In mountainous area, gravity survey external corrections, including terrain and Bouguer corrections, are the prerequisites for gravity data processing and interpretation. This paper presents a suite of techniques for ...In mountainous area, gravity survey external corrections, including terrain and Bouguer corrections, are the prerequisites for gravity data processing and interpretation. This paper presents a suite of techniques for spherical terrain and slab corrections for a finite spherical shell based on the analysis of conventional external corrections and deduces an equation for spherical terrain correction. The processing of gravity data acquired in the ZJJ area, South China shows that this technique significantly improves the accuracy of terrain corrections, and the quality of the data reaches or approaches the data acquired on plains.展开更多
A straightforward technique has been developed to quickly determine the wall contour of super/hypersonic nozzles working at multiply Mach number which share a common throat section.Mach number distribution along the c...A straightforward technique has been developed to quickly determine the wall contour of super/hypersonic nozzles working at multiply Mach number which share a common throat section.Mach number distribution along the centerline of the nozzle is specified in advance and divided into two sections,both of which are described by the b-spline function.The first section is shared by different exit Mach number nozzles.The nozzle contour is determined by the method of characteristics plus boundary layer correction.An example of this design method is employed to illustrate the technique with a computational fluid dynamics calculation.The simulation results indicate that desired Mach numbers are obtained at the nozzle exit,and the good flow quality is attained for different nozzles within δMa/Ma<±0.56% in the flow core region.This technique improves the design precision of the converging-diverging nozzle,cancels waves completely,and achieves nozzles with multiple Mach number exiting which share a common throat section.展开更多
Die-punch fractures or impaction fractures of distal radius articular surface are difficult to treat and hard to achieve satisfactory reduction, We present a unique, percutaneous and minimally invasive technique to el...Die-punch fractures or impaction fractures of distal radius articular surface are difficult to treat and hard to achieve satisfactory reduction, We present a unique, percutaneous and minimally invasive technique to elevate the depressed lunate fossa and maintain the reduction of the elevated fragment with no need of grafting in such fractures. This technique is simple, reproducible and can be executed with simple instrumentations. We think it deserves a variety of implications in the treatment of distal radius fractures.展开更多
Metallic implants are commonly used in various orthopaedic surgeries, like fracture fixation, spinal instrumentation, joint replacement and bone tumour surgery.Patients may need to adapt to the fixed dimensions of the...Metallic implants are commonly used in various orthopaedic surgeries, like fracture fixation, spinal instrumentation, joint replacement and bone tumour surgery.Patients may need to adapt to the fixed dimensions of the standard implants. It may result in suboptimal fit to the host bones and possible adverse clinical results. The standard traditional implants may not address the reconstructive challenges such as severe bone deformity or bone loss after implant loosening and bone tumour resection. With the advent of digital technologies in medical imaging, computer programming in three-dimensional（3 D） modelling and computer-assisted tools in precise placement of implants, patient-specific implants（PSI） have gained more attention in complex orthopaedic reconstruction. Additive manufacturing technology, in contrast to the conventional subtractive manufacturing, is a flexible process that can fabricate anatomically conforming implants that match the patients’ anatomy and surgical requirements. Complex internal structures with porous scaffold can also be built to enhance osseointegration for better implant longevity. Although basic studies have suggested that additive manufactured（AM） metal structures are good engineered biomaterials for bone replacement, not much peer-reviewed literature is available on the clinical results of the new types of implants. The article gives an overview of the metallic materials commonly used for fabricating orthopaedic implants, describes the metal-based additive manufacturing technology and the processing chain in metallic implants; discusses the features of AM implants;reports the current status in orthopaedic surgical applications and comments on the challenges of AM implants in orthopaedic practice.展开更多
文摘In mountainous area, gravity survey external corrections, including terrain and Bouguer corrections, are the prerequisites for gravity data processing and interpretation. This paper presents a suite of techniques for spherical terrain and slab corrections for a finite spherical shell based on the analysis of conventional external corrections and deduces an equation for spherical terrain correction. The processing of gravity data acquired in the ZJJ area, South China shows that this technique significantly improves the accuracy of terrain corrections, and the quality of the data reaches or approaches the data acquired on plains.
基金Project(11072264) supported by the National Natural Science Foundation of China
文摘A straightforward technique has been developed to quickly determine the wall contour of super/hypersonic nozzles working at multiply Mach number which share a common throat section.Mach number distribution along the centerline of the nozzle is specified in advance and divided into two sections,both of which are described by the b-spline function.The first section is shared by different exit Mach number nozzles.The nozzle contour is determined by the method of characteristics plus boundary layer correction.An example of this design method is employed to illustrate the technique with a computational fluid dynamics calculation.The simulation results indicate that desired Mach numbers are obtained at the nozzle exit,and the good flow quality is attained for different nozzles within δMa/Ma<±0.56% in the flow core region.This technique improves the design precision of the converging-diverging nozzle,cancels waves completely,and achieves nozzles with multiple Mach number exiting which share a common throat section.
文摘Die-punch fractures or impaction fractures of distal radius articular surface are difficult to treat and hard to achieve satisfactory reduction, We present a unique, percutaneous and minimally invasive technique to elevate the depressed lunate fossa and maintain the reduction of the elevated fragment with no need of grafting in such fractures. This technique is simple, reproducible and can be executed with simple instrumentations. We think it deserves a variety of implications in the treatment of distal radius fractures.
文摘Metallic implants are commonly used in various orthopaedic surgeries, like fracture fixation, spinal instrumentation, joint replacement and bone tumour surgery.Patients may need to adapt to the fixed dimensions of the standard implants. It may result in suboptimal fit to the host bones and possible adverse clinical results. The standard traditional implants may not address the reconstructive challenges such as severe bone deformity or bone loss after implant loosening and bone tumour resection. With the advent of digital technologies in medical imaging, computer programming in three-dimensional（3 D） modelling and computer-assisted tools in precise placement of implants, patient-specific implants（PSI） have gained more attention in complex orthopaedic reconstruction. Additive manufacturing technology, in contrast to the conventional subtractive manufacturing, is a flexible process that can fabricate anatomically conforming implants that match the patients’ anatomy and surgical requirements. Complex internal structures with porous scaffold can also be built to enhance osseointegration for better implant longevity. Although basic studies have suggested that additive manufactured（AM） metal structures are good engineered biomaterials for bone replacement, not much peer-reviewed literature is available on the clinical results of the new types of implants. The article gives an overview of the metallic materials commonly used for fabricating orthopaedic implants, describes the metal-based additive manufacturing technology and the processing chain in metallic implants; discusses the features of AM implants;reports the current status in orthopaedic surgical applications and comments on the challenges of AM implants in orthopaedic practice.
