圆棒轧材超声波探伤方法

论述圆棒轧材探伤中伤波和底波的比值关系及底波的降低幅度。

鼻内镜下微波电凝并湿润烧伤膏外贴治疗鼻出血

鼻出血位于鼻腔前段者止血较易;位于较深且隐蔽的部位要迅速而有效的止血并不容易;尤其是顽固性鼻腔出血,出血量大,部位隐匿,深在,如反复填塞,必将损伤鼻腔黏膜,给患者带来很大痛苦,且疗效不佳,易导致鼻腔感染等并发症。我科于2004年6月～2010年11月采用鼻内镜下寻找出血点微波电凝并湿润烧伤膏外贴治疗鼻出血患者312例,疗效满意报告如下。

Linear and Nonlinear Ultrasonic Detections of Impact Damage in Composite Laminate

The appearance and accumulation of internal impact damage seriously influence overall performance of carbon fiber reinforced plastic(CFRP).Thus,this study evaluates the change in impact damage number by using linear and nonlinear ultrasonic Lamb wave detection methods,and compares these two detection results.An ultrasonic wave simulation model for composite structure with impact damage is established using the finite element method,and the interaction between impact damage and the ultrasonic wave is simulated.Simulation results demonstrate that the ultrasonic amplitude linearly decreases,and the relative nonlinear parameter linearly increases in proportion to the impact number,respectively.The linear-fitting slope of nonlinear parameter is 0.38 per impact number at an input frequency of 1.0 MHz.It is far higher than that of the linear ultrasonic amplitude,which is only-0.12.However,with the increase of impact damage,the linear growth of nonlinear parameters mainly depends on the decrease in ultrasonic amplitude rather than the accumulation of second harmonic amplitude.In the linear ultrasonic amplitude detection,the linear fitting slope at 1.1 MHz is-0.14,which is lower than those at 0.9 MHz and 1.0 MHz.Meanwhile,in the nonlinear ultrasonic parameter detection,the linear fitting slope at 1.1 MHz is 0.92,which is higher than those at 0.9 MHz and 1.0 MHz.The results show that higher frequencies lead to greater attenuation of ultrasonic amplitude and a larger increase in nonlinear parameters,which can enhance the sensitivity of both linear and nonlinear ultrasonic detections.The accuracy of simulation results is demonstrated through the low-velocity impact and ultrasonic experiments.The results show that compared with nonlinear ultrasonic technology,the linear ultrasonic technology is more suitable for impact damage assessment of carbon fiber reinforced plastic because of its simpler detection process and higher sensitivity.

地雷爆炸所致下肢离断时器官和组织损伤机制

地雷爆震伤的发生机制与其他火器伤不同，下肢各段纵向和横向生物机械牢度明显不同，牢固组织和松散组织对爆震能量的吸收能力也不同，所以损伤范围各不相同，由于同样原因，爆炸气体和冲击组织波在伤口周腔内的作用条件不同，所有这些决定着爆震伤复杂多形，作口周边和远位内脏器官结构破坏多样性。

Theoretical research on structural damage alarming of long-span bridges using wavelet packet analysis

The state equation and observation equation of the structural dynamic systems under various analysis scales are derived based on wavelet packet analysis. The time-frequency properties of structural dynamic response under various scales are further formulated. The theoretical analysis results reveal that the wavelet packet energy spectrum （WPES） obtained from wavelet packet decomposition of structural dynamic response will detect the presence of structural damage. The sensitivity analysis of the WPES to structural damage and measurement noise is also performed. The transfer properties of the structural system matrix and the observation noise under various analysis scales are formulated, which verify the damage alarming reliability using the proposed WPES with preferable damage sensitivity and noise robusticity.

Effect of Sound Stimulation on the Lipid Physical States and Metabolism of Plasma Membrane from Chrysanthemum Callus

Plasma membrane vesicles of chrysanthemum ( Dendranthema morifolium (Ramat.) Tzvel.) callus was purified by sucrose gradient centrifugation to investigate the influence of sound stimulation on the lipid physical states and metabolism of plasma membrane. The results showed that sound stimulation decreased the content of phosphodiesters and the fluorescent intensity of DPH, but increased the light scattering value of the membrane, the fluorescent intensity of MC540 and the content of phosphomonoesters, indicating that the vesicles got looser, the charge density and hydrophobicity of membrane surface decreased under sound stimulation of some strength and frequency. However, the membrane fluidity increased under the condition. Meanwhile, the anabolism of membrane lipid increased and the catabolism decreased. It can be seen that the physical state and metabolism of membrane lipid is sensitive to sound stimulation.

Dynamic response and failure of rock in initial gradientstress field under stress wave loading

Once an opening is created in deep underground,the stresses surrounding the opening will be redistributed,inducing a gradient stress field.To understand how the ground rock in such a gradient stress field responses to dynamic stress loading,the gradient stress distribution at a circular opening was first analyzed and the propagation of 1D stress wave in rock mass under gradient stress field was theoretically derived.By using an implicit to explicit solution method in LS-DYNA code,the dynamic mechanical behaviors of rock in gradient stress field were numerically investigated.The results indicate that the damage is mainly produced at or near the free face,partly due to the straight action of compressive stress wave and the tensile stress wave generated at the free face.The range of the induced damage zone is narrowed under the conditions of higher gradient stress rate and lower dynamic stress amplitude.However,under lower gradient stress field and higher dynamic stress,the damage becomes severer and wider with discontinuous failure regions.

AN OPTICAL FIBER SENSOR TECHNIQUE BASED ON SLIGHT DISTURBANCE RADIATION LOSS OF STOCHASTIC WALL

This paper presents an optical sensor technique used in the damage evaluation which is formed by structurally integrated fiber optic reticulate sensors embedded in the composite materials. The fibers are processed by chemical method and their outsides are peeled to form particles of irregular distribution and they differ in size, so the slight disturbance range of stochastic wall are formed in fibers. According to the characteristics of power loss of waveguide mode caused by slight disturbance of stochastic wall and radiative mode transmission, the range of slight disturbance of stochastic wall may be served as the sensitive range of the sensor. On the basis of theory of slight disturbance of stochastic wall of planar optical waveguide, the relation between the corrosion time and the opposite power loss by experiments is investigated. In this paper, the measurement results of object of SIFORS are also presented. The results show that the optical sensor technique may be used in the damage evaluation of an aircraft.

Damage and fragmentation of rock under experiencing impact load

The principle of energy dissipation in rock impacted by impulse loading was investigated. Associated with damage mechanics, a new method was proposed to calculate the cumulative damage of rock under a repeated loading at the damage stage, which was studied from the point of the action density of energy. The concept of abstract fractal characteristic of damage parameter was put forward based on the intrinsic physical meaning of damage, which was applied to the fragmentation phase of rock. The relationship between fractal damage and the number of fragments was set up. According to the principles of energy dissipation and dynamic fracture of rock experiencing impact load, the damage evolution equation in the fragmentation phase of rock was presented. The results of experiment show that the two methods coincide well with each other.

QUANTITATIVE ASSESSMENT OF MYOCARDIAL PERFUSION DEFECTS WITH REAL-TIME THREE-DIMENSIONAL MYOCARDIAL CONTRAST ECHOCARDIOGRAPHY

Objective To evaluate the feasibility and accuracy of measurement of myocardial perfusion defects with intravenous contrast-enhanced real-time three-dimensional echocardiography (CE-RT3DE). Methods RT3DE was performed in 21 open-chest mongrel dogs undergoing acute ligation of the left anterior descending artery (LAD, n=14) or distal branch of the left circumflex artery (LCX, n=7). A perfluorocarbon microbubble contrast agent was injected intravenously to assess the resulting myocardial perfusion defects with Philips Sonos-7500 ultrasound system. Evans blue dye was injected into the occluded coronary artery for subsequent anatomic identification of underperfused myocardium. In vitro anatomic measurement of myocardial mass after removal of the animal’s heart was regarded as the control. Blinded off-line calculation of left ventricular mass and perfusion defect mass from RT3DE images were performed using an interactive aided-manual tracing technique.Results Total left ventricular (LV) myocardial mass ranged from 38.9 to 78.5 (mean±SD: 60.0±10.1) g. The mass of perfusion defect ranged from 0 to 21.4 (mean±SD: 12.0±5.0) g or 0 to 27% of total LV mass (mean±SD: 19%±6%). The RT3DE estimation of total LV mass (mean±SD: 59.8±9.9 g) strongly correlated with the anatomic measurement (r=0.98; y=2.01+0.96x). The CE-RT3DE calculation of the mass of underperfused myocardium (mean±SD: 12.3±5.3 g) also strongly correlated with the anatomic measurement (r=0.96; y=-0.10+1.04x) and when expressed as percentage of total LV mass (r=0.95; y=-0.20+1.04x). Conclusions RT3DE with myocardial contrast opacification could accurately estimate underperfused myocardial mass in dogs of acute coronary occlusion and would play an important role in quantitative assessment of myocardial perfusion defects in patients with coronary artery disease.

Ultrasonic flaw detection using EMD-based signal processing

The precise detection of flaw echoes buried in backscattefing noise caused by material microstructure is a problem of great importance in uhrasonic non-destructive testing （NDT）. In this work, empirical mode decomposition （EMD） is proposed to deal with ultrasonic signal. A time-frequency filtering method based on EMD is designed to suppress noise and enhance flaw signals. Simulated results are presented, showing that the proposed method has an excellent performance even for a very low signal-to-noise ratio （SNR）. The improvement in flaw detection was experimentally verified using stainless steel pipe sample with artificial flaws.

Experimental study of structural damage identification based on WPT and coupling NN

Too many sensors and data information in structural health monitoring system raise the problem of how to realize multi-sensor information fusion. An experiment on a three-story frame structure was conducted to obtain vibration test data in 36damage cases. A coupling neural network (NN) based on multi-sensor information fusion is proposed to achieve identification of damage occurrence, damage localization and damage quantification, respectively. First, wavelet packet transform (WPT) is used to extract features of vibration test data from structure with different damage extent. Then, data fusion is conducted by assembling feature vectors of different type sensors. Finally, three sets of coupling NN are constructed to implement decision fusion and damage identification. The results of experimental study proved the validity and feasibility of the proposed methodology.

Use of second generation contrast-enhanced ultrasound in the assessment of focal liver lesions

Ultrasound (US) is often the first imaging modality employed in patients with suspected focal liver lesions. The role of US in the characterisation of focal liver lesions has been transformed with the introduction of specific contrast media and the development of specialized imaging techniques. Ultrasound now can fully characterise the enhancement pattern of hepatic lesions, similar to that achieved with contrast enhanced multiphasic computed tomography (CT) and magnetic resonance imaging (MRI). US contrast agents are safe, well-tolerated and have very few contraindications. Furthermore, real-time evaluation of the vascularity of focal liver lesions has become possible with the use of the newer microbubble contrast agents. This article reviews the enhancement pattern of the most frequent liver lesions seen, using the second generation US contrast media. The common pitfalls for each type of lesion are discussed. The recent developments in US contrast media and specific imaging techniques have been a major advance and this technique, in view of the intrinsic advantages of US, will undoubtedly gain popularity in the years to come.

DAMAGE DETECTION FOR COMPOSITE STRUCTURE UNDER TEMPERATURE CHANGES USING LAMB WAVES

A two-step method is proposed for detection and identification of invisible impact damage in composite structure under temperature changes using Lamb waves.First,a statistical outlier analysis is employed to distinguish whether the changes of Lamb wave signals are induced by damage within a monitoring area or are only affected by temperature changes.Damage indices are defined after the Lamb wave signals are processed by Fourier transform,and a Monte Carlo procedure is used to obtain the damage threshold value for the damage indices at the undamaged state.If the damage indices in the operation state exceed the threshold value,the presence of damage is determined.Then,a probabilistic damage imaging algorithm displaying probabilities of the presence of damage within the monitoring area is adopted to fuse information collected from multiple actuator-sensor paths to identify the location of damage.Damage indices under damaged state are used to generate the diagnostic image.Experimental study on a stiffened composite panel with random temperature changes is performed to demonstrate the effectiveness of the proposed method.

Volumetric measurement of rock movement using photogrammetry

NIOSH ground control safety research program at Spokane,Washington,is exploring applications of photogrammetry to rock mass and support monitoring. This paper describes two ways photogrammetric techniques are being used. First,photogrammetric data of laboratory testing is being used to correlate energy input and support deformation. This information can be used to infer remaining support toughness after ground deformation events. This technique is also demonstrated in a field application.Second,field photogrammetric data is compared to crackmeter data from a deep underground mine.Accuracies were found to average 8 mm,but have produced results within 0.2 mm of true displacement,as measured by crackmeters. Application of these techniques consists of monitoring overall fault activity by monitoring multiple points around the crackmeter. A case study is provided in which a crackmeter is clearly shown to have provided insufficient information regarding overall fault ground deformation.Photogrammetry is proving to be a useful ground monitoring tool due to its unobtrusiveness and ease of use.

Evaluating the Effect of Algal Extracts against Ultraviolet B-Induced Skin Damage in BALB/c Mice

Ethanol extract of mixed algae--spirogyra and ulothrix was investigated to assess the effect on some biochemical parameters in UVB irradiated mice. The dorsal-thoracic region of mice were shaved and exposed to UVB radiation for 24 h for two consecutive weeks. Five groups of ten mice each were conducted： non-irradiated control and irradiated control. Mice treated with commercial cream （S.M.） at a dose of 0.1 mg/cm2 and mice treated with ethanol extract of mixed spirogyra and ulothrix at a dose of 0.1 mg/cm2 or 0.2 mg/cm2. Topical application was performed to all treated mice groups once a day for four consecutive weeks. Results showed significant differences between treated and control groups during the whole period of experiment. The clear potentiality of the ethanol extract was detected through body and skin weight, level of total protein, Superoxide Dismutase （SOD） and Catalase （CAT） activities in skin. However, UVB irradiated mice treated with 0.2 mg/cm2 exhibited the most significant effect when compared to control groups. That may be attributed to anti-inflammatory and anti-oxidant effects of algal extract.

Value of contrast-enhanced ultrasound in diagnosis of focal liver lesions

Objective： By observing the pattern of the focal liver lesions （FLL） in different phases by real time contrast-enhanced ultrasound （CEUS）, compared to enhanced CT, investigate the value of CEUS in diagnosing focal liver lesions. Meth. ods： 35 patients with unconfirmed focal liver lesions were studied by contrast agent SonoVue and Technos DU 8 produced by Esaote company. Results： Among the 14 cases of hepatocellular carcinoma （HCC）, 10 were typical, presented with early artery enhancement and immediate wash-out. The enhancement patterns of 6 livers metastasis were diverse, including peripheral or entire degree enhancement. The wash-out time in malignant tumors was eadier than other focal liver lesions （P 〈 0.05）, appeared as hypoechoic in the portal phase or parenchyma phase. The 6 cases of hemangioma were enhanced centripetally nodular in artery phase and washed out after several minutes. The patterns of different lesions were similar compared to contrast-enhanced CT, without significant statistic differences. Conclusion： The contrast enhanced ultrasound technique can significantly improved the value of diagnosing focal liver lesions.

Attenuation law of explosive stress wave in damaged rock mass

The attenuation regularity of explosion stress waves in damaged rocks is discussed according to physical and geometric attenuation of waves in this paper. The relation between numerical decrement and damaged parameter is given and the results have an important significance to design and control blasting effect accurately in a concrete rock.

Investigation of Combination Characteristic of Damage Location and Intensity in Arch Using Wavelet Coefficient

Arch is a typical complex structure comparing with beam and plate in bridge system. This paper investigates the damage characteristic combining the crack location with the crack intensity in arch. Initially, the first four displacement modes of intact and different damaged arch are simulated and the displacement mode changes are obtained. Next, the wavelet transformation is applied to the displacement mode changes in arch and wavelet coefficients at damage loci are picked. Finally, the damage index including damage location and damage intensity in arch is provided and plotted. The results show that wavelet coefficient module maximum of mode changes can be the damage indicator and is influenced by damage location and damage intensity. The damage indicator is proportional to the damage intensity and present monotonic trend according to damage location which depend on the mode order. At the same time, the large modulus maximum corresponds to small damage combination of location and intensity in the first four modes.

Corrosion-fatigue evaluation in Q235A steel using nonlinear Rayleigh surface waves

This paper presents a non-destrcutive evaluation method for the evolution of corrosion fatigue of Q235A steel. Specimen surface degradation due to corrosion fatigue from the combined interaction of corrosion and cyclic loading leads to harmonic generation during Rayleigh wave propagation along the specimen surface,which allows for an early prediction of material fatigue life. The relative nonlinearity parameter β as an evaluation parameter,which is denoted as a ratio of fundamental and second-order harmonic amplitudes,is measured by using an experimental platform based on a pair of wedge transducers to launch and receive Rayleigh wave signal. Subjected to an immersion corrosion method with 10% NaCl solution and a 20 Hz cyclic loading,a corrosion-fatigue specimen was made,and its relative nonlinearity parameter was measured every 10 5 cycles until to 7 ×10^5 cycles. A measured curve of relative nonlinearity parameter versus fatigue load cycles,which is produced by surface degradation of specimen corrosion fatigue,showed an initial steady trend followed by a rapid increase. Experimental results demonstrate that corrosion fatigue results in the sudden destruction of a Q235A steel specimen and nonlinear Rayleigh surface waves measurement technique can be used to quantitatively characterize fatigue life of Q235A steel.