Arc additive manufacturing of gradient hot forging die with shaped waterways

Under the working environment of high temperature and strong load impact,hot forging die is prone to failure which reduces the service life of die.Using arc additive manufacturing in the die cavity,a gradient material hot forging die with high precision,superior per-formance,and conformal cooling channels is developed.This improves the toughness of the die cavity and reduces the working temperature,thereby forming an isothermal field,which is an effective method to enhance the lifespan of the hot forging die.Three kinds of gradient flux-cored wires are designed for the surface of 5CrNiMo steel,and the microstructure and mechanical properties between gradient interfaces were studied.Based on the spatial curved structure of shaped waterways in the hot forging die cavity,a study was conducted on the strategy of partitioned forming for the manufacturing of the die with shaped waterways.In order to avoid interference with the arc gun,the hot for-ging die is divided into four regions,namely the transition region,upper,middle,and lower region,based on a combination of cavity depth and internal U-shaped and quadrilateral structures.The results show that the developed flux-cored wires have good moldability with straight sides of deposited metal under different process parameters and flat surface without cracks,pores and other defects.Under the same working conditions,the life of hot forging die formed by the gradient materials is more than multiple times that of the single material hot forging die,and the temperature gradient field of the shaped waterway die is 7℃/cm smaller than that of traditional straight waterway.

Analysis of Landscape Design of the Visual Aids to Navigation of Inland Waterway

The visual navigation marks are established purposely,which transfer information to the trained observer in order to navigate.The visual aids to navigation in freshwater could give aid to navigation.In addition,through its basic shape,appearance forms and colors,the landscape of navigation waterway is also displayed.The aids to navigation together with channel revetment and other surrounding landscape elements determine the landscape effect of the navigation waterway.Through analyzing the design of aids to navigation features,the design impact factors,the landscape design principles and methods of treatment are proposed in this research,in order to provide some references for the design of future visual aids to navigation.

相对化One-Way函数的存在性

One- Way函数在计算复杂性和密码技术中均有重要的应用 .将 Grollmann和 Selman的结果推广到相对化和非一致复杂类的情形 ,证明了复杂类 UP/ poly,UP,P/ poly等之间的包含关系与强相对化 one- way函数、弱相对化 one-

A new group key management scheme based on keys tree, XOR operation and one-way function

By introducing XOR operation and one-way function chains to group key management schemes based on the keys tree, a new group key management scheme based on the keys tree, XOR operation and one-way function chains is proposed. Initialization, member adding and member evicting operations are introduced. The new scheme is compared with three other group key management schemes which are based on the keys tree： SKDC, LKH, and OFF. As far as transmission, computation and storage costs are concerned, the performance of the new group key management scheme is the best. The security problem of the new scheme is analyzed. This new scheme provides backward and forward security, i.e.. newly admitted group members cannot read previous multicast messages and evicted members cannot read future multicast messages, even with collusion by many arbitrarily evicted members.

Possibilities and challenges of expanding dimensions of waterway downstream of Three Gorges Dam

The waterway in the middle and lower reaches of the Yangtze River has long been known as the Golden Waterway and has served as an important link in the construction of the Yangtze River Economic Belt.Therefore,expanding its dimensions is a significant goal,particularly given the long-range cumulative erosion occurring downstream of the Three Gorges Dam (TGD),which has been concentrated in the dry river channel.With the regulation of the volume from upstream reservoirs and the TGD,the minimum discharge and water level of the river downstream are increasing,and creating favorable conditions for the increase of the depth of the waterway.The discharge compensation effect during the dry season offsets the decline in the water level of the river channel caused by the down-cutting of part of the riverbed,but the minimum navigable water level of the segment near the dam still shows a declining trend.In recent years,several waterway remediation projects have been implemented in the downstream reaches of the TGD and although the waterway depth and width have been increased,the channel dimensions are still insufficient in the Yichang-Anqing reach (with a total length of 1026 km),as compared to the upstream reservoir area and the deep water channel in the downstream tidal reaches.A comprehensive analysis of the water depth and the number and length of shoals in the waterway indicates that its dimensions can be increased to 4.5 m ×200 m and 6.0 m×200 m in the Yichang-Wuhan and Wuhan-Anqing reaches,respectively.This is also feasible given the remediation technologies currently available,but remediation projects need to be coordinated with those for flood prevention and ecological protection.

Heavy Metal Pollution and Ecological Risk Assessment in Sediments of Xiling Channel Inland Waterway of Guangdong Province

Using the sediment monitoring data of five sections of the Xiling Channel inland waterway of the Pearl River Delta,and using Nemerow composite index,the coefficient of variation,and the index of geoaccumulation( Igeo) and the potential ecological risk index,this paper analyzed and assessed the heavy metal pollution of sediments. The results indicate that Cr reached mild pollution;Cu had a large degree of variation,and the changes of Cr and Zn were significant with fluctuation;the enrichment of heavy metals decreased as follows: Cd > Cu > Cr > Zn> Pb > Ni > Hg > As;Cd had the highest degree of enrichment and belonged to moderate pollution;the ecological hazard of heavy metals was Cd > Hg > Cu > Pb > As > Cr > Ni > Zn,and Cd had the highest ecological hazard and was the main controlling factor of potential ecological risk. In conclusion,the sediments in Xiling Channel inland waterway were polluted by heavy metals to some extent,and cadmium was the main pollutant and had the largest potential ecological risk.

Accuracy analysis of the optimal separable approximation method of one-way wave migration

An approximation for the one-way wave operator takes the form of separated space and wave-number variables and makes it possible to use the FFT, which results in a great improvement in the computational efficiency. From the function approximation perspective, the OSA method shares the same separable approximation format to the one-way wave operator as other separable approximation methods but it is the only global function approximation among these methods. This leads to a difference in the phase error curve, impulse response, and migration result from other separable approximation methods. The difference is that the OSA method has higher accuracy, and the sensitivity to the velocity variation declines with increasing order.

One-way wave equation seismic prestack forward modeling with irregular surfaces

Mathematical geophone （MG） and equal-time stacking （ETS） principles are used to implement seismic prestack forward modeling with irregular surfaces using the oneway acoustic wave-equation. This method receives seismic primary reflections from the subsurface using a set of virtual MGs. The receivers can be located anywhere on an irregular observing surface. Moreover, the ETS method utilizes the one-way acoustic wave equation to easily and quickly image and extrapolate seismic reflection data. The method is illustrated using high single-noise ratio common shot gathers computed by numerical forward modeling of two simple models, one with a flat surface and one with an irregular surface, and a complex normal fault model. A prestack depth migration method for irregular surface topography was used to reoroduce the normal fault model with high accuracy.

Design and analysis of logarithmic spiral type sprag one-way clutch

A complete mathematical model for logarithmic spiral type sprag one-way clutch design and analysis is given.It assumes that the motion of all clutch components can be expressed by a model of epicyclic gearing.It takes advantage of Hunt-Crossley contact impact theory to calculate the contact forces between sprags and races,and it can be used for optimization of design and comparison with other types of sprag clutches.A good deal of analysis shows that the parameters of the steady windup angle,the steady contact force,the natural frequency and natural cycle of clutch have nothing to do with the initial velocity of outer race,while the parameters of the maximum transient windup angle,the maximum transient impact force and the steady engagement time increase linearly in the mode of engaging operation of clutch.It is also shown that the strut angle has great influence on the dynamic engagement performance of clutch.The parameters of the steady windup angle,the maximum transient windup angle,the steady engaging time,the steady contact force,the maximum transient impact force and the natural cycle of clutch decrease linearly nearly with the inner strut angle,while the natural frequency of the system increases linearly with the inner strut angle.

Pressure-impulse diagram with multiple failure modes of one-way reinforced concrete slab under blast loading using SDOF method

Two loosely coupled single degree of freedom (SDOF) systems were used to model the flexural and direct shear responses of one-way reinforced concrete slabs subjected to explosive loading. Blast test results show that the SDOF systems are accurate in predicting the failure mode of the slab under blast loads by incorporating the effects of the strain rate effect caused by rapid load application. Based on different damage criteria, pressure-impulse (P-I) diagrams of the two failure modes were analyzed with the SDOF systems. The effects of span length, concrete strength, and reinforcement ratio of the slab on the P-I diagram were also investigated. Results indicate that a slab tends to fail in direct shear mode when it is of a smaller span length and tends to fail in flexure mode when it is of a larger span length. With the increase of the concrete strength or reinforced ratio, both the flexure and shear capacity increase. Based on numerical results, a simplified method and a semi analytical equation for deriving the P-I diagram are proposed for different failure modes and damage levels.

Physical Modeling of Localized Scour for the Yangtze Estuary Waterway Improvement Project,Phase Ⅰ

In order to examine the effectiveness of engineering protection against localized scour in front of the south groin-group of the Yangtze Estuary Waterway Improvement Project, Phase I , an undistort-ed physical model on a geometric scale of 1:250 is built in this study, covering two groins and their adacent estuarine areas. By use of rinsing fix-bed model as well as localized mobile-bed model, the experiment is undertaken under bi-directional steady flow. According to the experimental results, waterway dredging leads to the increase in steram velocity, the increase being larger during the ebb than during the flood. Construction of the upstream groin has some influence on the flow patterns near the downstream groin. Localized scour in front of the groin-heads is controlled mainly by ebb flow. In the case of a riverbed composed entirely of silt, the depths of localized scour in front of the two groin- heads are 27 m and 29 m, respectively. In reality, the underneath sediment of the prototype riverbed is clay whose threshold velocity is much higher than the stream velocity in the Yangtze Estuary; therefore, the depths of localized scour will not be much larger than the thickness of the silt layer, i. e. 7.4 m and 4.7 m, respectively. The designed aprons covering the riverbed in fron of the groin-heads are very effective in scour control. Aprons of slightly smaller size can also fulfill the task of protection, but the area of localized scour increases significantly.

Application of direct computing of one-way coupling technique in seismic analysis of concrete gravity dam

A dam-reservoir system subjected to an earthquake is a nonlinear system, because the fluid equations are always nonlinear regardless of the linear or nonlinear model used for the dam body. Therefore, transient analysis is necessary. In this study, dam-reservoir interaction during earthquake excitation was modeled by utilizing coupled finite element equations based on the Eulerian approach. Direct computing of the one-way coupling technique was used to solve the coupled equations. This technique is based on a simple assumption that the fluid hydrodynamic pressure is applied to the dam body while the deformation of the dam has no influence on the water field. Seismic response analysis of the Sonla concrete gravity dam constructed in Sonla Province, Vietnam was carried out as a verification example. The results of the methodology introduced are in close agreement with results of the iterative method and the solution procedure is found to be less time-consuming than that of the iterative method. This method is very convenient and can be easily implemented in finite element programs with fluid-structure interaction modules.

A parametric bootstrap approach for one-way classification model with skew-normal random effects

In this paper,several properties of one-way classification model with skew-normal random effects are obtained,such as moment generating function,density function and noncentral skew chi-square distribution,etc.Based on the EM algorithm,we discuss the maximum likelihood(ML)estimation of unknown parameters.For testing problem of fixed effect,a parametric bootstrap(PB)approach is developed.Finally,some simulation results on the Type I error rates and powers of the PB approach are obtained,which show that the PB approach provides satisfactory performances on the Type I error rates and powers,even for small samples.For illustration,our main results are applied to a real data problem.

Application of simple array method in one-way traffic synthetic asessment

One-Way Traffic synthetic assessing can not only determine the assessment method, but can also provide an opportunity for further study of road systems. Comparing three Road Traffic Planning methods, which are Value Analysis method, Simple Array method and Step Analysis method, this paper concludes that Simple Array method has one prominent merit, avoiding the complicated relationship of various factors and simplifying the complex problem. Therefore Simple Array method is firstly presented in this paper to be the assessing measure to assess the One-Way Traffic Planning project. Although this assessing method cannot wholly give way to man’s will, through consistently testing on qualitative factors and with the decision-making results of a multi-program, this method is still an effective method. Using an example of Harbin One-Way Traffic planning, with seven assessing indexes including economic benefit index, Simple Array method is applied to synthetically assessing the program. This fully reflects the general function of One-Way Traffic planning program and objectively evaluates the program. It also proves that, as the method of One-Way Traffic synthetic assessing, Simple Array method is rational and practical.

Urban One-way Traffic Organization and Its Evaluation

One-way traffic organization is a direct, efficient and economic method to solve traffic congestion and expand traffie capacity. With its evolution, advantages and disadvantages introduced its setting conditions demonstrated. The general method and processes are summarized in planning for urban one-way streets project, viz. investigation, drawing out and evaluation of project, selecting of project and beneficial analysis. Fuzzy synthetical evaluation other fields is employed to evaluate the project. Its evaluation system and method is introduced and Delphi method is adopted to obtain evaluation index. Finally, taking Harbin city as an example, the application process of above-mentioned method is illuminated. Accordingly, it is proved that the method is exercisable.

The Use of Hydrogen as a Fuel for Inland Waterway Units

Escalating apprehension about the harmful effects of widespread use of conventional fossil fuels in the marine field and in internal combustion engines in general, has led to a vast amount of efforts and the directing of large capital investment towards research and development of sustainable alternative energy sources. One of the most promising and abundant of these sources is hydrogen. Firstly, the use of current fossil fuels is. discussed focusing on the emissions and economic sides to emphasize the need for a new, cleaner and renewable fuel with particular reference to hydrogen as a suitable possible alternative. Hydrogen properties, production and storage methods are then reviewed along with its suitability from the economical point of view. Finally, a cost analysis for the use of hydrogen in internal combustion engines is carried out to illustrate the benefits of its use as a replacement for diesel. The outcome of this cost analysis shows that 98% of the capital expenditure is consumed by the equipment, and 68.3% of the total cost of the equipment is spent on the solar photovoltaic cells. The hydrogen plant is classified as a large investment project because of its high initial cost which is about 1 billion US$; but this is justified because hydrogen is produced in a totally green way. When hydrogen is used as a fuel, no harmful emissions are obtained.

ONE-WAY MULTIVARIATE REPEATED MEASUREMENTS ANALYSIS OF VARIANCE MODEL

The one-way multivariate repeated measurements analysis of variance (1-way MRM ANOVA) model for complete data and the sphericity test are studied.

How Waterways, Glacial Melt Waters, and Earthquakes Re-aligned Ancient Rivers and Changed Illinois Borders

The borders of Illinois were established when Illinois became a state in 1818. The western border was delineated using the Mississippi River, and the Ohio River was used as the southern border. The eastern border was formed by the Ohio and Wabash Rivers plus the line along latitude 42030＇30＇＇ connecting the Wabash River to Lake Michigan. As initially proposed, the northern border of Illinois would have been 82 km （51 mi） to the south of the current longitude line of 87~31 ＇. This 2,160,000 ha （5,440,000 ac） addition to Illinois resulted in the territory having the required minimum of 40,000 people to qualify as a state. The northern border was moved to allow the linkage of the Great Lakes shipping route to the Illinois and Mississippi River navigation channels. Illinois thus gained a valuable shoreline on Lake Michigan and a location for a shipping port hub which became Chicago. Initially the transfer of goods between these waterways required a portage, but later a shipping canal was created to link the waterways. During the Civil War, Union forces used the connected waterway systems as a northern supply route to avoid the contested Ohio River.

One-way hash function based on hyper-chaotic cellular neural network

The design of an efficient one-way hash function with good performance is a hot spot in modern cryptography researches. In this paper, a hash function construction method based on cell neural network with hyper-chaos characteristics is proposed. First, the chaos sequence is gotten by iterating cellular neural network with Runge Kutta algorithm, and then the chaos sequence is iterated with the message. The hash code is obtained through the corre- sponding transform of the latter chaos sequence. Simulation and analysis demonstrate that the new method has the merit of convenience, high sensitivity to initial values, good hash performance, especially the strong stability.

On Unobservability of One-Way Speed of Light

In this paper we recall the different definitions of simultaneity, the coordinate time interval and the velocity. It is emphasized that the above second two definitions depend on the simultaneity. We review the test theories on special relativity. It is shown that anisotropy (if possible) of one-way speed of light has not any ef- fects in the physical experiments. Therefore anisotropy of one-way speed of light cannot be determined by the experiments, except if an absolute (standard) simultaneity would be found.