Value-added strategies and forward integration in the Swedish sawmill industry: positioning and profitability in the high-volume segment

Abstract

The changing market conditions for the Swedish sawmill industry place a focus on a better understanding of the pros and cons of value-added and forward integration strategies. The purpose of this article is to describe and explain recent value-added strategies in the Swedish sawmill industry. The study includes strategies from 13 of the 15 largest sawmill companies for the period between 2002 and 2005, describing a differentiation between value added in primary sawmill production and forward integration into secondary production. It also aims to relate some basic conditions, such as company size, company growth and corporate strategy, to value added and forward integration to profitability. The results show strong positive and significant correlations between forward integration, value added in primary production (somewhat weaker) and unit revenue, and profitability measured as return on investment. There were no strong or significant correlations between size and profitability, playing down the importance of economies of scale (among these already large companies). An interesting result is the much higher profitability of the buying sawmill companies compared with the forest corporations, stressing the importance of both a long-term strategy when investing in value-added activities and ultimately the priorities of ownership.     

河北省玉米生产现状及主推品种分析

对河北省玉米生产现状及河北省主推玉米杂交种种质基础进行了分析,指出了河北省玉米生产中存在的主要问题,提出了解决问题的方法,以期对促进河北省玉米生产发展提供参考。     

基于MATLAB的机械用举升机构运动学分析

利用MATLAB对机械用举升机构进行运动学和动力学分析,编制相应的程序并通过实例进行分析和计算,这对分析机构稳定性和优化设计都具有一定的参考价值.     

分洪区口门流量淹没系数的研究

采用平面二维数学模型,计算分析了分洪区口门的堰流流量系数和淹没系数的变化过程。结果表明,在自由溢流时,分洪区口门的堰流流量系数和正向堰流的流量系数基本一致。在淹没溢流时,在淹没度为0.8～0.98范围内,分洪区口门堰流的淹没系数与普通水力学的正向堰流的淹没系数基本一致;对淹没度在0.98～1.0范围(正向堰流不存淹没度为0.98～1.0范围的堰流),通过数学模型的计算分析给出了淹没度在这个范围内的分洪区口门堰流的淹没系数。所得结果可以为分洪区口门的流量计算作参考。     

The Influence of Speed and Height at the Withers on the Kinematics of Sound Horses at the Hand-Led Trot

The influence of speed and height at the withers on some biokinematic stride parameters (linear, temporal and angular) was measured in 15 Spanish Thoroughbreds (Andalusian Purebred) trotted hand-led along a track; analysis was made of the correlation between speed and height at the withers and of some biokinematic parameters of equine locomotion. Both height at the withers and speed were positively and significantly correlated to the linear parameters examined. Temporal parameters did not reveal a significant correlation with the height at the withers. The correlations with the angular parameters were variable, often being significant for both height at withers and speed, although in most cases the coefficient was relatively low, probably owing to the narrow ranges of speed and height at the withers and their low variability. It was concluded that horses at the hand-led trot tend to have low variability in speed during successive trials, although the speed at which they move does have a significant influence on both linear and temporal stride parameters, and also on several angular parameters, while height at the withers has a major effect on linear parameters but less on angular parameters, and does not affect the temporal parameters.     

Racing performance following the laryngeal tie-forward procedure: a case-controlled study

REASONS FOR PERFORMING STUDY: The laryngeal tie-forward procedure (LTFP) is becoming widely used for correction of dorsal displacement of the soft palate (DDSP) despite the absence of an evidence-based assessment of its efficacy. HYPOTHESES: The LTFP returns racing performance to preoperative baseline levels and to that of matched controls; and post operative laryngohyoid position is associated with post operative performance. DESIGN AND POPULATION: Case-controlled study of racehorses undergoing a LTFP for dorsal displacement of the soft palate at Cornell University between October 2002 and June 2007. METHODS: The presence of at least one post operative start and race earnings ($) were used as outcome variables. Controls were matched by age, breed and sex from the third race prior to surgery. A novel radiographic reference system was used to determine laryngohyoid position pre- and post operatively. Data for definitively and presumptively diagnosed cases were analysed separately. RESULTS: During the study interval, 263 racehorses presented, of which 106 were included in the study; 36 had a definitive diagnosis of DDSP and 70 a presumptive diagnosis. Treated horses were equally likely to race post operatively as controls in the equivalent race. Treated horses had significantly lower earnings in the race before surgery than matched controls. The procedure moved the basihyoid bone dorsally and caudally and the larynx dorsally and rostrally. A more dorsal post operative basihyoid position and more dorsal and less rostral laryngeal position were associated with an increased probability of racing post operatively. CONCLUSIONS: Horses undergoing a LTFP are as likely to race post operatively as matched controls. The procedure restores race earnings to preoperative baseline levels and to those of matched controls. POTENTIAL RELEVANCE: This study provides strong evidence supporting the use of the LTFP in racehorses. Further work is needed to determine the relationship between laryngohyoid conformation and nasopharyngeal stability in horses.     

鸭嘴式钵苗移栽机的设计和试验研究

设计出一种钵苗移栽机,通过对移栽机的工作过程的阐述及运动学分析,确定了钵苗落苗过程中零速投苗点,使移栽效果最佳。对移栽机进行试验分析,选择机车前进速度﹑滚筒深度﹑可调连杆角度为试验因素,得出各试验因素与试验指标的关系。通过正交试验结果分析各试验因素对试验指标的影响大小,得出最优组合。结果表明:当机车前进速度0.30m/s、滚筒深度60mm、连杆角度40°时,直立度合格指数为85.18%,株距变异指数8.73%,漏栽指数1.68%,为移栽机结构和性能参数进一步优化提供了理论依据。     

3T1R并联机构运动学分析与优化设计

提出了一种可实现三维移动和一维转动的四自由度并联机构,它的2条相同支链通过被动转动副连接到动平台上,每条支链有2个相同分支,通过安装在基座上的移动副驱动。首先,阐述4PPa-2PaR并联机构的构型,通过螺旋理论验证机构的运动性质,基于机构自身特点研究机构的运动学特性;其次,利用数值法确定机构的工作空间,分析各设计参数对工作空间的影响,基于解析法研究机构工作空间的形状及满足的几何约束条件;最后,以工作空间占机构自身的比重为目标函数,设置影响工作空间的约束条件(如边界约束、不干涉性约束、避奇异约束和工作空间形状约束),并选择遗传算法对机构的尺寸参数进行优化设计。分析结果表明,优化后工作空间占机构自身的比重增大,工作空间体积也明显增大,优化结果可为后续样机研制提供参考依据。     

WalkawayVSP试射法正演方法研究

介绍了Walkaway VSP观测系统及Walkaway VSP地震波类型。结合模型的理论基础,以及射线理论,阐述了任意倾角多界面情况下,Walkaway VSP射线追踪模型的制作方法,论述了试射法原理。结合Walkaway VSP模型,使用 Fortran语言编写程序,实现了Walkaway VSP试射法正演模拟。利用Fortran编写的程序试算了3个模型,成功得到了任意倾角多界面情况下其射线追踪结果图和合成地震记录图,验证了程序算法的正确性和有效性。     

串联机构运动学反解的D-H四元数方法

普通四元数方法在串联机构运动学反解时存在方程数量不足和求解困难的问题,为了解决这些问题并建立新的串联机构运动学反解方法,提出串联机构运动学反解的D-H四元数方法。首先给出了包含D-H参数的四元数变换通用方程式,提出将四元数变换方程式分离为位置和姿态两个方程式,这两个方程式可构造出含有7个方程的方程组,使方程数量满足4R以上串联机构运动学反解的要求。为了降低方程组的求解难度,提出了取姿态方程中三角函数的一半组成新的姿态方程,将方程次数降低为原来的一半。采用所提出的D-H四元数方法对PUMA机器人进行运动学反解分析,得到了该机器人的8组反解。根据所求得的8组解,建立了PUMA机器人的8个位姿的三维模型,并测量了PUMA机器人三维模型的末端位姿数值,与所给末端位姿数值完全相同,验证了所提出的DH四元数方法的正确性和有效性。