| 1. |
- Dabhilkar, Mandar, et al.
(författare)
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Supplier selection or collaboration? : Determining factors of performance improvement when outsourcing manufacturing
- 2009
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Ingår i: Journal of Purchasing and Supply Management. - : Elsevier BV. - 1478-4092 .- 1873-6505. ; 15:3, s. 143-153
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Tidskriftsartikel (refereegranskat)abstract
- An empirical study was designed to determine factors of performance improvement when outsourcing manufacturing. Findings from a survey of 136 manufacturing plants in Sweden show that most of them achieve their outsourcing motives, but not without trade-offs. Factors of performance improvements such as economies of scale or operations in low-cost countries can improve one performance dimension, such as product cost, yet negatively impact volume flexibility, speed or product innovation. The results show part characteristics and supplier operating capabilities are more important than supplier relationship strategies when outsourcing manufacturing, meaning that supplier selection trumps supplier collaboration in the make-or-buy decision.
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| 2. |
- Jahedi, Mohammad, 1984-, et al.
(författare)
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Quenching a rotary hollow cylinder by multiple configurations of water-impinging jets
- 2019
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier. - 0017-9310 .- 1879-2189. ; 137, s. 124-137
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Tidskriftsartikel (refereegranskat)abstract
- Experiments have been conducted to analyze quenching of a hot rotary hollow cylinder by one and two rows of water-impinging jets. Sub-cooled water jets (ΔTsub = 45–85 K) with flow rate 8006 to 36,738 impinged on hollow cylinder with rotation speed 10 to 70 rpm at various initial wall superheat temperatures from 250 to 600ºC. Jet-to-jet and jet-to-surface spacing varied between 4 to 10d and 1.5 to 7d respectively and angular position of impinging jets were tested from 0 to 135º. Effectiveness of the defined parameters on stagnation point’s local average heat flux was found lower in the film and nucleate boiling compare to transition boiling regime where rotation speed had the highest impact. Characteristic of maximum heat flux (MHF) at stagnation point and upwash flow point were analyzed based on surface heat flux, time and temperature corresponding to MHF. Same maximum heat flux levels were captured in the both points which reveals importance of the flow behavior at the upwash flow point. The effectiveness of the parameters to improve average heat transfer was studied based on cooling area of each water impingingjet in the multiple configurations. Higher average heat transfer was obtained by increasing flow rate and subcooling temperature and lower initial wall superheat temperature corresponding to onset of transition boiling regime.
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| 3. |
- Abid, Muhammad, et al.
(författare)
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Factors affecting global supply chain design
- 2012
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Konferensbidrag (refereegranskat)abstract
- Due to the limited existing knowledge pertaining to the factors which govern localization of operations and capabilities in a global supply chain, the purpose of the paper is to find out which factors and how they jointly affect the design of global supply chains. The relevant literature is reviewed and a concept matrix is developed. Five companies were selected in order to illustrate the issues of global supply chain design. Among them, three companies are considered to have efficient supply chain and less complex products, while the two others are considered to have responsive supply chain and more complex products. The issues discussed with the selected companies cover global sourcing, challenges, technological advancement and issues related to management control. The study identifies about fifty factors that affect global supply chain design, and specifically how theses relate to design decisions on location of factories and production, supplier selection and development, distribution of products and organisation of interfaces along the supply chain. The discrepancies between theory and practice as well as the implications for further research are discussed.
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| 4. |
- Bengtsson, Lars, et al.
(författare)
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Manufacturing outsourcing and its effect on plant performance-lessons for KIBS outsourcing
- 2009
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Ingår i: Journal of evolutionary economics. - : Springer Science and Business Media LLC. - 0936-9937 .- 1432-1386. ; 19:2, s. 231-257
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Tidskriftsartikel (refereegranskat)abstract
- Despite the proclaimed advantages and popularity of outsourcing manufacturing and knowledge-intensive business services, there are few and mainly contradictory studies of its short- and long-term effects. The main purpose of this paper is to analyze the way in which outsourcing manufacturing and design work relates to performance at plant level. The study is based on a large-scale survey among a representative sample of Swedish engineering plants. The results show no significant effects from outsourcing manufacturing on plant operating performance. The paper further shows that investments in technological and organizational capabilities explain the improvements of performance to a significantly higher extent than does outsourcing. The problems of additional costs and managing dependencies when applying partial outsourcing and separating interdependent key processes provide important insights to the analysis on the effects of outsourcing knowledge-intensive business services (KIBS).
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| 5. |
- Jahedi, Mohammad, 1984-, et al.
(författare)
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Effect of Multiple Water Impinging Jet Array on Quenching Hot Rotary Hollow Cylinders
- 2020
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Konferensbidrag (refereegranskat)abstract
- Experimental study has been carried out to investigate transient quenching of a rotary hollow cylinder by water impinging jets in multiple jet arrays. Subcooled water jets (Δ????= 55-85K) were placed into two types of nozzle arrays: 1-row and 2-row in-line array. The flow rate of water jets varied from 2.7 to 10.9 L/min, impinging on hot rotary cylinder (?? =600℃) with rotation speed 10-50 rpm and different curvature ratio (??/d = 12, 19 and 24). The local average and maximum boiling heat transfer at water jet’s stagnation point revealed effect of studied quenching parameters and multiple jet arrays in the boiling heat transfer. The result showed among the studied parameters, jet’s flow rate and curvature ratio influenced heat transfer in all the boiling regimes. Rotation speed was effective in film and transition boiling regime and strong effect of subcooling was captured in the transition boiling regime. The characteristics of maximum heat flux point in the boiling curve were found to be dependent on the studied quenching parameters as well as array of nozzles. Multiple jet arrays had effect on the spatial variation and rate of boiling heat transfer on quenching surface. Higher area-averaged and maximum surface heat flux was obtained by 2-row array while array’s total flow rate was kept constant. It was found that by impinging constant water flow rate into the jets, 2-row array with twice the number of impinging jets enhanced heat transfer significantly in film and transition boiling regime in combination with other quenching parameters.
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| 6. |
- Anton Remirez, Raul, et al.
(författare)
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Detailed CFD modelling of EMC screen for radio base stations : a benchmark study
- 2007
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Ingår i: IEEE transactions on components and packaging technologies. - 1521-3331 .- 1557-9972. ; 30:4, s. 754-763
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper is to investigate the performance of five well-known turbulence models, in order to find a model that predicts the details of the flow patterns through an electromagnetic compatibility (EMC) screen. The turbulence models investigated in the present study are five different eddy-viscosity models; the standard k-ε model, the renormalization group (RNG) k-ε model, the realizable k-ε model, the standard k-ω model, as well as the shear stress transport k-ω model. A steady-state 3-D detailed model, which serves as the most accurate representation of the model, was used in order to evaluate the details of the airflow paths and pressure field. The flow was assumed to be isothermal, turbulent and incompressible. A general model that covers a considerable range of velocities and geometries was validated experimentally by wind tunnel measurements. The result shows that for most of the k-ε models used with correct y+ and mesh strategy, the pressure drop and the velocity field deviation is small compared to experimental data. The k-ω models overpredict the overall pressure drop. When using the RNG k-ε model, the total static pressure drop predicted differs around 5%-10% and the average velocity deviation at several locations before and after the screen is around 5%.
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| 7. |
- Chen, Huijuan, et al.
(författare)
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Numerical investigation of ventilation performance of different air supply devices in an office environment
- 2015
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 90, s. 37-50
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare ventilation performance of four different air supply devices in an office environment with respect to thermal comfort, ventilation efficiency and energy-saving potential, by performing numerical simulations. The devices have the acronyms: Mixing supply device (MSD), Wall confluent jets supply device (WCJSD), Impinging jet supply device (IJSD) and Displacement supply device (DSD). Comparisons were made under identical set-up conditions, as well as at the same occupied zone temperature of about 24.2°C achieved by adding different heat loads and using different air-flow rates. Energy-saving potential was addressed based on the air-flow rate and the related fan power required for obtaining a similar occupied zone temperature for each device. Results showed that the WCJSD and IJSD could provide an acceptable thermal environment while removing excess heat more efficiently than the MSD, as it combined the positive effects of both mixing and stratification principles. This benefit also meant that this devices required less fan power than the MSD for obtaining equivalent occupant zone temperature. The DSD showed a superior performance on heat removal, air exchange efficiency and energy saving to all other devices, but it had difficulties in providing acceptable vertical temperature gradient between the ankle and neck levels for a standing person.
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| 8. |
- Janbakhsh, Setareh
(författare)
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A Ventilation Strategy Based on Confluent Jets : An Experimental and Numerical Study
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study presents air distribution systems that are based on confluent jets; this system can be of interest for the establishment of indoor environments, to fulfill the goals of indoor climate and energy-efficient usage. The main objective of this study is to provide deeper understanding of the flow field development of a supply device that is designed based on wall confluent jets and to investigate the ventilation performance by experimental and numerical methods. In this study, the supply device can be described as an array of round jets on a flat surface attached to a side wall. Multiple round jets that issue from supply device apertures are combined at a certain distance downstream from the device and behave as a united jet or so-called confluent jets. Multiple round jets that are generated from the supply device move downward and are attached to the wall at the primary region, due to the Coanda effect, and then they become wall confluent jets until the floor wall is reached. A wall jet in a secondary region is formed along the floor after the stagnation region.The characteristics of the flow field and the ventilation performance of conventional wall confluent jets and modified wall confluent jets supply devices are investigated experimentally in an office test room. The study of the modified wall confluent jets is intended to improve the efficiency of the conventional one while maintaining acceptable thermal comfort in an office environment. The results show that the modified wall confluent jets supply device can provide acceptable thermal comfort for the occupant with lower airflow rate compared to the conventional wall confluent jets supply device.Numerical predictions using three turbulence models (renormalization group (RNG k– ε), realizable (Re k– ε), and shear stress transport (SST k– ω) are evaluated by measurement results. The computational box and nozzle plate models are used to model the inlet boundary conditions of the nozzle device. In the isothermal study, the wall confluent jets in the primary region and the wall jet in the secondary region, when predicted by the three turbulence models, are in good agreement with the measurements. The non-isothermal validation studies show that the SST k– ω model is slightly better at predicting the wall confluent jets than the other two models. The SST k– ω model is used to investigate the effects of the nozzle diameter, number of nozzles, nozzle array configuration, and inlet discharge height on the ventilation performance of the proposed wall confluent jets supply device. The nozzle diameter and number of nozzles play important roles in determining the airflow pattern, temperature field, and draught distribution. Increased temperature stratification and less draught distribution are achieved by increasing the nozzle diameter and number of nozzles. The supply device with smaller nozzle diameters and fewer nozzles yields rather uniform temperature distribution due to the dominant effect of mixing. The flow behavior is nearly independent of the inlet discharge height for the studied range.The proposed wall confluent jets supply device is compared with a mixing supply device, impinging supply device and displacement supply device. The results show that the proposed wall confluent jets supply device has the combined behavior of both mixing and stratification principles. The proposed wall confluent jets supply device provides better overall ventilation performance than the mixing and displacement supply devices used in this study.This study covers also another application of confluent jets that is based on impinging technology. The supply device under consideration has an array of round jets on a curve. Multiple jets issue from the supply device aperture, in which the supply device is positioned vertically and the jets are directed against a target wall. The flow behavior and ventilation performance of the impinging confluent jets supply device is studied experimentally in an industrial premise. The results show that the impinging confluent jets supply device maintains acceptable thermal comfort in the occupied zone by creating well-distributed airflow during cold and hot seasons.
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| 9. |
- Larsson, Johan, et al.
(författare)
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Leadership, quality and health: using McGregor's X and Y theory for analyzing values in relation to methodologies and outcomes
- 2007
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Ingår i: Total Quality Management and Business Excellence. - : Informa UK Limited. - 1478-3363 .- 1478-3371. ; 18:9-10, s. 1147-1168
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Tidskriftsartikel (refereegranskat)abstract
- Sweden has experienced an increase in sickness absenteeism, stress related health problems and a deterioration of psychosocial working conditions. Several researchers have emphasized that leadership with a focus on developing human resource practices is a necessary component of a high organizational performance. The purpose of this article is to explore whether there are patterns in leadership values and methodologies associated with subordinates´ views of leadership, health outcomes and quality aspects. Four public and four private organizations in northern Sweden were studied. McGregor´s X and Y hypotheses, plus three other hypotheses, were used as a base for the analyses. Data was gathered through in-depth interviews with the leaders, questionnaires (completed by leaders and co-workers), and assessment of selected human resource accounting data (sickness absenteeism). The leader views were mirrored with the co-worker views through a comparison of qualitative and quantitative results in a stepwise analysis process. The study´s main findings were that leaders with more X hypotheses get lower results concerning employee judged leadership and quality aspects and, to some extent, lower results concerning health outcomes. The explanatory analyses concerning leadership and health are complex with many influencing factors.
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| 10. |
- Larsson, Johan, et al.
(författare)
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Leadership Values for Quality and Health - How does McGregor's X and Y Theory Influences Methodologies and Outcomes?
- 2005
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Ingår i: Proceedings of the 8th International Conference on Quality Management for Organisational and Regional Development : QMOD 2005. - Luleå. ; , s. 691-702, s. 691-702, s. 691-702
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Konferensbidrag (refereegranskat)abstract
- During the last years the Swedish working life has been characterized by increased levels of sickness absenteeism, stress related health problems and a deterioration of the psychosocial work conditions. Since there are clear local variations concerning health at different workplaces, it is often stated that differences in working environment and work organizational factors constitute an important explanation. Several researchers emphasizes that leadership with a focus on developing human resource practices is a necessary component of high organizational performance. The purpose of this article is to explore if there are patterns in leadership values and methodologies connected to health outcomes and quality aspects. McGregor�s X and Y hypotheses plus three other hypotheses are used as a base for the analyses. Data has been collected by in-deep interviews with the leaders, questionnaires to both leaders and all employees, and human resource accounting figures. The leader views are mirrored with the employee views, by comparing qualitative and quantitative results in a step wise analyses process. Case study organizations are four public and four private organizations in northern Sweden. The study main findings are that leaders with more X hypotheses get lower results concerning employee judged leadership and quality aspects, and to some extent also lower results concerning health outcomes. Clear differences between the studied organizations are noted. One interesting result is that one organization (C1) positively distinguishes concerning quality and health aspects. A conclusion in this study is that Y oriented leaders work more intense with the TQM values continuous improvements, base decisions on facts, co-worker commitment and leadership commitment.
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