Using multimedia for e‐learning

This paper reviews 12 research‐based principles for how to design computer‐based multimedia instructional materials to promote academic learning, starting with the multimedia principle (yielding a median effect size of d = 1.67 based on five experimental comparisons), which holds that people learn better from computer‐based instruction containing words and graphics rather than words alone. Principles aimed at reducing extraneous processing (i.e., cognitive processing that is unrelated to the instructional objective) include coherence (d = 0.70), signalling (d = 0.46), redundancy (d = 0.87), spatial contiguity (d = 0.79) and temporal contiguity (d = 1.30). Principles for managing essential processing (i.e., mentally representing the essential material) include segmenting (d = 0.70), pre‐training (d = 0.46) and modality (d = 0.72). Principles for fostering generative processing (i.e., cognitive processing aimed at making sense of the material) include personalization (d = 0.79), voice (d = 0.74) and embodiment (d = 0.36). Some principles have boundary conditions, such as being stronger for low‐ rather than high‐knowledge learners.     

Design of Nonuniform Linear Antenna Array Geometry and Signal Processing Algorithm for DOA Estimation of Gaussian Sources

Abramovich, Yuri I., and Spencer, Nicholas K., Design of Nonuniform Linear Antenna Array Geometry and Signal Processing Algorithm for DOA Estimation of Gaussian Sources, Digital Signal Processing10 (2000), 340–354.This paper discusses the problem of direction-of-arrival (DOA) estimation for Gaussian sources that have arbitrary correlation: from independent to fully correlated. For independent sources, the antenna array design is governed by two competing considerations: maximum aperture, which inclines toward increasing sparsity for a given number of array sensors, and identifiability, which tends to exclude extreme sparsity. For fully correlated sources, these two competing criteria are augmented by a third which allows for the initialization of DOA estimation by the generalized spatial smoothing (GSS) technique. The maximum number of fully correlated sources is in turn an important factor in the GSS algorithm and subsequent array geometry design. We present a geometry optimization technique that permits accurate DOA estimation of arbitrarily correlated sources.     

A combined neural network and genetic algorithm based approach for optimally designed femoral implant having improved primary stability

Excessive implant-bone relative micromotion is detrimental to both primary as well as long-term stability of a hip stem in cementless total hip arthroplasty (THA). The shape and geometry of the implant are known to influence the resulting post-operative micromotion. Finite element (FE)-based design evaluations are manually intensive and computationally expensive, especially when a large number of designs need to be evaluated for an optimum outcome. This study presents a predictive mathematical model based on back-propagation neural network (BPNN) to relate femoral stem design parameters to the post-operative implant-bone micromotion, with no recourse to tedious nonlinear FE analysis. The characterization of the design parameters were based on our earlier study on shape optimization of femoral implant. The BPNN led to faster prediction of the implant-bone relative micromotion as compared to the FE analysis. Using the BPNN-predicted output as the objective function, a genetic algorithm (GA) based search was performed in order to minimize post-operative micromotion, under simulated physiological loading conditions. The micromotion predicted by the neural network was found to have a significant correlation with FE calculated results (correlation coefficient R² = 0.80 for training; R² = 0.82 for test). The optimal stems, evolved from the GA search of over 12,500 designs, were found to offer improved primary stability, as compared to the initial TriLock (DePuy) design. Our predicted results favour lateral-flared designs having rectangular proximal transverse sections with greater stem-sizes.     

A classification of generic families of control-affine systems and their bifurcations

We study control-affine systems with n − 1 inputs evolving on an n-dimensional manifold for which the distribution spanned by the control vector fields is involutive and of constant rank (equivalently, they may be considered as 1-dimensional systems with n − 1 inputs entering nonlinearly). We provide a complete classification of such generic systems and their one-parameter families. We show that a generic family for n > 2 is equivalent (with respect to feedback or orbital feedback transformations) to one of nine canonical forms which differ from those for n = 2 by quadratic terms only. We also describe all generic bifurcations of 1-parameter families of systems of the above form.     

Social impact in technologically-mediated communication: An examination of online influence

This study used Social Impact Theory to explore sources and functions of interpersonal influence in Computer-Mediated Communication. Participants were 43 female and 17 male graduate students ranging from 25 to 60 years of age. In each of five distinct graduate classes (n₁ = 15, n₂ = 11, n₃ = 10, n₄ = 12, n₅ = 12) delivered online at a research university, participants engaged in anonymous and computer-mediated discourse and then nominated peers who were directive and/or influential (positive and negative) during the online interaction. High numbers of peer nominations were expected to characterize participants perceived as emanating social impact. Four interpersonal factors were chosen as strength operants in accordance with Social Impact Theory and were, therefore, expected to predict social impact. Of the four, assertiveness and exaggeration were significant, while emotional intensity and sensitivity were not. Two factors, contribution total and word total, were chosen as immediacy operants in accordance with Social Impact Theory. Both factors were found to be significant predictors of social impact. Implications of these findings relative to online learning and interpersonal influence as it occurs in an online context are discussed.     

A gender matching effect in learning with pedagogical agents in an immersive virtual reality science simulation

The main objective of this study is to determine whether boys and girls learn better when the characteristics of the pedagogical agent are matched to the gender of the learner while learning in immersive virtual reality (VR). Sixty‐six middle school students (33 females) were randomly assigned to learn about laboratory safety with one of two pedagogical agents: Marie or a drone, who we predicted serve as a role models for females and males, respectively. The results indicated that there were significant interactions for the dependent variables of performance during learning, retention, and transfer, with girls performing better with Marie (d = 0.98, d = 0.67, and d = 1.03; for performance, retention, and transfer, respectively) and boys performing better with the drone (d = ?0.41, d = ?0.45, d = ?0.23, respectively). The results suggest that gender‐specific design of pedagogical agents may play an important role in VR learning environments.     

Direct electrochemistry of cytochrome c and biosensing for hydrogen peroxide on polyaniline grafted multi-walled carbon nanotube electrode

Cytochrome c (cyt c) was immobilized into a matrix consisting of polyaniline (PANI) and multi-walled carbon nanotubes (MWNT) by a new strategy. First, PANI chains were grafted onto MWNT through electropolymerization. Second, the amine groups in PANI chains were oxidized at an applied potential of +0.80 V to acquire positive charges that would effectively immobilize negatively charged cyt C. The ITO/MWNT-g-PANI(O)/cyt c electrode exhibited a pair of redox peaks with a peak potential separation (anodic to cathodic) of 0.25 V (vs Ag/AgCl) in 0.1 M phosphate buffer (pH 7.0). The results demonstrated that ITO/MWNT-g-PANI(O)/cyt c promoted direct electron transfer between cyt c and electrode with a high electron transfer rate constant (17 s⁻¹). The ITO/MWNT-g-PANI(O)/cyt c electrode catalyzes the reduction of H₂O₂. The ITO/MWNT-g-PANI(O)/cyt c biosensor displays an amperometric response to H₂O₂ with a linear concentration range from 0.5 μM to 1.5 mM (r = 0.99, n = 12), a high sensitivity (32.2 μAm M⁻¹) and fast response (9 s) and detection limit of 0.3 μM (S/N = 3).     

On Abelian 2-avoidable binary patterns

We give the first example of a binary pattern which is Abelian 2-avoidable, but which contains no Abelian fourth power. We introduce a family of binary morphisms which offer a common generalization of the Fibonacci morphism and the Abelian fourth-power-free morphism of Dekking. We show that the Fibonacci word begins with arbitrarily high Abelian powers, but for n ≥ 2, the fixed point of f _n avoids x ⁿ⁺² in the Abelian sense. The sets of patterns avoided in the Abelian sense by the fixed points of f _n and f _n+1 are mutually incomparable for n ≥ 2. Here A and B are finite alphabets, u a word over A, and w a word over B. The authors are supported by NSERC Discovery Grants.     

Research on Fractional Critical Covered Graphs

A graph G is called a fractional (g, f)-covered graph if for any e ∈ E(G), G admits a fractional (g, f)-factor covering e. A graph G is called a fractional (g, f, n)-critical covered graph if for any S ? V(G) with ∣S∣ = n, G ? S is a fractional (g, f)-covered graph. A fractional (g, f, n)-critical covered graph is said to be a fractional (a, b, n)-critical covered graph if g(x) = a and f(x) = b for every x ∈ V(G). A fractional (a, b, n)-critical covered graph was first defined and studied in [1]. In this article, we investigate fractional (g, f, n)-critical covered graphs and present a binding number condition for the existence of fractional (g, f, n)-critical covered graphs, which is an improvement and generalization of a previous result obtained in [2].

     

Touch‐typing for better spelling and narrative‐writing skills on the computer

This study investigated the effect of a touch‐typing course on the spelling and narrative‐writing skills on the computer of elementary school students. Data of 207 students in Grades 4, 5, and 6 were analysed using a pretest–posttest design. Students in the experimental group (n = 154) followed a touch‐typing course, and those in the control group (n = 53) did not. The experimental group showed more progress in typing, spelling, and narrative‐writing skills on the computer than the control group. It can be concluded that the touch‐typing course had a positive effect, not only on typing skills but also on spelling and narrative‐writing skills on the computer.     

An efficient architecture for designing reverse converters based on a general three-moduli set

In this paper, a high-speed, low-cost and efficient design of reverse converter for the general three-moduli set {2^α, 2^β − 1, 2^β + 1} where α < β is presented. The simple proposed architecture consists of a carry save adder (CSA) and a modulo adder. As a result it can be efficiently implemented in VLSI circuits. The values of α and β are set in order to provide the desired dynamic range and also to obtain a balanced moduli set. Based on the above, two new moduli sets {2^n+k, 2²ⁿ − 1, 2²ⁿ + 1} and {2²ⁿ⁻¹, 2²ⁿ⁺¹ − 1, 2²ⁿ⁺¹ + 1}, which are the special cases of the moduli set {2^α, 2^β − 1, 2^β + 1} are proposed. The reverse converters for these new moduli sets are derived from the proposed general architecture with better performance compared to the other reverse converters for moduli sets with similar dynamic range.     

Novel optimized tree-based stack-type architecture for 2n-bit comparator at nanoscale with energy dissipation analysis

Comparator is an essential building block in many digital circuits such as biometric authentication, data sorting, and exponents comparison in floating-point architectures among others. Quantum-dot Cellular Automata (QCA) is a latest nanotechnology that overcomes the drawbacks of Complementary Metal Oxide Semiconductor (CMOS) technology. In this paper, novel area optimized 2n-bit comparator architecture is proposed. To achieve the objective, 1-bit stack-type and 4-bit tree-based stack-type (TB-ST) comparators are proposed using QCA. Then, two tree-based architectures of 4-bit comparators are arranged in two layers to optimize the number of quantum cells and area of an 8-bit comparator. Thus, this design can be extended to any 2n-bit comparator. Simulation results of 4-bit and 8-bit comparators using QCADesigner 2.0.3 show that there is a significant improvement in the number of quantum cells and area occupancy. The proposed TB-ST 8-bit comparator uses 2.5 clock cycles and 622 quantum cells with area occupancy of 0.49 µm² which is an improvement by 10.5% and 38%, respectively, compared to existing designs. Scaling it to a 32-bit comparator, the proposed architecture requires only 2675 quantum cells in an area of 2.05 µm² with a delay of 3.5 clock cycles, indicating 9.35% and 28.8% improvements, respectively, demonstrating the merit of the proposed architecture. Besides, energy dissipation analysis of the proposed TB-ST 8-bit comparator is simulated on QCADesigner-E tool, indicating average energy dissipation reduction of 17.3% compared to existing works.

     

An Improved Approximation Algorithm for the Traveling Tournament Problem

This paper describes the traveling tournament problem, a well-known benchmark problem in the field of tournament timetabling. We propose an approximation algorithm for the traveling tournament problem with the constraints such that both the number of consecutive away games and that of consecutive home games are at most k. When k≤5, the approximation ratio of the proposed algorithm is bounded by (2k−1)/k+O(k/n) where n denotes the number of teams; when k>5, the ratio is bounded by (5k−7)/(2k)+O(k/n). For k=3, the most investigated case of the traveling tournament problem to date, the approximation ratio of the proposed algorithm is 5/3+O(1/n); this is better than the previous approximation algorithm proposed for k=3, whose approximation ratio is 2+O(1/n).     

Calculating optimal addition chains

An addition chain is a finite sequence of positive integers 1 = a ₀ ≤ a ₁ ≤ · · · ≤ a _r = n with the property that for all i > 0 there exists a j, k with a _i = a _j + a _k and r ≥ i > j ≥ k ≥ 0. An optimal addition chain is one of shortest possible length r denoted l(n). A new algorithm for calculating optimal addition chains is described. This algorithm is far faster than the best known methods when used to calculate ranges of optimal addition chains. When used for single values the algorithm is slower than the best known methods but does not require the use of tables of pre-computed values. Hence it is suitable for calculating optimal addition chains for point values above currently calculated chain limits. The lengths of all optimal addition chains for n ≤ 2³² were calculated and the conjecture that l(2n) ≥ l(n) was disproved. Exact equality in the Scholz–Brauer conjecture l(2 ⁿ − 1) = l(n) + n − 1 was confirmed for many new values.     

Students and instructors perspective on blended synchronous learning in a Canadian graduate program

Blended synchronous learning (BSL) represents several contexts that enable to bring remote students into the classroom, in real time, by the means of videoconferencing, web conferencing and virtual world. As BSL seems to be more and more implemented in many higher education institutions, especially in the current context of the COVID-19 pandemic, and given the recent interest and scarce published research in BSL, more studies are needed on this kind of learning. The purpose of this research was to explore students and instructors perspective regarding their experience in BSL, according to three dimensions: pedagogy, technology and organization/logistics. To meet the study objective, a qualitative methodology was adopted. The study participants were remote students (n = 4) and face-to-face students (n = 4) enrolled in a graduate program in education offering only blended synchronous courses, and instructors (n = 5) in this program. Semi-structured interviews were selected as the data collection method. Nine sub-themes in reference to the three dimensions emerged from the study participants. They have also highlighted some challenges associated with BSL. The results reported in this study should provide faculties and higher education administrators with additional information and guidance, based on empirical data, on the use of BSL if they wish to implement it in academic programs. Moreover, in regard to the challenges revealed by the study participants, the results will permit to surpass the obstacles when implementing BSL successfully.     

Feasibility of PSO–ANFIS model to estimate rock fragmentation produced by mine blasting

Desired rock fragmentation is the main goal of the blasting operation in surface mines, civil and tunneling works. Therefore, precise prediction of rock fragmentation is very important to achieve an economically successful outcome. The primary objective of this article is to propose a new model for forecasting the rock fragmentation using adaptive neuro-fuzzy inference system (ANFIS) in combination with particle swarm optimization (PSO). The proposed PSO–ANFIS model has been compared with support vector machines (SVM), ANFIS and nonlinear multiple regression (MR) models. To construct the predictive models, 72 blasting events were investigated, and the values of rock fragmentation as well as five effective parameters on rock fragmentation, i.e., specific charge, stemming, spacing, burden and maximum charge used per delay were measured. Based on several statistical functions [e.g., coefficient of correlation (R ²) and root-mean-square error (RMSE)], it was found that the PSO–ANFIS (with R ² = 0.89 and RMSE = 1.31) performs better than the SVM (with R ² = 0.83 and RMSE = 1.66), ANFIS (with R ² = 0.81 and RMSE = 1.78) and nonlinear MR (with R ² = 0.57 and RMSE = 3.93) models. Finally, the sensitivity analysis shows that the burden and maximum charge used per delay have the least and the most effects on the rock fragmentation, respectively.

     

Traffic overflow in loss systems with selective trunk reservation

We consider two traffic streams competing for service at an n-server queuing system. Jobs from stream 1, the protected stream, are blocked only if all n servers are busy. Jobs from stream 2, the best effort stream, are blocked if n−r, r≥1, servers are busy. Blocked customers are diverted to a secondary group of c−n servers with, possibly, a different service rate. For the case r=1, we calculate the joint probabilities of the number of primary and secondary busy servers. For r>1, we describe a procedure for deriving the joint probabilities. These probabilities allow for the calculation of various performance measures including the overflow probabilities of the primary server and secondary server group. Our model is applicable to traffic control in communication networks that use the selective trunk reservation method.     

Strongly Hamiltonian laceability of the even k-ary n-cube

The interconnection network considered in this paper is the k-ary n-cube that is an attractive variance of the well-known hypercube. Many interconnection networks can be viewed as the subclasses of the k-ary n-cubes include the cycle, the torus and the hypercube. A bipartite graph is Hamiltonian laceable if there exists a Hamiltonian path joining every two vertices which are in distinct partite sets. A bipartite graph G is strongly Hamiltonian laceable if it is Hamiltonian laceable and there exists a path of length N − 2 joining each pair of vertices in the same partite set, where N = |V(G)|. We prove that the k-ary n-cube is strongly Hamiltonian laceable for k is even and n  2.     

Analysis of muscle fatigue in helicopter pilots

Helicopter pilots espouse ergonomically unfavourable postures and endure vibration which result in low back pain. The objective of this study was to investigate the effects of a helicopter flight on pilots back and shoulder muscles using surface Electromyography (sEMG) analysis. This study also correlates low back pain symptoms from Rehabilitation Bioengineering Group Pain Scale (RBGPS) questionnaire with muscle fatigue rates obtained. RBGPS was administered on 20 Coast Guard helicopter pilots. sEMG was acquired before and after flight from erector spinae and trapezius muscles in 8 of these 20 pilots. Statistical analysis of time and frequency domain parameters indicated significant fatigue in right trapezius muscle due to flying. Muscle fatigue correlated with average duration of flight (r² = 0.913), total service as pilot (r² = 0.825), pain (r² = 0.463) and total flying hours (r² = 0.507). However, muscle fatigue weakly correlated with Body Mass Index (BMI) (r² = 0.000144) and age (r² = 0.033).