Simulation study of a Squall line hailstorm using High-Resolution GRAPES-Meso with a modified Double-Moment Microphysics scheme

This study uses the high-resolution GRAPES_Meso (the mesoscale version of the Global/Regional Assimilation and Prediction System) to simulate a severe squall line hailstorm in Shandong province. The accumulated precipitation, radar reflectivity, and cloud hydrometeor properties simulated using a modified double-moment microphysics scheme are compared with observation. Results show that simulations captured the basic character of this squall line hailstorm. The simulated accumulation precipitation and radar reflectivity are comparable with the observation. The cross-section of the dynamic, microphysical, and radar reflectivity structures of the simulated hailstorm was analyzed. The simulated hailstorm has shown a reasonable result in both macrostructure and micro hail production rates. The development of the simulated hailstorm is consistent with the conceptual model of hailstorm evolution. Results imply the ability of high-resolution GRAPES_Meso on forecasting hailstorm.

Linking the Historical Sample of the Netherlands with the USA Censuses, 1850–1940

During the 19th and early 20th century about 220,000 Dutch born persons migrated to the USA. The Historical Sample of the Netherlands (HSN) contains about 85,500 persons born in the Netherlands between 1812 and 1922. In this article we report the way we have matched persons from the HSN with the American censuses from the period 1850 till 1940. For this purpose, a linking process was designed, comprising of three stages: harmonization, matching and validation. The different nature of the two datasets (HSN and the USA Censuses) asked for some harmonization prior to the matching. Once the data had been properly prepared, two strategies were applied in order to link the data sets. The first one, called Similarity Approach, matched individuals from both datasets by comparing on the basis of resemblance of first and last names. The second approach, called Transformation Approach, made use of dictionaries with Anglicized versions of Dutch first and last names and their most common or most likely Dutch original(s). Because of the sample character of the HSN even exact matches showed ambiguity that needs to be resolved. For this reason, a validation process comparing the household context was run to provide a more trustworthy result. In the end we identified 484 individuals present in the HSN database with reliable links to the American censuses. We also evaluated the result in the light of what we know from emigration patterns to the USA over time and period and we concluded that our efforts have produced a reasonable result. Nevertheless, we are aware that we may have missed links. We also found that at least 45% of the emigrants returned to the Netherlands at some point during their life course.

The effect of the obstacle on the hydraulic response of the composite hydraulic structure

Experimental investigations are carried out to study the physics of the flow that passes weir-gate hydraulic structure and encounters obstruction with or without installation of downstream opening. This study approaches the comparison between two different options; the first option deals with free flow condition while the second option deals with submerged flow condition. Various cases are performed considering different hydraulics variables and dimensions variables to evaluate the existence of obstruction with or without openings. Overall the flow pattern is more sensitive to the presence of obstruction at downstream region than in its absence. The hydraulic variables that are considered in the study are divided into dimensional variables such as discharge, downstream flow velocity and water depths at downstream and non-dimensional variables such as discharge coefficient, Froude number and Reynolds number. The obstacles which are used in this study have variable heights with constant width and length. Constant spacing between the obstacles is adopted. Different arrangements of obstacles are considered in this study and it is found that a significant and reasonable result is different among the cases. The effect of rectangular opening in the obstruction on flow pattern is studied. The effect of obstacles with rectangular opening gives a noticeable result in the assessment of the discharge coefficient of the composite hydraulic structure.

Sum of Squares Approach for Nonlinear H∞ Control

A proper Hamilton-Jacobi-Isaacs (HJI) inequality must be solved in a nonlinear H∞ control problem. The sum of squares (SOS) method can now be used to solve an analytically unsolvable nonlinear problem. A HJI inequality suitable for SOS approach is derived in the paper. The SOS algorithm for solving the HJI inequality is also provided. Conservativeness of the SOS method is then discussed in the paper. The conservativeness of the SOS approach is caused by the method itself, because it is really a synthesis method over the entire state space. To reduce the conservativeness, a local H∞ design on a restricted state-space region is proposed. But the SOS approach for the local H∞ design also suffers from the conservativeness problem, because the S-procedure for solving the set-containment constraint provides only a sufficient condition. The above-mentioned sources of conservativeness are peculiar for the SOS approaches. So a proper approach must be carefully selected in the design process to get a reasonable result. A design example is also given in the paper.

Improved DEA Cross Efficiency Evaluation Method Based on Ideal and Anti-Ideal Points

A new model is introduced in the process of evaluating efficiency value of decision making units (DMUs) through data envelopment analysis (DEA) method. Two virtual DMUs called ideal point DMU and anti-ideal point DMU are combined to form a comprehensive model based on the DEA method. The ideal point DMU is taking self-assessment system according to efficiency concept. The anti-ideal point DMU is taking other-assessment system according to fairness concept. The two distinctive ideal point models are introduced to the DEA method and combined through using variance ration. From the new model, a reasonable result can be obtained. Numerical examples are provided to illustrate the new constructed model and certify the rationality of the constructed model through relevant analysis with the traditional DEA model.

A Diagnosis Method for Rotation Machinery Faults Based on Dimensionless Indexes Combined withK-Nearest Neighbor Algorithm

It is difficult to well distinguish the dimensionless indexes between normal petrochemical rotating machinery equipment and those with complex faults. When the conflict of evidence is too big, it will result in uncertainty of diagnosis. This paper presents a diagnosis method for rotation machinery fault based on dimensionless indexes combined withK-nearest neighbor (KNN) algorithm. This method uses aKNN algorithm and an evidence fusion theoretical formula to process fuzzy data, incomplete data, and accurate data. This method can transfer the signals from the petrochemical rotating machinery sensors to the reliability manners using dimensionless indexes andKNN algorithm. The input information is further integrated by an evidence synthesis formula to get the final data. The type of fault will be decided based on these data. The experimental results show that the proposed method can integrate data to provide a more reliable and reasonable result, thereby reducing the decision risk.

Performance Analysis for Spindle System of Special Friction Welder Machine Based on ROMAX Software

This paper focus on the spindle system of special friction welder machine with conductive device made up of aluminum electrolytic prebaked anode. The ROMAX software is employed to analyze the spindle system, and the spindle axial force and displacement, radial displacement, and natural frequency are obtained by the analysis. The reasonable result can be got by analyzing the corresponding results, respectively. Thereby, the gist to improve the fiction welder is attained.

Numerical Simulation of Condenser Combining with Low-Pressure Exhaust Hood and Condenser Throat

In order to obtain the more real condition of the flow field at condenser, the commercial software FLUENT is used to simulate the flow field of the condenser tube bundle area, alone or coupling with the low-pressure exhaust hood and condenser throat. The analysis indicates that the calculation result of combined model is different from the single calculation result of condenser tube bundle area. The flow field of condenser tube bundle area is strongly influenced by low-pressure exhaust hood, the frustums diffuse-angle, the low-pressure heater and the injection of the exhaust steam from the small turbine. The uneven velocity distribution at the outlet of the throat has great influence on the heat exchange of condenser tube. Combined numerical simulation gives more reasonable result.

Optimization of Pendulum for a High-Impact Shock Testing Machine with Medium Weight

Collision impulse to pendulum shaft is tend to be generated when hammer impacting the anvil. In order to eliminate the collision impulse and find a preferential size of the pendulum, based on the rigid body dynamical model, the conditions of the coincidence of the center of strike and the center of percussion are established; calculation formula of the distance between the axis of the pendulum shaft and the center of percussion is derived. By selecting certain geometric parameters of the pendulum as design variables and transferring the multi-objective nonlinear optimal design problem into single objective problem, a mathematical model of the optimal design of the pendulum is established. Matlab optimization toolbox is utilized to calculate the model, and a reasonable result is obtained. The work of this paper has considerable significance in the far field of engineering design.

Determining Harmonic Contributions Based on Reweighted Complex Least Squares Method

Determining harmonic contribution quantitatively at the point of common coupling is an important task for power quality management. Outliers and influential points could have strong influences on regressors. This paper puts forward a method named reweighted complex least squares to eliminate or reduce the influences to ensure the robustness of the regression. The method can improve precision of the equivalent harmonic impedance and it can get a more reasonable result in harmonic contribution determination than previous methods. A case study based on the IEEE 14-bus test system was conducted, which shows the validity of the proposed method.