奇异值分解(Singular value decomposition,SVD)作为一种有效的信号降噪方法广泛应用于旋转机械振动信号周期性瞬态冲击提取中。传统SVD以能量为导向,无法提取出能量较弱但含故障信息丰富的奇异分量(Singular Component,SC)。为此,提出...奇异值分解(Singular value decomposition,SVD)作为一种有效的信号降噪方法广泛应用于旋转机械振动信号周期性瞬态冲击提取中。传统SVD以能量为导向,无法提取出能量较弱但含故障信息丰富的奇异分量(Singular Component,SC)。为此,提出加权firm阈值奇异值分解(Weighted Firm Singular Value Decomposition,WFSVD)方法。该方法首先引入平方包络谱峭度(Squared Envelope Spectrum Kurtosis,SESK)作为量化故障敏感度的指标,以评估各个SC所含故障信息的丰富程度;其次,将SESK作为权重因子引入到基于firm阈值的SC去噪中,设计基于SESK的加权firm阈值SC去噪策略;最后,重构信号,实现信号降噪并有效提取故障特征。对于仿真信号与试验数据的分析验证了所提方法在周期性微弱瞬态冲击提取及旋转机械故障诊断中的有效性。展开更多
Annular grooved projectiles(AGPs)have drawn ongoing concerns as an advanced penetrator for their excellent anti-rebound capability in impacting metal plates.They could become embedded solidly in the target surface dur...Annular grooved projectiles(AGPs)have drawn ongoing concerns as an advanced penetrator for their excellent anti-rebound capability in impacting metal plates.They could become embedded solidly in the target surface during low-velocity impact.In this investigation,the firm embedding behavior of AGP was observed by impact experiments.Corresponding numerical simulations provided a better understanding of this process.Experimental and numerical results indicated that the firm embedding behavior of AGP was mainly due to the filling-material in the groove rather than the friction between the projectile and target,unlike traditional shape such as conical projectile.According to observation,firm embedding process can generally be subdivided into four stages:initial-cratering stage,groove-filling stage,fillingmaterial failure stage and rebound vibration stage.Moreover,the damage mechanics of target material around crater was obtained through microscopic tests.A comparison of the cross-sectional figures between the experiment and simulation proved that the analysis and the proposed method were reasonable and feasible,which further demonstrated that the firm embedding behavior has application potential in new concept warheads.展开更多
In recent decades, the world economy has been stron gl y driven by worldwide foreign direct investment (FDI) of transnational corporati ons (TNCs). And business globalisation is leading to widespread re-structuring of...In recent decades, the world economy has been stron gl y driven by worldwide foreign direct investment (FDI) of transnational corporati ons (TNCs). And business globalisation is leading to widespread re-structuring of international manufacturing systems in TNCs. However, still very little sys tematic research in manufacturing engineering or production/operations managemen t (P/O M) has focused on these new types of globalised manufacturing systems, an d little communication is organised between different academic disciplines such as manufacturing, management/ business studies, economics, geography, internatio nal development studies and so on. Many critical issues are still poorly unders tood and are not covered by current research agendas, for example: · properties of international manufacturing network systems in terms of structu ral architecture, dynamic mechanisms, strategic capabilities, strategy processes , new technology, and alliance relationships · knowledge management and organisational learning mechanisms in international manufacturing context, especially in globally coordinated networks at both intra - and inter- organisational levels · global economic trends, regional collaboration, national culture/identity, an d their impacts on industrial sector development, and company’s manufacturin g system design/re-structuring In industry, lack of global vision and appropriate strategies during internation alisation have become major barrier to the effective management of international operations. In academia, limited multi-discipline exchanges have inhibited de velopments not only in each area but also knowledge contribution to industry whi ch could arise from discipline integration. This paper, based on recent years case observations and action research work on manufacturing internationalisation, especially globalisation, introduces an evol utionary process of manufacturing systems. It seeks to explore the external and internal driving forces of the transformation and the responses of manufacturin g systems in terms of static architectures, dynamic mechanisms, and strategic ca pabilities in the evolutionary process. The paper Reviews recent researches on manufacturing internationalisation in dif ferent disciplines to gain a comprehensive picture about international manufactu ring system from different perspectives. Based on the empirical observations of industrial issues and difficulties, a further research framework is proposed to tackle wider issues in international manufacturing covering manufacturing value creation process, internationalisation process, and strategic alliance formatio n process. The paper argues that, besides deep research on three dimensions of international manufacturing system, development of strategy process to synthesis e these three processes is more important in the future research work. It sugge sts that it is necessary to enhance the collaboration between countries and disc iplines, and stimulate explorations of new frameworks that can provide more insi ghts about new manufacturing systems and foresights their development.展开更多
基金financially supported by the National Natural Science Foundation of China [grant number 11472053]
文摘Annular grooved projectiles(AGPs)have drawn ongoing concerns as an advanced penetrator for their excellent anti-rebound capability in impacting metal plates.They could become embedded solidly in the target surface during low-velocity impact.In this investigation,the firm embedding behavior of AGP was observed by impact experiments.Corresponding numerical simulations provided a better understanding of this process.Experimental and numerical results indicated that the firm embedding behavior of AGP was mainly due to the filling-material in the groove rather than the friction between the projectile and target,unlike traditional shape such as conical projectile.According to observation,firm embedding process can generally be subdivided into four stages:initial-cratering stage,groove-filling stage,fillingmaterial failure stage and rebound vibration stage.Moreover,the damage mechanics of target material around crater was obtained through microscopic tests.A comparison of the cross-sectional figures between the experiment and simulation proved that the analysis and the proposed method were reasonable and feasible,which further demonstrated that the firm embedding behavior has application potential in new concept warheads.
文摘In recent decades, the world economy has been stron gl y driven by worldwide foreign direct investment (FDI) of transnational corporati ons (TNCs). And business globalisation is leading to widespread re-structuring of international manufacturing systems in TNCs. However, still very little sys tematic research in manufacturing engineering or production/operations managemen t (P/O M) has focused on these new types of globalised manufacturing systems, an d little communication is organised between different academic disciplines such as manufacturing, management/ business studies, economics, geography, internatio nal development studies and so on. Many critical issues are still poorly unders tood and are not covered by current research agendas, for example: · properties of international manufacturing network systems in terms of structu ral architecture, dynamic mechanisms, strategic capabilities, strategy processes , new technology, and alliance relationships · knowledge management and organisational learning mechanisms in international manufacturing context, especially in globally coordinated networks at both intra - and inter- organisational levels · global economic trends, regional collaboration, national culture/identity, an d their impacts on industrial sector development, and company’s manufacturin g system design/re-structuring In industry, lack of global vision and appropriate strategies during internation alisation have become major barrier to the effective management of international operations. In academia, limited multi-discipline exchanges have inhibited de velopments not only in each area but also knowledge contribution to industry whi ch could arise from discipline integration. This paper, based on recent years case observations and action research work on manufacturing internationalisation, especially globalisation, introduces an evol utionary process of manufacturing systems. It seeks to explore the external and internal driving forces of the transformation and the responses of manufacturin g systems in terms of static architectures, dynamic mechanisms, and strategic ca pabilities in the evolutionary process. The paper Reviews recent researches on manufacturing internationalisation in dif ferent disciplines to gain a comprehensive picture about international manufactu ring system from different perspectives. Based on the empirical observations of industrial issues and difficulties, a further research framework is proposed to tackle wider issues in international manufacturing covering manufacturing value creation process, internationalisation process, and strategic alliance formatio n process. The paper argues that, besides deep research on three dimensions of international manufacturing system, development of strategy process to synthesis e these three processes is more important in the future research work. It sugge sts that it is necessary to enhance the collaboration between countries and disc iplines, and stimulate explorations of new frameworks that can provide more insi ghts about new manufacturing systems and foresights their development.
