前列腺增生合并膀胱结石体外冲击波碎石治疗206例分析

为了探讨前列腺增生患者膀胱结石体外冲击波碎石治疗的规律,对206例高龄男性患者膀胱结石进行体外冲击波碎石治疗,疗效满意.体外冲击波碎石治疗前列腺增生患者膀胱结石安全可靠,治愈率高,是较理想的方法.     

新型物料可控流、转、运除尘系统设计与应用

针对物料皮带输送中二次扬尘的问题,设计了新型物料可控流转运除尘系统.利用物料的运行特性,采用“约束”物料运行轨迹的办法抑制二次扬尘,避免了物料冲击,延长了输嘴使用寿命.     

采购供应链系统订货策略的设计

针对宝钢采购供应链系统中不同物料对应订货策略不同的问题,建立了物料的订购量模型;给出了物料安全库存设定的经验公式,并针对实际应用过程中有些量不能准确找到概率分布的问题,引入灰色模型对物料需求量、消耗量进行预测.通过对采购供应链系统中需求量的预测,给物料设定安全库存,采用不同物料的订购量模型,解决了采购供应链系统中的订货策略问题.实例表明,订货策略模型具有很强的实用性,为用户提供了较为实用的订货策略.     

钢铁业大宗物料堆料体积测定探讨

钢铁业原、燃大宗物料是生产主要成本,物料的收、发、存数据动态跟踪管理对指导生产经营有着指导意义,因而迫切需要快速、准确地测出各种物料的库存量,有利于控制物料采购量、降低大宗物料资金占用率,对科学决策和提升经济效益有着重要意义.提高钢铁企业大宗原燃料盘库的准确性,是困扰钢铁行业多年的难题,文章以常规盘点方式,探讨大宗物料体积测定发展方向.     

泡沫铝夹芯板水下抗爆性能的实验和数值模拟

采用PVDF压力传感器收集应力波数据的方法,对不同密度的泡沫铝夹芯板结构进行实爆实验,考察在有限水域爆炸下泡沫铝夹芯结构的抗爆炸冲击波衰减能力,并使用ANSYS/LS-DYNA软件对爆炸冲击波的传递过程进行数值模拟分析.研究结果表明,在相同爆炸加载条件下,四种密度泡沫铝夹芯板的抗爆炸冲击波衰减率均高于90％,低密度泡沫...     

炭素回转窑内物料活动层厚度的确定

根据炭素回转窑内物料的质量守恒定律和动量守恒定律,借助无量纲分析法,建立了回转窑内物料层的数学模型,并推导出了计算物料在滚落运动中活动层厚度的公式,该公式不仅为计算物料轴向速度和物料体积流率提供了重要参数,还为炭素回转窑工程设计提供了参考.     

京唐550m2烧结机台车上物料和烧结矿分区研究(Ⅰ)

通过在烧结现场吊取正常生产的烧结机台车,对台车上物料和烧结矿进行分区域研究,考察料层各区域烧结物料和烧结矿性能,发现京唐两台550 m2烧结机台车上物料分布存在以下问题:①粒度方面,1号机料层下部物料粒度过粗、偏析过大,导致熔剂粘附少；2号机台车横向上物料分布不均匀,从一侧到另一侧粒度差异较大.②成分方面,1号机熔剂主要偏析分布在料层上层,下层的物料粒度粗、熔剂少,物料化学成分和C含量的偏析均加剧；2号机上物料化学成分和C含量在第二层出现异常,表现出非线性偏折,仅在SiO,和Al2O3含量偏析上具有单调性.这些问题的存在,制约了烧结矿质量的提高.     

ISF处理高SiO2低Fe物料的生产实践

高SiO2低Fe物料的投入一度使ISF生产产生较大的波动.针对此类物料入炉后的炉况,分析了烧结块中SiO2和Fe在熔炼过程中的变化,及此类物料对生产的危害,并提出了相应的解决措施.根据实际生产中的实践操作实例可以看出,韶关冶炼厂的经验措施能有效地降低处理这类物料所带来的不利影响.     

一种从低品位铅物料中回收粗铅的方法

针对现有技术不能单独处理低品位铅物料,而只能与高品位铅物料配料处理的问题,提供一种利用富氧侧吹单独处理低品位铅物料的方法.     

异钢种连浇时物料消耗计算方法优化

异钢种连浇时存在铸坯划拨现象,导致利用ERP采集数据所计算的炼钢物料消耗失真.通过对异钢种连浇时物料消耗计算方法进行优化,解决了物料消耗失真现象,为同行业处理相同问题提供了借鉴经验.     

Flow Conditions of Undular Hydraulic Jumps in Horizontal Rectangular Channels

The flow conditions of undular jumps for fully developed inflow condition have been investigated systematically. If the inflow Froude number is larger than 1.2, an undular jump has lateral shock waves near the toe of the jump. For a narrow channel, the shock waves cross upstream of the first wave crest, and the flow conditions of undular jumps depend on the aspect ratio and the inflow Froude number. In contrast, for a wide channel the shock waves do not cross upstream of the first wave crest, and the flow conditions of undular jumps are independent of the aspect ratio. The flow conditions of undular jumps are classified by considering the cross position of the lateral shock waves and the inflow Froude number. Also, the hydraulic conditions for the formation of nonbreaking and breaking undular jumps are determined. The effect of the Reynolds number on undular-jump formations is discussed, and changes of the flow conditions with the Reynolds number are described.     

The effect of high-dose right upper quadrant lithotripsy on normal swine tissue

To assess the effects of high doses of shock waves to organs in the right upper quadrant of the abdomen, 36 adolescent swine were given one treatment of either 2,000 (2k), 6,000 (6k), or 10,000 (10k) shock waves at 24 kV peak pressure using a spark-gap lithotriptor. Shock waves were sonographically focused on the lumen of the gallbladder. Blood and tissue were examined for each group at 48 hours, at 35 days, and at 6 months. This study showed that administration of up to five times the accepted upper limit of shock waves produced no permanent damage. Transient injury, most commonly hematoma, was encountered. No posttreatment intra-abdominal catastrophes occurred. Although no renal injury was seen, it should be noted that the focus of maximum energy was 5 cm cephalad to the right kidney. This study suggests that an increased number of shock waves may be administered safely to this area of the abdomen.     

In vitro study of the mechanical effects of shock-wave lithotripsy

Impulsive stress in repeated shock waves administered during extracorporeal shock-wave lithotripsy (ESWL) causes injury to kidney tissue. In a study of the mechanical input of ESWL, the effects of focused shock waves on thin planar polymeric membranes immersed in a variety of tissue-mimicking fluids have been examined. A direct mechanism of failure by shock compression and an indirect mechanism by bubble collapse have been observed. Thin membranes are easily damaged by bubble collapse. After propagating through cavitation-free acoustically heterogeneous media (liquids mixed with hollow glass spheres, and tissue) shock waves cause membranes to fail in fatigue by a shearing mechanism. As is characteristic of dynamic fatigue, the failure stress increases with strain rate, determined by the amplitude and rise time of the attenuated shock wave. Shocks with large amplitude and short rise time (i.e., in uniform media) cause no damage. Thus the inhomogeneity of tissue is likely to contribute to injury in ESWL. A definition of dose is proposed which yields a criterion for damage based on measurable shock wave properties.     

Shock-wave lithotripsy in choledocholithiasis in a female patient with a cardiac pacemaker

BACKGROUND: Extracorporeal shock wave lithotripsy is relatively contraindicated in patients with an implanted cardiac pacemaker. Shock waves can damage the pacemaker by mechanical pressure and also by electromagnetic induction. Since the distance between the applicator and the pacemaker is small during biliary lithotripsy, the risk of damaging the pacemaker is greater. In the following case, the patient presented with a stone in the common bile duct, and had an implanted pacemaker. Lithotripsy with non-synchronized shock waves was the method of choice since conventional surgery was high risk in this specific case. CASE REPORT: In an 84-year-old woman with a stone in the proximal part of the common bile duct, endoscopic attempts of extraction failed. Therefore, shock wave lithotripsy was indicated. This patient had serious heart disease with an interference of spontaneous heart action with the pacemaker at a ratio of 1:1. We decided to treat with shock wave lithotripsy. The application of shock waves was without side effects on the patient and the pacemaker. CONCLUSION: This case is interesting as it highlights the possibility of using the Czech made MEDILIT lithotriptor in the treatment of choledocholitiasis in patients with a pacemaker. Even so, it is necessary to monitor the patient's ECG to ensure the possibility of immediate external stimulation.     

氧枪喷头射流的数值模拟

采用可实现k-ε模型对4孔氧枪的一个喷孔进行了二维流场模拟。以O2、N2和CO2射流为例,通过模拟计算确定在实际炼钢转炉环境下3种射流的流场分布,并对比分析了3种不同气源的射流特性,为进一步优化氧枪参数提供了依据;模拟计算也得出了激波和膨胀波的产生形式。结果表明,O2和N2的射流流场分布几乎不存在差别,而CO2射流流场核心区长度比前两射流要短,因此要达到同样的射流流场效果,要提高CO2射流的入口压力;在实际的操作环境下,很难做到完全满足喷孔的设计条件,产生了微弱的斜激波。     

Effects of atrial defibrillation shocks on the ventricles in isolated sheep hearts

BACKGROUND: The effects of cardioversion of atrial fibrillation on the activation sequence of the ventricles have not been previously studied. In this study we examined the events in the ventricle that follow the application of atrial defibrillatory shocks. METHODS AND RESULTS: We used video imaging technology to study the sequence of activation on the surface of the ventricles in the Langendorff-perfused sheep heart. We recorded transmembrane potentials simultaneously from over 20000 sites on the epicardium before and after biphasic shocks applied by a programmable atrial defibrillator. The first epicardial activation after the shock depended on both the voltage and timing of the shock. During ventricular diastole shocks as low as 10 V produced ventricular excitation, although the time between the shock and the first epicardial activation (latency) was approximately 30 ms. As the shock voltage was increased to 120 V, latency decreased to zero and the entire epicardium was depolarized within 30 ms. For 120-V shocks delivered late in systole, the depolarization sequence produced by the shock was similar to the previous repolarization sequence. Shocks of 120 V applied 150 to 300 ms after the previous ventricular excitation induced ventricular fibrillation. Ventricular fibrillation was induced by multiple focal beats after the shock, which produced waves that propagated but broke down into reentry within regions of high repolarization gradients. CONCLUSIONS: These results demonstrate that atrial defibrillation shocks excite the ventricles even at low shock voltages. In addition, ventricular fibrillation can be induced by shocks given in the vulnerable period by producing focal patterns that break down into reentrant waves.     

S100a0 protein as a marker for tissue damage related to extracorporeal shock wave lithotripsy

We assayed serum and urine S100a0 protein levels in patients with renal stones (n = 21) or ureteral stones (n = 18), before and after extracorporeal shock wave lithotripsy (ESWL) to evaluate tissue injury. Serum S100a0 protein levels increased significantly immediately after, and at 2 and 24 h after ESWL in patients with renal stones, and at 2 and 24 h after ESWL in patients with ureteral stones. Significant increases in urine S100a0 protein levels were observed immediately and 2 h after ESWL in both groups of patients. The patients receiving a higher number of shock waves had a more pronounced increase in serum S100a0 protein especially in the case of more than 3,500 shock waves. Because S100a0 protein exists at relatively high concentrations in the proximal renal tubules and skeletal muscles, serum and urine S100a0 protein levels appear to be useful markers of tissue injury, including damage in the kidney and skeletal muscles, in the early post-ESWL phase.     

Shock synthesis of silicides—I. experimentation and microstructural evolution

Niobium and molybdenum silicides were synthesized by the passage of high-amplitude shock waves through elemental powder mixtures. These shock waves were generated by planar parallel impact of explosively-accelerated flyer plates on momentum-trapped capsules containing the powders. Recovery of the specimens reveaved unreacted, partially-reacted, and fully-reacted regions, in accord with shock energy levels experienced by the powder. Electron microscopy was employed to characterize the partially-and fully-reacted regions for the MoSi and NbSi systems, and revealed only equilibrium phases. Selected-area and compositions of the reacted products. Diffusion couples between Nb and Si were crystal structure and compositions of the reacted products. Diffusion couples between Nb and Si were fabricated for the purpose of measuring static diffusion rates and determining the phases produced under non-shock condition. Comparison of these non-shock diffusion results with the shock synthesis results indicates that a new mechanism is responsible for the production of the NbSi₂ and MoSi₂ phases under shock compression. At the local level the reaction can be rationalized, for example, in the NbSi systems under shock compression, through the production of a liquid-phase reaction product (NbSi₂) at the Nb-particle/Si-liquid interface, the formation of spherical nodules (∼2 μm diameter) of this product through interfacial tension, and their subsequent solidification.     

An interview with Kathleen Scharer, MS, RN, CS, FAAN. Interview by Linda M. Fink

Urolithiasis occurs more frequently in the pilots than in the ground-service personnel. To decrease a damaging effect of the focused shock waves on the renal tissue while using remote lithotripsy technique, a new domestic-certified lithotriptor "URAT-P2" which shows a significantly low energy of shock wave with sufficient effectiveness of crushing the renal stones, is devised. Urolithiasis in the pilots is apparent at the early stages of its development and its complicated forms are less common than in the subjects of other professions. The stones are predominantly located in the renal calyces (73,3% of cases), in the left kidney and urethra in 63,3% of cases and there were urate stones in 40% of cases. The clinical use of the URAT-P2 complex in 30 pilots indicated that it holds advantages over the production domestic-certified lithotriptor. The stones are crushed in all the patients but the complications associated with a negative effect of the focused shock waves on the renal tissue are absent. The use of the new lithotriptor for treating urolithiasis in the pilots will allow one to improve the treatment response and to maintain professional worthiness of the pilots for a long time.     

Pulsed laser induced deformation in an Fe-3 Wt Pct Si alloy

The plastic deformation produced by laser induced stress waves was investigated on an Fe-3 wt pct Si alloy. The intensity and duration of the stress waves were varied by changing the intensity and pulse length of the high energy pulsed laser beam, and also by using different overlays on the surfaces of the specimens. The resulting differences in the distribution and intensity of the deformation caused by the stress waves within the samples were determined by sectioning the specimens and etching (etch pitting) the transverse sections. The magnitude of the laser shock induced deformation depended on the laser beam power density and the type of surface overlay. A combination transparent plus opaque overlay of fused quartz and lead generated the most plastic deformation. For both the quartz and the quartz plus lead overlays, intermediate laser power densities of about 5×10⁸ w/cm² caused the most deformation. The shock induced deformation became more uniform as the thickness of the material decreased, and uniform shock hardening, corresponding to about 1 pct tensile strain, was observed in the thinnest specimens (0.02 cm thick). 200 ns laser pulses caused some surface melting, which was not observed for 30 ns pulses, the pulse length used in most of the experiments. Deformation of the Fe-3 wt pct Si alloy occurred by both slip and twinning. B. A. WILCOX, formerly affiliated with Battelle, Columbus Laboratories