2,143 research outputs found

    Design of Large Diameter Mine Countermeasure Hybrid Power Unmanned Underwater Vehicle

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    Mines are one of the most cost-effective and moderated weapon systems that are easy to deploy, but difficult to clear. Not only has the development of the mine countermeasure (MCM) underwater unmanned vehicle (UUV) improved cost- and time-effectiveness in operation, but also it has avoided unnecessary human casualties

    Deep reflection-mode photoacoustic imaging of internal organs

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    A deep reflection-mode photoacoustic imaging system was developed and demonstrated to possess a maximum imaging depth up to 38 mm in chicken breast tissue. Using this system, structures in the thoracic cavity and vasculature in cervical area of rats were clearly imaged. Particularly, part of the heart was imaged. In the thoracic cavity, the right atrium imaged, which is one of deepest, was situated ~7 mm deep. In the cervical area, common carotid artery and jugular vein were imaged, which are appropriate for the study of oxygenation between artery and vein. In the abdominal cavity, the embedded structures of a kidney, spinal cord, and vena cava inferior were also clearly imaged in situ and in vivo. The depth of the vena cava inferior was as deep as ~15 mm in vivo. This study shows the depth capability of the system in animals. This imaging modality can be a useful tool to diagnose the disease of organs by assessing the morphological and functional changes in the blood vessels and the organs

    Deep reflection-mode photoacoustic imaging of biological tissue

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    A reflection-mode photoacoustic (PA) imaging system was designed and built to image deep structures in biological tissues. We chose near-infrared laser pulses of 804-nm wavelength for PA excitation to achieve deep penetration. To minimize unwanted surface signals, we adopted dark-field ring-shaped illumination. This imaging system employing a 5-MHz spherically focused ultrasonic transducer provides penetration up to 38mm in chicken breast tissue. At the 19-mm depth, the axial resolution is 144μm and the transverse resolution is 560μm. Internal organs of small animals were imaged clearly

    Solutions of xqk+⋯+xq+x=ax^{q^k}+\cdots+x^{q}+x=a in GF2nGF{2^n}

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    Though it is well known that the roots of any affine polynomial over a finite field can be computed by a system of linear equations by using a normal base of the field, such solving approach appears to be difficult to apply when the field is fairly large. Thus, it may be of great interest to find an explicit representation of the solutions independently of the field base. This was previously done only for quadratic equations over a binary finite field. This paper gives an explicit representation of solutions for a much wider class of affine polynomials over a binary prime field

    Research on Over-Strength of RC Shear Wall Structure

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    Building is of a high degree of statically indeterminacy and should be designed with strict requirement on stability, load combinations, aseismic measures and so on. And in some cases, designers tend to decide dimensions and reinforcement over standards intentionally. Thus, seismic capacity exceeds standard required to design Stage in the well-operated structure abided by design code.  This results in considering the problem of over-strength of buildings with high requirement of seismic demand and economic efficiency. In this paper, we decided the minimum value of over-strength factor of RC shear wall structure with evaluating the over-strength designed strictly according to Design Code of DPRK
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