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For on-site analysis of surface materials on the Moon, planets, and small bodies and for the monitoring of air quality in crewed spacecraft, we have developed a portable gas chromatograph (GC) equipped with a ball surface acoustic wave (SAW) sensor. In this study, we fabricated a 10 cm cube GC that implements the forward flush method using two metal micro-electro-mechanical-system columns coated with different stationary phases in microchannels fabricated by wet etching and diffusion bonding of stainless-steel plates. Using this GC, we succeeded in analyzing 10 kinds of gas within 10 min. In addition, for the application of the ball SAW GC on the ground, we also developed a palm-sized GC with a single metal capillary column and used it in the analysis of the headspace gas of sake. We showed that the ratio of peak areas differed among odorants depending on the brand and brewing process of sake.

This study investigates the computer simulation of fracture process in compressive failure of cross-ply laminate of composite materials. The purpose of this study is to establish the numerical analysis method to understand the fracture mechanism and predict the mechanical response of composite materials through the computer simulation. The stacking sequence of the simulated laminate is [0/90] s. The reinforcement fibers in 0-degree plies are modeled by circle cross-section beam elements to represent the three-dimensional effect in bending of fibers. Cohesive elements are inserted in the connection of beam elements to simulate the bending breaking of fibers. For the purpose of parallel computing, the domain decomposition method is applied, and for pre-conditioned conjugate gradient algorithm, incomplete Cholesky conjugate gradient method is applied. The simulated results show that in the initial state of the loading, the stress concentration occurs around the initial misalignment of fiber in 0-degree plies, and it also occurs around the area where fibers come close in 90-degree plies. At average applied strain 1.20 %, the fiber breaking damage initiates in 0-degree ply, and after this point the damage develops in the material. The simulated damage is close to the microscope picture of the actual composite materials obtained in the experiment. The current simulation is considered to correspond with the actual material deformation.

Optical fiber sensors have attracted considerable attention in health monitoring of aerospace composite structures. This paper briefly reviews our recent advancement mainly in Brillouin-based distributed sensing. Damage detection, life cycle monitoring and shape reconstruction systems applicable to large-scale composite structures are presented, and new technical concepts, “smart crack arrester” and “hierarchical sensing system”, are described as well, highlighting the great potential of optical fiber sensors for the structural health monitoring (SHM) field.

A beamforming array technique with four sensors is applied to a cylindrical geometry for detecting point of impact. A linear array of acoustic sensors attached to the plate record the waveforms of Lamb waves generated at the impact point with individual time delay. A beamforming technique in conjunction with an optimization scheme that incorporates the direction dependent guided Lamb wave speed in cylindrical plates is developed. The optimization is carried out using the experimentally obtained wave speed as a function of propagation direction. The maximum value in the beamforming plot corresponds to the predicted point of impact. The proposed technique is experimentally verified by comparing the predicted points with the exact points of impact on a cylindrical aluminum plate and a cylindrical composite shell. For randomly chosen points of impact the beamforming technique successfully predicts the location of the acoustic source.

Structural health monitoring refers to the process of making an assessment, based on nondestructive, in-situ, autonomous measurements, about the ability of a structure to perform its intended function. This paper presents work done on a bolted connection in carbon-fiber reinforced polymer composite materials. A composite specimen is bolted in a double lap joint configuration to a test apparatus that applies an increasing tensile load. Ultimately, the load results in bearing failure of the material around the bolt hole. To monitor the progression of damage, macro fiber composite sensors are bonded in a circular array around the bolt hole. These sensors are then used to generate ultrasonic guided waves, a popular technique in nondestructive evaluation because of the favorable combination of propagation distance and sensitivity to damage. As the specimen is subjected to increasing load levels, measurements are taken repeatedly and compared with one another. Because damage will change the local mechanical properties of the material, the ultrasonic waves passing through the damaged region will be scattered differently in each direction, resulting in a different waveform arriving at the other surrounding sensors. By applying appropriate signal processing techniques, these changes may be interpreted as indicating the extent of damage that has occurred in the specimen. Preliminary analysis is presented demonstrating the correlation between changes in received strain signals and increasing damage levels.

The authors proposed fiber-optic-based damage monitoring of carbon fiber reinforced plastic (CFRP) bolted joints. Optical fibers were embedded along bolt holes and strain change along the optical fiber induced by internal damage was measured by a Brillouin Optical Correlation Domain Analysis (BOCDA), which is a high spatial resolution distributed strain sensing system. This study began by investigating damage modes of CFRP bolted joints after bearing failure. Effective embedding positions of optical fibers were then proposed and their feasibility was evaluated by finite element analysis simulating the damage propagation in the bolted joint and consequent strain change. Finally, verification tests were conducted using specimens with embedded optical fibers at various positions. It was clearly shown that damage could be detected using residual strain due to fiber-microbuckling (kinking) damage or permanent deformation of neighboring plies. Furthermore, damage size and direction could be estimated from the change in the strain distribution. The system developed is quite useful for a first inspection of large-scale composite structures in aerospace applications.

Understanding the chemical state of lead in fly ash generated from a waste thermal treatment is important, since the toxicity and solubility of the element depends on its chemical state. This study identified three potential methods for obtaining quantitative information regarding the chemical state of lead in fly ash: X-ray absorption near edge structure (XANES) analysis, extended X-ray absorption fine structure (EXAFS) analysis, and the sequential extraction procedure. The result of this procedure was strongly affected by the pH and sample matrix, and did not necessarily accurately reflect the chemical state. It was difficult to quantitatively examine the chemical species using only EXAFS. However, an XANES fitting enabled direct quantification of the chemical species. An XANES analysis showed that PbSiO3, PbCl2, or Pb2O(OH)2was the predominant chemical species in fly ash. We concluded that multiple analyses should be compared multilaterally to improve the accuracy of the final analysis.

A beamforming array technique with 4 sensors is applied to a cylindrical plate for detecting point of impact. Linear array of acoustic sensors attached to the plate record the waveforms of Lamb waves generated at the impact point with individual time delay. An optimization technique with an objective function is incorporated into the beamforming technique in order to deal with the direction dependent Lamb wave speeds in a cylindrical geometry. The optimization is carried out using the experimentally obtained wave speed as a function of propagation direction. The maximum point in beamforming plot with minimized objective function corresponds to the localized point of impact. The proposed technique is experimentally verified by comparing the predicted points with the exact points of impact on a cylindrical aluminum plate. For randomly chosen points of impact the beamforming technique successfully predicts location of the exact acoustic source.

This talk describes the embedded optical fiber sensor systems for smart aircraft composite structures. First, a summary of the current Japanese national project on structural integrity diagnosis of aircraft composite structures is described with special emphasis on the use of embedded small-diameter optical fiber sensors including FBG sensors. Then, some examples of life-cycle monitoring of aircraft composite structures are presented using embedded small-diameter optical fiber sensors for low-cost and reliable manufacturing merits.

This study demonstrated fiber-optic-based life cycle monitoring of an L-shaped carbon fiber reinforced plastic (CFRP) part. Fiber Bragg grating (FBG) sensors were embedded in the corner of the L-shaped specimen during the laminate lay-up process, and was then utilized to monitor the local strain change during the cure process, the demolding, the assembly, and a subsequent bending test. FBG spectral changes induced were comprehensively presented and discussed from the viewpoint of the mechanical and thermal deformation of the specimen. Internal state of the L-shaped part was successfully monitored throughout its life, confirming effectiveness of life cycle monitoring by embedded fiber-optic-based sensors for developing highly-reliable composite structures.

An optimization based technique for detecting the impact point on isotropic and anisotropic flat plates developed by Kundu and his associates is extended here to the cylindrical geometry. An objective function is defined that uses the cylindrical coordinates of four sensors attached to the cylinder and four arrival times to locate the point of impact by minimizing the objective function that gives the least squares error. The proposed technique is experimentally verified by predicting the points of impact and comparing the predicted points with the actual points of impact.

This paper examines the stress distribution around a fiber break in alumina-fiber reinforced aluminum matrix (Al2O3/Al) composites using finite element analysis and predicts the tensile strength using tensile failure simulations. In particular, we discuss the effect of the matrix hardening on the tensile failure of the Al2O3/Al composites. First, we clarify the differences in the stress distribution around a fiber break between an elastic-perfect plastic matrix and an elastic-plastic hardening matrix using finite element analysis. Second, the procedure for simulating fiber damage evolution in the Al2O3/Al composites is presented. The simulation incorporates the analytical solution for the axial fiber stress distribution of a broken fiber in the spring element model for the stress analysis of the whole composite. Finally, we conduct Monte Carlo simulations of fiber damage evolution to predict the tensile strength of the Al2O3/Al composites, and discuss the effect of matrix hardening on the tensile strength of the Al2O3/Al composites. Coupled with size-scaling analysis, the simulated results express the size effect on the strength of the composites, which is seen in experimental results.

The present study examined the effect of the nitric oxide (NO) donor NOC18 on lipopolysaccharide (LPS)-induced NO production to investigate a regulation mechanism of NO production by microglial cells. LPS increased the levels of NO and inducible NO synthase (iNOS) protein in BV-2 murine microglial cells in a concentration-dependent manner. Pretreatment with NOC18 for 24 h concentration-dependently attenuated the LPS-induced iNOS protein expression and NO production. The inhibitory effect of NOC18 on LPS-induced NO production was partially blocked by LY83583, a soluble guanylate cyclase inhibitor. Pretreatment with dibutyryl guanosine-3′,5′-cyclic monophosphate (DBcGMP), a cell-permeable cGMP analogue, for 24 h attenuated partially LPS-induced iNOS protein expression and NO production. Furthermore, the effects of LPS on iNOS and NO production were inhibited by the c-Jun N-terminal kinase (JNK) inhibitor SP600125, and LPS-induced phosphorylation of JNK and c-Jun was inhibited by NOC18 and DBcGMP. These results suggest that NO production by microglial cells is controlled by a negative feedback mechanism via the NO/cGMP signaling pathway.

An Occupational Health Study of Emergency Physicians in Japan: Health Assessment by Immune Variables (CD4, CD8, CD56, and NK cell activity) at the Beginning of Work: Hiroteru Okamoto, et al. Department of Preventive Medicine and Public Health, School of Medicine, Kyorin University—This study was conducted to evaluate the occupational health of Japanese physicians in emergency medicine. Subjects participating in this study were eighty‐nine physicians working at 12 medical facilities (10 critical care emergency centers) in Japan. Participants were asked to complete a questionnaire of work conditions and to provide blood samples for immune variable measurements (CD4, CD8, CD56 and natural killer cell (NK cell) activity) before commencing their work. The data collected from seventy‐four of 89 participating physicians were analyzed. The traditional work group comprised of 39 emergency physicians, who were significantly overworked compared to other two groups: the shift work group and the day work group. Among these three groups, no immune variable was significantly different except lymphocyte, number of CD4, and NK cell activity; and the NK cell activity of the shift work group was significantly lower than those of the traditional work group (p<0.01) and the day work group (p<0.01) in terms of Bonferroni's multiple comparison, probably due to circadian rhythm. It was indicated that NK cell activity was significantly lower in samples collected at night versus in the morning (OR=8.34, 95%CI: 1.95–35.6, p<0.01) through multiple logistic regression analyses. NK cell activity was significantly lower in individuals taking 0–3 days off per month, as compared to those taking 4 or more days off (OR=4.65, 95%CI: 1.27–17.0, p=0.02), according to multiple logistic regression analyses. Therefore, the low NK cell activity appears to have reflected the extent of fatigue arising from physicians' overwork. Overwork would have been a potential risk for the physicians' health, resulting in a lower quality of Japanese emergency medical services than that which could have been achieved otherwise. This study suggests that it would be better for the Japanese emergency physicians to take 4 or more days off per month for their health and the quality of their services.

An Occupational Health Study of Emergency Physicians in Japan: Health Assessment by Immune Variables (CD4, CD8, CD56, and NK cell activity) at the Beginning of Work: Hiroteru Okamoto, et al. Department of Preventive Medicine and Public Health, School of Medicine, Kyorin University—This study was conducted to evaluate the occupational health of Japanese physicians in emergency medicine. Subjects participating in this study were eighty-nine physicians working at 12 medical facilities (10 critical care emergency centers) in Japan. Participants were asked to complete a questionnaire of work conditions and to provide blood samples for immune variable measurements (CD4, CD8, CD56 and natural killer cell (NK cell) activity) before commencing their work. The data collected from seventy-four of 89 participating physicians were analyzed. The traditional work group comprised of 39 emergency physicians, who were significantly overworked compared to other two groups: the shift work group and the day work group. Among these three groups, no immune variable was significantly different except lymphocyte, number of CD4, and NK cell activity; and the NK cell activity of the shift work group was significantly lower than those of the traditional work group (p<0.01) and the day work group (p<0.01) in terms of Bonferroni’s multiple comparison, probably due to circadian rhythm. It was indicated that NK cell activity was significantly lower in samples collected at night versus in the morning (OR=8.34, 95%CI: 1.95–35.6, p<0.01) through multiple logistic regression analyses. NK cell activity was significantly lower in individuals taking 0–3 days off per month, as compared to those taking 4 or more days off (OR=4.65, 95%CI: 1.27–17.0, p=0.02), according to multiple logistic regression analyses. Therefore, the low NK cell activity appears to have reflected the extent of fatigue arising from physicians’ overwork. Overwork would have been a potential risk for the physicians’ health, resulting in a lower quality of Japanese emergency medical services than that which could have been achieved otherwise. This study suggests that it would be better for the Japanese emergency physicians to take 4 or more days off per month for their health and the quality of their services.

The authors developed a damage detection system that generates ultrasonic waves with a piezo-ceramic actuator and receives them by a fiber Bragg grating (FBG) sensor. In this research, this system was applied to evaluate debonding progress in CFRP skin/stringer bonded structures. FBG sensors were bonded on the stringer or embedded in the adhesive layer. Then, ultrasonic wave at 300kHz was propagated through the debonded region, and the wavelet transform was applied to the received waveform. After that, a new damage index[removed info]and a correlation coefficient were calculated from the distribution of the wavelet transform coefficient. As a result, the damage index increased and the correlation coefficient decreased with an increase in the debonded area. Hence the length of the debonding between the skin and the stringer could be well evaluated.

Although demand for composite structures rapidly increase due to the advantages in weight, there are few effective assessment techniques to enable the quality control and guarantee the durability. In particular, an invisible microscopic damage detection technology is highly required because damages such as transverse cracks, debondings, or delaminations can lead to the critical failure of the structures. Among many non-destructive evaluation (NDE) methods for composite structures, fiber optic sensors are especially attractive due to the high sensitivity, the lightweight, and the small size. In the current trend of the structural health monitoring technology, fiber Bragg gratings (FBG) sensors are frequently used as strain or temperature sensors, and Brillouin scattering sensors are also often used for a long distance distributed measurement. The Brillouin distributed sensors can measure strain over a distance of 10km while a spatial resolution was limited to 1m. Some novel sensing method is proposed to improve the spatial resolution. The pulse-prepump Brillouin optical time domain analysis (PPP-BOTDA) is one of the latest distributed sensing applications with a cm-order high spatial resolution. The PPP-BOTDA commercial product has the spatial resolution of 10cm, and can measure the strain with a precision of ±25og. This precision, however, can be achieved by using conventional single-mode optical fibers. In our research, small-diameter optical fibers with a cladding diameter of 40om were embedded in the CFRP laminate to avoid the deterioration of the CFRP mechanical properties. Thus, in order to verify the performance of PPP-BOTDA, the distributed strain measurement was conducted with the small-diameter optical fibers embedded in the CFRP laminate.

This article presents the real-time strain measurement of a composite liquid hydrogen (LH2) tank using fiber Bragg grating (FBG) sensors. The tank was composed of carbon fiber reinforced plastic (CFRP), and an aluminum liner was fabricated by the filament winding method and mounted on a reusable rocket. This rocket (vertical takeoff and landing) is called a reusable rocket vehicle test (RVT) and was developed by the Institute of Space and Astronautical Science of the Japan Aerospace Exploration Agency (ISAS/JAXA). Considering the high operational pressure and the iterative use of the tank, its structural integrity must be guaranteed. Thus, the authors have attempted a real-time strain measurement of the composite LH2tank using FBG sensors during rocket operations. First, the adhesive properties of the FBG sensors were investigated at cryogenic temperatures. As a result, UV-coated FBG sensors and polyurethane adhesives were adopted. An onboard FBG demodulator was then developed to be mounted on the rocket and its performance was assessed. Finally, the strain measurement was attempted during the flight experiments of the RVT using the onboard FBG demodulator. FBG sensors were glued on the surface of the composite LH2tank and connected to the onboard FBG demodulator. During these rocket operations, the output of the onboard FBG demodulator was continuously monitored via a telemetry system. The results obtained by the demodulator agreed well with those of the conventional foil strain gage.

Structural health monitoring of cracked aircraft panels repaired with bonded patches for extending the service life of aging aircraft has received wide attention. In this paper, the identification of the locations and shapes of fatigue crack and disbond fronts in aircraft panels repaired with double-sided bonded patches using fiber Bragg grating (FBG) sensors is studied. The identification is performed by minimizing the difference between the detected and calculated reflection spectra of FBG sensors at multiple positions on the free surface of patches. The validity and effectiveness of the identification in practical use is verified by comparing the identification results with the exact ones.Structural health monitoring of cracked aircraft panels repaired with bonded patches for extending the service life of aging aircraft has received wide attention. In this paper, the identification of the locations and shapes of fatigue crack and disbond fronts in aircraft panels repaired with double-sided bonded patches using fiber Bragg grating (FBG) sensors is studied. The identification is performed by minimizing the difference between the detected and calculated reflection spectra of FBG sensors at multiple positions on the free surface of patches. The validity and effectiveness of the identification in practical use is verified by comparing the identification results with the exact ones.

This paper presents the results of experimental and analytical studies with respect to the damage onset/growth suppression behavior using quasi-isotropic CFRP laminates with embedded pre-strained SMA foils under quasi-static uniaxial tension load. In our previous studies, we conducted some preliminary quasi-static load–unload tests using CFRP laminates with embedded pre-strained SMA foils (smart composites). The results confirmed that these smart composites had excellent effects on damage onset/growth suppression, in comparison with the conventional CFRP laminates. In this study, systematic load–unload tests are conducted for quasi-isotropic laminates, with and without SMA foils and adhesive layers. Following this, a detailed observation of the damage onset/growth suppression behavior is conducted. This observation verified that the microcracks, which originated at the −45/90 interface, generally grow into transverse cracks in a 90° ply of the quasi-isotropic CFRP laminates ([45/0/−45/90]s). It has also been experimentally confirmed that the damage onset/growth suppression effects of smart composites are obtained by the suppression of crack opening displacement. Furthermore, the stress and strain distributions of all the composite systems with microcracks are calculated by FEM analysis at room temperature (RT) and at 80 °C for conventional composites ([45/0/−45/90]s) and smart composites ([45/0/−45/90/Ad/SMA/Ad/90/−45/0/45]), respectively. From the results of the FEM analysis, the strain energy release rate is calculated using the ‘crack closure method’ for the evaluation of the damage onset/growth suppression effect. It is confirmed that the damage onset/growth suppression effects of the CFRP laminates with embedded pre-strained SMA foils are obtained by the suppression of crack opening displacement in 90° layers, which is generated by the suppression of the strain energy release rate for smart composites by the recovery stress of SMA.

Only limited information is available about the behavior of antimony (Sb) in contaminated soils. However, understanding the behavior of Sb in contaminated soils is important, because the toxicity or solubility of this element depends on its chemical state. In this study, we investigated the levels of Sb and the chemical forms of Sb in the soil around a smelter using X-ray absorption fine structure (XAFS) spectra. The highest Sb concentration in the contaminated soil was 2900 mg/kg dry soil. According to Sb-K edge X-ray absorption near edge (XANE) spectra, the Sb in the soil was in the form of Sb(V) compounds. The similarity of extended XAFS (EXAFS) spectra suggests that Sb speciation was independent of the sampling site, which indicates that Sb or Sb2O3emitted from the smelter was converted into Sb(V) compounds in the soil.

Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs); they produce negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and assessing associated health risks. In the present study, water is used as a safe and environmentally friendly solvent in microwave‐assisted extraction (MAE) for PCB and CBz analyses. MAE is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies. The evaluation of extraction efficiencies shows that MAE has a high extraction efficiency compared with that of SE when water content is lower than 60%. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE.

AbstractThe control of Hg emissions from a municipal solid waste incinerator (MSWI) is very important, because more than 78% of municipal solid waste (MSW) is incinerated. The Hg content of coal used in utility boilers is relatively low in Japan. In this study, recent trends in the Hg content of MSW in Japan and activated carbon (AC) injection as a control technology of Hg emission from an MSWI are discussed. The effect of AC injection on Hg removal from flue gas in an MSWI was investigated by pilot-scale experiments using a bag filter (BF). The injection of AC increases the Hg reduction ratio by 20–30% compared with cases without AC injection. The Hg reduction ratio increases as the flue gas temperature decreases. The Hg reduction ratio is closely related to the inlet Hg concentration and was expressed with a Langmuir-type adsorption isotherm.

Microscopic damage behavior in quasi-isotropic CFRP laminates with interlaminar-toughened layers under tensile fatigue loading is investigated. Damage observation is conducted using an optical microscope and soft X-ray radiography. The material used is CFRP with interlaminar-toughened layers, T800H/3900-2. The laminate configurations are quasi-isotropic [45/0/−45/90] s , [0/45/−45/90] s and [45/−45/0/90] s to discuss the effect of stacking sequence on microscopic fatigue damages. A damage mechanics analysis is used to obtain the energy release rate for transverse cracking which is correlated to the transverse crack density growth rate. The modified Paris-law analysis proves to be valid for characterization of transverse crack multiplication when the effect of other damage is small.

First, a methodology for observation and modeling of microscopic damage evolution in quasi-isotropic composite laminates is presented. Based on the damage observation using both an optical microscope and a soft X-ray radiography, a damage mechanics analysis is conducted to formulate the stiffness change due to transverse cracking. Then, both energy and stress criteria are combined to provide a valid procedure to predict the transverse crack evolution. The theoretical prediction is found to agree well with the experimental results for the transverse crack density as a function of strain as well as stress-strain curves. Then, another methodology is introduced using two kinds of embedded optical fiber sensors to detect and monitor the transverse crack evolution in composite laminates. One is plastic optical fibers (POF), where the loss in optical power is generated by local deformation of POF due to transverse cracking. The other is fiber Bragg grating (FBG) sensors, where the local strain distribution within the FBG gage length due to transverse cracking alters the power spectrum of the light reflected from the FBG sensors. Embedded optical fiber sensors are found to be a powerful method to detect and monitor the transverse crack evolution in composite laminates.

Compressive failure of carbon fiber reinforced unidirectional vinyl ester composites (CFRP) under impact is studied experimentally and analytically. Both impact and quasi-static compressive tests are carried out for CFRP with Vf= 10% to 60%. Stress-stain curves at strain rates of 10-3 s-1 and 10-3 s-1 are obtained. The compressive strength increases under impact loading. As the fiber volume fraction increases, the failure mode changes from shear failure to kinking. The local stress fields in the fiber and matrix are analysed to illustrate the deformation and compressive failure mechanisms for unidirectional composites. Based on analysing the local matrix yield at the fiber-matrix interface due to shear stress concentration, the compressive strength is predicted. Assuming that shear failure and kinking occurs on the plane of the maximum shear strain in composites, the angle of the plane of the maximum shear strain is determined. The analytical model is utilised to explain the various experimental observations of CFRP failure, as well as GFRP failure reported in Reference [17], such as, the compressive strength, the failure mode, the effects of fiber volume fractions and strain rates.

Transverse cracking under tensile loading in high-temperature CFRP, carbon/BMI (bismaleimide), G40-800/5260, has been investigated experimentally. Carbon/epoxy, T800H/3900-2, composite laminates are also examined for comparison. Both material systems have toughened-interlaminar layers. Laminate configurations are [0/90]s, [0/902]s,[±45/90]sand [±45/902]sfor G40-800/5260, while [0/90]sand [±45/90]sfor T800H/3900-2. In all laminates, the first microscopic damage observed is a 90° ply transverse crack. In [±45/90n]stype laminates, cracking in 45°ply and delaminations are also observed. The cracking behavior is quantified by measuring crack densities as a function of the laminate strain. The difference between the damage progress near the 90° ply transverse crack tips between the material systems are observed. Damage mechanics analysis is used to predict 90° ply transverse cracking based on both the energy and stress criteria. The present analysis can be used as a means of characterization of the transverse cracking resistance of a material, which will be helpful in ranking materials.

In this study, polychlorinated biphenyls (PCBs) were decomposed by low‐temperature heat treatment with metallic catalyst, and with metallic catalyst and a hydrogen source. Of the catalysts used, iron (Fe) was the most active catalyst for the decomposition of PCBs, and the decomposition was due to dechlorination. The addition of hydrogen sources accelerated the decomposition of PCBs in the presence of catalyst. Surface analysis of the catalyst using X‐ray photoelectron spectroscopy (XPS) suggested that the emitted chlorine was presumed to form metal chloride. The reactions of each homolog can be expressed by a successive first‐order reaction model. This means that a substituted chlorine is successively detached during this reaction. The overall decomposition rate in this reaction system was controlled by that of the lower chlorinated homologs. The decomposition rates with Fe and NaBH4for the lower chlorinated homologs were about 10 times as fast as the rates with only Fe.

Background/Aim:In the present study, we investigated the acute and late phases of splenic circulation after spleen-preserving distal pancreatectomy (SPDP) involving the division of splenic vessels. Methods:An acute phase of splenic circulation was evaluated by laser flow meter and the late phase was estimated by 99mTc-galactosyl human serum albumin spleen scintigraphy. Results:Splenic blood supply, evaluated by laser flow meter immediately after SPDP, dropped to one half of the prior blood supply. However, blood supply recovered 10 days after SPDP, as estimated by 99mTc-galactosyl human serum albumin spleen scintigraphy. Conclusion:There are two variations of SPDP: SPDP without preservation of the splenic artery and vein, and SPDP with preservation of the splenic artery and vein. The disadvantage of the former is the resulting decrease in splenic blood supply. The present findings may help to make up for this disadvantage.

A damage mechanics analysis is applied to predict transverse cracking in a laminated composite. Two criteria based on the energy release rate and the average ply stress are used to predict transverse cracking. The analytical prediction of transverse crack density as a function of applied laminate strain is favorably compared with the experimental results. An advantage of the present predictive method is that it can be applied to laminates with arbitrary stacking sequences.

In this study, limestone powder was directly added to synthetic MSW, which was fed into a small‐scale fluidized bed incinerator. The concentration of CBzs and CPs in the flue gas were measured before and after a secondary combustion air injection. Finally, the PCDDs and PCDFs concentrations were also measured in the flue gas after the secondary combustion zone. The CaCO3added to synthetic MSW not only controls HCl in the flue gas, but suppresses the formation of chlorinated aromatic compounds like CBzs, CPs, PCDDs, and PCDFs. The main mechanisms to control the formation of chlorinated aromatic compounds was more likely related to the suppression of catalytic capability of flyash than the HCl reduction in the flue gas. However, the NO concentration was increased by catalytic reaction of limestone in the fluidized bed.

This paper presents the results of elastic constant determination of Ceramic Matrix Composites (CMC) using two types of ultrasonic measurement systems, and shows the possibility of the elastic constants determination for transversely isotropic materials not only in a macroscopic area but also in a microscopic one at the order of 1 mm. Macroscopic elastic constants were determined from the transmitted wave velocities measured by a double-through-transmission method. Microscopic elastic constants were inverted from the reflection coefficients at a small spot on the surface, which were measured using an ultrasonic micro-spectrometer. The inversion from the reflection coefficients was tried by two ways of analysis: (1) fitting to phase curves of reflection coefficients; (2) fitting to surface wave velocity dispersion. By comparison between these values and those measured by tensile tests, it was conformed that all elastic constants of a unidirectional CMC could be determined by ultrasonic waves appropriately not only in a macroscopic area but also in a microscopic one.

Influence of temperature on the fracture of a SiOxfilm (PVD) on a PET substrate was investigated. Parallel multiple cracks were observed in situ during tensile tests at different temperatures ranging from 26 to 150°C. Fewer cracks were observed at elevated temperatures. On the other hand, the crack onset strain was not affected by the temperature. The residual strain in the SiOxfilm remained constant in this temperature range. These observations were successfully predicted by the shear lag model with an assumption of a unique stress criterion.

Effects of thermal cycling on transverse cracking behavior in interlaminartoughened CFRP cross-ply laminates are investigated. Material systems used are T800H/363 1 carbon/epoxy composite with FM300 epoxy resin film between 0°/90° interface (T800H/363 I -FM300) and T800H/3900-2 with polyamide particle-dispersed layers at every ply interface. The laminate configurations are cross-ply (0/90n/0) where n = 4, 8 and 12. The laminates are thermally cycled between -70°C and 1500 up to 100 cycles. No damage is observed by the thermal cycles. After thermal cycling, the laminates are subjected to static tensile loading at room temperature. The transverse crack density in 90° ply is measured as a function of the laminate strain by using the replica technique. It is found that transverse crack behavior depends on the number of thermal cycles. Transverse crack density increases as the number of thermal cycles increases. Change in thermal residual strain in 900ply is measured as a function of the number of thermal cycles by measuring the deformation of an unsymmetric laminate. The effects of thermal cycles on the transverse cracking are characterized by a micromechanical model considering the thermal residual stresses.

The difficulty in the removal of mercury in flue gas of combustion processes is mainly due to the high volatility of elemental mercury. Various sulfide compounds were tested to check which compounds can convert mercury into stable mercury sulfide and remove mercury from flue gas. The results indicate that lead, cadmium, copper, antimony, tungsten, molybdenum, and palladium sulfides removed more than 80% of mercury from synthetic gas with mercury. On the other hand, zinc, silver, barium, calcium, and nickel sulfides were not effective for mercury removal and their removal efficiencies were less than 20%. The surface analysis using X‐ray photoelectron spectroscopy suggested that mercury which reacted with sulfide compounds was presumed to form black mercury sulfide.

Micro-grid methods were applied to measure displacements in 90° ply in CFRP cross-ply laminates with only transverse cracks or with both transverse cracks and delaminations. The COD (crack opening displacement) of the transverse cracks were also measured. Micro-grids were printed on the specimen edge surfaces by using the photo-lithography technique. The displacement fields of the specimen edge surface obtained from the experiment were compared with McCartney's [1] and Lee et al.'s [2] analyses which predicted the displacement field of a cross-ply laminate with only transverse cracks. Furthermore these analyses were modified to consider the existence of delamination.

This paper presents the effects of moisture content on nonlinear stress-strain behavior of CFRP composites. First, a plane-stress elastic-plastic constitutive model is newly developed based on a fourth-order complementary elastic energy function and a one-parameter plastic potential in which an anisotropy parameter changes with plastic deformation. Secondly, elastic constants, the anisotropy parameter and the effective stress-effective plastic strain relation are determined at various moisture contents for both the present model and the conventional model where the anisotropy parameter is constant. Finally, the above results are utilized to predict the off-axis stress-strain response. The transverse and shear elastic moduli decrease with increasing moisture content, and the anisotropy parameter and the effective stress-effective plastic strain relation also vary with moisture content. Off-axis stress-strain curves predicted by the present model agree with experimental results better than those predicted by the conventional model.

The effects of the hole size and the specimen width on the fracture behavior of several woven fabric composite plates are experimentally investigated in tension. It is shown in this paper that the characteristic length (do) in the Point Stress Criterion (PSC) depends on the hole size and the specimen width. A modified PSC for predicting the notched strength is proposed. An excellent agreement is found between the experimental results and the analytical predictions using the modified PSC. When the unstable fracture occurred, the equivalent critical crack length (ac) corresponding to the damage zone size is about twice the characteristic length. The characteristic length decreases with an increase in the notched strength. The critical energy release rate (Gc) corresponding to the unstable fracture criterion is independent of the hole size for the same specimen width. Gcincreases with an increase in the specimen width. These results can be explained by the correlation between the Gcand the notch sensitivity factor (k).

The details of the time history of the elastic waves in ballistically im pacted composite laminates have been obtained by using surface and em bedded strain gages. Records show that a very low-amplitude in-plane tensile wave arrives first followed by a medium-amplitude flexural wave and then a high-amplitude flexural wave. Measured and calculated values of wave speeds agree well.

Mullite/SiC continuous fiber composites were fabricated by hot‐pressing under different processing conditions. The interfacial shear strength was measured during the pull‐out test, and the effect of fabrication conditions on interfacial debonding behavior was discussed. The debonding length during the pull‐out test was quantitatively evaluated using acoustic emission. The interfacial shear strength was evaluated by stress analysis. The control of interfacial shear strength was achieved by controlling the hot‐press temperature. An increase of load was found during the pull‐out process after complete debonding. In order to explain the increased load, a new model is presented.

For CFRP used as structural materials in space, the flexural strength and mode-I interlaminar fracture toughness (GIc) at high, room and low temperatures, and the effect of irradiation were studied. Conventional and toughened carbon fiber reinforced plastic (CFRP) kept high flexural strength even at 120 MGy. For conventional CFRP, GIc was improved by irradiation, and it kept good properties at 60 MGy. For toughened CFRP, apparent GIc was really high because fibers bridge between the beams. The fracture modes in the three point bending test and the fracture surfaces of DCB specimens were observed to study the fracture mechanisms.

So-called spall fractures (through-the-thickness tensile impact fractures) in simple uniaxial strain were examined for typical glass fiber reinforced thermosetting and thermoplastic polymer composite plates. An exploding foil technique was used to accelerate thin flyer plates towards composite plates to generate spall fractures. For thermosetting polyester composites, different fiber surface treatments were applied to study the effects of interfacial strengths on the impact fracture threshold conditions and the spall mechanism. The static interfacial strength could be well correlated with the threshold condition for the spall fracture initiation, but not with that for the complete separation fracture. Brittle debonding between fillers and resin was the main spall fracture mechanism. For thermoplastic polypropylene composites, on the other hand, plastic deformation played an important role in spall fractures to absorb considerable impact energy. Ellipse-shaped spall fractures were found in accordance with the fiber orientation of short fibers.

In recent years, interlaminar-toughened laminates have been developed in which resin rich layers are placed in interlaminar regions in order to enhance the interlaminar fracture toughness of CFRP laminates. In the present study, a predictive method is developed for transverse cracking in CFRP cross-ply laminates with interlaminar resin layers at 0/90° interfaces under static tensile loading. The analysis is based on a two-dimensional approximate elastic analysis considering the interlaminar resin layers and thermal residual stresses. To predict transverse cracking, both energy and stress criteria are used. The change in thermoelastic properties of a laminate due to transverse cracking is also predicted. To investigate the validity of the analysis, loading-unloading tests are performed to obtain Young's modulus reduction as a function of the transverse crack density. The predictions of transverse crack density as a function of the laminate strain are compared with our previous experimental results. A good agreement is obtained which implies the validity of the present analysis.

In recent years, to enhance the interlaminar fracture toughness of CFRP laminates, interlaminar-toughened laminates have been developed in which resin rich layers are placed in interlaminar regions. In the present study, stress and displacement fields in interlaminar-toughened cross-ply laminates with transverse cracks are analyzed. The analysis is based on a two-dimensional model which assumes that generalized plane strain conditions prevail. Account is taken of thermal residual stresses arising from a mismatch in thermal expansion coefficients of the 0° ply, interlaminar resin and 90° ply. The analytical results are shown for the laminates with interlaminar resin layers of various thicknesses. The analysis will be a basis for the optimal design of laminates with interlaminar resin layers.

Microscopic damage progress under static tensile loading in quasi-isotropic CFRP laminates was observed by an optical microscope and a scanning acoustic microscope (SAM). Material systems used were toughened-type CFRP, T800H/3631 and newly developed CFRP with interlaminar-toughened layers, T800H/3900-2. The laminate configurations were quasi-isotropic [0/45/90/- 45]s2for T800H/3631 and [0/45/90/-45]sfor T800H/3900-2. Both plain specimens and specimens with a circular hole were tested. By the edge observation of the plain specimens, transverse crack density was measured as a function of laminate strain. The effect of interlaminar-toughened layers on the behavior of the microscopic damage was clarified experimentally. By the SAM observation of specimens with a hole, delamination onset and growth were detected. To discuss the delamination onset from the edge of the open hole, the energy release rate associated with delamination growth was calculated following O'Brien and Raju. The energy release rate predictions of delamination onset and growth was qualitatively consistent with the experimental observation.

Degradation properties of epoxy matrix GFRP and CFRP composites irradiated by high-energy electrons were evaluated by interlaminar fracture toughness measurements in Mode I (GIc) and in mixed mode (Mode I+II, Gmc). The results were then compared with microscopic observations of fracture surfaces and dynamic viscoelastic properties to explain the radiation-induced degradation mechanisms. The sensitivity of radiation-induced degradation was much more pronounced in GIcthan in Gmc, or in the interlaminar shear strength. Interlaminar fracture toughness measurements were found necessary for proper evaluation of the radiation-induced degradation of FRP composites. For GFRP, a significant decrease in GIcwas found. Debonding of glass fibers and epoxy matrix (or degradation of silane coupling agents) plays an important role in degradation, in addition to resin degradation. Thus, the improvement of the radiation resistance of fiber-resin interfaces as well the matrix itself is of supreme importance in order to increase the radiation resistance of GFRP. For CFRP, on the other hand, no degradation in fiber-resin interfaces was found in irradiated specimens, and the slight decrease in GIcseems to be due to resin degradation.

This paper presents the effect of strain rates on nonlinear deformation behavior of CFRP composites. An elastic-plastic constitutive model is developed on the basis of both a complementary elastic energy function and a plastic potential, assuming that linear elastic deformation occurs in the fiber direction and that nonlinear strain in the shear direction is decomposed into nonlinear elastic strain and plastic strain. A one-parameter and a two-parameter plastic potential are employed to describe post-yielding behavior of composite laminae. Nonlinear elastic shear strain is measured by means of loading/unloading tensile tests of [±45°]s specimens. Off-axis tensile tests are performed to obtain the universal effective stress-effective plastic strain relation under monotonic loading. It is shown that rate-dependence of effective stress-effective plastic strain relation can be explained by determining anisotropy parameters of the plastic potential as functions of initial effective plastic strain rate.

Microscopic damage progress in CFRP cross-ply laminates under tensile fatigue loading was measured by the replica technique. Material systems were interleaved CFRP, T800H/3631-FM300 and toughness-improved CFRP, T800H/3900-2, with selectively toughened interlaminar layers. The damage parameter, the transverse crack density, was presented. A Paris law model was proposed, which related the cyclic strain range and the number of cycles at the transverse crack initiation. Based on the experimental data, a variational stress analysis combined with the modified Paris law was conducted to model the transverse crack multiplication.