Compressive performance of innovative reinforced pillars in closed/abandoned mines

Pillar is closely related to the stability and reliability of underground spaces in closed/abandoned mines.The present research introduced a new technique to strengthen square cement mortar columns via fiber-reinforced polymer(FRP)strips to verify the strengthening effect of FRP on pillars.Compared to a fully wrapped FRP jacket,the advantages of FRP strip are cost-effective and easy-to-construct.A series of compression tests as well as theoretical analysis were carried out to explore the mechanical behavior of square cement mortar specimens partially strengthened with FRP strips.The results verified the effectiveness of FRP strips in enhancing the stress and strain of cement mortar.Different from unconfined cement mortar specimens,these FRP-strengthened cement mortar specimens are featured with the double-peaked behaviors,mainly attributed to the stress state transformation from a one-dimensional to a three-dimensional stress state.It also indicated that the enhancement of stress increased with the FRP strip width.Moreover,the brittle-ductile transition ductile failure characteristics were also observed in FRP-confined cement mortar specimens.The ultimate ductility of the cement mortar specimen decreases gradually with the growth of the FRP strip width.The main contribution of this research is to enrich the strengthening techniques for residual pillars.

Application Research of Image Compression Technology in Monitoring System of Rape Crop in Areas of Qinling Mountains

[Objective] The aim was to present a proposal about a new image compression technology, in order to make the image be able to be stored in a smaller space and be transmitted with smaller bit rate on the premise of guaranteeing image quality in the rape crop monitoring system in Qinling Mountains. [Method] In the proposal, the color image was divided into brightness images with three fundamental colors, followed by sub-image division and DCT treatment. Then, coefficients of transform domain were quantized, and encoded and compressed as per Huffman coding. Finally, decompression was conducted through inverse process and decompressed images were matched. [Result] The simulation results show that when compression ratio of the color image of rape crops was 11.972 3∶1, human can not distinguish the differences between the decompressed images and the source images with naked eyes; when ratio was as high as 53.565 6∶1, PSNR was still above 30 dD,encoding efficiency achieved over 0.78 and redundancy was less than 0.22. [Conclusion] The results indicate that the proposed color image compression technology can achieve higher compression ratio on the premise of good image quality. In addition, image encoding quality and decompressed images achieved better results, which fully met requirement of image storage and transmission in monitoring system of rape crop in the Qinling Mountains.

Effects of hot compression on carbide precipitation behavior of Ni-20Cr-18W-1Mo superalloy

The effect of hot compression on the grain boundary segregation and precipitation behavior of M6C carbide in theNi-20Cr-18W-1Mo superalloy was investigated by thermomechanical simulator, scanning electronic microscope （SEM） and X-raydiffraction （XRD）. Results indicate that the amount of M6C carbides obviously increases in the experimental alloy after hotcompression. Composition analyses reveal that secondary M6C carbides at grain boundaries are highly enriched in tungsten.Meanwhile, the secondary carbide size of compressive samples is 3？5 μm in 10% deformation degree, while the carbide size ofundeformed specimens is less than 1 μm under aging treatment at 900 and 1000 ℃. According to the thermodynamic calculationresults, the Gibbs free energy of γ-matrix and carbides decreases with increase of the compression temperature, and the W-rich M6Ccarbide is more stable than Cr-rich M23C6. Compared with the experimental results, it is found that compressive stress accelerates theW segregation rate in grain boundary region, and further rises the rapid growth of W-rich M6C as compared with the undeformedone.

A New Measurement System for Static and Dynamic Clothing Pressure

This study aims to develop a system and measurement method for investigating the static and dynamic pressure behavior of compression products. The self-designed measurement system, named "cloth-press" (LLY-56B), is a direct measurement method, which is based on a rigid hemisphere with three pressure sensors distributed on its surface. The static pressure is measured at predetermined press depth, and the dynamic pressure is measured under the processing of fabric 3D deformation. The pressure distributions at the basic three sites are accepted as the measurement results. The measurement results provide much information in the field of compression fabric assessment, and the measurement system can be used in scientific research institutes and factories, contributing to optimize process parameters and quality control of compression garment.

Energy dissipation rate: An indicator of coal deformation and failure under static and dynamic compressive loads

Dynamic disasters in Chinese coal mines pose a significant threat to coal productivity. Thus, a thorough understanding of the deformation and failure processes of coal is necessary. In this study, the energy dissipation rate is proposed as a novel indicator of coal deformation and failure under static and dynamic compressive loads. The relationship between stress-strain, uniaxial compressive strength, displacement rate, loading rate, fractal dimension, and energy dissipation rate was investigated through experiments conducted using the MTS C60 tests(static loads) and split Hopkinson pressure bar system(dynamic loads). The results show that the energy dissipation rate peaks are associated with stress drop during coal deformation, and also positively related to the uniaxial compressive strength. A higher displacement rate of quasi-static loads leads to an initial increase and then a decrease in energy dissipation rate, whereas a higher loading rate of dynamic loads results in larger energy dissipation rate. Theoretical analysis indicates that a sudden increase in energy dissipation rate suggests partial fracture occurring within coal under both quasi-static and dynamic loads. Hence, the energy dissipation rate is an essential indicator of partial fracture and final failure within coal, as well as a prospective precursor for catastrophic failure in coal mine.

Automatic relational database compression scheme design based on swarm evolution

Compression is an intuitive way to boost the performance of a database system. However, compared with other physical database design techniques, compression consumes large amount of CPU power. There is a trade-off between the re- duction of disk access and the overhead of CPU processing. Automatic design and adaptive administration of database systems are widely demanded, and the automatic selection of compression schema to compromise the trade-off is very important. In this paper, we present a model with novel techniques to integrate a rapidly convergent agent-based evolution framework, i.e. the SWAF (SWarm Algorithm Framework), into adaptive attribute compression for relational database. The model evolutionally consults statistics of CPU load and IO bandwidth to select compression schemas considering both aspects of the trade-off. We have im- plemented a prototype model on Oscar RDBMS with experiments highlighting the correctness and efficiency of our techniques.

Dynamic recrystallization and silicide precipitation behavior of titanium matrix composites under different strains

In order to elucidate the microstructure evolution and silicide precipitation behavior during high-temperature deformation,TiB reinforced titanium matrix composites were subjected to isothermal hot compression at 950℃,strain rate of 0.05 s^(−1) and employing different strains of 0.04,0.40,0.70 and 1.00.The results show that with the increase of strain,a decrease in the content,dynamic recrystallization of theαphase and the vertical distribution of TiB along the compression axis lead to stress stability.Meantime,continuous dynamic recrystallization reduces the orientation difference of the primaryαphase,which weakens the texture strength of the matrix.The recrystallization mechanisms are strain-induced grain boundary migration and particle stimulated nucleation by TiB.The silicide of Ti_(6)Si_(3) is mainly distributed at the interface of TiB andαphase.The precipitation of silicide is affected by element diffusion,and TiB whisker accelerates the precipitation behavior of silicide by hindering the movement of dislocations and providing nucleation particles.

Hot deformation behavior and related microstructure evolution in Au−Sn eutectic multilayers

Hot compression was performed on a multilayered Au−20Sn eutectic alloy to investigate the deformation behavior and microstructure evolution.During hot compression,microstructural spheroidization was initiated from plastic instability regions,and it was preferentially activated in vertical lamellae with a growth direction parallel to the compressive direction.Continuous dynamic recrystallization associated with lattice dislocations was the mechanism in both AuSn and Au5Sn multilayers.After spheroidization,strain accumulations were weakened in both of the equiaxed phases,and the deformation mechanism was substantially replaced by grain boundary sliding and migration.Based on these findings,hot rolling was conducted on an as-cast Au−20Sn alloy and a foil with a thickness of~50μm was successfully prepared.The present study can promote the development of Au−20Sn foils,and provide insights into the deformation behavior and microstructure evolution of multilayered eutectic alloys.

Extractability of Cu in Alkaline Biosolids-Amended Soilsas Influenced by γ-Irradiation

An incubation experiment was conducted to investigate themicrobial biomass associated Cu in four contrasting soils to which analkaline stabilised sewage sludge cake was applied. The organisms ofsludge- amended and control soils were killed using γ-irradiationtechnique, and the aqueous and acid-extractable Cu concentrationswere determined. Addition of the sludge product increasedsignificantly the concentration of both the aqueous and diluteHOAc-extractable Cu in all the irradiated soils compared to thenon-sterilised sludge/soil mixtures, but the increase was morepronounced in the dilute acid-extractable Cu, indicating that the Curendered extractable in water and dilute acetic acid by γ-irradiation existed in the both soil liquid and solid phases. Theadditional increase in extractable Cu following the biocidaltreatment is likely to be due to release of Cu from the same fractionof soil microbial biomass.

Laboratory testing of a densified municipal solid waste in Beijing

Municipal solid waste （MSW） and its disposal are gaining significant importance in geotechnical and geoenvironmental engineering. However, conventional research is primarily focused on fresh MSW or MSW that is compacted under its own weight in the landfill. In this work, a series of tests to study the properties of a densified MSW after ground treatment were presented. The tests involved oedometer test, simple shear test, triaxial shear test, and permeability test, which were conducted to investigate the compressibility, shear strength, creep behavior and permeability of the MSW. The results show that the compressibility modulus of the MSW increases as the dry density increases. However, the influence of density on modulus decreases once the density reaches a certain value. Like most soils, the stress-strain curve of the densified MSW can be approximated by a hyperbola in the triaxial shear test. Fibrous components provide additional cohesion for MSW, but have a relatively smaller effect on friction angle. Permeability is also found to be closely related to the dry density of the MSW, i.e., MSW with a higher dry density has a smaller permeability. The permeability coefficient may be less than 10 7 cm/s if the density is high enough.

Sutureless Intestinal Anastomosis with a Novel Device of Magnetic Compression Anastomosis

Objective To explore the feasibility and efficiency of a novel magnetic compression anastomats(MCAs) in intestinal anastomosis.Methods A total of 36 male mongrel canines underwent intestinal anastomosis using traditional hand-sewn(n=18) or a novel MCAs(n=18).We compared the anastomosis time,postoperative complications,bursting strength of anastomoses,gross appearance,and pathology between two groups at each time-point of follow-up.Results The mean anastomosis time with MCAs was significantly less than that with hand-sewn(8.50±1.95 vs.31.1±4.32 minutes,P<0.001).The blood stools and intussusceptions occurred in both groups during follow-up period.Only 1 mongrel canine receiving intestinal anastomosis by MCAs experienced anastomotic leakage.The average bursting pressure of anastomoses obtained from mongrel canines undergoing intestinal anastomosis by MCAs was significantly higher than that by traditional hand-sewn at 1 week's follow-up time(P<0.05).Gross appearance of the anastomoses constructed by MCAs was relatively smoother and flatter.Pathological evalution of anastomoses revealed that general inflammation was greater in hand-sewn anastomoses than magnetic anastomosis.Conclusion The magnetic compression anastomat is a safe and effective device of sutureless intestinal anastomosis in canine models.

Mechanism of burst feeding in ZL205A casting under mechanical vibration and low pressure

The burst feeding behavior of ZL205 A casting under mechanical vibration and low pressure was investigated by casting experiment and physical model. Experimental results indicated that the burst feeding appeared repeatedly during solidification and left a shrinkage cavity with layered structure under mechanical vibration. The castings with less shrinkage and higher density could be achieved through the vibration. The calculation results of physical model showed that the burst feeding could perform spontaneously under vibration while difficultly without vibration in low-pressure die casting. The obstruction of a casting could be broken and the grains could be rearranged by the vibration. And the obstruction could be carried away due to the inner and outer pressure difference, causing a burst feeding.

Influence of infilling stiffness on mechanical and fracturing responses of hollow cylindrical sandstone under uniaxial compression tests

Hollow cylindrical sandstone specimens filled with Al,Pb and polymethyl methacrylate(PMMA),as well as hollow and solid specimens were tested under monotonic unconfined compression.The discrepancies in the elastic modulus,unconfined compressive strength and failure pattern of the specimens were studied and then illustrated.The interaction stress threshold and localized failure stress threshold were identified by the strain gauges on the rock and filling rod.The results indicated that unobvious changes in the strength and elastic modulus were found between the solid and hollow specimens,while for the hollow specimens with infillings,the strength decreases with increasing the stiffness of the infilling material.The filling material with a higher stiffness leads to a high hoop stress,and hence a stronger interfacial force.The specimens coupled with filling rod are mainly fractured with tensile cracks,while the solid and hollow specimens are typically split into blocky fragments with dominated shear fractures.Finally,the equivalent inner pressure in the opening was theoretically derived.The findings suggested in the experiments can be well explained using the theoretical thick-walled cylinder model.

Applications of the Fictitious Compress Recovery Approach in Physical Geodesy

The fictitious compress recovery approach is introduced, which could be applied to the establishment of the Rungerarup theorem, the determination of the Bjerhammar＇s fictitious gravity anomaly, the solution of the ＂downward con- tinuation＂ problem of the gravity field, the confirmation of the convergence of the spherical harmonic expansion series of the Earth＇s potential field, and the gravity field determination in three cases： gravitational potential case, gravitation case, and gravitational gradient case. Several tests using simulation experiments show that the fictitious compress recovery approach shows promise in physical geodesy applications.

Vibratile Coherence and Squeezing in Two Trapped Ions

It is shown that two trapped ions interacting with laser beams resonant to the first red side-band of center-of-mass mode, in Lamb Dicke regime and under rotating wave approximation, is described by a Jaynes-Cummingsmodel. For the initial condition that the motional state of center-of-mass mode is in vacuum state and the internal stateis prepared in a coherent superposition of states, coherence and squeezing for the vibratile motion of center-of-mass modeare discussed, particularly, a 'weak' coherent state and a 'weak' squeezed vacuum state are obtained. Collapse andrevival are also observed in this type of initial condition.

Conditionally Teleported States Using Optical Squeezers and Photon Counting

By virtue of the neat expression of the two-mode squeezing operator in the Einstein, Podolsky and Rosen entangled state representation, we provide a new approach for discussing the teleportation scheme using optical squeezers and photon counting devices. We derive the explicit form of the teleported states, so that the conditional property of teleportation and teleportation fidelity of this protocol can be seen more clearly. The derivation is concise.

JPEG-Compatibility Steganalysis that Distinguishes Embedding Changes from Recompression Artifacts

JPEG-Compatibility steganalysis detects the presence of secret message embedded in the JPEG decompressed images and estimates the embedding rate. We propose a JPEG-Compatibility steganalysis algorithm that estimates the embedding rate based on the difference between the stego image and its recompression based predicted co-vet image. In particular, compression artifacts and embedding changes are distinguished based on the amplitude of pixel value changes. This is done independent of the embedding positions, thus is effective for both content non-adaptive and content adaptive steganography. In addition, we also improve the recompression prediction scheme to more accurately estimate the JPEG quantization table. Experimental results show that the proposed algorithm is significantly more effective in detecting spatial ±1 steganography across a wide range of quality factors and embedding rates, when compared to the previous works.

Deformation characteristics and constitutive model of seafloor massive sulfides

Deformation characteristics and constitutive model of seafloor massive sulfide(SMS)were selected as the research object.Uniaxial/triaxial compression test were carried out on the mineral samples,and the deformation characteristics of specimens under various conditions were studied.According to characteristics of the mineral,a new three stages constitutive equation was proposed.The conclusions are as follows:The axial strain,peak strain and maximum strength of seafloor massive sulfide increase with the confining pressure.The elastic modulus of the metal sulfide samples is decreased sharply with the increase of confining pressure.According to characteristics of seafloor massive sulfide,the constitutive equation is divided into three parts,the comparison between theoretical curves and experimental data shows that both of them are in good agreement,which also proves the correctness of the constitutive equation for uniaxial compression.

Design of small-area multi-bit antifuse-type 1 kbit OTP memory

A multi-bit antifuse-type one-time programmable （OTP） memory is designed, which has a smaller area and a shorter programming time compared with the conventional single-bit antifuse-type OTP memory. While the conventional antifuse-type OTP memory can store a bit per cell, a proposed OTP memory can store two consecutive bits per cell through a data compression technique. The 1 kbit OTP memory designed with Magnachip 0.18 μm CMOS （complementary metal-oxide semiconductor） process is 34% smaller than the conventional single-bit antifuse-type OTP memory since the sizes of cell array and row decoder are reduced. And the programming time of the proposed OTP memory is nearly 50% smaller than that of the conventional counterpart since two consecutive bytes can be compressed and programmed into eight OTP cells at once. The layout area is 214 μm× 327 μ,, and the read current is simulated to be 30.4 μA.