考虑振动频率的爆破振动安全标准的探讨

爆破振动安全标准如果不考虑振动频率的影响,则难以准确地衡量爆破振动的危害。文中在分析爆破振动频率对爆破振动的作用后,运用分形理论对其进行定量计算,得出考虑振动频率的爆破振动速度安全判别标准。并针对现场应用。提出采用简单易行的计频允许振速代替单一的爆破质点振动速度来判别爆破安全标准。     

Effects of vibration on the grain morphology

Pairs of halogen lamps were heated simultaneously at various rates of temperature increase through the recrystallization temperature and were held for five hours at 120 volts. One lamp in each of 20 pairs was vibrated during lightup. Examination of the grain boundaries of the filaments revealed that 63 pct of the boundaries in the vibrated lamps were “transverse.” In the lamps not vibrated, 52 pct of the boundaries were “transverse.” The greater number of “trans- verse” grain boundaries in the vibrated lamps is attributed to grain boundary sliding, which generates additional energy to allow the grain boundary to overcome the restraint to migration provided by the strings of potassium bubbles in the lamp wire. Formerly with GE Corporate Research and Formerly with GE Corporate Research and Formerly with the Technology Division, GE Lighting, Nela Park, Formerly with the Technology Division, GE Lighting, Nela Park,     

一种振动流化床式煤调湿工艺的半工业化试验

以新开发的一套振动流化床式煤调湿半工业化试验装置为研究对象,考察了这种煤调湿工艺的可行性,以焦炉烟道废气作为煤粉干燥介质,研究了烟气用量、烟气初始温度、煤粉下料速度和煤粉初始湿度对煤调湿结果的影响,得到了这种煤调湿工艺运行的控制参数。结果表明:当烟气用量为1200m3/h,烟气初始温度在220℃以上,煤粉下料速度在600kg/h,煤粉初始湿度在9%～12%之间,得到上、下筛出口的煤粉的湿度在5%～7%范围,能够满足焦化对煤粉湿度的要求。     

Cold rolling with vibration of the working rollers

By means of DEFORM-2 software, cold rolling with vibration of the working rollers is simulated. It is found that self-oscillation significantly affects the fluctuation of the longitudinal stress in the metal and the rolling forces in adjacent stands of the continuous mill; and only slightly affects the longitudinal thickness variation of the strip. That leads to deviations in the surface profile.     

Basilar membrane vibration in the gerbil hemicochlea

Excised gerbil cochleae were cut along the mid-modiolar plane (hemicochlea). Along one-half turn of this preparation, fluorescent microbeads were placed on the basilar membrane (BM). The BM was vibrated with click stimuli (50 micros) produced mechanically by a piezo pusher. The stimulus delivery probe could be positioned either more apical or more basal from the beads. Vibration patterns were measured with a wide bandwidth photomultiplier from the movements of the beads. When the probe was positioned more basal, the responses to click stimuli were brief, damped sinusoids. According to the fast Fourier transforms (FFTs) of the averaged time wave forms, the best frequency between successive beads decreased toward the apex (0.8 octave/mm). Sharpness of tuning of the normalized FFT spectra (NQ10dB) on average was 1.5. Response amplitude at a fixed input level, measured at different beads away from the stimulation site, dropped exponentially (58 dB/mm). In addition, for each individual bead, amplitude dropped linearly with decreasing stimulus intensity. In experiments where the stimulating probe was placed more apical, two major properties were observed: first, beads revealed only the spectral components present in the motion of the probe. Second, magnitude reduction of the displacement of the cochlear partition was greater, on average 155 dB/mm, indicating a lack of significant propagation in the reverse direction.     

超声振动钻削试验系统设计

对超声振动钻削系统各关键部分的设计进行介绍,利用该系统对HT200、ZcuPb30进行超声振动钻削试验.结果表明,振动钻削具有钻削扭矩小、钻孔扭矩波动小、扩孔量小等优点.     

轧机主传动电机振动故障处理

振动是电机的常见故障之一。结合一起轧机主传动电机振动故障的处理经过，对电机振动故障的分析方法和处理经验进行总结。     

槽电压振动解析

该文介绍了一种实际应用在106kA上插自焙电解槽上的计算机检测电压振动并进行振动解析的方法。     

Torsional vibration measurement of the viscosity of a metallic melt

The liquid Co₉₁B₉ alloy is used as an example to study the influence of boundary conditions at the upper melt boundary on the results of viscosity measurements using torsional vibrations. Specific features related to film effects and wetting phenomena are shown to appear in the temperature dependence of logarithmic decrement. To exclude the influence of these effects and phenomena, viscosity measurements should be performed under the experimental conditions where the melt to be studied is in closed volume and the internal crucible walls are fully wetted. The temperature dependence of the kinematic viscosity of the Co₉₁B₉ melt that is obtained under such experimental conditions has a monotonic character.     

Efficacy of vibration, electric current and thermal perception tests in diagnosis of hand-arm vibration syndrome

We previously found that human melanoma (A375M) and human breast cancer (MDA-MB-231) cells formed osteolytic bone metastasis in vivo. These cancer cells produced interleukin-11 (IL-11) by themselves and stimulated its production from osteoblasts. Interleukin-11 could increase the number of osteoclasts and raise the calcium concentration in the medium of neonatal murine calvaria organ culture, indicating bone resorption in vitro. Therefore, IL-11 could play an important role in the promotion of osteolysis at the site of bone metastasis. In the present study, we used the calvaria culture system to try to clarify the mechanisms of IL-11-mediated bone resorption. The murine calvaria expressed both the specificity-determining alpha subunit and the signal-transducing beta subunit (gp130) of the IL-11 receptor. When IL-11 was added to the calvaria culture, the concentrations of prostaglandin E2 (PGE2) was elevated. Pretreatment of calvaria with cyclooxygenases inhibitors (e.g., indomethacin, NS-398, and dexamethasone) suppressed the production of PGE2 and the bone resorption induced by IL-11. Addition of exogenous PGE2 overcame the inhibitory effect of cyclooxygenases inhibitors and promoted bone resorption. These results indicate that IL-11 promotes bone resorption through a PGE2 synthesis-dependent mechanism and that cyclooxygenases inhibitors could be interesting drugs to suppress IL-11-mediated osteolytic bone metastasis of cancer cells.     

Magnetic fluid separation of gold-containing products in the vibration field

New data on the process of the magnetic fluid (MF) separation, which is based on the ponderomotive effect of the magnetized separation medium—or ferromagnetic fluid (FMF) on the nonmagnetic bodies arranged in it—are obtained. The magnetization of the FMF in a nonuniform magnetic field increases the strength of the field of mass forces affecting the FMF and, as a consequence, the pressure gradient in the FMF. This phenomenon can be considered pseudoweighting of the FMF and, when controlling the magnetic field force, it can be used to separate nonmagnetic materials according to their specific weights. The behavior of the FMF in the vibration field is investigated theoretically, and the dependence of energy absorbed by it on the amplitude and frequency of vibrations is revealed. Under industrial conditions, a series of tests on separation of free gold from the products of washing the goldfields by the method of MF separation is performed. The results of these tests prove the prospects of including secondary Au-containing resources with difficult-to-recover gold in processing.     

轧机液压系统振动故障的诊断与分析

主要介绍了轧机中的液压系统的振动的类型、原因,以及抑制液压系统振动的对策,对轧机的液压系统的振动故障的避免和解决作了积极的探索.     

Evaluating the effectiveness of gloves in reducing the hazards of hand-transmitted vibration

OBJECTIVES: A method of evaluating the effectiveness of gloves in reducing the hazards of hand-transmitted vibration is proposed. METHOD: The glove isolation effectiveness was calculated from: (a) the measured transmissibility of a glove, (b) the vibration spectrum on the handle of a specific tool (or class of tools), and (c) the frequency weighting indicating the degree to which different frequencies of vibration cause injury. With previously reported tool vibration spectra and glove transmissibilities (from 10-1000 Hz), the method was used to test 10 gloves with 20 different powered tools. RESULTS: The frequency weighting for hand-transmitted vibration advocated in British standard 6842 (1987) and international standard 5349 (1986) greatly influences the apparent isolation effectiveness of gloves. With the frequency weighting, the gloves had little effect on the transmission of vibration to the hand from most of the tools. Only for two or three tools (those dominated by high frequency vibration) did any glove provide useful attenuation. Without the frequency weighting, some gloves showed useful attenuation of the vibration on most powered tools. CONCLUSIONS: In view of the uncertain effect of the vibration frequency in the causation of disorders from hand-transmitted vibration, it is provisionally suggested that the wearing of a glove by the user of a particular vibratory tool could be encouraged if the glove reduces the transmission of vibration when it is evaluated without the frequency weighting and does not increase the vibration when it is evaluated with the frequency weighting. A current international standard for the measurement and evaluation of the vibration transmitted by gloves can classify a glove as an antivibration glove when it provides no useful attenuation of vibration, whereas a glove providing useful attenuation of vibration on a specific tool can fail the test.     

风机振动的原因浅析

在风机的各种故障当中,由于振动引起的故障最为常见.针对风机振动的原因进行了分析,同时对存在的问题进行了改进,提高了风机的寿命,为故障的诊断和日常检验提供了重要依据.     

The hemorheologic effects of hand-transmitted vibration

Vibration white finger (VWF) is an ischemic condition of the hands that is associated with long-term exposure to hand-held vibration tools. The pathophysiology of VWF remains unknown. The aim of this study was to assess the hemorheologic effect of acute hand-transmitted vibration. This study investigated 52 men divided into two groups: VWF = 29, mean age 46.9 years (range twenty-two to sixty-six); Controls = 23, mean age 42.8 years (range twenty to sixty-four). Each subject gripped a vibrating handle for seven minutes thirty seconds at a vibration frequency of 120 Hz with an amplitude of displacement of 0.25 mm. Venous blood was analyzed before and after acute vibration to determine the hematocrit, the plasma hemoglobin concentration, plasma viscosity, and red cell deformability, expressed as red cell transit time (RCTT). At rest, there was no significant difference in RCTT, plasma viscosity, hematocrit, and plasma hemoglobin concentration between the VWF group and controls. Acute vibration did, however, significantly increase the red cell transit time in the VWF group but not in the control group. In both groups vibration resulted in a significant increase in plasma viscosity, hematocrit, and plasma hemoglobin concentration in hand venous blood. Moreover, in each group there was a highly significant correlation between the change in plasma viscosity and the change in the hemoglobin concentration and the hematocrit. The authors conclude that hand-transmitted vibration is associated with hemoconcentration.