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.

基于水动力载荷混合数据集的高精度神经网络代理模型构建

In this work,we constructed a neural network proxy model(NNPM)to estimate the hydrodynamic resistance in the ship hull structure design process,which is based on the hydrodynamic load data obtained from both the potential flow method(PFM)and the viscous flow method(VFM).Here the PFM dataset is applied for the tuning,pre-training,and the VFM dataset is applied for the fine-training.By adopting the PFM and VFM datasets simultaneously,we aim to construct an NNPM to achieve the high-accuracy prediction on hydrodynamic load on ship hull structures exerted from the viscous flow,while ensuring a moderate data-acquiring workload.The high accuracy prediction on hydrodynamic loads and the relatively low dataset establishment cost of the NNPM developed demonstrated the effectiveness and feasibility of hybrid dataset based NNPM achieving a high precision prediction of hydrodynamic loads on ship hull structures.The successful construction of the high precision hydrodynamic prediction NNPM advances the artificial intelligence-assisted design(AIAD)technology for various marine structures.

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.

Arc Grounding Fault Identification Using Integrated Characteristics in the Power Grid

Arc grounding faults occur frequently in the power grid with small resistance grounding neutral points.The existing arc fault identification technology only uses the fault line signal characteristics to set the identification index,which leads to detection failure when the arc zero-off characteristic is short.To solve this problem,this paper presents an arc fault identification method by utilizing integrated signal characteristics of both the fault line and sound lines.Firstly,the waveform characteristics of the fault line and sound lines under an arc grounding fault are studied.After that,the convex hull,gradient product,and correlation coefficient index are used as the basic characteristic parameters to establish fault identification criteria.Then,the logistic regression algorithm is employed to deal with the reference samples,establish the machine discrimination model,and realize the discrimination of fault types.Finally,simulation test results and experimental results verify the accuracy of the proposed method.The comparison analysis shows that the proposed method has higher recognition accuracy,especially when the arc dissipation power is smaller than 2×10^(3) W,the zero-off period is not obvious.In conclusion,the proposed method expands the arc fault identification theory.

凸F-多边形内部的F-点数

An F-polygon is a simple polygon whose vertices are F-points, which are points of the set of vertices of a tiling of R~2 by regular triangles and regular hexagons of unit edge. Let f(v) denote the least possible number of F-points in the interior of a convex F-polygon K with v vertices. In this paper we prove that f(10) = 10, f(11) = 12,f(12) = 12.

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).

Effect of Spray Rails on Takeoff Performance of Amphibian Aircraft

Amphibian aircraft have seen a rise in popularity in the recreational and utility sectors due to their ability to take off and land on both land and water, thus serving a myriad of purposes, such as aerobatics, surveillance, and firefighting. Such seaplanes must be aerodynamically and hydrodynamically efficient, particularly during the takeoff phase. Naval architects have long employed innovative techniques to optimize the performance of marine vessels, including incorporating spray rails on hulls. This research paper is dedicated to a comprehensive investigation into the potential utilization of spray rails to enhance the takeoff performance of amphibian aircraft. Several spray rail configurations obtained from naval research were simulated on a bare Seamax M22 amphibian hull to observe an approximate 10% - 25% decrease in water resistance at high speeds alongside a 3% reduction in the takeoff time. This study serves as a motivation to improve the design of the reference airplane hull and a platform for detailed investigations in the future to improve modern amphibian design.

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.

船体风机叶片对中速船水动力性能影响的计算分析

The importance of reducing ship resistance is growing considerably as a result of the increase in atmospheric emissions and the drive towards green shipping through decarbonization.Until this point,Energy Saving Devices(ESD),in particular,Hull Vane®(HV),have been widely applied as a potential technique for reducing wave-making resistance for vessels with higher Froude Number(Fr).The advantages of HV for a medium-speed vessel,where the wave-making component accounts for almost 50%of total resistance,have yet to be investigated.This study presents the computational analysis of the KCS model(1∶75.5);for a particular trim condition by using the VOF method and RANS solver.The hull acts as a candidate vessel for the class of medium-speed characteristics.A total of 36 numerical simulations were carried out to study the changes in resistance and motion characteristics of the vessel with and without HV.To validate the numerical setup,the experimental work of Hou et al(2020)on the DTMB hull was used.The effectiveness of HV can be comprehended by the reduction percentage in total resistance,trim,sinkage,and transom wave height,in comparison to bare hull condition.The reduction in total resistance extends up to 6%for Fr=0.32 with configuration 2 with negative AoF.The CFD results indicate that there is a reduction in trim up to 57%for the maximum speed with a corresponding Fr=0.34 with a positive angle of foil(AoF).The trim correction effect is increasing with the depth of submergence of HV.Concerning sinkage,there occurs nearly a 31%reduction for Fr=0.34 with a positive AoF.There exists a substantial reduction in the height of the transom wave with the inclusion of HV,the results of which are discussed in detail.From the presented results,retrofitting the Hull Vane®is effective in the selected speed range but pronouncing as the speed of the vessel increases.

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.

Unitariness in Ordered Semigroups

We introduce the concepts of unitary, almost unitary and strongly almost unitary subset of an ordered semigroup. For the notions of almost unitary and strongly almost unitary subset of an ordered semigroup, we use the notion of translational hull of an ordered semigroup. If (S,⋅,≤) is an ordered semigroup having an element e such that e ≤ e2 and U is a nonempty subset of S such that u ≤ eu, u ≤ ue for all u ∈ U, we show that U is almost unitary in S if and only if U is unitary in . Also if (S,⋅,≤) is an ordered semigroup, e ∉ S, U is a nonempty subset of S, Se:= S ∪ {e} and Ue:= U ∪ {e}, we give conditions that an (“extension” of S) ordered semigroup and the subset Ue of Se must satisfy in order for U to be almost unitary or strongly almost unitary in S (in case U is strongly almost unitary in S, then the given conditions are equivalent).

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。

Genetic Diversity of Gli-1,Gli-2 and Glu-1 Alleles Among Chinese Endemic Wheats

Genetic diversity at Gli_1, Gli_2 and Glu_1 loci was investigated in 32 accessions of Chinese endemic wheat by using acid polyacrylamide gel electrophoresis (APAGE) and sodium dodecyl sulfate (SDS)_PAGE. There were 8 gliadin and 3 high_molecular_weight (HMW)_glutenin patterns in 14 Yunnan hulled wheat ( Triticum aestivum ssp. yunnanese King) accessions, 9 gliadin and 4 HMW_glutenin patterns in 9 Tibetan weedrace ( T. aestivum ssp. tibetanum Shao ) accessions, and 9 gliadin and 5 HMW_glutenin patterns in 9 Xinjiang rice wheat ( T. petropavlovskyi Udacz. et Migusch.) accessions. One accession (i.e. Daomai 2) carried new subunits 2.1+10.1 encoded by Glu_D1. Among the three Chinese endemic wheat groups, a total of 10, 14 and 11 alleles at Gli_1 locus; 11, 14 and 12 alleles at Gli_2 locus; and 5, 6 and 8 alleles at Glu_1 locus were identified, respectively. Among Yunnan hulled wheat, Tibetan weedrace and Xinjiang rice wheat, the Nei's genetic variation indexes were 0.3798, 0.5625 and 0.5693, respectively. These results suggested that Tibetan weedrace and Xinjiang rice wheat had higher genetic diversity than Yunnan hulled wheat.

基于无套利模型的利率衍生产品定价研究

随着我国利率市场化进程的加快,市场迫切需要各种利率衍生产品来进行风险管理及资产负债管理,利率衍生品的定价自然成为了一个焦点问题。本文从利率衍生品定价的相关理论入手,重点研究利率衍生品定价的动态利率模型。首先运用两种代表性无套利利率模型Hull-White以及BDT(Black-Derman-Toy)模型对中国市场进行了定价实证对比,探讨利率期限结构的选择对模型效果的影响;接着运用Hull-White模型对银行间市场可回售债券进行了定价,指出了利率处在加息预期之中可回售债券并不存在明显的溢价。

硫酸盐体系三价铬电镀黑铬的工艺

为了寻找更环保、更稳定的三价铬电镀黑铬工艺,采用Hull Cell和小槽试验优选了硫酸盐体系三价黑铬电镀液中发黑剂、辅助发黑剂的种类及用量,并对镀液和镀层性能进行了测试。结果表明:最优三价铬电镀黑铬工艺为35 g/L碱式硫酸铬,30 mL/L配位剂,150 g/L硫酸钠,80 g/L硫酸钾,70 g/L硼酸,3 mL/LBNW-1润湿剂,2～4 g/L半胱氨酸,1～2 g/L硫氰酸钾,pH值3.4～3.8,温度50～60℃,阴极电流密度5～10A/dm2;以该工艺进行三价铬电镀黑铬,镀液稳定性好、分散能力强,电流密度范围宽,可达2.5～15.0 A/dm2;该工艺制备的黑铬镀层主要成分为Cr,S以及少量有机物;镀层黑度好,耐蚀性好,与基体结合良好。

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.

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。

Effects of Different Diuretics on Water Drinking Amount, Urination Volume and Related Blood Indices of Sheep Fed with Cottonseed

[Objective] This study aimed to investigate the effects of three kinds of diuretics on the water drinking amount and urination volume of sheep fed with cottonseed hulls. [Method] The method of self-control was adopted. Five two-year-old male Kazak sheep about 40 kg which never had intake of the feeds containing gossypol were selected. The experiment was divided into five periods, namely the control period, a period with the supplement of 300 mg/d of hydrochlorothiazide, a period with the supplement of 200 mg/d of hydrochlorothiazide, a period with the supplement of 350 mg of GY-01 and a period with the supplement of 200 mg of GY-01. The sheep were fed with the concentrate and the cottonseed hulls in the control period, and corresponding diuretics were supplemented in the rest four periods. The water drinking amount, urination volume and the contents of the hormone and ion in the blood were determined in each period. [Result] After 350 mg GY-01 was supplemented, the water drinking amount of each sheep had an increase of 60.14% compared with that of the sheep in the control period and the urination volume was 2.67 times of that of the latter, and the differences were both significant （P0.01）. The antidiuretic hormone declined by 32.59% compared with that of the sheep in the control period, with the significant difference （P 0.05）. The adrenocorticotropic hormone content increased by 81.93% compared with that of the sheep in the control period and the difference was significant （P0.01）. An increase of 28.04% （P 0.05） and 39.39% （P 0.01） was found in the contents of serum potassium and phosphorus respectively compared with that of sheep in the control period. [Conclusion] The diet with supplement of GY-01 can increase the urination volume of livestock fed with the cottonseed hulls, and the most appropriate supplement amount is 200 mg GY-01.

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.