original article   noise and vibration are the common problems in industrialized countries which can affect individual's job performance. the present study aimed to investigate the combination of the whole body vibration and the noise and their effects on the students' mental performance in the laboratory setting. twenty male students of tehran university of medical sciences, tehran, iran were ...

in this study, the mf285 tractor engine vibrations resulting from the use of different combinations of biodiesel, bioethanol and diesel as fuel were studied. engine vibrations in three directions and three engine speeds: 1000, 1600 rpm 2000 and ten fuel level was measured. to investigate the influence of measured parameters on engine vibration of factorial design in a randomized complete block ...

In this case, the diagnosis is admittedly challenging when based on coronal and sagittal images only. Indeed, the os acromiale, an un-united acromial ossification center in adults, is one of the most frequently missed abnormalities by physicians who interpret MR. The reason is twofold. For one, the os acromiale, when viewed in the coronal or sagittal planes, bears a strong resemblance to a norm...

Most of the holographic techniques applied so fa( for non·contacting measurements of surface displacements are highly sensitive. But the interpretation of the interference fringes obtained is usually rather difficult for a non-.expeft. especially for the study of tilts in the presence of lateral in-plane movements. Moire techniques could be applied to overcome some of the difficulties encounter...

whole body vibration can deteriorate health bringing about or back pain or spinal column injury, resulted from continuing exposure to vibration. also exposure to vibration can cause disorder in central nervous system and adversely influence vascular and skeletal systems. in this research, the vibration of universal 650m tractor seat and its effect on the operator in five levels of engine speeds...

Tool wear is one of the most important considerations in machining operations, as it affects surface quality and integrity, productivity, and cost. The most commonly used model for tool life analysis is the one proposed by F. W. Taylor about a century ago. Although the extended form of this equation includes the effects of important cutting conditions on tool wear, tool life studies are mostly ...

We study the effects of a small curvature of the middle plane of a thickness-shear mode crystal plate resonator on its vibration frequencies, modes and acceleration sensitivity. Two-dimensional equations for coupled thickness-shear, flexural and extensional vibrations of a shallow shell are used. The equations are simplified to a single equation for thickness-shear, and two equations for couple...

A classical example of chatter prone machining is the boring operation. Turning under conditions with high vibrations in the cutting tool deteriorates the surface finish and may cause tool breakage. Severe noise is also a consequence of the high vibration levels in the boring bar. Active control is one possible solution to the noise and vibration problem in boring operations. In boring operatio...

this research is carried out to design and manufacturing of lathe vibration tool and their tests. firstly, one-dimensional vibration tool is designed and made of the bending vibration mode. one-dimensional vibration tool with half piezoelectric rings is considered to excite the bending mode of tool. structure of vibration tool is designed in abaqus software about 20 khz and then is made with re...