Browsing by Author "Ahmad, Wasim"
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Item Open Access Cost modelling system for lean product and process development(Cranfield University, 2012-09) Ahmad, Wasim; Shehab, Essam; Abdalla, Hassan S.This PhD project aims to develop a cost modelling system to support lean product and process development. The system enables the designers to assess the design along with associated manufacturing processes and provides decision support at an early development stage. Design assessment at early development stage can help designers to take proactive decisions, eliminate mistakes and enhance product value. The developed cost modelling system to support lean product and process development incorporates three lean product and process development enablers, namely set-based concurrent engineering, knowledge-based engineering, and mistake-proofing (poka-yoke). To facilitate above explained lean enablers, the system architecture contains six modules, six separate groups of database, a CAD modelling system, and a user interface. The system modules are: (i) value identification; (ii) manufacturing process/machines selection; (iii) material selection; (iv) geometric features specification; (v) geometric features and manufacturability assessment; and (vi) manufacturing time and cost estimation. The group of database includes: (i) geometric features database, (ii) material database, (iii) machine database, (iv) geometric features assessment database, (v) manufacturability assessment database, and (vi) previous projects cost database. A number of activities have been accomplished to develop the cost modelling system. Firstly, an extensive literature review related to cost estimation, and lean product and process development was performed. Secondly, a field study in European industry and a case study analysis were carried out to identify current industrial practices and challenges. Thirdly, a cost modelling system to support lean product and process development was developed. Finally, validation of the system was carried out using real life industrial case studies. The system provides a number of benefits, as it enables designers to incorporate lean thinking in cost estimation. It takes into consideration downstream manufacturable process information at an early upstream stage of the design and as a result the designer performs the process concurrently and makes decisions quickly. Moreover, the system helps to avoid mistakes during product features design, material and manufacturing process selection, and process parameters generation; hence it guides toward a mistake-proof product development. The main feature of the system, in addition to manufacturing cost estimation, is set-based concurrent engineering support; because the system provides a number of design values for alternative design concepts to identify the feasible design region. The major contribution of the developed system is the identification and incorporation of three major lean product and process development enablers, namely set-based concurrent engineering, knowledge-based engineering and poka-yoke (mistake-proofing) in the cost modelling system. A quantification method has been proposed to eliminate the weaker solution among several alternatives; therefore only the feasible or strong solution is selected. In addition, a new cost estimation process to support lean product and process development has been developed which assists above explained three lean product and process development enablers.Item Embargo Do new CEOs really care about innovation?(Wiley, 2023-01-04) Ahmad, Wasim; Farag, Hisham; Wang, YaopengThis study asks whether new CEOs care about innovation post-turnover. Using a large sample of Chinese listed firms between 2008 and 2019, our identification strategy relies on the exogenous variation in CEO turnovers. Our difference-in-difference estimates indicate that new CEOs improve R&D efficiency and generate more and higher quality patents. We further show that this positive effect is more pronounced when CEOs have longer career horizons and overseas experience. Overall, our findings indicate that CEO turnover represents an effective mechanism for fostering innovation and new CEOs indeed care about innovation. Our results could benefit several groups of stakeholders with respect to CEO selection process.Item Open Access Effect of different dielectrics on material removal rate, electrode wear rate and microstructures in EDM(Elsevier, 2017-05-09) Niamat, Misbah; Sarfraz, Shoaib; Aziz, Haris; Jahanzaib, Mirza; Shehab, Essam; Ahmad, Wasim; Hussain, SalmanDiesinker electric discharge machining is widely used non-conventional technique for making high precision and complex shaped parts. Dielectrics and electrical parameters were considered as the main factors for EDM performance. In this paper, the effects of pulse-on-time (μs) and current (ampere) were evaluated for performance measures using kerosene and water as dielectrics. A comparison was performed for both dielectrics in terms of material removal rate (mm3/min), electrode wear rate (mm3/min), and microstructures. Aluminum 6061 T6 alloy was used as material for this research due to its extensive use in aerospace and automotive industries. Experiments were designed using Taguchi L9 orthogonal array (OA). Time series graphs were plotted to compare material removal rate and electrode wear rate. Microstructures were taken by scanning electron microscope to analyze the surface produced in terms of cracks, globules and micro-holes. Higher material removal rate and lower electrode wear were achieved with kerosene dielectric. The novelty of this research work, apart from its practical application, is that Aluminum 6061 T6 alloy is used as work material to compare the performance of dielectrics (kerosene and distilled water). Paper presented at: Complex Systems Engineering and Development Proceedings of the 27th CIRP Design Conference Cranfield University, UK 10th – 12th May 2017.Item Open Access Parametric modelling and multi-objective optimization of electro discharge machining process parameters for sustainable production(MDPI, 2019-12-19) Niamat, Misbah; Sarfraz, Shoaib; Ahmad, Wasim; Shehab, Essam; Salonitis, KonstantinosElectro Discharge Machining (EDM) can be an element of a sustainable manufacturing system. In the present study, the sustainability implications of EDM of special-purpose steels are investigated. The machining quality (minimum surface roughness), productivity (material removal rate) improvement and cost (electrode wear rate) minimization are considered. The influence and correlation of the three most important machining parameters including pulse on time, current and pulse off time have been investigated on sustainable production. Empirical models have been established based on response surface methodology for material removal rate, electrode wear rate and surface roughness. The investigation, validation and deeper insights of developed models have been performed using ANOVA, validation experiments and microstructure analysis respectively. Pulse on time and current both appeared as the prominent process parameters having a significant influence on all three measured performance metrics. Multi-objective optimization has been performed in order to achieve sustainability by establishing a compromise between minimum quality, minimum cost and maximum productivity. Sustainability contour plots have been developed to select suitable desirability. The sustainability results indicated that a high level of 75.5% sustainable desirability can be achieved for AISI L3 tool steel. The developed models can be practiced on the shop floor practically to attain a certain desirability appropriate for particular machine limits.Item Open Access Shareholder litigation and private benefits of control: evidence from derivative lawsuits(SSRN: Social Science Research Network, 2024-02-02) Yang, Chaoran; Ahmad, Wasim; Radic, NemanjaWe examine the effects of derivative litigation risks on the value of private benefits of control. Quantifying the value of private benefits of control using the voting premiums from option prices, we find that the value of the voting premium significantly decreases after firms experience derivative lawsuits. To address endogeneity concerns, we exploit the staggered adoption of Universal Demand (UD) laws across 23 U.S. states from 1989 to 2005 to investigate whether and how the reduction in litigation risks affects the level of voting premium. The results show that the adoption of UD laws increases the value of voting premiums. Our DID results are robust to a battery of tests. We also find that the adoption of UD laws leads to a decrease in the value of cash holdings, an increase in CEO cash compensation, and a decrease in investment efficiency and these effects are more pronounced for dual-class firms. Overall, our findings suggest that shareholder litigation can effectively curb the managerial extraction of private benefits. It has important implications for managers, shareholders, and policymakers.