基于PSO的工业机器人时间-脉动最优轨迹规划

为提高工业机器人的工作效率,并且保持机器人关节平稳运动,提出一种基于粒子群优化算法的时间-脉动最优轨迹规划方案;通过权重法将多目标优化转化为单目标优化,再运用粒子群优化算法得到时间-脉动最优的运动轨迹;轨迹规划中,采用了关节空间五次非均匀B样条插值法,以确保脉动曲线的连续性;最后以GRB4016工业机器人为研究对象进行仿真实验,结果表明,该方案可以得到较理想的运动轨迹,并验证了方案的有效性。

基于遗传算法的机械手时间-脉动优化轨迹规划

为提高机械手的工作效率,同时确保机械手运行平稳,提出了一种基于遗传算法的时间-脉动优化轨迹规划方法。通过机械手运动学逆运算获得与路径点相对应的关节空间序列点,采用三次B样条曲线构造初步的关节轨迹。采用加权系数法定义目标函数,同时考虑关节的运动学约束,基于遗传算法求取时间-脉动优化轨迹。最后以IRB6640工业机器人为研究对象进行仿真分析,结果表明,该方法可以得到较为理想的机械手运动轨迹,在满足工作要求的前提下提高了工作效率。

Effect of transcatheter aortic valve replacement on P-wave duration, P-wave dispersion and left atrial size

Background P-wave dispersion （PWD）, a measure of heterogeneity of atrial refractoriness, is defined as the difference between the maximum and minimum P-wave duration. In patients with severe aortic stenosis （AS）, P-wave duration and PWD were shown to be increased, indicating atrial electrical remodeling. However, the effect of transcatheter aortic valve replacement （TAVR） on P-wave morphology has not been established yet. The aim of this study is to assess the short and long-term effects of TAVR with two types of bioprosthetic valves on P-wave duration and PWD in association with left atrial （LA） size. Methods Fifty-two （36 female） eligible patients in sinus rhythm who underwent transfemoral TAVR between June 01, 2012 and July 31, 2014 with either a Medtronic CoreValve （MCV） （n = 32） or an Edwards SAPIEN XT Valve （n = 20） were enrolled. Standard 12-lead electrocardiogram and echocardiographic evaluations were per- formed pre-procedurally, post-TAVR day one and 6 months post-TAVR. P-wave duration and PWD were measured and correlation analyses with echocardiographic variables were performed. Results P-wave duration and PWD were significantly decreased on post-TAVR day one （P 〈 0.05）. They continued to decrease during the six month follow-up period, but were not significantly different from short-term values （P 〉 0.05）. The decrease of LA diameter was found significant at the sixth-months of follow-up （P 〈 0.05）. These changes were independent from the types of bioprosthetic valves implanted （P 〉 0.05）. A positive correlation was detected between minimum P-wave duration and maximum aortic valve gradients at post-TAVR day one （r = 0.297, P = 0.032）. Conclusions P-wave duration and PWD were significantly reduced early after TAVR indicating early reverse atrial electrical remodeling. Moreover, structural reverse remodeling of atrium was detected at the 6-months of follow-up. The effects of two types of bioprosthetic valves on atrial remodeling were similar.

A Theoretical Study on the Interaction of Crown Tetraalanylpeptide with NO3- and SO4/2-

Crown peptide is a kind of special conformation found on the homodetic cyclopeptide, regular array about the main chain containing imido groups, and the monolithic conformation presents coronary analogy to crown ether. There are high symmetrical ionophores belonging to Cn point group. The channels or apertures can form easily for recognizing certain ion or molecular, and also the function of intending dual-recognition and the ability for transporting as ionophores can be possessed. Under the method of density functional theory, the geometry structures, values energy and population analysis of the combo of crown tetraalanylpeptide （C4-Ala） with NO3- and SO4/2- are calculated, based on the foundation of former studies. Compared with the structure of C4-AIa without NO3- and SO4/2- it is found that the coronary shape changes little in the complex of C4-Ala-YOm/n-, and the electrons transfer between C4-AIa and YOm/n- at the mean time. There are hydrogen bond between oxygen of YOm/n- and the hydrogen from imine groups of C4-AIa, and they become weaker when the average charge density lessens.

Selective Alignment of D2 Induced by Two Ultrashort Laser Pulses

The dynamics of molecular rotational wave packets of D2 induced by ultrashort laser pulses was investigated numerically by solving the time-dependent SchrSdinger equation. Results show that an ultrashort pulse can manipulate a coherent rotational wave packet of D2 se- lectively. In the calculation, a first laser pulse was used to create a coherent rotational wave packet from an initial thermal ensemble of D2 at the temperature of 300 K. The second laser pulse was used to manipulate the rotational wave packet selectively around the first quarter and the three quarters revival. The alignment parameter and its Fourier transform amplitude both illustrate that the relative populations of even and odd rotational states in the final rotational wave packet of D2 can be manipulated by precisely selecting the time delay between the first and the second ultrashort pulse.

Ascent schedules,acute altitude illness,and altitude acclimatization:Observations on the Yushu Earthquake

During the Yushu Earthquake on April 14,2010,a large number of rescuers from sea level or lowlands ascended to the quake areas very rapidly or rapidly less than 24 h. However,Yushu Earthquake is the highest quake in the world at altitudes between 3 750 m and 4 878 m where is a serious hypoxic environment. A high incidence of acute altitude illness was found in the unacclimatized rescuers;the mountain rescue operation changed as "rescue the rescuers". Lesson from the Yushu Earthquake is that the occurrence of acute altitude illness may be closely related to the ascent schedules. This prompted us to study the relationship between ascent rate and the incidence and severity of acute altitude illness;five different groups were compared. The first group was 42 sea level male young soldiers who ascended to quake area very rapidly within 8 h at 4 000 m;the second group was 48 sea level male young soldiers who ascended to 4 000 m rapidly less than 18 h;the third group was 66 acclimatized medical workers from 2 261 m who ascended to 4 000 m rapidly within 12 h;the fourth group was 56 Tibetan medical workers from 2 800 m who ascended to 4 000 m rapidly within 8 h;the fifth group was 50 male sea level workers who ascended to 4 000 m gradually over a period of 4 d. The results showed that the sea level rescuers ascended to 4 000 m very rapidly or rapidly had the highest incidence of acute mountain sickness (AMS) with the greatest AMS scores and the lowest arterial oxygen saturation (SaO2);the sea level workers ascended to 4 000 m gradually had moderate incidence of AMS with moderate AMS scores and SaO2 values;whereas the acclimatized and adapted rescuers had the lowest incidence of AMS,lowest AMS scores and higher SaO2;especially none AMS occurred in Tibetan rescuers. AMS score is inversely related to the ascent rate (r=-0.24,p< 0.001). Additionally,acute altitude illness is significantly influenced by altitude acclimatization. The ascent rate is inversely re- lated to the period of altitude acclimatization whereas the time of perfect recovered from AMS is positively correlated to the time taken to acclimatize. Generally,the best means of preventing acute altitude illness is slow and gradual ascent to high altitude,as this allows time for establishing altitude acclimatization and tolerance to the hypoxic environment. However,during an emergency circumstance,such as mountain rescue operation,the rescuers must rapidly ascend to high altitude,so a series of preventive strategies including pre-acclimatization,using some prophylactic drugs and oxygen supplementary are sorely necessary.

Residence Time Distribution at Laminar Pulsatile Flow in a Straight Pipe

This paper deals with the problem of theoretical identification of the residence time distribution （RTD） characteristics of a straight pipe at laminar pulsatile flow, if tracer diffusion can be neglected. This situation is typical for micro-apparatuses （e.g. fluidic element） and also for flow in large arteries. Residence time distribution based on velocity profiles at pulsatile flow of a Newtonian liquid in a rigid pipe will be derived theoretically and compared with the well known results for a constant flow rate E（τ） = τ-^2/2τ^3 at τ 〉 τ^-/2, where E （τ） is differential distribution, x is residence time and τ^- is the mean residence time. The following part of the paper deals stimulus response experimental techniques using tracers. The principal problem related to laminar and convection dominated pulsatile flows is discussed： Can the impulse response also be identified with the actual residence time distribution in the case of variable flow？ The general answer is no, and differences between RTD and impulse responses are evaluated as a function of the frequency and amplitude of pulsatile flows.

Effects of Reducing River Flow on Pulse Residence Time in Little Manatee River,USA

Residence time is an important indicator for river environmental management.In this paper,a 3D hydrodynamic model has been successfully applied to Little Manatee River to characterize the mixing and transport process and residence time.The model employs horizontal curvilinear orthogonal grids to represent the complex river system that consists of branches and bayous.The model has been satisfactorily calibrated and verified by using two continuous data sets.The data sets consist of hourly observations of all forcing boundaries,including freshwater inputs,tides,winds,salinity and temperatures at bay boundary,and air temperatures for model simulations.The data sets also consist of hourly observations of water levels,salinity,and temperature at several river stations.The calibrated and verified hydrodynamic model was used to predict residence time in the Little Manatee River.Under the minimum flow of 0.312 m3/s,the pulse residence time(PRT) is 108 days.Model simulations were also conducted for 17 flow scenarios.Empirical regression equations have been satisfactorily derived to correlate PRT to freshwater inflow.Correlation coefficient R2 is 0.982 for PRT.

Anti-embolic effect of Taorenchengqi Tang in rats with embolic stroke induced by occluding middle cerebral artery

OBJECTIVE: To investigate the anti-embolic effect of Taorenchengqi Tang(TRCQT), a formulas from Traditional Chinese Medicine, plus aspirin in rats with embolic stroke induced by selective occlusion of the middle cerebral artery(MCA). Possible side effects of hemorrhagic incident and other bleeding events and anti-platelet effect were also explored.METHODS: Ninety rats were randomly separatedinto 9 groups(n = 10): group 1 a sham-operated group(n = 10); groups 2 and 3 orally treated with an isovolumetric solvent(distilled water) for 1 and3 months, followed by thromboembolic occlusion(n = 10); groups 4 and 5 orally treated with aspirin(5 mg/kg) alone for 1 and 3 months, followed by thromboembolic occlusion(n = 10); groups 6 and 7orally treated with TRCQT(0.5 g/kg) alone for 1 and3 months, followed by thromboembolic occlusion(n = 10); groups 8 and 9 orally treated with TRCQT plus aspirin for 1 and 3 months, respectively followed by thromboembolic occlusion(n = 10). The ischemic stroke in rats was induced by selective MCA occlusion. One was orally administered. After the treatments, rats' brains were removed, sectioned and stained with triphenyltetrazolium chloride(TTC) for infarct volume measurement. The incidence of subarachnoid hemorrhage(SAH) and intracerebral hemorrhage(ICH) were observed. A potential gastric bleeding side effect was assessed by measuring hemoglobin(Hb), and prothrombin time(PT). Collagen-induced platelet activation and tail vein bleeding time were measured.RESULTS: Treatment with TRCQT alone or in combination with aspirin reduced infarct volume for 1(P < 0.05), and 3(P < 0.01) months without SAH and ICH incidences, and gastric bleeding. TRCQT treatment for 1 month was also not altered PT. Moreover, a concentration dependent inhibition of collagen-induced platelet activation, followed by increasing of tail vein bleeding time was observed after TRCQT treatment.CONCLUSION: Either TRCQT alone or TRCQT plus aspirin exhibits potent neuroprotective effect by reducing infarct volume without changing the status of SAH, ICH and gastric bleeding possibly via inhib-iting the platelet activation and increasing bleeding time.

Numerical simulation of physiologically relevant pulsatile flow of blood with shear-rate-dependent viscosity in a stenosed blood vessel

Pulsatile flow of blood in a blood vessel having time-dependent shape （diameter） is inves-tigated numerically in order to understand some important physiological phenomena in arteries. A smooth axi-symmetric cosine shaped constriction is considered. To mimic the realistic situation as far as possible, viscosity of blood is taken to be non-uniform, a shear-thinning viscosity model is considered and a physiologically relevant pulsatile flow is introduced. Taking advantage of axi-symmetry in the proposed problem, the stream function-vorticity formulation is used to solve the governing equations for blood flow. Effect of different parameters associated with the problem on the flow pattern has been investigated and disparities from the Newtonian case are discussed in detail.

Dynamic analysis of a stage-structured predator-prey system with disturbed time delay and birth pulse

In this paper, a stage-structured predator prey system with birth pulse and disturbed time delay is investigated. The conditions of the prey-extinction periodic solution of the system which are globally attractive have been obtained. Furthermore, the sufficient corlditions for the permanence of the system are established. Finally, numerical analysis is given to confirm the theoretical results.

基于遗传算法的排爆机械手最优轨迹规划

针对一种排爆机械手的轨迹规划问题,提出了一种时间-脉动-能量最优策略优化其运动轨迹,以减小机械手的运动时间、关节脉动和消耗能量。采用改进三次样条曲线连接路径点,保证关节始末速度、加速度可任意指定,在各关节运动约束条件下采用遗传算法对路径点之间的运动时间进行搜索优化。仿真结果表明:优化后的运动轨迹十分平滑,可以避免关节速度、加速度的突然变化,控制振动。与时间最优规化结果对比表明:该优化方法可以有效地减小关节运动的平均速度、加速度和脉动。

Clinical study of midazolam sequential with dexmedetomidine for agitated patients undergoing weaning to implement light sedation in intensive care unit

Purpose： To evaluate midazolam sequential with dexmedetomidine for agitated patients undergoing weaning to implement light sedation in ICU. Methods： This randomized, prospective study was conducted in Tianjin Third Central Hospital, China. Using a sealed-envelope method, the patients were randomly divided into 2 groups （40 patients per group）. Each patient of group A received an initial loading dose of midazolam at 0.3 3 mg/kg-h 24 h before extubation, followed by an infusion of dexmedetomidine at a rate of 0.2-1 μg/kg-h until extubation. Each patient of group B received midazolam at a dose of 0.3 3 mg/kg.h until extubation. The dose of sedation was regulated according to PASS sedative scores maintaining in the range of-2-1. All patients were continuously monitored for 60 min after extubation. During the course, heart rate （HR）, mean artery pressure （MAP）, extubation time, adverse reactions, ICU stay, and hospital stay were observed and recorded continuously at the following time points： 24 h before extubation （T1）, 12 h before extubation （T2）, extubation （T3）, 30 rain after extubation （T4）, 60 min after extubation （TS）. Results： Both groups reached the goal of sedation needed for ICU patients. Dexmedetomidine was associated with a significant increase in extubation quality compared with midazolam, reflected in the prevalence of delirium after extubation （20% （8/40） vs 45% （18140））, respectively （p=0.017）. There were no clinically significant decreases in HR and MAP after infusing dexmedetomidine or midazolam. In the group A, HR was not significantly increased after extubation; however, in the group B, HR was significantly increased compared with the preextubation values （p 〈 0.05）. HR was significantly higher in the group B compared with the group A at 30 and 60 min after extubation （both, p 〈 0.05）. Compared with preextubation values, MAP was significantly increased at extubation in the group B （p 〈 0.05） and MAP was significantly higher at T3, T4, T5 in the group B than group A （p 〈 0.05）. There was a significant difference in extubation time （（3.0± 1.5） d vs （4.3 ± 2.2） d, p 〈 0.05）, ICU stay （（5.4 ± 2.1 ） d vs （8.0± 1.4） d, p 〈 0.05）, hospital stay （（10.1 ± 3.0） d vs （15.3 ± 2.6） d, p 〈 0.05） between group A and B. Conclusion： Midazolam sequential with dexmedetomidine can reach the goal of sedation for ICU agitated patients, meanwhile it can maintain the respiratory and circulation parameters and reduce adverse reactions.

Experimental Research of Pressure Distribution in the Casing of Inducer

In this paper the inducer of the advanced-researched pump is studied. During multi-rotation speed experimentwith the medium of water, the dynamic pressures near inducer casing are obtained by transducer at each measuringpoint mounted on the casing along the axial direction, both in the steady rotation speed period and the up anddown period. Bases on analyses, the regularity of the axial distribution of time averaged pressure and pressurepulsation amplitude, the connection between pressure pulsation frequency and rotation speeds, and the relationshipbetween the pressure pulsation amplitude and the site of inducer blade are obtained.

Determination of delay time in individual transfer function for central aortic pressure reconstruction

In previous research, time-delay （△t） was a more important parameter than the reflection coefficient in the individual transfer function of central aortic pressure reconstruction. The At can be obtained by electrocardiography （ECG） or phonocardiography （PCG）. Because the pre-ejection period remains an uncertain factor, the present study used ECG and PCG to define the delay time and analyzed the accuracy of the reconstruction results. The △tpre is the actual delay time derived from the aorta to the carotid pressure wave, △tpco is the time delay between the aortic valve component of the second heart sound and the dicrotic incisura of the carotid pressure wave, and AtEcc represents the delay from the interval of the ECG R-peak to the foot of the carotid pressure wave. Compared with the measured aortic pressure, the reconstruction result obtained by △t=△tpcslightly differed from the best result estimated by △t=△tpre. However, the differences between the result obtained by △t=△tEco and the best result were significant in terms of the diastolic blood pressure, and pulse pressure, and especially in terms of the augmentation index and root-mean-square-error. Thus, the At should be determined by PCG for central aortic pressure reconstruction in practice.