Performance investigations on optimum mechanical design aspects of planar parallel manipulators

This paper presents a comparative analysis of three degrees of freedom planar parallel robotic manipulators (x, y and θ_z motion platforms) namely 2PRP-PPR, 2PRR-PPR, 3PPR (Hybrid), 3PRP (Hephaist) and 3PPR U-base in terms of optimal kinematic design performance, static structural stiffness and dynamic performance (energy and power consumption). Kinematic and dynamic performance analyses of these platforms have been done using multibody dynamics software (namely ADAMS/View). Static stiffness of the above-mentioned manipulators have been analysed, compared using the conventional joint space Jacobian stiffness matrix method, and this method has been verified through a standard finite-element software (namely NASTRAN) as well. The size of the fixed base or aspect ratio (width/height) can be varied for various working conditions to understand its design parameters and optimal design aspects which are depending on the fixed base structure. Different aspect ratios (fixed base size) are considered for the comparative analyses of isotropy, manipulability and stiffness for the above-mentioned planar parallel manipulators. From the numerical simulation results, it is observed that the 2PRP-PPR manipulator is associated with a few favourable optimum design aspects such as singularity-free workspace, better manipulability, isotropy, higher stiffness and better dynamic performance in terms of power and energy requirement as compared to other planar parallel manipulators.     

A pseudo‐stochastic approach for optimal decision making under limited information: a case of an aggregate production system

In this study, which is both analytical and numerical, we compute the effective information horizon (EIH), i.e., the minimal time interval over which future information is relevant for optimal control and for measuring the performance of a single part‐type production system. Optimal control modeling and process solving, which consider aspects of decision making with limited forecast, are exemplified by a single part‐type production system. Specifically, the analysis reveals practical situations in which there is both a performance loss as well as feasibility violation when only information expected within the planning horizon is considered. The analysis is carried out by developing a pseudo‐stochastic model. We follow previous “pseudo‐stochastic” approaches that solve stochastic control problems by using deterministic, optimal control methods. However, we model the expected influences of all future events, including those that are beyond the planning horizon, as encapsulated by their density functions and not only by their mean values.     

Microeconomic analysis using dominant relationship analysis

The concept of dominance has recently attracted much interest in the context of skyline computation. Given an N-dimensional data set S, a point p is said to dominate q if p is better than q in at least one dimension and equal to or better than it in the remaining dimensions. In this article, we propose extending the concept of dominance for business analysis from a microeconomic perspective. More specifically, we propose a new form of analysis, called Dominant Relationship Analysis (DRA), which aims to provide insight into the dominant relationships between products and potential buyers. By analyzing such relationships, companies can position their products more effectively while remaining profitable. To support DRA, we propose a novel data cube called DADA (Data Cube for Dominant Relationship Analysis), which captures the dominant relationships between products and customers. Three types of queries called Dominant Relationship Queries (DRQs) are consequently proposed for analysis purposes: (1) Linear Optimization Queries (LOQ), (2) Subspace Analysis Queries (SAQ), and (3) Comparative Dominant Queries (CDQ). We designed efficient algorithms for computation, compression and incremental maintenance of DADA as well as for answering the DRQs using DADA. We conducted extensive experiments on various real and synthetic data sets to evaluate the technique of DADA and report results demonstrating the effectiveness and efficiency of DADA and its associated query-processing strategies.     

Verification of causal models using petri nets

Many different approaches, mainly based on logical formalisms, have been proposed for modeling causal knowledge and the inferential mechanisms based on this type of knowledge. In this article we present an alternative approach to this problem in which the semantics of a causal model is provided by adopting Petri nets. We show how this scheme of modeling is powerful enough to capture all crucial aspects of the corresponding causal model, without resorting to very complex structures; indeed, the model is obtained using a particular type of deterministic Petri net. Moreover, a complete formalization of the aspects concerning the correctness of the represented causal model is provided in terms of reachability in the Petri net. We believe that this aspect is very important in the knowledge acquisition phase when precise correctness criteria should be defined and respected in the construction of the model. We analyze some of these criteria and we discuss an algorithm (based on a backward simulation of the net) capable of discovering incorrectness by exploiting analysis tools available for Petri nets and the explicit parallelism of the model. © 1992 John Wiley & Sons, Inc.     

Design of active inductors in SiGe/SiGe:C processes for RF applications

Applicability of silicon‐based heterojunction bipolar processes is investigated for designing active inductors with high quality factors (Q). Results for grounded type one‐port active inductor incorporating frequency‐dependent as well as frequency‐independent negative resistances are examined. Later, the negative resistance aspect is extended from one‐port to two‐port active inductor circuit to ensure its use as a series element. The enhanced Q‐values of all the inductive circuits are observed in accordance with the theory. Moderately high‐Q values (～100) with considerable inductances (～0.2–1 nH) are obtained in the RF frequency ranges (～5–9 GHz). © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

一种Data Matrix条码的快速识别方法*

为满足工业流水线对条码识别实时性的要求,提出了一种Data Matrix条码快速识别方法。采用形状参数、圆形性作为矩形特征,初步确定Data Matrix条码位置;采用距离为角度的函数对Data Matrix条码边界进行标记,将Data Matrix 的2D条码边界转换为1D波形函数进行分析,进行一次求导获取条码边界的位置及角度;利用边界角度作为仿射变换的角度,将条码旋转到规格化位置,采用网格法进行数据提取并进行条码解码。对像素大小为640×480的400幅含Data Matrix条码图片在PC机上进行测     

Type-directed weaving of aspects for polymorphically typed functional languages

Incorporating aspect-oriented paradigm to a polymorphically typed functional language enables the declaration of type-scoped advice, in which the effect of an aspect can be harnessed by introducing possibly polymorphic type constraints to the aspect. The amalgamation of aspect orientation and functional programming enables quick behavioral adaption of functions, clear separation of concerns and expressive type-directed programming. However, proper static weaving of aspects in polymorphic languages with a type-erasure semantics remains a challenge. In this paper, we describe a type-directed static weaving strategy, as well as its implementation, that supports static type inference and static weaving of programs written in an aspect-oriented polymorphically typed functional language, AspectFun. We show examples of type-scoped advice, identify the challenges faced with compile-time weaving in the presence of type-scoped advice, and demonstrate how various advanced aspect features can be handled by our techniques. Finally, we prove the correctness of the static weaving strategy with respect to the operational semantics of AspectFun.     

A network approach to the French system of legal codes—part I: analysis of a dense network

We explore one aspect of the structure of a codified legal system at the national level using a new type of representation to understand the strong or weak dependencies between the various fields of law. In Part I of this study, we analyze the graph associated with the network in which each French legal code is a vertex and an edge is produced between two vertices when a code cites another code at least one time. We show that this network distinguishes from many other real networks from a high density, giving it a particular structure that we call concentrated world and that differentiates a national legal system (as considered with a resolution at the code level) from small-world graphs identified in many social networks. Our analysis then shows that a few communities (groups of highly wired vertices) of codes covering large domains of regulation are structuring the whole system. Indeed we mainly find a central group of influent codes, a group of codes related to social issues and a group of codes dealing with territories and natural resources. The study of this codified legal system is also of interest in the field of the analysis of real networks. In particular we examine the impact of the high density on the structural characteristics of the graph and on the ways communities are searched for. Finally we provide an original visualization of this graph on an hemicyle-like plot, this representation being based on a statistical reduction of dissimilarity measures between vertices. In Part II (a following paper) we show how the consideration of the weights attributed to each edge in the network in proportion to the number of citations between two vertices (codes) allows deepening the analysis of the French legal system.     

The generalized Radon transform: Sampling, accuracy and memory considerations

The generalized Radon (or Hough) transform is a well-known tool for detecting parameterized shapes in an image. The Radon transform is a mapping between the image space and a parameter space. The coordinates of a point in the latter correspond to the parameters of a shape in the image. The amplitude at that point corresponds to the amount of evidence for that shape. In this paper we discuss three important aspects of the Radon transform. The first aspect is discretization. Using concepts from sampling theory we derive a set of sampling criteria for the generalized Radon transform. The second aspect is accuracy. For the specific case of the Radon transform for spheres, we examine how well the location of the maxima matches the true parameters. We derive a correction term to reduce the bias in the estimated radii. The third aspect concerns a projection-based algorithm to reduce memory requirements.     

Evaluation of formats for aircraft control/display units

Control/display unit (CDU) technology has been advancing more rapidly than the human factors research needed to establish guidelines for the design of display formats. Such guidelines must be established and followed to ensure effective and efficient human performance in the cockpit environment. A preliminary study which addressed the issue of defining an optimal CDU display format design was completed.

Subjects were asked to search visually alphanumeric displays for a single piece of information and indicate when it was found. Data were collected on the elapsed time to isolate the information as well as the accuracy of the information retrieval. Ten formats of two information densities each were evaluated. Each format contained labels and associated data for typical flight information such as communications data (radio type and frequency) and navigation data (waypoint identifier, longitude and latitude). The ten basic format designs were developed by changing the location relationship between the labels and their associated data.

Data were collected while subjects did and did not perform a two-dimensional tracking task. Preliminary findings indicate that both format design and density affect operator response time and response accuracy. Implications of the results for the design of cockpit displays are discussed.     

Modeling and detecting semantic-based interactions in aspect-oriented scenarios

Interactions between dependent or conflicting aspects are a well-known problem with aspect-oriented development (as well as related paradigms). These interactions are potentially dangerous and can lead to unexpected or incorrect results when aspects are composed. To date, the majority of aspect interaction detection methods either have been based on purely syntactic comparisons or have relied on heavyweight formal methods. We present a new approach that is based instead on lightweight semantic annotations of aspects. Each aspect is annotated with domain-specific markers and a separate influence model describes how semantic markers from different domains influence each other. Automated analysis can then be used both to highlight semantic aspect conflicts and to trade-off aspects. We apply this technique to early aspects, namely, aspect scenarios, because it is desirable to detect aspect interactions as early in the software lifecycle as possible. We evaluate the technique using two case studies—one from industry and one posed as a challenge problem by the community—and show that the technique detects interactions that cannot be discovered using syntactic techniques. In addition, we show that the technique can apply to many languages through the use of different aspect-oriented scenario notations in the case studies, namely, MATA sequence diagrams and Aspect-oriented Use Case Maps.     

Optimal M/G/1 server location on a tree network with continuous link demands

This paper represents two major extensions of Hakimi's one-median problem specialized on a tree network T:(i) queueing delay is explicitly included in the objective function, and (ii) probabilistic demands for service can originate continuously along a link as well as discretely at a node. Calls for service occur as a time-homogeneous Poisson process. A single mobile server resides at a facility located on T. The server, when available, is dispatched immediately to any demand that occurs. When a customer finds the server busy with previous demand, it is entered into a first-come first-served queue. One desires to locate a facility on T so as to minimize the average response time, which is the sum of mean queueing delay and mean travel time. Convexity properties of the average response time and related functions allow us to develop an efficient two-stage algorithm for finding the optimal location. We also analytically trace the trajectory of the optimal location when the Poisson arrival rate is varied. A numerical example is constructed to demonstrate the algorithm as well as the trajectory results.     

A Hybrid Approach to Online and Offline Partial Evaluation

This article presents a hybrid method of partial evaluation (PE), which is exactly as precise as naive online PE and nearly as efficient as state-of-the-art offline PE, for a statically typed call-by-value functional language.PE is a program transformation that specializes a program with respect to a subset of its input by reducing the program and leaving a residual program. Online PE makes the reduction/residualization decision during specialization, while offline PE makes it before specialization by using a static analysis called binding-time analysis. Compared to offline PE, online PE is more precise in the sense that it finds more redexes, but less efficient in the sense that it takes more time.To solve this dilemma, we begin with a naive online partial evaluator, and make it efficient without sacrificing its precision. To this end, we (1) use state (instead of continuations) for let-insertion, (2) take a so-called cogen approach (instead of self-application), and (3) remove unnecessary let-insertion, unnecessary tags, and unnecessary values/expressions by using a type-based representation analysis, which subsumes various monovariant binding-time analyses.We implemented and compared our method and existing methods—both online and offline—in a subset of Standard ML. Experiments showed that (1) our method produces as fast residual programs as online PE and (2) it does so at least twice as fast as other methods (including a cogen approach to offline PE with a polyvariant binding-time analysis) that produce comparable residual programs.     

Linear-time simulation of multihead turing machines

The main result of this paper is that, given a Turing machine M with k-heads on a d-dimensional tape, one can effectively construct a Turing machine M′ with k d-dimensional tapes but only one head per tape and one additional linear single-head tape which simulates M in linear-time.     

Location and Configuration Management in Mobile-Switch ATM Networks

The features of two important application scenarios, supporting mobile switches with fixed end users and mobile switches with mobile users, are dramatically different from those of the traditional wired network structure. To exploit mobile switches, the location and configuration management of mobile switches is essential to handle the mobility and topology change of the wireless/mobile ATM network. In this paper we address the location management and configuration problems of mobile switches in an ATM network. We investigate several aspects of the location management problem including architecture to support switch mobility, mobile switch tracking, and mobile switch locating. We propose an approach that is based on the Private Network-Network Interface (PNNI) protocol. We extend the PNNI protocol to enable it to handle mobile switches. Moreover, we develop analytical models to determine the tracking and locating costs for mobile switches under the proposed scheme. The models illustrate the relation between total cost (tracking cost + locating cost) and peer group size. The models can be used to derive the optimal configuration for an ATM network with mobile switches.     

Accuracy assessment of the processed SRTM-based elevation data by CGIAR using field data from USA and Thailand and its relation to the terrain characteristics

Shuttle radar topographic mission (SRTM) has created an unparalleled data set of global elevations that is freely available for modeling and environmental applications. The global availability (almost 80% of the Earth surface) of SRTM data provides baseline information for many types of the worldwide research. The processed SRTM 90 m digital elevation model (DEM) for the entire globe was compiled by Consultative Group for International Agriculture Research Consortium for Spatial Information (CGIAR-CSI) and made available to the public via internet mapping interface. This product presents a great value for scientists dealing with terrain analysis, thanks to its easy download procedure and ready-to-use format. However, overall assessment of the accuracy of this product requires additional regional studies involving ground truth control and accuracy verification methods with higher level of precision, such as the global positioning system (GPS).The study presented in this paper is based on two independent datasets collected with the same GPS system in Catskill Mountains (New York, USA) and Phuket (Thailand). Both datasets were corrected with differential base station data. Statistical analysis included estimation of absolute errors and multiple regression analysis with slope and aspect variables. Data were analyzed for each location separately and in combination. Differences in terrain and geographical location allowed independent interpretation of results.The results of this study showed that absolute average vertical errors from CGIAR dataset can range from 7.58 ± 0.60 m in Phuket to 4.07 ± 0.47 m in Catskills (mean ± S.E.M.). This is significantly better than a standard SRTM accuracy value indicated in its specification (i.e. 16 m). The error values have strong correlation with slope and certain aspect values. Taking into account slope and aspect considerably improved the accuracy of the CGIAR DEM product for terrain with slope values greater than 10°; however, for the terrain with slope values less than 10°, this improvement was found to be negligible.     

An evaluative study of TRMM precipitation estimates over multi-day scales in a semi-arid region,Iran

Data from the Tropical Rainfall Measuring Mission (TRMM) rainfall estimations have been evaluated at different time scales in the previous research, in particular, sub-daily, monthly, seasonally and annually. However, in arid and semi-arid regions water balance may be reached several days after a rainfall event. Hence, it becomes of crucial importance to investigate sub-monthly time periods (i.e. multi-day periods). For this reason, TRMM precipitation data version 3B42 (3B42) were evaluated and calibrated for 1, 2, 3, 5, 7, 10, 15, 20 days and monthly time scales using rain gauges data in Fars province, Islamic Republic of Iran, 1 January 2000 to 31 December 2014. Pearson’s correlation coefficient (r), Root Mean Square Error (RMSE), Normalized Root Mean Square Error (NRMSE), Mean Bias (MB), Prediction of Detection (POD), False Alarm Ratio (FAR) and Critical Success Index (CSI) were used for the purpose of evaluation. The results showed that with a logarithmic trend, r, NRMSE, and FAR values decreased while RMSE, CSI, and POD values increased with increasing time scales. Moreover, the spatial average MB was almost constant for various time scales, although the percentage of grid cells with over-estimated rainfall increased from 1 day to 1 month. By fitting logarithmic functions over the values of r, RMSE, NRMSE, POD, FAR, and CSI at 1, 10 days, and monthly time scales, the corresponding values of these measures were predicted for other time scales with the relative error (NRMSE) of less than 0.1, which indicates the accurate performance of these functions. Through linear regression analysis, the slope (M) and interception (B) of the equations for calibrating 3B42 precipitation estimates at various time scales were obtained. Furthermore, the results showed that the obtained values of M and B in 1, 10 days, and monthly time scales can be estimated with a high accuracy at 2, 3, 5, 7, 15, and 20 days.     

Collecting and Sharing Location-based Content on Mobile Phones in a Zoo Visitor Experience

The augmentation of visitor experiences with location-based technologies has been available for some time. Through in-depth studies of users during these experiences the field is building a rich picture of user behaviour in relation to certain location-based technologies. However, little work has explored the use of mobile camera phones and 2D barcodes on situated signs and their properties as a way of delivering such augmented visitor experiences. In this paper we present a study of people engaged in such a location-based experience at London zoo in which they use mobile camera phones to read 2D barcodes on signs at the animal enclosures in order to access related content. Through the fieldwork we highlight the social and collaborative aspects of the experience and how particular characteristics of the mobile phone and barcode technology shape these behaviours. The paper also highlights some of the non-instrumental aspects of the location-based experience, in particular in relation to the importance of collecting location-based content. We explore the social aspects of collecting as well as certain competitive elements it introduces into people’s behaviour. This creates an interesting tension in that aspects of the application encourage cooperation and sharing among the visitors whereas others encourage competition. In the course of presenting the fieldwork, we explore this tension further.     

Robust Performance Controller Synthesis Based on Discrete‐Time Noncausal Linear Periodically Time‐Varying Scaling

This paper is concerned with the technique called discrete‐time noncausal linear periodically time‐varying (LPTV) scaling for robust stability analysis and synthesis. It is defined through the lifting treatment of discrete‐time systems, and naturally leads to a sort of noncausal operation of signals. In the robust stability analysis of linear time‐invariant (LTI) systems, it has been shown that even static noncausal LPTV scaling induces some frequency‐dependent scaling when it is interpreted in the context of lifting‐free treatment. This paper first discusses in detail different aspects of the effectiveness of noncausal LPTV scaling, with the aim of showing its effectiveness in controller synthesis. More precisely, we study the robust performance controller synthesis problem, where we allow the controllers to be LPTV. As in the LTI robust performance controller synthesis problem, we tackle our problem with an iterative method without guaranteed convergence to a globally optimal controller. Despite such a design procedure, the closed‐loop H_∞ performance is expected to improve as the period of the controller is increased, and we discuss how the frequency‐domain properties of noncausal LPTV scaling could contribute to such improvement. We demonstrate with a numerical example that an effective LPTV controller can be designed for a class of uncertainties for which the well‐known μ‐synthesis fails to derive even a robust stabilization controller.