排序方式： 共有18条查询结果，搜索用时 15 毫秒
1.
2.
3.
Aimed at attaining to an integrated and effective pattern to guide the port design process, this paper pats forward a new conception of feature solution, which is based on the parameterized feature modeling. With this solution, the overall port pre-design process can be conducted in a virtual pattern. Moreover, to evaluate the advantages of the new design pattern, an application of port system has been involved in this paper; and in the process of application a computational fluid dynamic analysis is concerned. An ideal effect of cleanness, high efficiency and high precision has been achieved. 相似文献
4.
针对旋风除尘器的磨损,堵塞以及排尘效率低下等问题,探析原因,并提出了新的改进方案,以提高旋风除尘器的分离效率,为进一步挖掘旋风除尘器的潜在性能提供新的策略。 相似文献
5.
AZ31B magnesium alloy was subjected to friction stir welding with various welding parameters. The equivalent Young’s moduli of the friction stir welded samples and the base material were obtained by the three-point method, and their transverse rigidities were obtained as well. Furthermore, the sound transmission characteristics of those samples were experimentally studied by four-microphone impedance tube method. The experimental results indicate that the transverse rigidities of the friction stir welded samples were only 79%, 83% and 92% of those of the base material, respectively. The sound transmission losses of the processed samples were also lower, which was largely due to the reduction of transverse rigidities induced by the decrease of equivalent Young’s moduli. 相似文献
6.
A hybrid of ensemble empirical mode decomposition and empirical mode decomposition (EEMD-EMD) is introduced to diagnose the valve-slap vibration signal,which is relative to the dominant combustion knock vibration signal given out by a diesel engine around the top dead center (TDC).The time-frequency representations of intrinsic mode functions (IMFs) decomposed by EEMD-EMD are obtained by adaptive generalized S transform (AGST).A type 493 diesel engine was used for the experiment,and the result indicates that the valve-slap of the diesel engine is serious,and the vibration frequencies are higher than the combustion knock.With EEMD-EMD-AGST approach,the valve-slap can be identified by the vibration analysis of the diesel engine. 相似文献
7.
根据汽轮发电机组转子轴系的结构特点建立了一种大型转子轴系弹性连续体扭振模型 ,推导了轴系连续质量分布系统的扭振波动方程 ,进行了 3 0 0 MW汽轮发电机组轴系扭振固有特性的解析研究和计算分析 相似文献
8.
Acoustic signals from diesel engines contain useful information but also include considerable noise components. To extract information for condition monitoring purposes, continuous wavelet transform (CWT) is used for the characterization of engine acoustics. This paper first reviews CWT characteristics represented by short duration transient signals. Wavelet selection and CWT are then implemented and wavelet transform is used to analyze the major sources of the engine front's exterior radiation sound. The research provides a reliable basis for engineering practice to reduce vehicle sound level. Comparison of the identification results of the measured acoustic signals with the identification results of the measured surface vibration showed good agreement. 相似文献
9.
“微课”是指按照新课程标准及教学实践要求,以视频为主要载体,记录教师在课堂内外教育教学过程中围绕某个知识点(重点难点疑点)或教学环节而开展的精彩教与学活动全过程.
1 “微课”的组成
“微课”的核心组成内容是课堂教学视频(课例片段),同时还包含与该教学主题相关的教学设计、素材课件、教学反思、练习测试及学生反馈、教师点评等辅助性教学资源,它们以一定的组织关系和呈现方式共同“营造”了一个半结构化、主题式的资源单元应用“小环境”.因此,“微课”既有别于传统单一资源类型的教学课例、教学课件、教学设计、教学反思等教学资源,又是在其基础上继承和发展起来的一种新型教学资源. 相似文献
10.
For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration
and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and primary balance shaft should be attached
to the cylinder block so that engine durability and ride comfortability may be further improved. Traditionally one third of
connecting rod assembly’s mass is treated as reciprocating mass, and two thirds as rotating mass when designing balance mechanism.
In this paper, a new method based on the multibody dynamics simulation is introduced to separate the reciprocating mass and
rotating mass of connecting rod assembly. The model consists of crankshaft, connecting rod, piston and the simulation is performed
subsequently. According to the simulation results of the main bearing loads, the reciprocating mass and rotating mass are
separated. Finally a new balance mechanism is designed and simulation results show that it completely balances inertial forces
to improve the engine’s noise vibration and harshness performance. 相似文献