Section Curves Research Articles

Stall‐delay modelling of wind turbine blades

AbstractMost aerodynamic design tools for horizontal‐axial wind turbines are based on the blade‐element momentum theory (BEM). Due to the nature of this theory, the design tools need 2‐D steady sectional lift and drag curves as an input. In practice, flow over a wind turbine rotor blade is neither two‐dimensional nor steady, and is affected by rotation. Pioneering experiments have identified a consequence: at inboard rotor blade sections stall is delayed. This so‐called Himmelskamp effect [1] gives a larger lift than predicted and, as a result, a higher power and loading than expected. Consequently, an aerodynamic model is needed to explain and predict sectional lift and drag under rotating conditions. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The Optimization of Curve Based on Genetic Algorithm and Energy Method

An optimization method based on genetic algorithm and energy method is presented to construct a fairing curve network from unconnected sectional curves. The curve’s quality is evaluated by its energy. The parameters of the intersecting points on existing curves are adopted as variable and genetic algorithm is used to optimize the energy of curve based on multi-parent crossover operator. The examples show that the interpolated surface of optimized curve network has good quality than other methods, which proves our method actually improves curve networks’ quality.

Constrained design of simple ship hulls with [formula omitted]-spline surfaces

This paper presents a mathematical method to define a ship hull based on numerical constraints directly related to geometric features of the hull surface and on naval architecture parameters that uniquely define a hull form. These geometric parameters have physical, hydrodynamic or stability implications from the design point of view. B -spline curves and surface representations were combined with a constrained approach to produce the final hull display. The presented method follows the traditional design principles of naval architecture, starting with a Sectional Area Curve (SAC) that controls buoyancy and a waterplane curve that ensures stability. A B -spline outline of these two curves is adopted and a nonlinear problem is solved to obtain their constrained definition that agrees with the geometric design parameters. Two boundaries are also introduced into the constrained definition that control the limits of the hull, the centre and deck lines, which are complemented with tangent values at these edges to gain local control of the hull. A net of curves or hull stations is created that matches the previously defined constraints. These curves follow an analytic expression that ensures that a given area, waterline breadth and initial tangent angle are obtained. This is an important advantage of the method because a hull form library or template is not necessary, but limit the type of ship hulls that can be attained. The method continues with a constrained B -spline fitting of points on the analytical curves that ensures the tangent angles and checks the distance from the points to the B -spline. A final lofting surface of the previous B -spline curves produces the hull surface.

A Path Planning Method for Robotic Belt Surface Grinding

The flexible contact and machining with wide strip are two prominent advantages for the robotic belt grinding system, which can be widely used to improve the surface quality and machining efficiency while finishing the workpieces with sculptured surfaces. There lacks research on grinding path planning with the constraint of curvature. With complicated contact between the contact wheel and the workpiece, the grinding paths for robot can be obtained by the theory of contact kinematics. The grinding process must satisfy the universal demands of the belt grinding technologies, and the most important thing is to make the contact wheel conform to the local geometrical features on the contact area. For the local surfaces with small curvature, the curve length between the neighboring cutting locations becomes longer to ensure processing efficiency. Otherwise, for the local areas with large curvature, the curve length becomes shorter to ensure machining accuracy. A series of planes are created to intersect with the target surface to be ground, and the corresponding sectional profile curves are obtained. For each curve, the curve length between the neighboring cutting points is optimized by inserting a cutter location at the local area with large curvatures. A method of generating the grinding paths including curve length spacing optimization is set up. The validity is completely approved by the off-line simulation, and during the grinding experiments with the method, the quality of surface is improved. The path planning method provides a theoretical support for the smooth and accuracy path of robotic surface grinding.

Study on Geometrical Parameters Definition for Section Curve of Fully Intermeshing Twin Screw

In accordance with the geometrical parameters deduction process for the fully intermeshing twin screw, analysis and calculation of the section curve are performed. Then the geometrical parameters for section curve are defined based on theories of relative motion and gear meshing principal. Do research on the co-rotating parallel axis fully intermeshing twin screw from intermeshing principle, cross section curves, volume parameters, center distance and so on are deduced. The parameters can be used to provide references to design some twin screw devices.

Study on Machining and Measurement for Borosilicate Glass Conical Ellipsoid

Surfaces formed by rotating quadratic curve are widely applied in engineering practice. After having studied machining methods and machines, the CNC grinding method based on macro program B for borosilicate glass elliptical cone surface machine with high precision is proposed. Within the allowable error, the coordinates are calculated according to the equation of axial section curve and the surface is formed with tools moving on axial section curve. Through setting parameters of the lathe, the new canned cycle can be defined to process all different kinds of the elliptical cone surface of same type. With surface triangle adaptive measurement method, machined elliptical cone surface can be detected on coordinate-measuring machine and compared with the theoretical curve. The tolerance resulted from analysis is within 0.025mm. Except ellipsoidal surface all solids of rotation and their deformation, in which their axial sections are represented with equation, can be processed and measured with this method.

An evaluation of the three-dimensional geometric shape of moulded bra cups

Bra cup moulding is currently a remarkable process in the production of seamless intimate apparel. The process is highly complex, time-consuming and error-prone due to the large variations of foam and lamination properties, cup styles and sizes, and geometric features of graduated padding. In particular, the three-dimensional (3D) geometric shape of foam cups is difficult to assess accurately because they are very soft and readily deform. In cases that involve fitting problems, shape modifications of the mould head and determination of the optimal moulding conditions have undergone repeated trials and errors. There is limited knowledge about the effects of foam properties and cup parameters in the controlling of moulding conditions. This study adopts a parameterization-based remesh algorithm method to evaluate the 3D shapes of the convex surface of scanned cup samples. The shape conformity of the cup is quantified in accordance to the corresponding mould head. In this respect, the moulding conditions that would achieve the most desirable geometric shapes of bra cups can be accurately and objectively demonstrated. Based on moulding experiments with 6 types of polyurethane (PU) foam materials, empirical equations that associate the cup shape conformity and the shape deviations from selected cup sectional curves are established. Through the use of non-linear regression models, the shape conformity of the moulded cups can be predicted by moulding conditions with reasonable accuracy. The shape conformity provides effective guidelines for quality assurance and improves production efficiency of bra cup moulding. Moreover, thermal-mechanical properties, such as compressive strain and softening temperature obtained from thermomechanical analysis (TMA) scans, provide a good understanding of cup shape conformity and determine the lowest moulding temperature at initial trails of the bra cup moulding process. Surprisingly, in pliable foams, the cup size does not have an apparent effect on the moulding conditions to achieve optimal cup shape conformity. The results reveal that the moulding conditions for sizes 34B and 34D could remain the same for pliable foam materials. Nevertheless, in the case of more rigid foams, a higher moulding temperature is required to achieve a desirable cup shape for size 34D as more energy is required for the heat-setting of foam materials with higher proportions of hard segments at the moulding of a larger cup size in anticipation of larger deformations.

Optimal Design for Roller Motion Track of Tire Building Machine

at present, the product quality that tire building machine presses tire is not ideal. The phenomenon that the tread isn’t pressed solidly often appears. Through analysis, the main reasons of this problem are those the actual rolling curve doesn’t accord with ideal curve enough, and roller pressure is unstable, pressure fluctuations are large. Therefore, ensuring the basic structure of institution is unchanged, this paper adopts optimization technique to calculate the size of planar linkage institutions and determine the best design result. It makes the moving point from the planar linkage institutions accord with tire section curve best. The article cites example of the engineering design, demonstrating the superiority of the new design method fully.

Experimental Research and Regression Analysis for Constant Temperature Drying of Wheat Straw

The constant temperature drying experiment on wheat straw at different initial moisture content and drying temperature were made with comprehensive thermal analyzer. The impact of initial moisture content, drying temperature and drying time on wheat straw procedure were reviewed, and the optimum drying result of wheat straw were gotten when initial moisture content was 32.5% and drying temperature was 100°C .The process of wheat straw drying was divided into three sections about preheating, constant temperature and falling rate drying. Regression equations on different sections were established by regression analysis, the result show that parabolic equation in preheating section, linear equation in constant rate drying section and power curve in falling rate drying section. Experiment data and reference frame from conclusion above were useful to crop straw drying technology.

Investigation of PEG-PLGA-PEG Nanoparticles-based Multipolyplexes for IL-18 Gene Delivery

Nanoparticles were formulated with biodegradable monomethoxy (poly ethylene glycol)-poly(lactide-co-glycolide)-monomethoxy (poly ethylene glycol) of three different proportional (PEG-PLGA-PEG, lactic acid: glycolic acid = 80/20, 70/30, 50/50) and the cytotoxicity of nanoparticle was characterized according to US Pharmacopoeia XXIII recommendations on various cell lines, including L929, Chang's hepatocytes, primary mouse myoblasts, osteoblasts, and renal vascular endothelial cells. mIL-18 gene was first condensed by polycationic peptide polylysine (PLL), and then encapsulated in the PEG-PLGA-PEG NPs as a novel multi-polyplex gene delivery system - Polymer-PLL-DNA. (PPDs) After lyopholization, the morphology, particle size, zeta potential, and the integrity of DNA in the NPs were investigated. The expression of mIL-18 gene on CT-26 cells in vitro were determined by western blot, while in vivo efficacy was evaluated by tumor inhibition rate, histological section, and survival curve in pulmonary metastasis of colon cancer in BALB/c mice model. Results showed that the cytotoxicity of blank nanoparticles was related to the degradation properties of the polymers with different compositions. The NPs with LA:GA = 70/30 (NPs-73) was optimal for intravenous injection due to its low cytotoxicity. Physicochemical properties of the PPDs were not changed during the lyopholization, while mIL-18 was successfully expressed in vitro. The anti-tumor efficacy in vivo of PPDs showed improvement especially combined with chemotherapy of cisplatin, and confirmed the promising application of the PPDs system, which compared with any single treatment.

2111 空間曲線の微分幾何学に基づく高速道路のコンピュータ支援設計(OS3-1 デジタルエンジニアリングI,OS3 デジタルエンジニアリング)

In the current highway design, a center curve of a highway is designed in three steps. In the first step the projection of the center curve onto the horizontal plane is designed with planar curves, i.e. x=x(t), y=y(t) consisting of straight lines, circular arcs, and clothoid curves. Secondly, the elevation z=z(t) is designed separately. Finally, the super elevation, which is the tilting of the road to account for the centripetal forces as the vehicle goes around a curve, is considered. Therefore, the resulting 3D curve may pass through the desired positions and tangents, however, in general, it does not have the correct normal and binormal vectors. In this research, we introduce a new method to generate the center curve with correct positions, tangents and curvature vectors at the input positions. Then, the section curves are generated along the normal vector at each input position, and blended together to form a lofted surface.

Growth charts: A diagnostic tool

Context:Assessment of growth by objective anthropometric methods is crucial in child care. India is in a phase of nutrition transition and thus it is vital to update growth references regularly.Objective:To review growth standards and references for assessment of physical growth of Indian children for clinical use and research purposes.Materials and Methods:Basics of growth charts and importance of anthropometric measurements are described. A comparison between growth standards and references is provided. Further, Indian growth reference curves based on the data collected by Agarwal et al. and adopted by the Indian Academy of Pediatrics, World Health Organization growth standards for children under the age of 5 years (2006) and contemporary Indian growth references published on apparently healthy affluent Indian children (data collected in 2007-08) are discussed. The article also discusses the use of adult equivalent body mass index (BMI) cut-offs for screening for overweight and obesity in Indian children.Results and Conclusions:For the assessment of height, weight and BMI, WHO growth standards (for children < 5 years) and contemporary cross sectional reference percentile curves (for children from 5-18 years) are available for clinical use and for research purposes. BMI percentiles (adjusted for the Asian adult BMI equivalent cut-offs) for the assessment of physical growth of present day Indian children are also available. LMS values and Microsoft excel macro for calculating SD scores can be obtained from the author (email: vamankhadilkar@gmail.com). Contemporary growth charts can be obtained by sending a message to 08861201183 or email: gntd@novonordisk.com.

The Form Error Inspection of Turbine Blade with Coordinate Measuring Machine

The form error of turbine blade impacts on the work performance of turbine directly. To inspect the blade form error, the cross section curve of turbine blade is constructed as NURBS by interpolating design points in the paper, then the mathematical model of form error of blade is developed by searching for four control points of the minimum distance between measure points and design curve, and the particle swarm optimization (PSO) is applied for solving the minimum distance between measure points and design curve. Comparing with BFGS and DFP, the experiment results show the proposed method is effective in inspecting the blade form error.

Doubly excited states resulting in H(2p) formation in the photoexcitation of water

The cross sections for the emission of Lyman-α fluorescence in the photoexcitation of H2O have been measured as a function of the incident photon energy in the 14–60 eV range, i.e. the outer- and inner-valence ranges. Four superexcited states have been found, two of which are doubly excited states, one is a singly excited state and one a state including electron configurations of both single and double excitations. The gross feature of the superexcited states of H2O resulting in the formation of excited hydrogen atoms has been obtained by combining the present results and the cross section curves of the Balmer fluorescences (Kato et al 2004 J. Phys. B: At. Mol. Opt. Phys. 37 3127). The breakdown of the independent electron model has been indicated in the inner-valence range of H2O, and the degree of breakdown has been compared among CH4, NH3 and H2O ten-electron molecules.

Contour curve reconstruction from cloud data for rapid prototyping

In this study, a method for generation of sectional contour curves directly from cloud point data is given. This method computes contour curves for rapid prototyping model generation via adaptive slicing, data points reducing and B-spline curve fitting. In this approach, first a cloud point data set is segmented along the component building direction to a number of layers. The points are projected to the mid-plane of the layer to form a 2-dimensional (2D) band of scattered points. These points are then utilized to construct a boundary curve. A number of points are picked up along the band and a B-spline curve is fitted. Then points are selected on the B-spline curve based on its discrete curvature. These are the points used as centers for generation of circles with a user-define radius to capture a piece of the scattered band. The geometric center of the points lying within these circles is treated as a control point for a B-spline curve fitting that represents a boundary contour curve. The advantage of this method is simplicity and insensitivity to common small inaccuracies. Two experimental results are included to demonstrate the effectiveness and applicability of the proposed method.

A new surface modification approach for CFD-based hull form optimization

The main focus of this study is on the development of an efficient and effective hull surface modification technique for the CFD-based hull form optimization. Two approaches are utilized. One is based on the radial basis function interpolation, and the other the sectional area curve of the hull. Both local and global modifications of hull forms can be achieved by combining these two approaches. The hull surface modification technique developed in this study is used to vary the hull forms during the optimization process, in which the objective functions associated with the resistance is evaluated by a practical design-oriented CFD tool (SSF), and a multi-objective genetic algorithm is adopted to allow for multi-design speeds. For the purpose of illustration, the KRISO container ship (KCS) is taken as an initial hull to be optimized for reduced drag at given design speeds. Numerical results obtained in this study have shown that the present hull surface modification technique can produce smooth hull forms with reduced drag effectively and efficiently in the CFD-based hull form optimization.

Stable carbon isotope development and sea-level changes during the Late Ludlow (Silurian) of the Łysogóry region (Rzepin section, Holy Cross Mountains, Poland)

The Ludlow deposits of the Winnica Formation in the Rzepin section (Holy Cross Mountains, Poland) have been studied with respect to their facies evolution and stable carbon isotope ratios from whole-rock samples. The C-isotope curve of the Rzepin section records a distinct positive excursion with maximal values of +8.9‰. A Late Ludlow positive isotope excursion is known from different paleocontinents and thus is regarded as a global isotope event. The presence of the event allows for a chemostratigraphic correlation of the Rzepin profile with the classical, biostratigraphically well-dated Gotland section. The Ludlow deposits of the Holy Cross Mountains are interpreted in terms of sea-level changes during the isotope excursion. Because the Rzepin and Gotland sections are positioned on the opposite sides of the same foreland basin, a comparison of their sequence stratigraphy allows to test the regularities of the sea-level changes on the shelf of Baltica. In the present paper, a modified view of the recently published sequence stratigraphy of the Gotland succession is presented. Our results indicate that the positive Ludlow δ13C excursion is connected with prolonged low-stand conditions with small, internal transgressive pulses.

Optimum Design on Trapezoidal Thread Parameters of Co-Rotating Twin Screw Extruder

In order to design trapezoidal thread parameters of co-rotating twin screw extruder that is used in non-fused materials processing, based on geometry of fully wiped co-rotating twin screw extruder by M. L. Booy, the paper adopts tangential approximation method to determine the parameters of trapezoidal thread choosing tangent of especial point of normal section curve. And reasonable spans of oblique angle, actual top width of flight, channel depth and thread lead are determined by the optimum design with objective function of maximal theoretical flux. Experiments show that a co-rotating twin screw pulping extruder of trapezoidal thread designed by the method is easier to machine and measure, and pulp processed by the twin screw pulping extruder can meet the quality requirements. Thus, twin screw designed by the method reserves the main strongpoint of the fully wiped co-rotating twin screw extruder.

マシウ関数を用いた級数展開法による制約条件下における最適横截面積曲線について

When a high speed vessel is designed, it is important how we make her sectional area curve effectively on purpose to minimize the hull resistance. But on a sectional area curve, there are, in general, some constraints caused by the requirement of ship arrangement and we cannot reject them simply because we must build not only a small resistance ship but also an easily operable ship. A sectional area curve under these constraints is usually made from the experience of designers by referring one of a type ship, but we don't think we can get a true optimal curve easily only by the experience.In this report, we introduce the linear wave-making resistance theory into the optimal problem and Series 64 model 4793 is chosen as the object for analysis. The sectional area curve of Series 64 model 4793 is expanded into Mathieu function series and the performance is evaluated from the viewpoint of the wave-making resistance. Then we make the optimal curve for the improved hull form theoretically using calculus of variation under some constraints which are established artificially by us.Finally, we carry out resistance experiment of the improved hull form to evaluate our optimal method and it shows good result that the residual resistance of improved hull form becomes around the half of that of the original hull form.

Surface Reconstruction and Capacity Measurement of Rail Tankers Based on Scattered Points

Aiming at the problems on operation and accuracy of the existing methods,an effective and exact capacity measurement method is proposed for the rail tankers.This method can obtain the tanker data by the 3D reconstruction of image sequence of tanker.Using the regularization technology of scattered points,sectional curves are designed.Tanker surface is constructed by skinning these curves.By means of the expression of surface,rapid capacity measurement is implemented.The experimental results demonstrate that the precision of the proposed method satisfies the national standard of the capacity measurement of tanker.