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排序方式: 共有197条查询结果,搜索用时 703 毫秒
71.
Alastair Parvin 《Architectural Design》2013,83(3):118-125
Alastair Parvin , an architectural and strategic designer at 00:/, calls for a focus on ‘the opposite side of the urbanisation story: the impact that urbanisation has on rural areas’. He advocates a rural design revolution that re-engages with farming and the countryside as a site of intense production, rather than as a preserve for nostalgia and leisure activities. 相似文献
72.
Different effects of process conditions on PA6/nanoclay composites at nanoclay contents above and below percolation threshold: Rheological,thermo‐dynamical,and thermal properties
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Mehdi Moghri Hamid Garmabi Parvin Kiany Seyed Ismail Seyed Shahabadi 《乙烯基与添加剂工艺杂志》2016,22(3):259-266
The effects of several factors (i.e., nanoclay content (NC), melt temperature, screw speed, and feeding rate), on morphology, rheology, thermodynamics, and thermal stability of PA6/NC samples produced in a co‐rotating twin‐screw extruder were studied. We discuss how changes in the level of these factors can vary diffusion or imposed shear, how these variations in diffusion and/or shear can affect NC dispersion, and how the changes in the state of NC dispersion can influence several properties of the samples. Samples with low NC content, below percolation threshold, showed exfoliated/intercalated structure with negligible sensitivity to changes in the level of the factors; whereas, samples with high NC content, above percolation threshold, showed intercalated with sporadic flocculated structures and noticeable sensitivity to the changes in the level of the factors. Moreover, NC dispersion was found to be mostly diffusion‐controlled: changes that resulted in higher diffusion or residence time (i.e., high melt temperature or low screw speed) also eventuated in better NC dispersion. What is more, percolation threshold was seen to move to lower NC contents as diffusion rate was increased. Moreover, as NC content increased, opposite thermal stability behaviors were observed at above and below the percolation threshold. J. VINYL ADDIT. TECHNOL., 22:259–266, 2016. © 2014 Society of Plastics Engineers 相似文献
73.
The incorporation of different percents of titanium dioxide (TiO2) nanoparticles into optically active poly(ester-imide) (PEI), afforded an opportunity to prepare several novel PEI/TiO2 bionanocomposites (BNC)s. To this point, firstly PEI was synthesized via direct polyesterification of chiral diacid monomer
and an optically active phenolic diol using tosyl chloride/pyridine/N,N-dimethylformamide system as a condensing agent. Novel BNC polymers containing TiO2 nanoparticles were synthesized through ultrasonic irradiation method. With the aim of γ-amidopropyl-triethoxylsilicane as
a coupling agent, the surface of nanoscale TiO2 was modified to decrease aggregation of nanoparticles in polymer matrix. The obtained PEI/TiO2 BNCs were characterized with FT-IR, thermogravimetric analysis (TGA), scanning electron microscopy, X-ray diffraction, and
transmission electron microscopy (TEM) techniques. Consequently, TEM image showed that the nanoparticles of smaller than 50 nm
in diameter were uniformly dispersed in the polymer matrix. TGA data demonstrated that new synthesized PEI/TiO2 BNCs are more thermally stable in compare to pure PEI. 相似文献
74.
T Ungi P Abolmaesumi R Jalal M Welch I Ayukawa S Nagpal A Lasso M Jaeger DP Borschneck G Fichtinger P Mousavi 《IEEE transactions on bio-medical engineering》2012,59(10):2766-2772
Purpose: Ultrasound (US) guidance in facet joint injections has been reported previously as an alternative to imaging modalities with ionizing radiation. However, this technique has not been adopted in the clinical routine, due to difficulties in the visualization of the target joint in US and simultaneous manipulation of the needle. Methods: We propose a technique to increase targeting accuracy and efficiency in facet joint injections. This is achieved by electromagnetically tracking the positions of the US transducer and the needle, and recording tracked US snapshots (TUSS). The needle is navigated using the acquired US snapshots. Results: In cadaveric lamb model, the success rate of facet joint injections by five orthopedic surgery residents significantly increased from 44.4% with freehand US guidance to 93.3% with TUSS guidance. Needle insertion time significantly decreased from 47.9 ± 34.2?s to 36.1 ± 28.7?s (mean ± SD). In a synthetic human spine model, a success rate of 96.7% was achieved with TUSS. The targeting accuracy of the presented system in a gel phantom was 1.03 ± 0.48?mm (mean ± SD). Conclusion: Needle guidance with TUSS improves the success rate and time efficiency in spinal facet joint injections. This technique readily translates also to other spinal needle placement applications. 相似文献
75.
Forensic examiners are in an uninterrupted battle with criminals in the use of Big Data technology. The underlying storage system is the main scene to trace
the criminal activities. Big Data Storage System is identified as an emerging challenge to digital forensics. Thus, it requires the development of a sound
methodology to investigate Big Data Storage System. Since the use of Hadoop as Big Data Storage System continues to grow rapidly, investigation process
model for forensic analysis on Hadoop Storage and attached client devices is compulsory. Moreover, forensic analysis on Hadoop Big Data Storage System
may take additional time without knowing where the data remnants can reside. In this paper, a new forensic investigation process model for Hadoop Big
Data Storage System is proposed and discovered data remnants are presented. By conducting forensic research on Hadoop Big Data Storage System, the
resulting data remnants assist the forensics examiners and practitioners for generating the evidences. 相似文献
76.
The research presented in this study involves full-scale experimental evaluation of carbon fiber-reinforced polymer (CFRP) rehabilitation for existing beam-column joints designed for gravity load with common pre-1970s deficient reinforcement details when subjected to cyclic loading. Numerous studies have demonstrated effectiveness of externally bonded fiber-reinforced polymer (FRP) materials for retrofitting the deteriorating RC structures. Although these materials are widely used in bridges, their applications in buildings have been somewhat limited. In particular, the experimental investigations on external FRP retrofit of deficient beam-column joints have not thoroughly been investigated and they are mainly on scaled-down specimens. The failure of these subassemblies, which possess lack of shear reinforcement within the joint core and shortly embedded positive beam reinforcement, would possibly result in catastrophic collapse of reinforced concrete frame structure during an earthquake event. Recognizing the urgent need to upgrade these structural subassemblies, the current investigation uses CFRP retrofit techniques to enhance the performance of such deficient joints. Experimental variables studied entail the developed CFRP retrofit configurations, and magnitude of the applied column axial load. Comparative analysis of the lateral loads versus drift hysteresis loops, stiffness degradation, and total dissipated energy curves of three as-built and three corresponding CFRP-retrofitted RC joints revealed that significant improvement in the shear capacity of the upgraded joints occurred. More importantly, the slippage of short embedded beam positive reinforcement into the joint was substantially controlled due to the developed CFRP retrofit. The results demonstrate the effectiveness of CFRP retrofit configurations in enhancing the structural performance of actual size connections. 相似文献
77.
78.
Ge Cong Parvin B. 《IEEE transactions on pattern analysis and machine intelligence》2000,22(9):1055-1061
A unique imaging modality based on equal thickness contours (ETC) has introduced a new opportunity for 3D shape reconstruction from multiple views. These ETC can be generated through an interference between transmitted and diffracted beams. We present a computational framework for representing each view of an object in terms of its object thickness and then integrating these representations into a 3D surface by algebraic reconstruction. In this framework, the object thickness is first derived from ideal contours and then extended to real data. For real data, the object thickness is inferred by grouping curve segments that correspond to points of second derivative maxima. At each step of the process, we use some form of regularization to ensure closeness to the original features as well as neighborhood continuity. We apply our approach to images of a submicron crystal structure obtained through a holographic process 相似文献
79.
Zahra Parvin Hadi Seyedarabi Mousa Shamsi 《Multimedia Tools and Applications》2016,75(17):10631-10648
In this paper, a new image encryption scheme is proposed with high sensitivity to the plain image. In proposed scheme, two chaotic functions and logical operator xor are used. Image encryption process includes substitution of pixels and permutation. Using the new method of substitution, algorithm sensitivity somewhat has elevated to changes in the plain image that by changing a single pixel of the plain image, amount of NPCR reaches 100 %. Results of tests show that the cipher image does not give any information of statistical such as entropy, histogram and correlation of adjacent pixels to attackers. Also the proposed scheme has the wide key space and is so safe to the noise ratio and compression. 相似文献
80.
Quantitation of limonin in Iranian orange juice concentrates using high-performance liquid chromatography and spectrophotometric methods 总被引:3,自引:0,他引:3
Soleiman Abbasi Parvin Zandi Esmaeil Mirbagheri 《European Food Research and Technology》2005,221(1-2):202-207
Bitterness is a major problem in the citrus industry worldwide, and is mostly due to the presence of limonoid compounds, especially limonin. In this study, the limonin content of orange juice concentrates from three active factories in west Mazandaran province, after reconstitution, was assayed using high-performance liquid chromatography (HPLC) and spectrophotometric methods. With HPLC, employing acetonitrile/water (v/v) (32:68) with a flow rate of 0.9 ml/min at =207 nm, the limonin content was in the range 11.7–23.3 g/ml with a mean ± standard deviation (SD) of 18.5±3.6 g/ml. Spectrophotometric measurement of limonin at 503 nm with Burnham reagent gave a range of 9.9–21.8 g/ml with a mean ± SD of 17.16±4.1 g/ml. The correlation coefficients of the detector linear response for the limonin standard (0–50 g/ml) for HPLC and spectrophotometry were 0.995 and 0.989, respectively. The percentages of limonin recovery with and without sample addition were 101.02–111.40 and 93.0–100.8, respectively, for HPLC. The percentages of limonin recovery for the spectrophotometric method resulted in 95.6–101.8 for limonin-added samples. The precision factors for the two assay methods were ±2.10% and ±1.69, respectively. The correlation coefficient of the two methods was 0.84. Sensory evaluation of the reconstituted samples from the view point of bitterness confirmed 85% of the results of the analytical methods. This study recommends spectrophotometric analysis as a useful and suitable method for quantitation of limonin in the quality control laboratories of orange juice plants. 相似文献