Welcoming two new Co-Editors-in-Chief for KAIS

This paper addresses link prediction problem in directed networks by exploiting reciprocative nature of human relationships. It first proposes a null model to present evidence that reciprocal links influence the process of “triad formation”. Motivated by this, reciprocal links are exploited to enhance link prediction performance in three ways: (a) a reciprocity-aware link weighting technique is proposed, and existing weighted link prediction methods are applied over the resultant weighted network; (b) new link prediction methods are proposed, which exploit reciprocity; and (c) existing and proposed methods are combined toward supervised prediction to enhance the prediction performance further. All experiments are carried out on two real directed network datasets.     

Large deformations of framed structures under static and dynamic loads

With reference to the problem of large deformations and stability of elastic framed structures, this paper explores the computational capabilities of a general beam-column type method which was recently developed by the senior author. The method is flexible in that the coordinate system used may be either Eulerian or Lagrangian. In addition, various types and levels of consistent approximations can be introduced into the analysis in a rather routine fashion.

In an effort to evaluate the merits of the method in the static case, extensive numerical studies were carried out on a group of specially selected and relatively simple structural systems. In formulating the dynamic case, use was made of a well-known numerical integration technique, namely, the so-called “Newmark's β-method”. Again, numerical studies were carried out, although on a smaller scale than in the static case. These studies clearly indicate that the suggested method is both practical and highly accurate.     

基于虚拟样机技术的某型摆臂机构研究

摆臂机构是舰炮发射系统的重要组成部分.某型舰炮摆臂机构采用电机作为外能源,带动齿轮齿条直线运动,进而通过连杆机构带动摆臂实现摆动.上述摆臂机构由多种动力传递和转换组成,采用传统设计方法进行论证研究成本高,难度大.为验证摆臂机构可行性以及机构运动可靠性,同时为摆臂机构电机设计提供依据,结合多刚体系统动力学理论,运用MTA...     

Molecular modeling of tricyclic compounds with anilino substituents and their intercalation complexes with DNA sequences

Although 9-anilinoacridines are among the best studied antitumoral intercalators, there are few studies about the effect of isosteric substitution of a benzene moiety for a heterocycle ring in the acridine framework. According to these studies, this approach may lead to effective cytotoxic agents, but good cytotoxic activity depends on structural requirements in the aniline ring which differ from those in 9-anilinoacridines. The present paper deals with molecular modeling studies of some 9-anilino substituted tricyclic compounds and their intercalation complexes (in various DNA sequences) resulting from docking the compounds into various DNA sequences. As expected, the isosteric substitution in 9-anilinoacridines influences the LUMO energy values and orbital distribution, the dipole moment, electrostatic charges and the conformation of the anilino ring. Other important differences are observed during the docking studies, for example, changes in the spatial arrangement of the tricyclic nucleus and the anilino ring at the intercalation site. Semiempirical calculations of the intercalation complexes show that the isosteric replacement of a benzene ring in the acridine nucleus affects not only DNA affinity but also base pair selectivity. These findings explain, at least partially, the different structural requirements observed in several 9-anilino substituted tricyclic compounds for cytotoxic activity. Thus, the data presented here may guide the rational design of new agents with different DNA binding properties and/or a cytotoxic profile by isosteric substitution of known intercalators.     

Molecular modeling of tricyclic compounds with anilino substituents and their intercalation complexes with DNA sequences

Although 9-anilinoacridines are among the best studied antitumoral intercalators, there are few studies about the effect of isosteric substitution of a benzene moiety for a heterocycle ring in the acridine framework. According to these studies, this approach may lead to effective cytotoxic agents, but good cytotoxic activity depends on structural requirements in the aniline ring which differ from those in 9-anilinoacridines. The present paper deals with molecular modeling studies of some 9-anilino substituted tricyclic compounds and their intercalation complexes (in various DNA sequences) resulting from docking the compounds into various DNA sequences. As expected, the isosteric substitution in 9-anilinoacridines influences the LUMO energy values and orbital distribution, the dipole moment, electrostatic charges and the conformation of the anilino ring. Other important differences are observed during the docking studies, for example, changes in the spatial arrangement of the tricyclic nucleus and the anilino ring at the intercalation site. Semiempirical calculations of the intercalation complexes show that the isosteric replacement of a benzene ring in the acridine nucleus affects not only DNA affinity but also base pair selectivity. These findings explain, at least partially, the different structural requirements observed in several 9-anilino substituted tricyclic compounds for cytotoxic activity. Thus, the data presented here may guide the rational design of new agents with different DNA binding properties and/or a cytotoxic profile by isosteric substitution of known intercalators.     

Incomplete geocoding and spatial sampling: The effects of locational errors on population total estimation

Due to the increasing availability of georeferenced microdata in several fields of research, surveys can benefit greatly from the use of the most recent spatial sampling methods. These methods facilitate selection of spatially balanced samples, which lead to particularly efficient estimates, by incorporating the distances between the exact locations of statistical units into the design. Unfortunately, since locations of units are rarely exact in practice due to imperfections in the geocoding processes, the implementation of spatial sampling designs is actually often limited. This paper aims at demonstrating that spatial sampling designs can be effectively carried out even when spatial information is not completely accurate. By means of Monte Carlo simulation studies, this paper proves that even when the geocoding of population is not exact, spatial sampling methods still facilitate more spatially balanced samples and more efficient estimates.     

一种遥感图像融合质量评价方法

针对遥感图像融合质量评价中多波段、无地面真实参考图像的特点,提出了基于结构相似度和全局融合质量评价指标的融合质量评价方法。该方法首先采用均值变化量构造局部光谱质量加权方法,计算融合图像的光谱质量;然后结合方差构造局部空间质量加权方法,获得融合图像的空间质量;最后使用线性加权方法,计算融合图像的整体质量。通过对8种典型融合方法的结果图像进行质量评价,结果表明提出的评价方法与主观评价结果基本一致,具有可行性。     

Research in progress

The research in the department is concerned mainly with computer-aided design. The fields in which c.a.d. is being applied include: the application of the Rademacher/Walsh transform to digital circuit synthesis; system simulation by digital filter methods; picture processing; and the design of optimal switching networks by linear programming techniques. A theoretical study of the properties of certain orthogonal transforms is also being carried out. Some of this research is outlined in the following sections.     

Hinge attention network: A joint model for diabetic retinopathy severity grading

Diabetic Retinopathy is one of the prominent reasons for permanent blindness in working age, long term diabetic patients. With the prevalence in raise of diabetics, majority of the people are endangered to permanent vision loss. The advancements in medical imaging techniques enabled the research community to focus on developing automated and computerized systems for diagnosing retinopathy in early stages. But, it is a very complex challenge due to the presence of high intra-class variations and imbalanced data distribution for higher grades of severity. In recent years, various deep learning based models have been designed for automating the process of retinopathy severity classification. In this research work, we present a fascinating deep learning model with multiple attention stages called Hinge Attention Network (HA-Net). Proposed model consists of a pre-trained VGG16 base to extract initial spatial representation from retinal scan images, spatial attention autoencoder to learn lesion specific latent representations in spatial dimensions and a channel attention based hinge neural network to grab category based discriminative features in channel dimension and classify the severity grade of retinopathy. In addition to spatial and channel attention mechanism, we use Convolutional LSTM layer to prioritize highly important spatial maps before passing to hinge neural network. All these components of HA-Net, enabled it to make generalised and accurate predictions on unseen data. The effectiveness and acceptability of proposed model is proved by validating it using two benchmark datasets, Kaggle APTOS 2019 and ISBI IDRiD. Extensive experimental studies on these datasets reveal that, proposed HA-Net outstrip several existing models by achieving an accuracy of 85.54% on Kaggle APTOS, and an accuracy of 66.41% on IDRiD datasets.

     

A new level set method for systematic design of hinge-free compliant mechanisms

This paper presents a new level set-based method to realize shape and topology optimization of hinge-free compliant mechanisms. A quadratic energy functional used in image processing applications is introduced in the level set method to control the geometric width of structural components in the created mechanism. A semi-implicit scheme with an additive operator splitting (AOS) algorithm is employed to solve the Hamilton-Jacobi partial differential equation (PDE) in the level set method. The design of compliant mechanisms is mathematically represented as a general non-linear programming with a new objective function augmented by the high-order energy term. The structural optimization is thus changed to a numerical process that describes the design as a sequence of motions by updating the implicit boundaries until the optimized structure is achieved under specified constraints. In doing so, it is expected that numerical difficulties such as the Courant-Friedrichs-Lewy (CFL) condition and periodically applied re-initialization procedures in most conventional level set methods can be eliminated. In addition, new holes can be created inside the design domain. The final mechanism configurations consist of strip-like members suitable for generating distributed compliance, and solving the de-facto hinge problem in the design of compliant mechanisms. Two widely studied numerical examples are studied to demonstrate the effectiveness of the proposed method in the context of designing distributed compliant mechanisms.     

基于有限元的杆端关节轴承结构优化

针对某型号杆端关节轴承在疲劳试验时发生断裂的问题,对其原结构进行有限元仿真分析,得到的最大应力位置与实际断裂位置吻合,圆柱段仿真结果误差与应力理论计算结果仅为0.5%,验证仿真结果的可靠性。对杆端体各结构参数依次进行单变量有限元仿真分析,获取各参数对杆端体最大应力和质量的影响,据此确定优化顺序并对关节轴承进行优化。优化后的杆端关节轴承质量增加9.8%,最大等效应力降低14.9%,计算疲劳寿命从500万次提高到4 600万次,大于目标疲劳寿命值3 000万次,优化后的样件均顺利通过疲劳试验。     

A Computational Model of “Active Vision” for Visual Search in Human–Computer Interaction

Human visual search plays an important role in many human–computer interaction (HCI) tasks. Better models of visual search are needed not just to predict overall performance outcomes, such as whether people will be able to find the information needed to complete an HCI task, but to understand the many human processes that interact in visual search, which will in turn inform the detailed design of better user interfaces. This article describes a detailed instantiation, in the form of a computational cognitive model, of a comprehensive theory of human visual processing known as “active vision” (Findlay & Gilchrist, 2003). The computational model is built using the Executive Process-Interactive Control cognitive architecture. Eye-tracking data from three experiments inform the development and validation of the model. The modeling asks—and at least partially answers—the four questions of active vision: (a) What can be perceived in a fixation? (b) When do the eyes move? (c) Where do the eyes move? (d) What information is integrated between eye movements? Answers include: (a) Items nearer the point of gaze are more likely to be perceived, and the visual features of objects are sometimes misidentified. (b) The eyes move after the fixated visual stimulus has been processed (i.e., has entered working memory). (c) The eyes tend to go to nearby objects. (d) Only the coarse spatial information of what has been fixated is likely maintained between fixations. The model developed to answer these questions has both scientific and practical value in that the model gives HCI researchers and practitioners a better understanding of how people visually interact with computers, and provides a theoretical foundation for predictive analysis tools that can predict aspects of that interaction.     

Optimal design of a three tape-spring hinge deployable space structure using an experimentally validated physics-based model

An optimal design approach is developed for a self-driven, self-locking tape-spring under a pure bending load in deployable space structures. A novel hinge with three tape springs is investigated and designed via an optimization process. Firstly, we investigate the steady-state moment and maximum stress of the hinge during deploying and folding processes using physics-based simulations. Experimental analyses are then conducted to verify the physics-based simulation results. Secondly, a parametric analysis is carried out to prove that both the tape spring thickness and subtended angle have significant effect on steady-state moment. A Response Surface Methodology (RSM) is employed to define an optimal surrogate model aimed at maximizing the steady-state moment, subjected to allowable stress. Finally, the Large Scale Generalized Reduced Gradient (LSGRG) optimization algorithm is used to solve the optimal design problem. Optimization results show that steady-state moment is increased by 19.5% while satisfying a maximum stress constraint. The proposed method is promising for designing novel deployable structures with high stability and reliability.     

Design of an auto-focusing actuator with a flexure-based compliant mechanism for mobile imaging devices

There is increasing consumer’s demand for high-quality and high-performance mobile imaging devices. In this paper, an auto-focusing (AF) actuator with a flexure hinge that uses the electromagnetic (EM) circuit of a voice coil motor was designed and evaluated. The flexure hinge was designed by using finite element analysis. The EM circuit was designed based on the structural stiffness of the device. The EM circuit was analyzed using the design of experiments procedure. Based on the results, the effective design parameters were selected, and improvements were made to the design. Finally, a prototype of the AF actuator was manufactured, and the feasibility and performance of the actuator with the flexure hinge were verified experimentally. The experimental results indicated that the proposed actuator performed adequately and satisfied the design requirements.     

Improved surface-micromachined hinges for fold-out structures

We describe a new surface-micromachined polysilicon micromechanical hinge that is designed for “foldout” surface-micromachined elements. The new hinge shows reduced wobble and enhanced accuracy as compared to previous foldout hinge designs. Features of the new hinge, which is built using only two structural layers of polycrystalline silicon, are two sets of cantilevers that are fixed to opposing hinge flanges. These cantilevers overlay an axle and thereby allow rotation while holding the rotating part to the support member. A precise locking mechanism for 90° out-of-plane rotation makes this hinge design especially suitable for applications to fixed-position vertical-foldout micromirrors. Measurements on such mirrors have confirmed predicted high precision in vertical locking. The new hinge has also permitted the construction of a mirror on a movable carriage that has been driven in a one-dimensional (1-D) sliding motion more than 100 μm by on-chip microvibromotors     

Coupling dynamic simulation and interactive multiobjective optimization for complex problems: An APROS-NIMBUS case study

Dynamic process simulators for plant-wide process simulation and multiobjective optimization tools can be used by industries as a means to cut costs and enhance profitability. Specifically, dynamic process simulators are useful in the process plant design phase, as they provide several benefits such as savings in time and costs. On the other hand, multiobjective optimization tools are useful in obtaining the best possible process designs when multiple conflicting objectives are to be optimized simultaneously. Here we concentrate on interactive multiobjective optimization. When multiobjective optimization methods are used in process design, they need an access to dynamic process simulators, hence it is desirable for them to coexist on the same software platform. However, such a co-existence is not common. Hence, users need to couple multiobjective optimization software and simulators, which may not be trivial. In this paper, we consider APROS, a dynamic process simulator and couple it with IND-NIMBUS, an interactive multiobjective optimization software. Specifically, we: (a) study the coupling of interactive multiobjective optimization with a dynamic process simulator; (b) bring out the importance of utilizing interactive multiobjective optimization; (c) propose an augmented interactive multiobjective optimization algorithm; and (d) apply an APROS-NIMBUS coupling for solving a dynamic optimization problem in a two-stage separation process.     

Spatial navigation in large-scale virtual environments: Gender differences in survey tasks

Most of the studies on gender differences in spatial abilities have focused on traditional paper and pencil cognitive tests, while these differences have been less investigated in navigational tasks carried out in complex virtual environments (VEs). The aim of the present study has been to evaluate gender differences in route and survey knowledge by means of specific tasks (route-learning, pointing, landmark-placing) carried out in two separate VEs. In addition the male and female participants were subjected to a battery of spatial abilities tests and specific self-report questionnaires. The results showed a significant difference favouring males in the survey tasks, as well as in the spatial abilities tests; on the contrary, no gender differences were found in the route task. Moreover, a different pattern of correlations among the measures were found in the male and female sub-groups.     

A methodology to assess the impact of design patterns on software quality

Context

Software quality is considered to be one of the most important concerns of software production teams. Additionally, design patterns are documented solutions to common design problems that are expected to enhance software quality. Until now, the results on the effect of design patterns on software quality are controversial.

Aims

This study aims to propose a methodology for comparing design patterns to alternative designs with an analytical method. Additionally, the study illustrates the methodology by comparing three design patterns with two alternative solutions, with respect to several quality attributes.

Method

The paper introduces a theoretical/analytical methodology to compare sets of “canonical” solutions to design problems. The study is theoretical in the sense that the solutions are disconnected from real systems, even though they stem from concrete problems. The study is analytical in the sense that the solutions are compared based on their possible numbers of classes and on equations representing the values of the various structural quality attributes in function of these numbers of classes. The exploratory designs have been produced by studying the literature, by investigating open-source projects and by using design patterns. In addition to that, we have created a tool that helps practitioners in choosing the optimal design solution, according to their special needs.

Results

The results of our research suggest that the decision of applying a design pattern is usually a trade-off, because patterns are not universally good or bad. Patterns typically improve certain aspects of software quality, while they might weaken some other.

Conclusions

Concluding the proposed methodology is applicable for comparing patterns and alternative designs, and highlights existing threshold that when surpassed the design pattern is getting more or less beneficial than the alternative design. More specifically, the identification of such thresholds can become very useful for decision making during system design and refactoring.