人力资本的概念界定及其性质研究

文章在概括国内外关于人力资本定义的基础上,对人力资本的概念进行科学界定,讨论了人力资本具有的三个性质:能动性质、难测性质和学习性质。

Effect of graphene on mechanical properties of cement mortars

Functionalized graphene nano-sheets(FGN) of 0.01%-0.05%(mass fraction) were added to produce FGN-cement composites in the form of mortars. Flow properties, mechanical properties and microstructure of the cementitious material were then investigated. The results indicate that the addition of FGN decreases the fluidity slightly and improves mechanical properties of cement-based composites significantly. The highest strength is obtained with FGN content of 0.02% where the flexural strength and compressive strength at 28 days are 12.917 MPa and 52.42 MPa, respectively. Besides, scanning electron micrographs show that FGN can regulate formation of massive compact cross-linking structures and thermo gravimetric analysis indicates that FGN can accelerate the hydration reaction to increase the function of the composite effectively.

Spray Evaporation of Different Liquids in a Drying Chamber--Effect on Flow, Heat and Mass Transfer Performances

Almost without exception literature data and modeling effort are understandably devoted to water as the sprayed liquid since it constitutes the most common liquid used in spray drying applications. In selected applications, however, the liquid making up the solution or suspension may not be water. The objective of this work is to examine the differences in flow patterns, thermal behavior and drying rates caused by different liquids having different thermo-physical properties spray into a spray dryer using a computational fluid dynamic model.Numerical experiments were carried out for water (base case), ethyl alcohol and isopropyl alcohol-the latter two as model non-aqueous liquids. The chamber geometry was cylinder type with a co-current axial pressure nozzle and also an axial central exit so that the configuration is two dimensional and axi-symmetric. It is shown that the liquid properties can have major influence on the thermal field, droplet trajectories, residence times and overall evaporation capacity when all parameters of the problem are held fixed. Deviations from the single phase turbulent airflow in the same chamber without spray are different for the three liquids examined.

Performance of dual-source CT with high pitch spiral mode for coronary stent patency compared with invasive coronary angiography

Objective To investigate the performance of dual-source computed tomography （DSCT） using high-pitch spiral fliPS） mode for coronary stents patency. Methods We conducted a prospective study on 120 patients with 260 previous stents implanted due to recurred suspicious symptoms of angina scheduled for invasive coronary angiography （ICA）, while DSCT were conducted using HPS mode. Results There was no significant impact of age, body mass index or heat rate （HR） on image quality （P 〉 0.05）, while HR variability had a slight impact on that （P 〈 0.05）. Sensitivity, specificity, positive predictive value （PPV）, negative predictive value （NPV） of DSCT in detection of in-stent restenosis （ISR） based per-patient were 92.3%, 96.7%, 88.9%, and 97.8%, respectively. And those based per-stent were 87%, 96.8%, 83.3%, and 97.7% with un-assessment stents, 97.4%, 99.5%, 97.4%, and 99.5% without un-assessment stents. There was significant differ- ence on sensitivity, specificity, PPV and NPV between diameter 〉 3.0 mm group （93.3%, 97.9%, 87.5%, and 98.9%） and diameter 〈 3.0 mm group （80%, 93.3%, 80.0%, and 93.3%） （P 〈 0.05）, and that between stent number 〉 3 group （82.3%, 77.8%, 66.7%, and 60%） with 〈 3 group （97.3%, 80%, 96.5%, and 75%）. The effective dose of DSCT （1.4 ± 0.5 mSv） is significantly less than that by invasive coronary angiography [4.0 ± 0.8 mSv （P 〈 0.01）]. Conclusion DSCT using HPS mode provides good diagnostic performance on stent patency with lower effective dose in patients with HR 〈 65 beats/rain.

Real and Legal Nutritional Alternative （e.g. Application of Free Amino Acids） to Replace Forbidden Doping Substances to Produce Excellent Sport Performance

Peformance enhancing drugs are widely used today in different sport fields, and therefore the successful anti-doping activity should be based not only on regular doping controls, but also it should show the real alternative： how to replace the forbidden doping substances with legal and effective supplements. The paper deals with application proposition of protein concentrates, free AA （amino acids）, HMB （hydroxy-methyle-butyrate）, creatine and camitine. If the athlete is involved in strength and power sport （e.g. throwing events in track and field, olympic weightlifting etc.）, the explosive and maximum strength is of primary importance. For strength athletes, these mentioned substances are those legal preparates, supplements, which can help effectively in performance improvement of sport results. The main reason is that using protein concentrates, AAs, HMB, creatine and camitine, the anabolic （and anticatabolic） effect will enhance the protein biosynthesis of the organism, improve the aerob and anaerob capacity of the athletes, activate and stimulate the own hormonal system. And the final result is creating higher loadability because of the faster recovery, and higher performance level on the competition. Of course, the athletes--as a minimum requirement--need an adequate nutrition （good balanced nourishment）, as well, with appropriate application and supplementation of all vitamins and essential minerals.

Symmetries of Energy-Momentum Tensor： Some Basic Facts

It has been pointed out by Hall et al. [Gen. Rel. Gray. 28 （1996） 299.] that matter collineations can be defined by using three different methods. But there arises the question whether one studies matter collineations by using LεTab=0, or LεT^ab = 0 or LεT^b a=0. These alternative conditions are, of. course, not generally equivalent. This problem has been explored by applying these three definitions to general static spherically symmetric spacetimes. We compare the results with each definition.

Natural ventilation performance of single room building with fluctuating wind speed and thermal mass

Natural ventilation is driven by either buoyancy forces or wind pressure forces or their combinations that inherit stochastic variation into ventilation rates. Since the ventilation rate is a nonlinear function of multiple variable factors including wind speed, wind direction, internal heat source and building structural thermal mass, the conventional methods for quantifying ventilation rate simply using dominant wind direction and average wind speed may not accurately describe the characteristic performance of natural ventilation. From a new point of view, the natural ventilation performance of a single room building under fluctuating wind speed condition using the Monte-Carlo simulation approach was investigated by incorporating building facade thermal mass effect. Given a same hourly turbulence intensity distribution, the wind speeds with 1 rain frequency fluctuations were generated using a stochastic model, the modified GARCH model. Comparisons of natural ventilation profiles, effective ventilation rates, and air conditioning electricity use for a three-month period show statistically significant differences （for 80% confidence interval） between the new calculations and the traditional methods based on hourly average wind speed.

The Influence of Blocking Mass Parameters on the Vibration Isolation Performance of a Power Cabin

Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-band vibration and sound radiation reduction effect of vibration isolation masses located in a base structure was researched.The influence of the blocking mass’ cross-section size and shape parameters and the layout location of the base isolation performance was discussed.Furthermore,the effectiveness of rigid vibration isolation design of the base structure was validated.The results show that the medium and high frequency vibration and sound radiation of a power cabin are effectively reduced by a blocking mass.Concerning weight increment and section requirement,suitably increasing the blocking mass size and section height and reducing section width can result in an efficiency-cost ratio.

Animal-Fats Biodiesel as a Heating Fuel for Agricultural Hot Air Heaters

Biodiesel （BD） was made from animal-fats reacting with methanol and potassium hydroxide in the laboratory. The biodiesel made in the laboratory was sent to K-petro, the government agency to inspect the quality of animal-fats biodiesel, of which generally the quality was acceptable for heating oil for agricultural hot air heater. Kinematic viscosity and calorific values of the biodiesels were measured. BD20（K）, kerosene based biodiesel, showed 18 cSt at -20 ~C. It seems that BD100 can not be suitable for heating fuel under some temperature. As BD content increased calorific value decreased up to 40,000 J/g for 100% BD （BD100） while, light oil calorific value was 45,567 J/g, showing difference of 5,567 J/g （about 12% difference）, Several different fuels including BD20 （biodiesel 20% ＋ light oil 80%）, BD50 （biodiesel 50% ＋ light oil 50%）, BD100 （biodiesel 100%） and light oil were prepared and tested for fuel combustion qualities for agricultural hot air heater and their combustion performances were compared and analyzed. Flame dimensions of biodiesels and light oil were almost same shape at the same combustion condition in the burner of the hot air heater. Generally, CO2 amounts of BDs were greater than light oil, but the differences were so small that it is hard to tell there was significant difference between the BDs combustion and light oil.

Effects of Vibration Technology and Polyvinyl Acetate Emulsion on Microstructure and Properties of Expanded Polystyrene Lightweight Concrete

To prevent expanded polystyrene （EPS） beads from rising up to the surface in the molding process of EPS lightweight concrete, vibration with pressure was applied and the polyvinyl acetate （PVA） emulsion was adopted to improve its mechanical properties. The mechanical properties, thermal properties and durability of EPS lightweight concrete were tested. The microstruetures of EPS lightweight concrete were observed by scanning electron microscope （SEM）. Vibration with pressure reduces the number of small cracks. The 180 d compressive strength and flexural strength increase obviously as a large amount of PVA was added. The mixed amount of PVA has no obvious influence on the thermal performance when it is not more than 10% of the cement. Vibration with pressure and surface modification of EPS beads by PVA improve the combination of EPS beads with cement stone and the mechanical properties of EPS lightweight concrete.

Quality oriented value and performance drivers

The quality endeavors of an organization, like other enterprise activities, must be oriented towards the economic principles. This approach gives a way to many organizations to question the extent to which the quality management contributes for the overall business success and to pin point the areas where particularly a high value or performance can be created in order to attain the maximum possible economic benefits out of quality management systems. Without including the answer of this question in the decision making process, the resources can not be allocated optimally for the quality purpose. Quality management activities create variety of effects that indirectly contributes towards the economic success and thus increase the company and stakeholder value. A closer look at the quality management philosophy reveals eight major principles namely： customer focus, leadership, involvement of people, process approach, system approach to management, continual improvement, factual approach to decision making, mutually beneficial supplier relationships. These eight principles lead the efforts in the domain of quality management to project a positive impact on the company. For an understanding of response relationships, it is necessary to consider in detail the indicators along the response relationships. They provide helpful clues and give an insight into the complex mechanisms of action of the quality approaches on the path to the company＇s success. The following illustration depicts how the quality based activities generate the value to enhance the performance and a variety of indicators reflects how they indirectly add value to an organization and hence contribute to its economic success.

Studying of Physical-Mechanical Properties of Rocks of Geological Section Considering the Influences of Recent Geodynamics

The method of determination of elastic moduli of the geological section rocks had been developed in real conditions. The method is based on application of non-classically linearized theory of elastic waves＇ propagation in the deformable media and utilization of neural networks when creating the geoseismic model. It is proposed to forecast the thin-layer model of medium by velocities of the shear waves on the base of seismic inversion of 2D profile by neural networks and geophysical well logging data. The method had been tested on materials of geophysical well logging data and 2D seismic profile related to one of the structures in the South-Caspian depression. The specific results for Poisson coefficient and elastic moduli of the third order had been obtained. The mentioned method can also be applied to forecast of other physical-mechanical properties of the medium.

Solution of Modern Thermo Physical Problems of Applied External and Internal Aerodynamics with Dark Matter-Energy Simulation

The paper is devoted to new, experimentally registered thermo physical problems of high temperature applied external and internal aerodynamics which is defined first of all by intensive interaction of the gaseous media and thermal radiation. The first report section analyses basic complexities of designing high temperature air breathing engines related to origin of so-called ＂unexpected＂ heat of working process. The next parts of the report consider physical, chemical and plasma features of aerodynamics of reentry space blunt bodies and meteors with specified account of thermal radiation influence. Our solutions are based on the classical Dark Matter-Energy simulation. We present special experimental data for Dark Matter pressure registration on the earth conditions.

Effects of electroacupuncture at Fengchi(GB20)on motor function and GFAP/NeuN expression around the ischemic tissue of the motor cortex in MCAO rats

Objective:To investigate the potential mechanism of electroacupuncture(EA)at bilateral Fengchi(GB20)in treating cerebral ischemia-reperfusion injury and to provide a scientific basis for future experimental research and clinical applications.Methods:Forty male specific-pathogen-free Sprague-Dawley rats were randomly divided into four groups:a normal group,a normal with EA group,a model group,and a model with EA group,with 10 rats in each group.The normal group received no intervention.The normal with EA group received EA at bilateral Fengchi(GB20).The model group underwent middle cerebral artery occlusion(MCAO)using the suture.The model with EA group underwent MCAO and received EA at bilateral Fengchi(GB20).Cerebral blood flow was monitored using a laser Doppler cerebral blood flow meter.Neurologic damage was assessed using the neurologic deficit score,and motor ability was observed using the CatWalk gait system.The expression of glial fibrillary acidic protein(GFAP)and neuronal nuclei(NeuN)protein,the neuron markers,was detected by Western blotting.The protein expression levels of GFAP and NeuN,as well as the number of positive cells in the motor cortex,were detected using immunofluorescence.Results:Compared to the normal group,the cerebral blood flow values in the model group and the model with EA group decreased by more than 50%during the modeling process(P<0.01)and returned to pre-modeling levels after reperfusion(P>0.05).The neurologic deficit score increased(P<0.05),the average motor velocity decreased(P<0.05),GFAP protein expression and the number of positive cells in the motor cortex increased(P<0.05),and the NeuN protein expression and the number of positive cells decreased(P<0.05)in the model group.Compared to the model group,the neurologic deficit score decreased(P<0.05),the average motor velocity accelerated(P<0.05),GFAP and NeuN protein expression and the number of positive cells in the motor cortex increased(P<0.01)in the model with EA group.Conclusion:EA at bilateral Fengchi(GB20)can reduce neuronal loss and increase GFAP and NeuN protein expression in the motor cortex of rats after ischemia-reperfusion,improve the motor function after ischemic stroke,and accelerate the recovery of balance and stability of the affected limbs.

Vibration uncoupling of germanium with different valence states lowers thermal conductivity of Cs2Ge3Ga6Se14

The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterization of a new compound, Cs2Ge3Ga6Se14, with a unique anisotropic structure simultaneously containing Ge^3+ and Ge^2+ that adopt(Ge1)2^3+ Se6 dimer or(Ge2)^2+Se6 octahedron, respectively. The thermal conductivity was measured to be 0.57–0.48 W m^-1 K^-1 from 323 to 773 K, the lowest value among all the known Ge-containing compounds, approaching its glass limit according to the Cahill’s formulation. More importantly, we discover for the first time that the vibration uncoupling of Ge with different valence states hinders the effective thermal energy transport between the(Ge1)2^3+ Se6 dimer and(Ge2)^2+Se6 octahedron, and consequently lowers the thermal conductivity. In addition, we propose a structure factor f = sin(180) ×d/l(i =A, B)iGe Qi, with which a structure map of the Cs2 Ge3 M6 Q14 family is given.

Experimental Study on Heat Transfer Performance of Pulsating Heat Pipe with Refrigerants

The effects of different refrigerants on heat transfer performance of pulsating heat pipe(PHP) are investigated experimentally.The working temperature of pulsating heat pipe is kept in the range of 20℃-50℃.The startup time of the pulsating heat pipe with refrigerants can be shorter than 4 min,when heating power is in the range of 10W-100W.The startup time decreases with heating power.Thermal resistances of PHP with filling ratio 20.55% were obviously larger than those with other filling ratios.Thermal resistance of the PHP with R134a is much smaller than that with R404A and R600a.It indicates that the heat transfer ability of R134a is better.In addition,a correlation to predict thermal resistance of PHP with refrigerants was suggested.

Constructal optimization for H-shaped multi-scale heat exchanger based on entransy theory

Analogizing with the definition of thermal efficiency of a heat exchanger,the entransy dissipation efficiency of a heat exchanger is defined as the ratio of dimensionless entransy dissipation rate to dimensionless pumping power of the heat exchanger.For the constraints of the total tube volume and total tube surface area of the heat exchanger,the constructal optimization of an H-shaped multi-scale heat exchanger is carried out by taking entransy dissipation efficiency maximization as optimization objective,and the optimal construct of the H-shaped multi-scale heat exchanger with maximum entransy dissipation efficiency is obtained.The results show that for the specified total tube volume of the heat exchanger,the optimal constructs of the first order T-shaped heat exchanger based on the maximizations of the thermal efficiency and entransy dissipation efficiency are obviously different with the lower mass flow rates of the cold and hot fluids.For the H-shaped multi-scale heat exchanger,the entransy dissipation efficiency decreases with the increase in mass flow rate when the heat exchanger order is fixed;for the specified dimensionless mass flow rate M(M<32.9),the entransy dissipation efficiency decreases with the increase in the heat exchanger order.The performance of the multi-scale heat exchanger is obviously improved compared with that of the single-scale heat exchanger.Moreover,the heat exchanger subjected to the total tube surface area constraint is also discussed in the paper.The optimization results obtained in this paper can provide a great compromise between the heat transfer and flow performances of the heat exchanger,provide some guidelines for the optimal designs of heat exchangers,and also enrich the connotation of entransy theory.

Performance Analysis of Thermal Energy System with Linear System Method

The paper addresses the system performance of coal-fired power unit with changed auxiliary system or other local heat disturbance. The idea of state space model is imported and the universal formula for the calculation of system performance output is deduced on the system state equation. Two important vector of system are worked out under linear system assumption and transform. The transfer matrix is the characteristics of system itself and is constant for a similar condition, which greatly facilitates the analysis. The concept of thermal disturbance vector is proposed to construct the thermal disturbance input easily. The method can be helpful for analyzing any thermal disturbance input satisfying the assumption and also for supplementing the correction means of performance test. An example of 600MW power unit is presented to demonstrate its availability.