Parks-McClellan滤波器在单相电机监控器中的应用

以Parks-McClellan算法为基础,根据单相异步电机监控的需求,通过MATLAB仿真与测试,设计了切比雪夫等波纹逼近FIR低通滤波器,对信号进行处理,并通过AVR单片机将其应用在电机监控器中,使系统监测功率更加准确,大大提高了对电机监控的稳定性,具有很高的实用价值.     

基于嵌入式系统的步进电机驱动设计

为了提高步进电机的稳定性,改善启动时出现的震动,论文介绍了一种基于嵌入式系统的步进电机驱动设计方案。系统中用FPGA来控制DA等器件来实现细分驱动技术,达到了1／64细分,使电机运行稳定;用ARM＋Linux编写电机驱动来实现升频启动,降低了启动时的震动;用QT编写的人机界面,可以控制电机正反转、运行速度、转动角度等,操作简易。该设计方案满足要求,已经得到了应用。     

Searle,Merleau-Ponty,Rizzolatti – three perspectives on Intentionality and action in sport

Actions in sport are intentional in character. They are directed at and are about something. This understanding of intentional action is common in continental as well as analytic philosophy. In sport philosophy, intentionality has received relatively little attention, but has more recently come on the agenda. In addition to what we can call ‘action intentionality,’ studied by philosophers like Searle, the phenomenological approach forwarded by Merleau-Ponty has opened up for a concept of ‘motor intentionality,’ which means a basic bodily attention and relatedness to the surrounding world. This conception is very relevant for the study of bodily actions as we find them in sports. However, there may be even deeper layers. The identification of mirror neurons in the brain has opened up for a type of almost ‘muscular intentionality’ whereby a simple bodily movement like grasping a cup to drink seems to be intentionally controlled and orchestrated. My goal in this paper is to discuss the relation between different levels of intentionality, such as a) ‘action intentionality’ operating at a conscious cognitive level, as for instance, when a player shoots a goal in football, b) the ‘motor intentionality’ directing the bodily movements when kicking the ball, and c) the muscular ‘mirror neuron intentionality’ of the goal keeper which is in operation when the keeper is seeing how the kicker’s foot hits the ball. How are these different layers of intentionality related and how can they give a more nuanced and integrated picture of the body–mind in action in sports?     

The fatigue effect of a simulated futsal match protocol on sprint performance and kinematics of the lower limbs

This study aimed to investigate the fatigue effects induced by a futsal-specific protocol (FIRP) on sprint performance and the kinematics of the lower limbs. Twenty-one futsal players participated in this study and performed a protocol to simulate the futsal demands. At pre-protocol, half-time and post-protocol, the athletes performed 10-m sprints that were recorded for kinematic analysis. Continuous relative phase (CRP) was calculated to assess the inter-segmental coordination. In addition, vertical (K_VERT) and leg (K_LEG) stiffness were calculated. Analysis of variance (ANOVA) for repeated measures was used (P < 0.05). The main results showed that sprint time increased (P < 0.01) post-protocol when compared to pre- and half-time conditions. Lower values of the step rate (P = 0.01) and higher values of the leg angular velocity (P = 0.02) were verified at the end of the FIRP. The CRP of thigh–leg and leg–foot and the stiffness did not change over the protocol. In addition, the high correlation of CRP between the conditions revealed no changes in coordination pattern. We concluded that futsal related-fatigue induced a decrement on sprint time, changing the kinematics of the lower limbs (decreasing step rate and increasing leg angular velocity). However, neither stiffness nor intersegment coordination during sprints was affected by fatigue.     

Comparison of performance on process- and product-oriented assessments of fundamental motor skills across childhood

Process-oriented motor competence (MC) assessments evaluate how a movement is performed. Product-oriented assessments evaluate the outcome of a movement. Determining the concurrent validity of process and product assessments is important to address the predictive utility of motor competence for health. The current study aimed to: (1) compare process and product assessments of the standing long jump, hop and throw across age groups and (2) determine the capacity of process assessments to classify levels of MC. Participants included 170 children classified into three age groups: 4–5, 7–8 and 10–11 years old. Participants’ skills were examined concurrently using three process assessments ((Test of Gross Motor Development-2nd edition [TGMD-2]), Get Skilled; Get Active, and developmental sequences) and one product measure (throw speed, jump and hop distance). Results indicate moderate to strong correlations between (1) process assessments across skills and age groups (r range = .37–70) and (2) process and product assessments across skills and age groups (r range = .26–.88). In general, sensitivity to detect advanced skill level is lowest for TGMD-2 and highest for developmental sequences for all three skills. The use of process and product assessments is suggested to comprehensively capture levels of MC in human movement.     

Impact sports and bone fractures among adolescents

The objective of the present study was to investigate the effects of different sports on stress fractures among adolescents during a 9-month follow-up period. The sample was composed of 184 adolescents divided into three groups (impact sports [n = 102]; swimming [n = 35]; non-sports [n = 47]). The occurrence of stress fracture was reported by participants and coaches. As potential confounders we considered age, sex, resistance training, body composition variables and age at peak of height velocity. There were 13 adolescents who reported fractures during the 9-month period. Bone mineral density values were higher in adolescents engaged in impact sports (P-value = 0.002). Independently of confounders, the risk of stress fracture was lower in adolescents engaged in impact sports than in non-active adolescents (hazard ratio [HR] = 0.23 [95% confidence interval (CI) = 0.05 to 0.98]), while swimming practice was not associated to lower risk of fracture (HR = 0.49 [95% CI = 0.09 to 2.55]). In conclusion, the findings from this study indicate the importance of sports participation among adolescents in the reduction of stress fracture risk, especially with impact sports. More importantly, these results could be relevant for recognising adolescents in danger of not reaching their potential for peak bone mass and later an increased risk of fractures.     

Sequence-dependent rotation axis changes in tennis

The purpose of this study was to evaluate the role of rotation axes during a tennis serve. A motion capture system was used to evaluate the contribution of the potential axes of rotation (minimum inertia axis, shoulder-centre of mass axis and the shoulder-elbow axis) during the four discrete tennis serve phases (loading, cocking, acceleration and follow through). Ten ranked athletes (International Tennis Number 1–3) repeatedly performed a flat service aiming at a target on the other side of the net. The four serve phases are distinct and thus, each movement phase seems to be organised around specific rotation axes. The results showed that the limbs’ rotational axis does not necessarily coincide with the minimum inertia axis across the cocking phase of the tennis serve. Even though individual serving strategies were exposed, all participants showed an effect due to the cocking phase and changed the rotation axis during the task. Taken together, the results showed that despite inter-individual differences, nine out of 10 participants changed the rotation axis towards the minimum inertia and/or the mass axis in an endeavour to maximise external rotation of the shoulder to optimally prepare for the acceleration phase.     

基于单片机的空调风扇控制系统

简单介绍了在无线遥控的基础上,通过89C52单片机[1]来控制交流电机的转速从而控制空调的风扇,通过步进电机来回运转72度从而实现风向的控制。并且采用过零检测技术,使可控硅输出完整的正弦波电压,避免了电网电压的干扰,增加了系统的稳定性。     

‘TRIPs‐plus’ patent privileges—an intellectual property ‘Cargo cult’ in Australia

This article challenges the desirability of implementing more than the minimum patent standards required by Australia’s commitment to the World Trade Organisation’s Agreement on Trade Related Aspects of Intellectual Property Rights (so‐called ‘TRIPs‐plus’ measures). We argue that there has not been an adequate analysis of what the various TRIPs‐plus measures actually are under the Patents Act 1990 (Cth), and that these measures have not been subjected to a competition analysis as required by the Competition Principles Agreement. This is, we contend, reminiscent of ‘cargo cult’ as Australian policy makers appear to reason that the most developed nations have benefited from innovation with TRIPs‐plus measures, and so with similar measures, those same benefits will accrue to Australia.