A universal matrix solver for integral-equation-based problems

A new method has been developed for compressing the matrices that occur in most integral-equation-based computer programs. This method is easy to interface with existing computer programs, and allows them to run significantly faster and with significantly less memory. This method applies not only to electromagnetic and acoustic computation, but also to most programs involving a Green's function or any integral equation with a kernel having some smoothness properties. Our numerical computations, running on a high-end personal computer, have achieved compression ratios of fifty times, and compressed inversion of the matrices fifty times faster than by previous methods. For larger problems, solved on high-performance computers, these ratios would improve to about one thousand to one for larger moment method problems.     

Identification and characterization of a cDNA encoding ribosomal protein S12 from Xenopus laevis

LY171883, a peroxisome proliferator and leukotriene D4-antagonist, induced a statistically significant increase in the number of hepatic lesions in B6C3F1 female mice in a 2 year oncogenicity study at dietary doses of 0.0225% and 0.075%. The mutation frequency and spectrum of the 61st codon of H-ras was determined for 64 independent, archived lesions from the LY171883 2 year oncogenicity study using the polymerase chain reaction (PCR), allele specific oligo hybridization (ASO) and DNA sequencing. Results showed 41 (64%) of these lesions had mutations at the 61st codon (16/21 hepatocellular carcinomas, 4/10 hepatocellular adenomas, 19/26 focal hepatocellular hyperplasias and 2/7 focal hepatocellular atypia). These mutations consisted of 18 C-A transversions, 16 A-G transitions and seven A-T transversions. Compared to the mutation frequency for spontaneously occurring archival B6C3F1 hepatic lesions (41%), the frequency of LY171883 lesions (64%) was significantly higher (P < 0.01). The frequencies of H-ras 61st codon mutations among the LY171883 lesion types (hepatocellular carcinomas 76%, hepatocellular adenomas 40%, focal hepatocellular hyperplasias 73% and hepatocellular atypia 29%) were also significantly different (P = 0.035). In contrast, spontaneous lesions showed no statistical difference in the frequencies of mutation among lesion types (P > 0.5). The mutation spectrum of the LY171883 lesions was not significantly different from the spontaneous spectra. It may be concluded that based on the similarity in mutation spectrum and the increase in mutation frequency, LY171883 may selectively promote spontaneous hepatic lesions containing H-ras 61st codon mutations. In addition, the difference in mutation frequency among lesion types does not support a linear progression of all LY171883 lesions through focal atypia, focal hepatocellular hyperplasias, hepatocellular adenomas and hepatocellular carcinomas.     

Symbolic pixel labeling for curvilinear feature detection

This paper describes a method of detecting thin curvilinear features in an image based on a detailed analysis of the local gray level patterns at each pixel. This allows operations such as thinning and gap filling to be based on more accurate information.     

Mapping the thermal distribution within a silica preform tube using regenerated fibre Bragg gratings

The temperature profile of the reaction zone inside the silica substrate tube during thermal heating with a H₂/O₂ flame under conditions identical to those used in the fabrication of optical fibre preforms using a modified chemical vapour deposition lathe has been characterised with ultra-high temperature stable regenerated optical fibre Bragg gratings. Experimental and theoretical results indicate a significant drop in temperature – up to several hundred degrees – across the tube wall from outside to inside. These results are in contradiction with the broadly accepted assumption that there is no significant thermal gradient across the tube itself. An array of regenerated gratings demonstrates that optical fibre grating based sensing can achieve distributed ultra-high temperature mapping and monitoring in harsh environments.     

An investigation of the composite action of an FRP/concrete prismatic beam

A novel composite/concrete beam has been fabricated to use two component materials, fibre-reinforced polymer composite and concrete, to their best advantage. The concrete and composite are wholly under compressive and tensile strains, respectively, together with any shear strain components, except where under direct compression at the supports. The shear transfer at the interface between these two components requires investigation and this paper describes six techniques used to develop this connection to give the most efficient shear transfer in order for the whole beam to act compositely. The six methods are used independently of one another and include the use of indents in the vertical walls of the permanent composite shuttering retaining the concrete, bonding the concrete to the permanent shuttering, forming the shear connection by using bolts through both the concrete and permanent shuttering, two methods using a resin injection to fill a pre-formed gap between the concrete and permanent shuttering and finally using an adhesive compatible with freshly made concrete. It was concluded that the most appropriate method of ensuring complete composite action between the two component materials was to bond the cured concrete to the permanent shuttering along the two vertical sides. However, this is not a practical option as it assumes that the concrete is removed from the mould after it has cured and then bonded back into the permanent shuttering. It is suggested that the best practical method is to use the adhesive compatible with freshly made concrete which still gave an adequate level of composite action.     

Sparse Pseudo Inverse of the Discrete Plane Wave Transform

An algorithm is presented for the sparse pseudo inversion of discrete forms of the plane wave transform. The starting point for the sparse pseudo inverse is a new sparse representation of the discrete plane wave transform (DPWT). While other sparse representations of the DPWT exist, the sparse representation developed here is shown to be amenable to sparse factorization. This feature is used to develop an efficient, error-controlled pseudo-inverse of the DPWT. Representative numerical examples are provided to illustrate the general properties of the proposed algorithms. Areas for additional work are identified, and potential applications of the results are discussed.     

Transient gratings in rare-earth-doped phosphosilicate opticalfibres through periodic population inversion

Transient gratings with R>96% at 1526 nm have been observed in Er³⁺/Yb³⁺-doped phosphosilicate optical fibres holographically processed with 193 nm light. These arise primarily from the index change associated with population inversion of the Er³⁺ ions     

山区拱桥缆索吊装施工模拟仿真设计分析

以宁德市寿宁县坪坑大桥拱桥缆索吊装施工过程监控为例,基于现场实测数据,利用桥梁分析软件Midas对施工过程监控进行仿真分析,重点探讨拱圈拱箱节段吊装合龙、桥面铺装完成及徐变10年后的计算分析结果,得出施工预拱度的合理建议值及正常使用极限状态的计算结论,成果将为保证拱桥成桥线形提供理论依据及更好地指导后续施工。     

Surgical repair of urethral circumcision injuries

PURPOSE: The 2 types of urethral injury that can occur during circumcision are urethrocutaneous fistula and urethral distortion secondary to partial glans amputation. We report the surgical repair of these rare injuries. MATERIALS AND METHODS: In 8 patients urethrocutaneous fistulas located on the distal penile shaft or at the coronal margin were managed by splitting the glans and using a Mathieu style skin flap in 4 or vascularized penile skin flap in 4 to bridge the urethral defect. Three patients underwent repair of a hypospadiac deviated urethra secondary to partial glans amputation by 1 cm. of urethral mobilization and repositioning the meatus into a terminal position within the remaining glans tissue. RESULTS: The 8 patients with urethrocutaneous fistulas voided via a terminal meatus without fistula recurrence at a mean followup of 3.2 years (range 1 to 6). The 3 patients with partial glans amputation and urethral deviation repaired by short urethral advancement had functionally acceptable results, defined as a normal urinary stream, although 1 required meatal dilation postoperatively. CONCLUSIONS: The 2 types of urethral injuries that can occur during circumcision are a subcoronal urethrocutaneous fistula and scarred abnormal urethra from partial glans amputation. The urethrocutaneous fistula can be successfully repaired by splitting the glans and forming a neourethra from a vascularized pedicle flap of penile skin. The abnormal urethra after partial glans amputation is more difficult to repair but repositioning the urethra in a more cosmetic location has restored function.