Selection of superior families of Pinus massoniana in southern China for large-diameter construction timber

This study addresses the increasing demand for large-diameter production timber,and considers the time and space variability of half-sib families of Pinus massoniana.Height,diameter at breast height(DBH)and timber volume of 440 open-pollinated half-sib progeny families were investigated in 14 progeny trials in different years and production regions.An evaluation of the genetic variation of all half-sib families was carried out during the sustainable rapid growth period and individual volumes were characterized as a major index.ANOVA analysis showed that there was considerable variance in the growth traits of most families in different years and on different sites.The variations caused by temporal and spatial changes of the mating system required three selection methods for analysis.The results show that there were differences among the heritabilities of different growth traits by different halfsib progenies.Average heritability values of height,DBH and volume were 0.33,0.34 and 0.36,respectively.Fortyfive superior families were selected in every progeny test,12 were selected in progeny trials by different years and five in different habitat progeny trials.Three superior families(Gui GC553A,Gui GC414A and Gui GC431A)were selected,although in different years and production regions.The genetic gains of timber volume of these selected r families ranged from 1.20 to 47.00%,which could provide a foundation for superior wood property selection and serve as material for seed improvement and extension in surrounding areas.

An Approach to Stability Analysis of Embedded Large-Diameter Cylinder Quay

The large-diameter cylinder structure, which is made of large successive bottomless cylinders placed on foundation bed or partly driven into soil, is a recently developed retaining structure in China. It can be used in port, coastal and offshore works. The method for stability analysis of the large-diameter cylinder structure, especially for stability analysis of the embedded large-diameter cylinder structure, is an important issue. In this paper, an idea is presented that is, embedded large-diameter cylinder quays can be divided into two types, i.e. the gravity wall type and the cylinder pile wall type. A method for stability analysis of the large-diameter cylinder quay of the cylinder pile wall type is developed and a method for stability analysis of the large-diameter cylinder quay of the gravity wall type is also proposed. The effect of significant parameters on the stability of the large-diameter cylinder quay of the cylinder pile wall type is investigated through numerical calculation.

Coupled BEM-FEM Analysis of the Large-Diameter Cylinder Structure System

A method of coupled BEM-FEM analysis for the elastic spatial structure system is presented. It can be applied to the calculation of the stress and deformation of the large-diamater cylinder structure system and it is suitable for symmetric or non-symmetric structures under the distributed or concentrated load. Numerical examples show that the proposed method and computer program BEFEM are quite efficient in the analysis of the large-diameter cylinder structure problems in ocean engineering.

A theoretical analysis of vertical dynamic response of large-diameter pipe piles in layered soil

Considering the viscous damping of the soil and soil-pile vertical coupled vibration,a computational model of large-diameter pipe pile in layered soil was established.The analytical solution in frequency domain was derived by Laplace transformation method.The responses in time domain were obtained by inverse Fourier transformation.The results of the analytical solution proposed agree well with the solutions in homogenous soil.The effects of the shear modulus and damping coefficients of the soil at both outer and inner sides of the pipe pile were researched.The results indicate that the shear modulus of the outer soil has more influence on velocity admittance than the inner soil.The smaller the shear modulus,the larger the amplitude of velocity admittance.The velocity admittance weakened by the damping of the outer soil is more obvious than that weakened by the damping of the inner soil.The displacements of the piles with the same damping coefficients of the outer soil have less difference.Moreover,the effects of the distribution of soil layers are analyzed.The results indicate that the effect of the upper soil layer on dynamic response of the pipe pile is more obvious than that of the bottom soil layer.A larger damping coefficient of the upper layer results in a smaller velocity admittance.The dynamic response of the pipe pile in layered soil is close to that of the pipe pile in homogenous soil when the properties of the upper soil layer are the same.

Failure mechanism of large-diameter shield tunnels and its effects on ground surface settlements

A new technique for the analysis of the three-dimensional collapse failure mechanism and the ground surface settlements for the large-diameter shield tunnels were presented.The technique is based on a velocity field model using more different truncated solid conical blocks to clarify the multiblock failure mechanism.Furthermore,the shape of blocks between the failure surface and the tunnel face was considered as an entire circle,and the supporting pressure was assumed as non-uniform distribution on the tunnel face and increased with the tunnel embedded depth.The ground surface settlements and failure mechanism above large-diameter shield tunnels were also investigated under different supporting pressures by the finite difference method.

A Theoretical Analysis of the Bearing Performance of Vertically Loaded Large-Diameter Pipe Pile Groups

This paper aims to present a theoretical method to study the bearing performance of vertically loaded large-diameter pipe pile groups.The interactions between group piles result in different bearing performance of both a single pile and pile groups.Considering the pile group effect and the skin friction from both outer and inner soils,an analytical solution is developed to calculate the settlement and axial force in large-diameter pipe pile groups.The analytical solution was verified by centrifuge and field testing results.An extensive parametric analysis was performed to study the bearing performance of the pipe pile groups.The results reveal that the axial forces in group piles are not the same.The larger the distance from central pile,the larger the axial force.The axial force in the central pile is the smallest,while that in corner piles is the largest.The axial force on the top of the corner piles decreases while that in the central pile increases with increasing of pile spacing and decreasing of pile length.The axial force in side piles varies little with the variations of pile spacing,pile length,and shear modulus of the soil and is approximately equal to the average load shared by one pile.For a pile group,the larger the pile length is,the larger the influence radius is.As a result,the pile group effect is more apparent for a larger pile length.The settlement of pile groups decreases with increasing of the pile number in the group and the shear modulus of the underlying soil.

Theoretical Analysis and Experimental Study on Breakaway Torque of Large-diameter Magnetic Liquid Seal at Low Temperature

The existing researches of the magnetic liquid rotation seal have been mainly oriented to the seal at normal temperature and the seal with the smaller shaft diameter less than 100 mm. However, the large-diameter magnetic liquid rotation seal at low temperature has not been reported both in theory and in application up to now. A key factor restricting the application of the large-diameter magnetic liquid rotation seal at low temperature is the high breakaway torque. In this paper, the factors that influence the breakaway torque including the number of seal stages, the injected quantity of magnetic liquid and the standing time at normal temperature are studied. Two kinds of magnetic liquid with variable content of large particles are prepared first, and a seal feedthrough with 140 mm shaft diameter is used in the experiments. All experiments are carried out in a low temperature chamber with a temperature range from 200℃ to -100℃. Different numbers of seal stages are tested under the same condition to study the relation between the breakaway torque and the number of seal stages. Variable quantity of magnetic liquid is injected in the seal gap to get the relation curve of the breakaway torque and the injecting quantity of magnetic liquid. In the experiment for studying the relation between the breakaway torque and the standing time at the normal temperature, the seal feedtrough is laid at normal temperature for different period of time before it is put in the low temperature chamber. The experimental results show that the breakaway torque is proportional to the number of seal stages, the injected quantity of magnetic liquid and the standing time at the normal temperature. Meanwhile, the experimental results are analyzed and the torque formula of magnetic liquid rotation seal at low temperature is deduced from the Navier-Stokes equation on the base of the model of magnetic liquid rotation seal. The presented research can make wider application of the magnetic liquid seal in general. And the large-diameter magnetic liquid rotation seal at low temperature designed by using present research results are to be used in some special fields, such as the military field, etc.

Simulation on flow, heat transfer and stress characteristics of large-diameter thick-walled gas cylinders in quenching process under different water spray volumes

Cooling strength is one of the important factors affecting microstructure and properties of gas cylinders during quenching process,and reasonable water spray volume can effectively improve the quality of gas cylinders and reduce production costs.To find the optimal water spray parameters,a fluid-solid coupling model with three-phase flow was established in consideration of water-vapor conversion.The inner and outer walls of gas cylinder with the dimensions of d914 mm×38 mm×12000 mm were quenched using multi-nozzle water spray system.The internal pressure,average heat transfer coefficient(have)and stress of the gas cylinder under different water spray volumes during quenching process were studied.Finally,the mathematical model was experimentally verified.The results show that both the internal pressure and have increase along with the increase of spray volume.The internal pressure increases slowly first and then rapidly,but have increases rapidly first and then slowly.To satisfy hardenability of gas cylinders,the minimum spray volume should not be less than 40 m^3/(h·m).The results of stress indicate that water spray quenching will not cause deformation of bottle body in the range of water volume from 40 to 290 m^3/(h·m).

Case Study on Synchronous Construction Technology for Secondary Lining of Large-diameter Single track Shiel Shield-bored ored Tunnel

The synchronous construction of the secondary lining during the boring of large-diameter shield faces challenges such as the design of the lining jumbo,the high requirements on the performance for the lining jumbo,the organization of the construction activities in the small and confined area,the horizontal transportation for shield boring and high safety management requirements.A super-long invert lining construction jumbo,as well as the matching California switch,is developed,which provides solution for the confliction between the invert lining construction and the horizontal transportation.The procedure and method for the synchronous operation of the shield boring and the secondary lining are developed by referring to the synchronous construction of the secondary lining during the boring of the TBMs in hard rocks.Due to the adoption of the synchronous operation of the shield boring and the secondary lining,the construction period is shortened and the construction cost is reduced.The paper can provide reference for the synchronous construction of the secondary lining in similar projects in the future.

Export Competitiveness and Sustainable Development of the Ukrainian Timber Industry

This paper conducts a comprehensive analysis of the export dynamics within the Ukrainian timber industry, emphasizing its pivotal role in the national economy. The study begins by outlining the research objectives, context, and innovative methodologies, setting the stage for a deep dive into the theoretical underpinnings of sustainable and competitive trade. It explores Ukraine’s rich forest biodiversity across varied vegetation zones and its geopolitical significance. Detailed evaluations of forest resource management, policy frameworks, and institutional support form the core of the analysis. Challenges such as imbalanced export structures and legal inconsistencies are critically examined. The research employs trade gravity models and competitive indicators like the Revealed Comparative Advantage (RCA) and Market Share (MS) to assess factors influencing exports and to forecast potential growth areas. The findings inform strategic recommendations aimed at enhancing export capacity through market diversification, brand development, and legal stability. The conclusion highlights the need for strategic interventions to harness Ukraine’s timber resources sustainably, balancing economic gains with environmental stewardship.

Control study of short-term curative effect of minimally invasive total hip arthroplasty using metal-on-metal large-diameter femoral head for the elderly patients with femoral neck fractures

Objective To discuss the postoperative curative effects of two surgical techniques of minimally invasive total hip arthroplasty (THA) using metal-on-metal largediameter and conventional diameter femoral head for the elderly patients

Application of single neuron adaptive PID controller during the process of timber drying

The paper presents a method of using single neuron adaptive PID control for adjusting system or servo system to implement timber drying process control, which combines the thought of parameter adaptive PID control and the character of neural network on exactly describing nonlinear and uncertainty dynamic process organically. The method implements functions of adaptive and self-learning by adjusting weighting parameters. Adaptive neural network can make some output trail given hoping value to decouple in static state. The simulation result indicates the validity, veracity and robustness of the method used in the timber drying process

Mechanical properties of monodirectional Gutou mortise-tenon joints of the traditional timber buildings in the Yangtze River region

The mechanical properties of the monodirectional Gutou mortise-tenon joints of the ancient Chinese traditional timber buildings in the Yangtze River region were studied using the experimental method. Three monodirectional Gutou mortise-tenon joints were designed according to the actual configurations. The failure modes,the hysteretic curves,the skeleton curves, the rotation rigidities, and the energy dissipation capacity of this type of mortise-tenon joints under the low cyclic reversed loading were obtained. The results show that the hysteretic curves of the monodirectional Gutou mortise-tenon joints appear to be Z shape and have obvious pinch effects. During the process of the test,these mortisetenon joints pass orderly through the elastic stage,the yield stage and the failure stage. The energy dissipation capacity of these mortise-tenon joints generally decreases with the increase in the rotation angle. The equivalent viscous damping coefficients of the monodirectional Gutou mortise-tenon joints are between 0. 161 and 0. 193. The results can provide the theoretical base for the computing analysis and repair design of Chinese traditional timber buildings in the Yangtze River region.

基于有限元分析的大理、丽江地区穿斗式木结构山架抗震性能

通过实地调查,分析了大理、丽江地区木结构榫卯结构的配置情况以及二者结构上的差异。为了研究二者的抗震性能与受力特性,通过有限元软件对两个地区的典型穿斗式木结构山架进行低周往复荷载模拟。结果表明:丽江地区穿斗式木结构山架抗震性能优于大理地区,两地木结构的薄弱点均在横向构件与纵向构件的榫卯节点处,榫卯节点的薄弱点位于榫头末端,二者的抗侧刚度均不高,易在水平荷载下倾斜。

Structural Carpentry in Qing Dynasty-A Framework for the Hierarchically Modularized Chinese Timber Structural Design

This article, by using mathematical expressions, offers a scientific framework for understanding how the grading system of Qing′s structural carpentry determines the design and construction in the grand style timber architecture.The Qing′s grand style timber structure, which is ready for prefabrication and assembly, is extremely hierarchical oriented and significantly standardized. The general procedure in designing a grand style timber structure is to start with the grade that defines the basic module (dou kou); next comes with the number of bracket set (cuan), the number of longitudinal bays and the number of purlins which affect its plan and cross section; thirdly choose a roof type that determines its longitudinal section and the facade as well. A series of formulae are conducted to help depict the layout, cross sectional roof curvature and special longitudinal treatments in 4 sloped and 9 spined roofs respectively.

Preservation Strategies of Timber-framed Arch Bridges as Cultural Landscape Heritage

Theoretical study on and safeguarding of cultural landscape heritage has been put on the agenda of heritage protection in Zhejiang and Fujian provinces.The safeguarding of timber-framed arch bridge heritage in the past 5 decades could be classified into 3 stages,and heritage protection in all 3 stages was closely related to original meaning of "landscape",which proved that timber-framed arch bridge heritage had profound inside information,and the safeguarding of timber-framed arch bridge from the perspective of cultural landscape heritage was worth further study.Safeguarding of timber-framed arch bridge cultural landscape heritage focused on integrated conservation,but not protection of individual bridges.Integrated conservation of world heritage is to maintain and restore the integrated environment landscape of the heritage,thus protection of timber-framed arch bridge heritage is not only to explore its architectural craftsmanship,but also to lay a foundation for the dynamic succession of such craftsmanship as intangible cultural heritage.Value of the existing timber-framed arch bridges as historic building heritage was discussed,and it was proposed that ultimate objectives of the safeguarding could be realized step by step from 3 layers.

Analysis of moisture diffusivity of larch timber during convective drying condition by using Crank＇s method and Dincer＇s method

Two analytical procedures （Crank＇s method and Dincer＇s method） for porous solid materials were reevaluated and used to determine moisture diffusion coefficients and moisture transfer coefficients for larch lumber subjected to drying. A diffusion-like equation was used to describe drying process data. The lumber was idealized in the modeling as infinite plates. The moisture transport process inside the board was assumed to be one-dimensional. The macroscopic drying kinetics curves of larch timber at particular conditions were determined experimentally. Based on these data, calculation for both the moisture diffusion coefficients and moisture transfer coefficients by the Dincer＇s analytical procedure were made. The dynamic moisture diffusion coefficients by the traditional Crank＇s method were calculated. In general, diffusion coefficients calculated by the Dincer＇s method were all higher than those by Crank＇s method. These results could be due to the differences between two analytical methods and also different characteristics between solid moisture diffusion process and heat transfer process. Therefore the analysis and solution procedures of moisture diffusion differential equations need to be adapted in the future. With drying temperature＇s increasing moisture diffusion coefficient （D） and moisture transfer coefficient （k） increases accordingly. Also the relationships between diffusion coefficients and temperature as well as material moisture contents were analyzed by using Arrhenius equation and bound water transport theory.

Shifting Private Timberland Ownership in South Carolina: Implications for Management Intensity

Beginning in the late 1970’s forest industry timberland gained the eye of financial investors. Diamond International and Crown Zellerbach were early firms that were purchased for the “break-up value” of their timberland. Timberland was perceived as undervalued by investors and made forest industry firms attractive takeover targets. This started a process where forest industry divested of its timberland. Some firms formed separate entities for its timberland base. Acquisitions and mergers became popular in the industry. Some forest industry companies converted to real estate investment trusts, for tax and defensive reasons. Large institutional investors became interested in timberland as means to diversify their portfolios and increase financial performance. Timber management investment organizations developed to manage and procure timberland for these institutional investors. Today little of the forest industry timberland remains with vertically-integrated forest products companies. South Carolina’s forest industry timberland decreased by about 800,000 ha since 1993 (or nearly 90%). This has implications for the state’s timber supply. Forest industry timberlands were some of the most productive and intensively managed forests in the state. We address how forest management might change on this timberland and how long-term timber supply might be impacted in the state.

Cost-effectiveness analysis of subsidy schemes for industrial timber development and carbon sequestration in Japanese forest plantations

This study uses simulations to investigate the effects of implementing two different Japanese forestry subsidy systems on timber production and carbon stock, and examines the consequences for harvesting strategies. An existing Local Yield Table Construction System （LYCS）, a wood conversion algorithm, and a harvesting cost model were used in the simulations to test the applicability of different subsidies to the thinning of stands. Using forest inventory data collected by local government staff, simulation output was used to calculate forestry profits, carbon stocks, subsidies, the amount of labor required, and the cost effectiveness of investing in subsidies. By comparing the output of simulations based on two scenarios, we found that both the clear-cutting area and the amount of harvested timber were larger under Scenario 2, in which the rules governing subsidy allocations are more relaxed, than under Scenario 1, in which the rules are more restrictive. Because the harvested timber under Scenario 1 was mainly produced by clear-cutting, the forestry profits and the subsidy predicted in the early period of the simulation, were larger under Scenario 1 than under Scenario 2. In contrast, the carbon stock was larger under Scenario 2 than under Scenario 1. The simulation model is likely to be useful for improving Plan-Do-Check-Act cyclesimplemented in Japanese forest management systems.

Comparison of three processing methods for laminated bamboo timber production

Three processing techniques, split-squaring(SS),V-grooving(VG), and split-edging(SE), were evaluated and compared in terms of their processing time and recovery. Semantan bamboo(Gigantochloa scortechinii Gamble) was used as a raw material and the results showed that the VG-method required the longest processing time(32.1 min), followed by the SS-method(18.2 min), and the SE-method(17.9 min). However, the VG-method showed the highest recovery(82.0%) compared to the SS-method and SE-method, 31.0 and 49.4%, respectively. When both processing time and recovery factors were combined with the same weighing factor, the highest value was recorded with the VG-method(49.1), while the SE-method had values of 31.1 and the SS-method 12.8. The results suggest that the VG-method is the best option. However, the V-grooving machine is still a prototype and therefore the SE-method could be an alternative option until the improved V-grooving machine is available.