Two dimensional collision-free path planning using linear parametric curve

Traditional geodetic network optimization deals with static and discrete control points. The modern space geodetic network is, on the other hand, composed of moving control points in space (satellites) and on the Earth (ground stations). The network configuration composed of these facilities is essentially dynamic and continuous. Moreover, besides the position parameter which needs to be estimated, other geophysical information or signals can also be extracted from the continuous observations. The dynamic (continuous) configuration of the space network determines whether a particular frequency of signals can be identified by this system. In this paper, we employ the functional analysis and graph theory to study the dynamic configuration of space geodetic networks, and mainly focus on the optimal estimation of the position and clock-offset parameters. The principle of the D-optimization is introduced in the Hilbert space after the concept of the traditional discrete configuration is generalized from the finite space to the infinite space. It shows that the D-optimization developed in the discrete optimization is still valid in the dynamic configuration optimization, and this is attributed to the natural generalization of least squares from the Euclidean space to the Hilbert space. Then, we introduce the principle of D-optimality invariance under the combination operation and rotation operation, and propose some D-optimal simplex dynamic configurations: (1) (Semi) circular configuration in 2-dimensional space; (2) the D-optimal cone configuration and D-optimal helical configuration which is close to the GPS constellation in 3-dimensional space. The initial design of GPS constellation can be approximately treated as a combination of 24 D-optimal helixes by properly adjusting the ascending node of different satellites to realize a so-called Walker constellation. In the case of estimating the receiver clock-offset parameter, we show that the circular configuration, the symmetrical cone configuration and helical curve configuration are still D-optimal. It shows that the given total observation time determines the optimal frequency (repeatability) of moving known points and vice versa, and one way to improve the repeatability is to increase the rotational speed. Under the Newton’s law of motion, the frequency of satellite motion determines the orbital altitude. Furthermore, we study three kinds of complex dynamic configurations, one of which is the combination of D-optimal cone configurations and a so-called Walker constellation composed of D-optimal helical configuration, the other is the nested cone configuration composed of n cones, and the last is the nested helical configuration composed of n orbital planes. It shows that an effective way to achieve high coverage is to employ the configuration composed of a certain number of moving known points instead of the simplex configuration (such as D-optimal helical configuration), and one can use the D-optimal simplex solutions or D-optimal complex configurations in any combination to achieve powerful configurations with flexile coverage and flexile repeatability. Alternately, how to optimally generate and assess the discrete configurations sampled from the continuous one is discussed. The proposed configuration optimization framework has taken the well-known regular polygons (such as equilateral triangle and quadrangular) in two-dimensional space and regular polyhedrons (regular tetrahedron, cube, regular octahedron, regular icosahedron, or regular dodecahedron) into account. It shows that the conclusions made by the proposed technique are more general and no longer limited by different sampling schemes. By the conditional equation of D-optimal nested helical configuration, the relevance issues of GNSS constellation optimization are solved and some examples are performed by GPS constellation to verify the validation of the newly proposed optimization technique. The proposed technique is potentially helpful in maintenance and quadratic optimization of single GNSS of which the orbital inclination and the orbital altitude change under the precession, as well as in optimally nesting GNSSs to perform global homogeneous coverage of the Earth.

Defining inventory control points in multiproduct stochastic pull systems

© 2015 The Authors. NURBS patches have a serious restriction: they are constrained to a strict rectangular topology. This means that a request to insert a single new control point will cause a row of control points to appear across the NURBS patch, a global refinement of control. We investigate a method that can hide unwanted control points from the user so that the user's interaction is with local, rather than global, refinement. Our method requires only straightforward modification of the user interface and the data structures that represent the control mesh, making it simpler than alternatives that use hierarchical or T-constructions. Our results show that our method is effective in many cases but has limitations where inserting a single new control point in certain cases will still cause a cascade of new control points to appear across the NURBS patch.

To guarantee the temporal correctness of a digital circuit a set of multiple path delay faults called primitive faults need to be tested. Primitive faults can contain one or more faulty paths. Existing techniques can identify and test primitive faults containing up to two or three paths. Identifying and testing primitive faults that consist of a larger number of paths is impractical for large designs. We propose a design for testability method that assures the temporal correctness of the circuit without the need to test all primitive faults in the circuit. In the test mode, only primitive faults that contain up to two paths can affect the circuit performance. Our methodology efficiently identifies a small set of potential locations for inserting control points to eliminate primitive faults with more than two paths. Addition of a single control point can lower the cardinality of several primitive faults. Our approach re-evaluates primitive delay fault testability of the circuit after insertion of every control point. After a few iterations only primitive faults with at most two paths can exist in the circuit in the test mode. Experimental results on several circuits are included to demonstrate our method.

© 2015 The Authors. NURBS patches have a serious restriction: they are constrained to a strict rectangular topology. This means that a request to insert a single new control point will cause a row of control points to appear across the NURBS patch, a global refinement of control. We investigate a method that can hide unwanted control points from the user so that the user's interaction is with local, rather than global, refinement. Our method requires only straightforward modification of the user interface and the data structures that represent the control mesh, making it simpler than alternatives that use hierarchical or T-constructions. Our results show that our method is effective in many cases but has limitations where inserting a single new control point in certain cases will still cause a cascade of new control points to appear across the NURBS patch.

K-surfaces are an interactive modeling technique for Bézier-spline surfaces. Inspired by k -curves by [Yan et al. 2017], each patch provides a single control point that is being interpolated at a local extremum of Gaussian curvature. The challenge is to solve the inverse problem of finding the center control point of a Bézier patch given the boundary control points and the handle. Unlike the situation in 2D, bi-quadratic Bézier patches may exhibit none, one, or several extrema, and finding them is non-trivial. We solve the difficult inverse problem, including the possible selection among several extrema, by learning the desired function from samples, generated by computing Gaussian curvature of random patches. This approximation provides a stable solution to the ill-defined inverse problem and is much more efficient than direct numerical optimization, facilitating the interactive modeling framework. The local solution is used in an iterative optimization incorporating continuity constraints across patches. We demonstrate that the surface varies smoothly with the handle location and that the resulting modeling system provides local and generally intuitive control. The idea of learning the inverse mapping from handles to patches may be applicable to other parametric surfaces.

Control point modifications that preserve the Pythagorean–hodograph nature of planar quintic curves

Transcriptome profiling via cDNA microarray analysis identified 869 genes that are differentially expressed in developing tomato (Solanum lycopersicum) pericarp. Parallel phenotypic and targeted metabolite comparisons were employed to inform the expression analysis. Transcript accumulation in tomato fruit was observed to be extensively coordinated and often completely dependent on ethylene. Mutation of an ethylene receptor (Never-ripe [Nr]), which reduces ethylene sensitivity and inhibits ripening, alters the expression of 37% of these 869 genes. Nr also influences fruit morphology, seed number, ascorbate accumulation, carotenoid biosynthesis, ethylene evolution, and the expression of many genes during fruit maturation, indicating that ethylene governs multiple aspects of development both prior to and during fruit ripening in tomato. Of the 869 genes identified, 628 share homology (E-value < or = 1 x 10(-10)) with known gene products or known protein domains. Of these 628 loci, 72 share homology with previously described signal transduction or transcription factors, suggesting complex regulatory control. These results demonstrate multiple points of ethylene regulatory control during tomato fruit development and provide new insights into the molecular basis of ethylene-mediated ripening.

In this investigation, a framework for integrating the CMM into the CAD/CAM environment is developed to automate the process of design, manufacturing and inspection. An algorithm to generate an optimum collision free CMM probe path is proposed. This algorithm uses the ray tracing technique to locate the collision of the possible paths, between the initial probe point and the target point, with the workpiece to be inspected. If there is a collision, the algorithm walks through the topological structure of the part and selects the midpoint of the edge, shared by the face with which the path collides and the adjacent face nearest to the target point, as the next probe point. This procedure is followed till the target point is reached. The first half of the proposed algorithm is implemented using Mechanical Desktop and its Runtime Extension (ARX) as the API, running on an Windows NT 4.0 platform. The effectiveness of the proposed algorithm is verified by the results of the implementation demonstrating optimum collision-free dimensional inspection path generation for three prismatic parts.

In this paper, we studied on measurement of soil deformation around the tip of model pile by close-range photogrammetry. The rigorous bundle adjustment method was utilized to monitor the soil deformation in the laboratory model pile-load test as function of incremental penetration of the pile. Control points were installed on the frame of the laboratory model box case and more than 150 target points were inserted inside the soil around the model pile and on the surface. Four overlapping images including three horizontal and one vertical image were acquired by a non-metric camera for each penetration step. The images were processed to automatically locate the control and target points in the images for the self-calibration and the bundle adjustment. During the bundle adjustment, the refraction index of the acrylic case of the laboratory model was accounted for accurate measurement. The experiment showed the proposed approach enabled the automated photogrammetric monitoring of soil deformation around the tip of model pile.

The necessity for scientific and methodical study of methods for monitoring the characteristics of flameresistance of building structures has the highest priority in the field of fire safety. The aim of this work was to provide the required degree of reliability of the results of quality control of flame-resistant coatings of building structures and high efficiency of decisions due to the risk-based approach to the development of control methods.Substantiated risk-based approach to the development of methods of control, involving the consideration on the basis of process model, control flame-resistance of building object in all possible potential problems that can cause the risk of incorrect decision-making. A model of the risks arising from the control of the flameretardant coating thickness has been developed. Two major risk groups have been identified. The first group is related to the uncertainty of coating thickness measurement at a single control point. The second group of risks is related to the unrepresentativeness of selective control over the entire surface of the construction object as a whole Potential risk sources have been identified for each group. For the entire range of sources of particular risks the results of studies of the mechanisms of their manifestation, the estimated degree of influence on the accuracy of the control of compliance of flame-retardant coating thickness requirements. The analysis is carried out on the basis of both theoretical and experimental statistical studies on a number of construction projects.According to the results of the analysis of all particular risks of control unreliability, rational ways of their minimization in the form of technical or organizational and technical measures, which are refl in the developed project of the control method, are proposed. Project control method was built on the basis of a agreed scheme of control of the thickness of the fl coating of building structures sequentially the three parties. Formulated and solved the task of the metrological control of the thickness of the flame-retardant coating as indirect measurement methods non-destructive thickness measurements. Theoretical and applied aspects of the process of flame-retardant coating thickness control of building structures under conditions of high risk of making incorrect decisions on the results of control are considered.

Purpose. This study explored a novel technique to improve the MV imaging based fiducial visibility for a cohort of prostate radiotherapy patients, without compromising the original treatment plan. The study also compared these results to visibility using single MLC control points, as well as short arcs. Methods. Geometric data from 68 prostate radiotherapy treatments, each with implanted gold fiducials, was retrospectively analysed. Fiducials were contoured for each patient, and conventional and SBRT treatment plans were generated using a VMAT technique. Using an in-house script, fiducial contours were projected onto the VMAT MLC control points. Resulting data was assessed to determine whether the fiducial contours were theoretically visible for single MLC control points and groups of MLC control points (short arcs), both being surrogates for intra-fraction MV imaging. Using this data, a theoretical quadrant technique was investigated that assessed the region surrounding each fiducial to determine if visualisation would theoretically improve. Results. Using a conventional treatment type, mean fiducial visibility for single MLC control points across the patient cohort ranged from 2.5% up to 17.8%. For SBRT, fiducial visibility ranged from 1.8% up to 19.7%. For short arcs, fiducial visibility for conventional treatment types ranged from 5.9% up to 20.7%. For SBRT, fiducial visibility ranged from 4.6% up to 23.1%. When the novel fiducial quadrant technique was used, theoretical visibility improved two-fold, from 22.7% up to 52.5% and from 24.7% up to 55.3% for conventional and SBRT treatment types respectively. Conclusions. Fiducial visibility was assessed for a cohort of VMAT prostate patients. Using the novel quadrant technique, it was demonstrated that theoretical visualisation and localisation of the implanted fiducials could be improved two-fold, without sacrificing treatment plan quality.

All data flow models describe computation in terms of locally controlled events; each event is the “firing” of an “actor”. There is no notion of a single point or locus of control—nothing corresponding to the program location counter of a conventional sequential computer. Since many actors may be ready to fire, these models can represent many asynchronous concurrent computational events. Nevertheless, they can guarantee an input/output behavior that is unaffected by the order in which the firing of actors is carried out. This property of data flow models—determinacy—ensures that their input/output behavior is functional. Thus the semantics of data flow graphs are closely related to the semantics of applicative programming languages, and we will illustrate the correspondence of data flow graphs to textual programs by means of program fragments written in Val, an applicative programming language developed at MIT for scientific applications.

Today's high performance computing systems have several reliability deficiencies resulting in availability and serviceability issues. Head and service nodes represent a single point of failure and control for an entire system as they render it inaccessible and unmanageable in case of a failure until repair, causing a significant downtime. This paper introduces two distinct replication methods (internal and external) for providing symmetric active/active high availability for multiple head and service nodes running in virtual synchrony. It presents a comparison of both methods in terms of expected correctness, ease-of-use and performance based on early results from ongoing work in providing symmetric active/active high availability for two HPC system services (TORQUE and PVFS metadata server). It continues with a short description of a distributed mutual exclusion algorithm and a brief statement regarding the handling of Byzantine failures. This paper concludes with an overview of past and ongoing work, and a short summary of the presented research.

Unified Enterprise application security is a new emerging approach for providing protection against application level attacks. Conventional application security approach that consists of embedding security into each critical application leads towards scattered security mechanism that is not only difficult to manage but also creates security loopholes. According to the CSI/FBI computer crime survey report, almost 80% of the security breaches come from authorized users. In this paper, we have worked on the concept of unified security model, which manages all security aspect from a single security window. The basic idea is to keep business functionality separate from security components of the application. Our main focus was on the designing of frame work for unified layer which supports single point of policy control, centralize logging mechanism, granular, context aware access control, and independent from any underlying authentication technology and authorization policy.