1,721,197 research outputs found
The Grudging Modernizer: A Trip to the Middle East and Cold War Social Science
No full textThe postwar era is generally recognized as a unique moment of impetuous growth of the social sciences, due to the interest of Western internationalist elites in the development of a set of pragmatically-oriented intellectual tools that could be of use in the confrontation between the self-proclaimed “Free World,” the Soviet bloc, and emerging postcolonial nations. In the last twenty years, however, doubts about the impact of the Cold War syndrome on the development of ideas, methods, and infrastructures of Western social science in the 1950s and the 1960s have been cast by historians and social scientists alike. This article uses the episode of the 1959 Middle East scholarly trip of a Harvard sociologist, Robert N. Bellah, to highlight the complexity and the ambivalence of individual trajectories, as well as the adumbrations of critical ideas and themes in the work of an intellectual who was a recognized, if peripheral, member of some of the most influential Cold War Social Science circles. A final hypothesis on a paradox of Cold War social science is advanced, according to which the need to staff centers and institutes for the training of Cold War technicians and elites put humanists and orientalists in the condition to influence those very students who should have been trained in the most advanced and practically-oriented social sciences
Analytic model to predict productivity in divisional Seru production environment
Full text linkAdvanced production environments emerged as the good solution to address the modern market challenges asking for a wide product mix and low time to market. Within cellular systems, made of independent, modular and flexible working areas, tailored on families of similar products, Serus are of increasing adoption for both manufacturing and assembly tasks. Among them, the so-called divisional Serus are the first step to move from the traditional production lines to a production environment made of a set of identical working areas, parallelising activities and enabling potential productivity increase. Despite their adoption in industry, starting from the electronic sector and moving forward, reference analytic models to predict divisional Seru productivity are rare in the literature, while their formulation and application is a gap to fill. This paper addresses this gap in theory, supporting the transition toward Seru production environment by proposing and proofing the analytic closed-form expressions getting the expected productivity of a divisional Seru made of a generic number of workers and a) one (base case), b) two (extension) and c) a generic number (general case) of product types to produce. Together with the steps to get the productivity expressions for these three cases of immediate practical applicability and not yet proposed by the literature, a case study and sensitivity analysis on the divisional Seru dimension showcase the proposed model industrial use and impact on the expected productivity. Key results highlight a stationary behaviour of the working time for all workers making the Seru productivity dependent on the sum of the workers speed and the product type workloads
La religione nell'evoluzione umana: Robert Bellah in discussione
No full textNumero monografico dedicato alla figura del sociologo americano Robert N. Bellah. Contiene la traduzione italiana di saggi di R.N. Bellah (a cura di M. Bortolini e P. Costa), P. Kitcher (a cura di P. Costa), J.C. Alexander (a cura di P. Costa), Ji Zhe (a cura di M. Bortolini
Bi-objective design of sustainable reconfigurable manufacturing systems
No full textReconfigurable Manufacturing Systems (RMSs) rose as advanced production systems able to meet the current market challenges rapidly changing their physical and logical structure. An RMS environment is usually characterized by intelligent machines called Reconfigurable Machine Tools (RMTs), consisting of fixed parts, i.e. the basic modules, and dynamic changeable parts, i.e. the auxiliary modules, which allow performing different tasks. The literature is rich in studies proposing methodologies for RMS design and management optimizing their operative and economic performances. Studies including the environmental sustainability perspective are still limited. To fill this gap, this paper proposes and applies a bi-objective mathematical model for the RMS design and management, optimizing the operative performances from one side, i.e. by minimizing the parts’ and auxiliary modules’ travel time and the RMT reconfiguration time, and the environmental performances from the other side, i.e. by minimizing the energy consumption for the part processing and the RMT reconfiguration. The application of the bi-objective model to an operative industrial case study showcases how to best balance operative and environmental objectives. The selected trade-off point allows a significant improvement of both time and energy performances compared to their worst values, rising as an efficient production system configuration
Crowd Logistics: A Survey of Successful Applications and Implementation Potential in Northern Italy
Full text linkNowadays, last-mile logistics represents the least efficient stage of supply chains, covering up to 28% of the total delivery cost and causing significant environmental emissions. In the last few years, a wide range of collaborative economy business models has emerged across the globe, rapidly changing the way services were traditionally provided and consumed. Crowd logistics (CL) is a new strategy for supporting fast shipping services, entrusting the management of the last-mile delivery to the crowd, i.e., normal people, who agree to deliver goods to customers located along the route they have to travel, using their own transport means, in exchange for a small reward. Most existing studies have focused on evaluating the opportunities and challenges provided by CL through theoretical analysis and literature reviews, while others have proposed models for designing such emerging distribution networks. However, papers analyzing real successful applications of CL worldwide are lacking, despite being in high demand. This study attempted to fill this gap by providing, at first, an overview of real CL applications around the globe to set the stage for future successful implementations. Then, the implementation potential of CL in northern Italy was assessed through a structured questionnaire delivered to a panel of 214 people from the Alma Mater Studiorum University of Bologna (Italy) to map the feasibility of a crowd-based system in this area. The results revealed that about 91% of the interviewees were interested in using this emerging delivery system, while the remaining respondents showed some concern about the protection of their privacy and the safeguarding of the goods during transport. A relevant percentage of the interviewees were available to join the system as occasional drivers (ODs), with a compensation policy preference for a fixed fee per delivery rather than a variable reward based on the extra distance traveled to deliver the goods
“Station-Sequence” parts feeding in mixed models assembly: Impact of variations and industry 4.0 possible solutions
Full text linkAbstract: Parts feeding is a complex logistic problem, stressed by the increasing product variety that
forces the assembly systems to manage a great number of models with a mixed model approach. In this
context a possible parts feeding policy is the “station-sequence”, sequences of parts supplied to the
assembly stations as function of the production models. This parts feeding policy can reduce stocks at the
assembly stations, but offers potential production stops due to its low robustness. Different external
elements can perturb the parts sequences (i.e. changing in production schedule, tasks times variation,
variable supply lead times, etc.). The aim of this paper is to study, through a simulation study and a
statistical analysis, the station-sequence part feeding policy considering its dynamic time-dependence the
impact of the model mix and time perturbations on the system performance. Authors discuss the possible
application of the real time events traceability, achievable through the I4.0 application, in order to
mitigate the variability influence on the system performances
Assembly kits with variable part physical attributes: warehouse layout design and assignment procedure
No full textPurpose: The kitting feeding policy creates kits with the parts of each product to assemble. Each kit contains elements with heterogeneous physical properties imposing heterogeneous logistic facilities and management solutions for storage and handling. The purpose of this paper is to present and apply a two-step procedure to design the part warehouse layout and to assign locations in case of kitting with high-variety part attributes. The proposed procedure aims at reducing the kitting travelled distance, shortening the picker paths, best positioning the components in the warehouse to enhance the possibility of creating kits through a single corridor access. The saturation of the warehouse and the minimization of the required storage space are also considered. Design/methodology/approach: Starting from part categorization, the proposed two-step procedure, of general applicability, designs the component warehouse, sizing the corridors (Step 1) before clustering the kits in terms of part commonality and best-assigning clusters to corridors (Step 2) with the goal of reducing the travelled distance and saturating the available storage space. Findings: A comparison model considers the traditional versus the proposed warehouse layout highlighting the potential saving in the picker travelled distance. A case study taken from the harvesting machine agricultural sector exemplifies the applicability and the practical implications of this research. Originality/value: Elements of originality are the warehouse design strategy and the assignment model for parts based on their physical attributes and their occurrence in the assembly kits. Finally, the case study taken from industry, with a high number of components and part categories, adds value to the research making the proposed procedure able to address large-scale industrial problems
Theoretical analysis of wind flow characteristics to investigate the mass and momentum parameters using a novel computational fluid dynamics-based approach
No full textIn this article, an experimental study of a wind turbine in a wind tunnel is performed. The objective has been to present a novel analytical computational fluid dynamics (CFD)-based approach through considering the residual levels of the mass and momentum parameters under effect of different air flow characteristics surrounding the wind turbine, which have an effect on the power losses, turbine’s performance and the economic viability. The involved decision variables are considered to be the wind velocity, the pressure and the turbulence. Evaluation of the convergence showed that the residual level for the maximum method is estimated to be approximately 10–1 to 10–3 times higher than the root mean square. Results also concluded that between two studied turbulence models, the turbulence eddy frequency is found to be more efficient compared with turbulence kinetic energy. In higher iterations compared with the initial iterations, a significant difference between the pressure and the Cartesian velocity components has occurred and the residual level of the velocity components indicated a more efficient convergence compared with the pressure. The overall environmental analysis concluded that on the basis of the CFD residual values, it would be possible to adequately determine the CFD efficiency of the wind energy system in a wind tunnel. It has been demonstrated that, among different decision variables, velocity components of the mass and momentum parameters and the turbulence eddy frequency were determined to produce further accurate results in comparison with the pressure and the turbulence kinetic energy
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