Buckling Properties of Water-Drop-Shaped Pressure Hulls with Various Shape Indices Under Hydrostatic External Pressure

The water-drop-shaped pressure hull has a good streamline,which has good application prospect in the underwater observatory.Therefore,this study conducted analytical,experimental and numerical investigation of the buckling properties of water-drop-shaped pressure hulls under hydrostatic pressure.A water-drop experiment was conducted to design water-drop-shaped pressure hulls with various shape indices.The critical loads for the water-drop-shaped pressure hulls were resolved by using Mushtari’s formula.Several numerical simulations including linear buckling analysis and nonlinear buckling analysis including eigenmode imperfections were performed.The results indicated that the critical loads resolved by Mushtari's formula were in good agreement with the linear buckling loads from the numerical simulations.This formula can be extended to estimate the buckling capacity of water-drop-shaped pressure hulls.In addition,three groups of pressure hulls were fabricated by using stereolithography,a rapid prototyping technique.Subsequently,three groups of the pressure hulls were subjected to ultrasonic measurements,optical scanning,hydrostatic testing and numerical analysis.The experimental results were consistent with the numerical results.The results indicate that the sharp end of the water-drop-shaped pressure hulls exhibited instability compared with the blunt end.This paper provides a new solution to the limitations of experimental studies on the water-drop-shaped pressure hulls as well as a new configuration and evaluation method for underwater observatories.

Improved spatio-temporal alignment measurement method for hull deformation

In this paper,an improved spatio-temporal alignment measurement method is presented to address the inertial matching measurement of hull deformation under the coexistence of time delay and large misalignment angle.Large misalignment angle and time delay often occur simultaneously and bring great challenges to the accurate measurement of hull deformation in space and time.The proposed method utilizes coarse alignment with large misalignment angle and time delay estimation of inertial measurement unit modeling to establish a brand-new spatiotemporal aligned hull deformation measurement model.In addition,two-step loop control is designed to ensure the accurate description of dynamic deformation angle and static deformation angle by the time-space alignment method of hull deformation.The experiments illustrate that the proposed method can effectively measure the hull deformation angle when time delay and large misalignment angle coexist.

Optimized Adsorption of Small and Medium Molecules by a Biosorbent Based on Hevea Hulls

In the context of the recovery of agricultural waste, many researches have focused on the preparation of adsorbents from natural waste from fruit trees, egg shells, palm waste or sawdust. This work aims to optimize the preparation of a biosorbent from rubber hulls by studying its ability to adsorb small and medium molecules. The influence of parameters such as drying temperature (X1), particle size (X2), stirring time (X3) and sodium hypochloride mass (X4) was studied. The results indicate that the model used for biosorbent optimization on methylene blue and iodine index is significant. In addition, this model has greater adsorption capabilities on small molecules than with large molecules. Statistical analysis of the data shows that temperature is the most influential factor in the adsorption of small molecules. On the other hand, particle size has a significant influence on the adsorption of large molecules. The optimum biosorbent preparation values are 1.0 for drying temperature (X1), −1.0 for biosorbent grain size (X2), 1.0 for stirring time (X3) and 1.0 for sodium hypochloride mass (X4).

Experimental and numerical analysis on suitability of S-Glass-Carbon fiber reinforced polymer composites for submarine hull

Suitability of S-Glass/carbon fiber reinforced polymer composite for submarine hull subjected to hydrostatic pressure has been investigated in the present study.Metallic materials have raised concerns owing to their decomposition due to low resistance towards salinity and hence polymer composites have been explored to showcase their mechanical stability to withstand transverse and impact loads.To this end,the mechanical properties of S-Glass/carbon fiber reinforced polymer composite were experimentally investigated and higher specific strength and stiffness of the composite in comparison to many metallic materials used for submarine hull were reported.The obtained experimental values were used for the static and dynamic crash analysis of the bow,stern and foil through Finite Element Analysis(FEA);where depth of travel was varied from sea surface level of 0-7000 m.Submarine assembly was later developed with the optimum shape and thickness of each part.We also report the nonlinear crash analysis upon impact at velocity ranging from 3 to 21 m/s.Besides,kinetic energy,acceleration peak and internal energy in struck submarine revealed that travel depth 1750 m and 3500 m is recommendable,more particularly,crash safety factor of the submarine is found to be within limit when submarine encounters crash at 1750 m.

Novel Gluten-Free Amaranth and Oat Flour Cookies Fortified with Soybean Hulls

Soybean hulls, an abundant byproduct of soybean processing, contain rich phytochemicals, fibers, proteins, and minerals. Currently soybean hulls are primarily used as animal feeds. For value-added soybean hull utilization, 25% soybean hulls were substituted for amaranth or whole oat flour (WOF) in novel gluten-free cookies. Composition, nutritional values, water-holding capacities, correlation between properties, and pasting and rheological properties of soybean hulls, amaranth, and WOF were appraised in comparison to wheat flour. Water loss, cookie texture, and geometrical properties of the cookies were examined. The results disclosed that soybean hulls, amaranth and WOF contain higher protein content, minerals, fiber, special amino acids, and critical vitamins (C and K) than wheat flour. Considerably higher total amino acid content was found in soybean hulls (18.33%) than wheat flour (12.77%). Water-holding capacities increased by replacing amaranth and WOF with soybean hulls. Soybean hulls exhibited higher rheological elastic properties than amaranth, WOF and wheat flours. The soybean hulls utilized in amaranth or WOF cookies greatly improved their nutritional value, the water retention and moisture content along with acceptable physical properties when compared to wheat flour cookies. This study explored the feasibility and potential of utilizing soybean hulls with amaranth and WOF in gluten-free bakery products and other food applications.

Evaluation of Physicochemical Parameters of Biosorbents Produced from Groundnut Hull Using Microwave Assisted Irradiation Method

Samples of ground nut hull were converted to biosorbents using microwave assisted method [groundnut hull treated with hydrogen peroxide (HP-GH), groundnut hull treated with distilled water (W-GH) and raw groundnut hull (R-GH)]. The biosorbents were further characterized using physicochemical procedures (pH dependence, bulk density, surface area, ash content, and volatile matter, moisture content). The results show that HP-GH has pH = 8.9, W-GH pH = 8.4 and R-GH pH = 8.5 which is an indication that all the biosorbents have the appropriate pH values for the uptake of cationic species within aqueous systems. Surface area analysis revealed that HP-GH has the largest surface area (74.20 m2·g-1) while W-GH and R-GH have surface area values of 29.40 m2·g-1 and 21.40 m2·g-1 respectively. This suggests that modification of raw groundnut hull biomass with hydrogen peroxide possibly instigated delignification of the biomass which resulted in increased surface area for HP-GH. Results from Bulk density analysis also confirm the data obtained from surface area analysis. Accordingly, R-GH displayed the highest bulk density followed by W-GH with HP-GH showing the least bulk density. The variation in pH values among the biomass used in this study may be explained by the variation in their ash content as well because pH and ash content are positively correlated. Hence, HP-GH with a pH = 8.9 has high ash content (117.31%), W-GH with pH = 8.4 has 97.93% ash content and R-GH with pH = 8.5 has 94.26% ash content. Results from moisture content analysis show that HP-GH (99.95%), W-GH (99.97%) and R-GH (99.89%) may necessitate exposure of the biosorbents to moderate heat before use. The results obtained from this study suggest that modification of ground nut hull with either distilled water or Hydrogen peroxide by means of microwave irradiation improves physicochemical properties which may perhaps increase the adsorption capacity of the biomass.

Resistance Characteristic of High-speed Unstaggered Pentamaran Model with Variations of Symmetric and Asymmetric Hull Configurations

Pentamaran,a vessel with five hulls,can be an alternative for high-speed vessels due to its advantages,for instance,its excellent stability and seakeeping performance and broader deck space than an equivalent monohull with the same displacement.The destructive interference between the system of waves produced by the vessel’s hulls might benefit the reduction of power consumption.This study investigated a Wigley hull form pentamaran model with five asymmetric and symmetric hull config-urations and three variations of hull separation.The ship model was towed in conditions of fixed towing and calm water with Froude numbers(Fr)ranging from 0.55 to 1.00.A resistance analysis had been carried out to ensure proper comparison between the asymmetric and symmetric hull configurations.Results showed that total resistance coefficient of the asymmetries created different properties from the symmetries,that is,symmetries produced steadier trends than asymmetries.The hull separation variation caused a slight alteration in the total resistant coefficient(in magnitude)under the same configuration.Although not a single configuration outperformed the others in the entire range of Fr,three configurations were noteworthy as optimum models based on their Fr range.Moreover,a configuration of asymmetric hull with S/L=0.22 could generate a constant destructive interference throughout the investigated Fr range.

采用带预处理的区间Hull算法求解区间直流潮流

随着间歇性能源接入电网,电网的潮流具有一定的随机性。考虑高压输电网中直流潮流的不确定性问题,文中提出了一种带预处理的区间Hull(P-Hull)算法来求解区间直流潮流。该方法首先通过预处理,形成主对角占优的区间系数矩阵,然后利用区间Hull算法得到系数H-矩阵。为了提高结果的精度,分别利用向上近似和向下近似方法处理H-矩阵的比较矩阵,进而采用迭代方法求得区间直流潮流分布的上下界。采用9节点系统,将文中所提出的算法与蒙特卡洛算法进行比较,揭示了误差主要受网络参数不确定性的影响。此外,采用IEEE 57和IEEE 118节点系统分别对P-Hull算法、区间Hull算法、Krawczyk算子迭代法以及高斯消去法在精度和计算时间上进行比较分析,可以看出P-Hull算法能够得到最高的精度,并且其时间复杂度远小于蒙特卡洛算法。

Monotricat, Innovative Displacement Hull High Hydrodynamic Efficiency and Energy Recovery, Navigating at Speeds of Planing Hulls on Spray Self-produced

The need to have naval units ever faster pushed the ship design to design hull shapes with increasingly higher performance thanks to the use of lightweight materials such as aluminum, and more powerful engines, etc., but without substantially modifying the traditional forms of hull. The hull patented Monotricat high hydrodynamic efficiency and energy saving it represents an evolution of the traditional architectures of the hulls, as its shape is adapted to recover wave formation engendered from the bow and sprays associated with it so as to reduce the resistance to the benefit of the speed, and navigating in displacement at speeds of planing hulls with an efficiency of about 20%. The patented hull Monotricat represents the overcoming of distinction between displacement and planing hulls, because, unlike previous solutions, the hull conventionally called Monotricat is the first displacement hull that can navigate at both displacement and planning speeds, with a resistance curve almost straight, maintaining the characteristics of a displacement hull, since it combines the characteristics of displacement and planning hull. It presents an innovative architecture that could be defined as a hybrid between a monohull and catamaran, navigating on spray self-produced. The combination of these three types of naval hulls allows it to ensure： safety, comfort navigation, best seakeeping and maneuverability in restricted waters, stability, reduction of resistance to motion, cost management, regularity on the routes even in adverse weather-sea. These characteristics of the hull have been studied, tested and validated by leading research institutes and universities with more ameliorative results in each subsequent experimentation, reported in the present work, which demonstrated a greater hydrodynamic efficiency compared to conventional hulls of 20%.

Hull-White随机波动率模型的欧式障碍期权

假定标的股票服从Hull-White随机波动率模型,应用鞅方法、条件分布的性质以及Black-Scholes模型的下降敲出欧式看涨障碍期权价格的Taylor展开式获得了期权价格的近似显示解。最后,通过对偶MonteCarlo模拟法比较了近似显示解的准确性,分析了波动率参数对期权价格的影响。

采用Hull树的贪婪地理位置路由算法的设计

地理位置路由算法是指借助节点获得的地理位置信息进行无线传感网络中的路由发现与数据转发工作。本文提出一种基于Hull树的贪婪地理位置路由算法——Greedy Hull Tree Geographic Routing(GHTGR)。通过图形学中凸包的概念,在网络初始阶段分布式地在各节点上建立Hull树以探查网络局部拓扑结构;同时在数据分组的路由转发阶段,通过Hull树内的搜索,寻找下一跳转发节点,完成数据分组的转发传输。通过仿真实验表明,与现有地理位置路由算法相比,该算法能够正确地寻找数据转发路径,有效地减少网络能耗,提高网络传输性能。

FPSO Hull项目进度测量系统的建立

对国内造船企业的项目进度测量现状进行了分析,并根据FPSOHull建造的管理要求和船舶企业的管理特点,详细论述船舶企业建立FPSOHull建造的进度测量系统原则、思路和方法.提出的思路与方法不仅适用于船舶企业的FPSOHull的建造的进度测量,亦适用于一般船舶的建造进度测量.

基于Hull-White模型的债券市场利率期限结构研究

现代利率研究中有许多理论和模型对利率期限结构问题进行探索,但是在中国还没有一种公认的理论或方法能够完全解决中国债券市场利率期限结构问题。本文尝试寻找一种更多的利用市场即时信息的定价方法对利率期限结构进行研究,应用三叉树模拟技术构建Hull-White模型,并对当前中国债券市场上几种常用利率进行比较分析。研究发现银行间质押式回购收益率具有较好的动态运动性质,比样本国债和政策性银行金融债更适宜作为短期金融产品定价的基础。

Study on Cotton Nursery Substrate Using Cotton Seed Hulls Residue after Producing Edible Mushroom

In order to discuss the localization application technology of cotton seedling using substrate, the author used cotton seed hulls after the production of edible fungi residue, river sand and peat in different proportion formula using in field and laboratory cotton seedling test. The results showed that： dry mass per plant and leaf area per plant of formula 3 were higher than Jiangxi cotton seedling nurs- ery substrate.the higher proportion were 48.4% and 73.5%; the rate of forming plantlets, survival rate of transplant and the unginned cotton yield had no obvious difference with the other matrix seedling and transplanting; nursery substrate was returned using as fertilizer, reduced environment pollution, achieved comprehensive utilization and cyclic utilization. Cotton seed hulls after the production of edible fungi residue was a cotton seedling substrate material of saving work,reducing cost and protecting environment and would have a good application prospect.

A new algorithm for computing the convex hull of a planar point set

When the edges of a convex polygon are traversed along one direction,the interior of the convex polygon is always on the same side of the edges. Based on this characteristic of convex polygons,a new algorithm for computing the convex hull of a simple polygon is proposed in this paper,which is then extended to a new algorithm for computing the convex hull of a planar point set. First,the extreme points of the planar point set are found,and the subsets of point candidate for vertex of the convex hull between extreme points are obtained. Then,the ordered convex hull point sequences between extreme points are constructed separately and concatenated by removing redundant extreme points to get the convex hull. The time complexity of the new planar convex hull algorithm is O(nlogh) ,which is equal to the time complexity of the best output-sensitive planar convex hull algorithms. Compared with the algorithm having the same complexity,the new algorithm is much faster.

基于正则化方法的Hull-White短期利率模型参数估计

基于市场债券价格,应用正则化方法对Hull-White短期利率模型中时间变量参数进行估计.通过变分原理,证明了该正则化方法具有稳定性和收敛性.最后,数值模拟确认该方法的有效性并给出实证结果.

Hull-White随机利率模型在债券价值分析中的应用

Hull-White随机利率模型既考虑了短期利率的均值回复(meanreversion)特性,又与初始期限结构相符合。本文就如何将Hull-White模型应用于债券定价进行了探讨,并将之应用于债券价值的风险分析。

混合分数维Hull-White利率模型下幂型期权的定价

文章假定原生资产的价格和利率的随机过程服从混合分数维布朗运动,利用风险对冲技术和偏微分方程方法得到了混合分数维Hull-White利率模型下幂型期权的定价公式,推广了相应基于几何布朗运动驱动的幂型期权定价公式和基于分数维布朗运动驱动的幂型期权定价公式。

分数维Hull-White利率模型下欧式期权的定价

假定原生资产的价格和利率的随机过程服从分数维布朗运动,利用风险对冲技巧和偏微分方程方法,得到分数维Hull-White利率模型下的欧式期权以及降低权利金权证的定价公式,推广了分数维BlackScholes期权定价公式.

Development of a Remotely Controlled Testing Platform with Low-drag Air-ventilated Hull

This paper addresses the development and testing of a remotely controlled boat platform with an innovative air-ventilated hull. The application of air cavities on the underside of ship hulls is a promising means for reducing hydrodynamic drag and pollutant emissions and increasing marine transportation efficiency. Despite this concept＇s potential, design optimization and high-performance operation of novel air-cavity ships remain a challenging problem. Hull construction and sensor instrumentation of the model-scale air-cavity boat is described in the paper. The modular structure of the hull allows for easy modifications, and an electric propulsion unit enables self-propelled operation. The boat is controlled remotely via a radio transmission system. Results of initial tests are reported, including thrust, speed, and airflow rate in several loading conditions. The constructed platform can be used for optimizing air-cavity systems and testing other innovative hull designs. This system can be also developed into a high-performance unmanned boat.