrid model of manufacturing and supply chain management was also a preferred approach to exclusive Lean and JIT (42%).
The production of non-Covid-19 medicines was adversely affected by the Covid-19 pandemic, but the pharmaceutical industry in Ireland demonstrated resilience and collaboration in response to these challenges. This study suggests that the JIT and Lean manufacturing model should be adjusted to ensure medicine supply chains are not disrupted during future global events.
JIT-Picking Bernhard, Lukas; Scharnowski, Tobias; Schloegel, Moritz ...
Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security,
11/2022
Conference Proceeding
Odprti dostop
Modern JavaScript engines that power websites and even full applications on the Web are driven by the need for an increasingly fast and snappy user experience. These engines use several complex and ...potentially error-prone mechanisms to optimize their performance. Unsurprisingly, the inevitable complexity results in a huge attack surface and varioustypes of software vulnerabilities. On the defender's side, fuzz testing has proven to be an invaluable tool for uncovering different kinds of memory safety violations. Although it is difficult to test interpreters and JIT compilers in an automated way, recent proposals for input generation based on grammars or target-specific intermediate representations helped uncovering many software faults. However, subtle logic bugs and miscomputations that arise from optimization passes in JIT engines continue to elude state-of-the-art testing methods. While such flaws might seem unremarkable at first glance, they are often still exploitable in practice. In this paper, we propose a novel technique for effectively uncovering this class of subtle bugs during fuzzing. The key idea is to take advantage of the tight coupling between a JavaScript engine's interpreter and its corresponding JIT compiler as a domain-specific and generic bug oracle, which in turn yields a highly sensitive fault detection mechanism. We have designed and implemented a prototype of the proposed approach in a tool called JIT-Picker. In an empirical evaluation, we show that our method enables us to detect subtle software faults that prior work missed. In total, we uncovered 32 bugs that were not publicly known and received a $10.000 bug bounty from Mozilla as a reward for our contributions to JIT engine security.
Purpose
The maintenance department of today, like many other departments, is under sustained pressure to slash costs, show outcome and support the assignment of the organization, as it is a ...commonsensical prospect from the business perspective. The purpose of this paper is to examine expected maintenance waste reduction benefits in the maintenance of organizations after the implementation of just-in-time (JIT) managerial philosophy. For this, a structured questionnaire was designed and sent to the 421 industries in India.
Design/methodology/approach
The designed questionnaire was divided into two sections A and B to assist data interpretation. The aim of the section A was to build general information of participants, type of organization, number of employees, annual turnover of the organization, etc. Section B was also a structured questionnaire developed based on a five-point Likert scale. The identified critical elements of the JIT were included in the questionnaire to identify the maintenance waste reduction benefits in the maintenance of organizations.
Findings
On the basis of the 133 responses, hypothesis testing was done with the help of Z-test, and it was found out that in maintenance, we can reduce a large inventory of spare parts and also shorten the excessive maintenance activities due to the implementation of JIT philosophy. All the four wastes: waste of processing; waste of rejects/rework/scrap in case of poor maintenance; waste of the transport of spares, and waste of motion, have approximately equal weightage in their reduction. Waste of waiting for spares got the last rank, which showed that there are little bit chances in the reduction of waiting for spares after the implementation of JIT philosophy in maintenance.
Practical implications
The implication of the research findings for maintenance of organizations is that if maintenance practitioners implement elements of JIT philosophy in maintenance then there will be a great reduction in the maintenance wastes.
Originality/value
This paper will be abundantly useful for the maintenance professionals, researchers and others concerned with maintenance to understand the significance of JIT philosophy implementation to get the expected reduction benefits in maintenance wastes of organizations which will be helpful in the great saving of maintenance cost and time side by side great increment in the availability of machines.
ERP systems provide important benefits to institutions, such as improved processes, improved data, supplier-customer integration, better planning and control, as well as real-time insight and ...just-in-time (JIT) management that can put a business organisation in front of the competition. In this study, the change and transformation experienced by establishing an ERP system are explained for an automotive supplier that was not using an integrated ERP system for a real-world problem. The pre-implementation situation, the problems of the existing system, the necessary reasons for such an application, the determined deficiencies of the installed system and the post-implementation situation are explained in detail. Thanks to the real-time information and integrated data generated by the reports, along with a more sophisticated business understanding, the risk to employees was lowered. As a result of a changeover to real-time Materials Requirement Planning, the decrease in inventory levels, stabilisation in delivery time and efficiency of control over the production processes were increased in addition to real-time tracking and reporting advantages. As a result of this work, the production processes were transformed into JIT. The inventory level was reduced to zero and a formerly used warehouse was no longer required.
Flow shop scheduling problem has a wide application in the manufacturing and has attracted much attention in academic fields. From other point, on time delivery of products and services is a major ...necessity of companies’ todays; early and tardy delivery times will result additional cost such as holding or penalty costs. In this paper, just-in-time (JIT) flow shop scheduling problem with preemption and machine idle time assumptions is considered in which objective function is minimizing the sum of weighted earliness and tardiness. A new non-linear mathematical model is formulated for this problem and due to high complexity of the problem meta-heuristic approaches have been applied to solve the problem for finding optimal solution. The parameters of algorithms are set by Taguchi method. Each parameter is tested in three levels. By implementation of many problems with different sizes these levels are determined .The proposed model is solved by three meta-heuristic algorithms: genetic algorithm (GA), imperialist competitive algorithm (ICA) and hybrid of GA and ICA. To evaluate the performance of the proposed algorithms many test problems have been designed. The Computational results indicate the superiority of the performance of hybrid approach than GA and ICA in finding thebest solution in reasonable computational time.
Purpose Although extensive research has been conducted on precast production, irregular component loading constraints have received little attention, resulting in limitations for transportation cost ...optimization. Traditional irregular component loading methods are based on past performance, which frequently wastes vehicle space. Additionally, real-time road conditions, precast component assembly times, and delivery vehicle waiting times due to equipment constraints at the construction site affect transportation time and overall transportation costs. Therefore, this paper aims to provide an optimization model for Just-In-Time (JIT) delivery of precast components considering 3D loading constraints, real-time road conditions and assembly time. Design/methodology/approach In order to propose a JIT (just-in-time) delivery optimization model, the effects of the sizes of irregular precast components, the assembly time, and the loading methods are considered in the 3D loading constraint model. In addition, for JIT delivery, incorporating real-time road conditions in the transportation process is essential to mitigate delays in the delivery of precast components. The 3D precast component loading problem is solved by using a hybrid genetic algorithm which mixes the genetic algorithm and the simulated annealing algorithm. Findings A real case study was used to validate the JIT delivery optimization model. The results indicated this study contributes to the optimization of strategies for loading irregular precast components and the reduction of transportation costs by 5.38%. Originality/value This study establishes a JIT delivery optimization model with the aim of reducing transportation costs by considering 3D loading constraints, real-time road conditions and assembly time. The irregular precast component is simplified into 3D bounding box and loaded with three-space division heuristic packing algorithm. In addition, the hybrid algorithm mixing the genetic algorithm and the simulated annealing algorithm is to solve the 3D container loading problem, which provides both global search capability and the ability to perform local searching. The JIT delivery optimization model can provide decision-makers with a more comprehensive and economical strategy for loading and transporting irregular precast components.
The popularity of mobile devices has led to an explosive growth in the number of mobile apps in which Android mobile apps are the mainstream. Android mobile apps usually undergo frequent update due ...to new requirements proposed by users. Just-in-time (JIT) defect prediction is appropriate for this scenario for quality assurance because it can provide timely feedback by determining whether a new code commit will introduce defects into the apps. As defect-prediction performance usually relies on the quality of the data representation and the used classification model, in this work, we propose a model, called Simplified Deep Forest (SDF), to conduct JIT defect prediction for Android mobile apps. SDF modifies a state-of-the-art deep forest model by removing the multigrained scanning operation that is designed for data with a high-dimensional feature space. It uses a cascade structure with ensemble forests for representation learning and classification. We conduct experiments on 10 Android mobile apps and experimental results show that SDF performs significantly better than comparative methods in terms of 3 performance indicators.
•Studies the impact of transportation risks on logistical performance.•Studies the impact of multi-locational buffer inventory strategies on logistical performance.•Demonstrates that service levels ...are impacted by border-crossing uncertainty.•Demonstrates that lead-time performance is most impacted by 3PL replenishment risk.
We study a dual delivery risk problem that firms inside the free trade zones (FTZ) along the US-Mexico border (i.e., maquiladoras) often face in their daily operations. It is commonly observed that maquiladoras’ suppliers keep buffer inventories of components in a 3rd party logistics (3PL) warehouse on the US side of border. Maquiladoras will “call-off” the components when they are needed for production runs, often multiple times a day. Each call-off shipment is an international shipment that is involved with export/import procedures and is subject to customs inspection, which often causes delays. Such delivery uncertainty, combined with the 3PL replenishment uncertainty, makes just-in-time (JIT) operations a challenging task for maquiladoras. In this study, we examine how a firm’s logistical performance can be affected by multiple transportation risks and multi-locational buffer inventory strategies in a border-crossing JIT supply chain. Our results show that a firm’s service level is more affected by the border-crossing uncertainty, whereas a firm’s order lead-time performance is predominantly attributed to the 3PL replenishment risk.
Purpose - The purpose of this paper is to study whether just in time (JIT) supply practices interact with JIT production practices by positively moderating the relationship between JIT production and ...efficiency delivery performance.Design methodology approach - In total, six hypotheses are developed on the relationships between JIT production, JIT supply, efficiency and delivery performance. The hypotheses are tested through a hierarchical regression analysis using data from a sample of 207 manufacturing plants.Findings - JIT production practices positively affect both efficiency and delivery. JIT supply practices positively moderate the relationship between JIT production and delivery, while there is no significant moderating effect when considering the impact on efficiency. The role of JIT supply as moderator is twofold. On the one hand, it strengthens the positive impact of JIT production on delivery through a complementary effect. On the other hand, low levels of adoption of JIT supply practices can hinder and - for extremely low levels - cancel the impact of JIT production practices on delivery.Practical implications - When efficiency is the priority, companies should direct their efforts on JIT production. However, when their aim is to maximize delivery, they should invest on both JIT production and JIT supply. Results found advise managers to implement some JIT supply practices during the early stages of JIT production programs, because the total absence of any JIT linkages with suppliers can limit JIT production benefits on delivery performance.Originality value - This study elaborates on the mutual influence between JIT production and JIT supply practices and demonstrates that they have a different weight and contribute to different aspects of performance improvement. This can help managers involved in JIT implementation to better allocate scarce resources.
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