Simple Instance Research Articles

Design of a portable anthropomimetic upper limb rehabilitation device for patients suffering from neuromuscular disability.

An upper limb anthropomimetic rehabilitation device has been designed for patients suffering from a neuromuscular disability. The developed device has been designed as a wearable device and attempts to supplement all known functions of the human hand and fingers. The actuation of individual joints of the hand and wrist has been implemented by using DC motors interfaced to a control system. A pulley system was adopted to ensure a low device profile with the aim of maximising functionality in the affected hand. Both actuators and the electronic assembly are sited in the forearm assembly for this purpose. The device is designed to fulfill multiple roles. At its simplest instance, it is designed as a device for providing resistance training in patients suffering from reversible neuromuscular weakness. The device also aims to provide support as an exoskeleton device in patients suffering from partial but permanent neuromuscular weakness. The measurement of finger and wrist bending in axial and radial directions were investigated by an array of potentiometers mounted around the wearable device covering different joints of the fingers and wrist, and were further analyzed to characterize the range of the device. The system is a composite device with diverse functions fulfilling all the requirements of an upperlimb orthotic device. The device is planned to be part of a comprehensive exoskeleton device for quadriparetic patients in the future.

Spacelike deformations: higher-helicity fields from scalar fields

In contrast to Hamiltonian perturbation theory which changes the time evolution, “spacelike deformations” proceed by changing the translations (momentum operators). The free Maxwell theory is only the first member of an infinite family of spacelike deformations of the complex massless Klein–Gordon quantum field into fields of higher helicity. A similar but simpler instance of spacelike deformation allows to increase the mass of scalar fields.

Neutron interaction with electromagnetic fields: a didactic approach

In physics, consideration of phenomena in one or two space dimensions (1 + 1 or 2 + 1 space-time dimensions) is often regarded as a useful step toward understanding them in three space dimensions (3 + 1 space-time dimensions). This article presents the basic dynamics of a neutron with a magnetic moment in the presence of certain electromagnetic fields in 2 + 1 space-time dimensions by using a polar coordinate system. We illustrate this approach with two simple instances within the theory of the Dirac equation: (i) a (neutron) harmonic oscillator, and (ii) a particular kind of hydrogen atom-like system; wherein the Aharonov–Casher discrete states are exemplified within the framework of relativistic quantum mechanics.

Vafa–Witten invariants from modular anomaly

Recently, a universal formula for a non-holomorphic modular completion of the generating functions of refined BPS indices in various theories with $N=2$ supersymmetry has been suggested. It expresses the completion through the holomorphic generating functions of lower ranks. Here we show that for $U(N)$ Vafa-Witten theory on Hirzebruch and del Pezzo surfaces this formula can be used to extract the holomorphic functions themselves, thereby providing the Betti numbers of instanton moduli spaces on such surfaces. As a result, we derive a closed formula for the generating functions and their completions for all $N$. Besides, our construction reveals in a simple way instances of fiber-base duality, which can be used to derive new non-trivial identities for generalized Appell functions. It also suggests the existence of new invariants, whose meaning however remains obscure.

Programmable Daisychaining of Microelectrodes to Secure Bioassay IP in MEDA Biochips

As digital microfluidic biochips (DMFBs) make the transition to the marketplace for commercial exploitation, security and intellectual property (IP) protection are emerging as important design considerations. Recent studies have shown that DMFBs are vulnerable to reverse engineering aimed at stealing biomolecular protocols (IP theft). The IP piracy of proprietary protocols may lead to significant losses for pharmaceutical and biotech companies. The microelectrode dot array (MEDA) is a next-generation DMFB platform that supports real-time sensing of droplets and has the added advantage of important security protection. However, real-time sensing offers opportunities to an attacker to steal the biochemical IP. We show that the daisychaining of microelectrodes and the use of one-time programmability in MEDA biochips provides effective bitstream scrambling of biochemical protocols. To examine the strength of this solution, we develop a Satisfiability (SAT)-based attack that can unscramble the bitstreams through repeated observations of bioassays executed on the MEDA platform. Based on insights gained from the SAT attack, we propose an advanced defense against IP theft. Simulation results using real-life biomolecular protocols confirm that while the SAT attack is effective for simple instances, our advanced defense can thwart it for realistic MEDA biochips and real-life protocols.

Project Portfolio Risk Response Selection Using Bayesian Belief Networks

Risk identification, impact assessment, and response planning constitute three building blocks of project risk management. Correspondingly, three types of interactions could be envisioned between risks, between impacts of several risks on a portfolio component, and between several responses. While the interdependency of risks is a well-recognized issue, the other two types of interactions remain unacknowledged in the risk response planning literature. This research suggests a Bayesian belief network for modeling portfolio risks, their impacts, and responses. There are three kinds of nodes in this network: nodes representing portfolio risks, nodes corresponding to risk impacts on each objective of each portfolio component, and nodes showing response actions. The problem is to decide which responses are to be selected. For this purpose, an optimization model is proposed that minimizes the sum of both residual risk effects on portfolio component objectives and response implementation costs. Subsequently, a genetic algorithm is introduced to solve the model. A simple portfolio instance is also provided to illustrate the proposed model.

Pedestrian collision avoidance with a local dynamic goal

We present here a general formalism for equipping simulated pedestrians with an avoidance mechanism. The central idea is to use a short-range target which is adjusted dynamically depending on the environment and thus modulating the desired velocity of the agent. This formulation can be implemented over any type of existing pedestrian model, being force-based or rule-based. As an example, we implement a simple instance of the formulation which is adjusted to reproduce previous reported and available experimental data of collision avoidance in scenarios of low density. The proposed minimal model shows good agreement with the real trajectories and other macroscopic observables.

Release of Unverified Plaintext: Tight Unified Model and Application to ANYDAE

Authenticated encryption schemes are usually expected to offer confidentiality and authenticity. In case of release of unverified plaintext (RUP), an adversary gets separated access to the decryption and verification functionality, and has more power in breaking the scheme. Andreeva et al. (ASIACRYPT 2014) formalized RUP security using plaintext awareness, informally meaning that the decryption functionality gives no extra power in breaking confidentiality, and INT-RUP security, covering authenticity in case of RUP. We describe a single, unified model, called AERUP security, that ties together these notions: we prove that an authenticated encryption scheme is AERUP secure if and only if it is conventionally secure, plaintext aware, and INT-RUP secure. We next present ANYDAE, a generalization of SUNDAE of Banik et al. (ToSC 2018/3). ANYDAE is a lightweight deterministic scheme that is based on a block cipher with block size n and arbitrary mixing functions that all operate on an n-bit state. It is particularly efficient for short messages, it does not rely on a nonce, and it provides maximal robustness to a lack of secure state. Whereas SUNDAE is not secure under release of unverified plaintext (a fairly simple attack can be mounted in constant time), ANYDAE is. We make handy use of the AERUP security model to prove that ANYDAE achieves both conventional security as RUP security, provided that certain modest conditions on the mixing functions are met. We describe two simple instances, called MONDAE and TUESDAE, that conform to these conditions and that are competitive with SUNDAE, in terms of efficiency and optimality.

Necessary Conditions of Optimality for a Time-Optimal Bi-level Sweeping Control Problem

This article concerns a simple instance of an optimal control problem paradigm combining bi-level optimization with sweeping processes, initially investigated in Khalil and Lobo Pereira (2019). This class of problems arises, for instance, in structured crowd motion control problems in a confined space. We propose a specific class of time-optimal bi-level problem with sweeping process dynamics represented in terms of a truncated normal cone at the lower level. We establish the necessary optimality conditions of the Maximum Principle of Pontryagin type in the Gamkrelidze’s form. Two techniques are at the core of the analysis: a) the smooth approximation of the low level sweeping control system, thereby avoiding the absence of Lipschitzianity inherent to the sweeping process, and, b) the flattening of the bi-level structure to a single level problem by using a exact penalization technique involving the value function of the low level problem to incorporate its inherent constraint in the bi-level structure. Necessary optimality conditions are applied to the resulting approximate flattened problem, and the main result of this article is obtained by passing to the limit.

Ethics and Time: After the Anthropocene

This “treatise” on ethics and literary practice is a self-reflective piece that argues and enacts ethical criticism through poetic form as well as content. That is, I deliberately employ poetry not only as a literary genre but also as rhetorical arguments—investigative, demonstrative, and evidentiary—and as forms of ethical action. The two previously unpublished poems here are drawn from a larger, lyrical discourse sequence tentatively entitled “Heidegger, Ethics, and Time: After the Anthropocene.” The “poetic arguments,” then, concern the possible interrelations and effects of time and ethics within the philosophical context of post-human “being” collectively, and also of personal death as a shared event. There are a couple of famous theories of time and ethics that ebb and flow within the different formal abridgements of time in these two poems. One set of theories is expounded in Martin Heidegger’s major work, Being and Time, as well as many of his other treatises on language, poetry, and ethics. Another set of theories is founded in Emmanuel Levinas’ work on time and alterity. But unlike these philosophies, the two poems here deal in detail with (1) the potential particularities of lived sensation and feeling (2) as they might be experienced by sentient and non-sentient ‘being’ (3) that survive death—of our species (poem II) and/or individual death (poem III). However, rather than simply rehearsing philosophy or recasting it into poetic form, these two poems argue for and against the notion that time is a physical and thus materially moral absolute, necessary for any (conscious) life to exist at all; and these two poems also argue physically, through their structure and style. They argue that physical dimension of time is not only a material force that is “unkind to material things” (aging, decay), as articulated in the content of one poem for example, but also a moral force that is revealed and played against in the constricted temporal motion and music of the poems (i.e., their forms, and variations within). In addition to philosophical arguments that poetry by its nature deliberately leaves ambiguous (indeterminate, but also will-free), the aural, temporal forms of the poems themselves flow in or move through but also reshape time. A simple instance of this is the way meter and rhyme are activated by time, yet also transform time, pushing back against its otherwise unmarked inexorable ineffable… The temporal properties of poetic forms in conjunction with content therefore constitute “lyrical ethics” in literary practice. Thinking (and putting aside as well) Heidegger and Levinas, these poems as temporal forms may physically shift, even if only momentarily, the relation of the listener or reader to Being/Death, or Alterity/Other. For example, the enhanced villanelle and modified Spenserian stanza offered here each shapes time differently, and thus differently shapes the intuitive, affective, cognitive responses of readers. With its cyclical repetition of lines, usually over five tercets and a quatrain, the villanelle with every advancing stanza physically ‘throws’ time (the concept and the line) back on itself (or perhaps is “thrown forward” [Geworfen]). In contrast, the pattern of the Spenserian nine-line stanza allows time to hover around a still but outward-expanding point (like a partial mini-[uni]verse) before drifting to the next stanza (especially here, where the final rhyme at the end of each stanza is much delayed.). Within and without the context of Heidegger and Levinas, I assert that these structural features are ethical statements in literary practice. The choice of these traditional forms of poetry in itself is an ethical statement. Stylistically as well as thematically, these two poems argue “all sides” of ethical positions in relation to the end of being human. Perhaps more importantly, these two poems explore the inevitably human experience of philosophically different ethical positions on death “post anthropocentrically”—what might come in the rhetorical after we can never know except poetically.

Neural Nets via Forward State Transformation and Backward Loss Transformation

This article studies (multilayer perceptron) neural networks with an emphasis on the transformations involved — both forward and backward — in order to develop a semantic/logical perspective that is in line with standard program semantics. The common two-pass neural network training algorithms make this viewpoint particularly fitting. In the forward direction, neural networks act as state transformers, using Kleisli composition for the multiset monad — for the linear parts of network layers. In the reverse direction, however, neural networks change losses of outputs to losses of inputs, thereby acting like a (real-valued) predicate transformer. In this way, backpropagation is functorial by construction, as shown in other works recently. We illustrate this perspective by training a simple instance of a neural network.

Mean-payoff Optimization in Continuous-time Markov Chains with Parametric Alarms

Continuous-time Markov chains with alarms (ACTMCs) allow for alarm events that can be non-exponentially distributed. Within parametric ACTMCs, the parameters of alarm-event distributions are not given explicitly and can be the subject of parameter synthesis. In this line, an algorithm is presented that solves the ε-optimal parameter synthesis problem for parametric ACTMCs with long-run average optimization objectives. The approach provided in this article is based on a reduction of the problem to finding long-run average optimal policies in semi-Markov decision processes (semi-MDPs) and sufficient discretization of the parameter (i.e., action) space. Since the set of actions in the discretized semi-MDP can be very large, a straightforward approach based on an explicit action-space construction fails to solve even simple instances of the problem. The presented algorithm uses an enhanced policy iteration on symbolic representations of the action space. Soundness of the algorithm is established for parametric ACTMCs with alarm-event distributions that satisfy four mild assumptions, fulfilled by many kinds of distributions. Exemplifying proofs for the satisfaction of these requirements are provided for Dirac, uniform, exponential, Erlang, and Weibull distributions in particular. An experimental implementation shows that the symbolic technique substantially improves the efficiency of the synthesis algorithm and allows us to solve instances of realistic size.

Worst case analysis of Relax and Fix heuristics for lot-sizing problems

We analyze the worst case behavior of Relax and Fix heuristics, which are often used to solve mixed integer linear programming problems. In these heuristics the integer variables are fixed in an iterative way, while having relaxed part of the integer variables in each iteration. In particular, we analyze Relax and Fix heuristics for lot-sizing problems. We show that even for simple instances with time-invariant parameters, the worst case ratio may be unbounded. Furthermore, we show some counterintuitive behavior of Relax and Fix heuristics from computational experiments.

Parametrized bar recursion: a unifying framework for realizability interpretations of classical dependent choice

Abstract During the last 20 years or so, a wide range of realizability interpretations of classical analysis have been developed. In many cases, these are achieved by extending the base interpreting system of primitive recursive functionals with some form of bar recursion, which realizes the negative translation of either countable or countable dependent choice. In this work, we present the many variants of bar recursion used in this context as instantiations of a parametrized form of backward recursion, and give a uniform proof that under certain conditions this recursor realizes a corresponding family of parametrized dependent choice principles. From this proof, the soundness of most of the existing bar recursive realizability interpretations of choice, including those based on the Berardi–Bezem–Coquand functional, modified realizability and the more recent products of selection functions of Escardó and Oliva, follows as a simple corollary. We achieve not only a uniform framework in which familiar realizability interpretations of choice can be compared, but show that these represent just simple instances of a large family of potential interpretations of dependent choice principles.

Approximation algorithms for minimizing the maximum lateness and makespan on parallel machines

We consider a multiobjective scheduling problem, with the aim of minimizing the maximum lateness and the makespan on two identical machines. In this problem, we are given a set J of n jobs to be scheduled on two identical machines. Each job $$j\in J$$ has a processing time $$p_j$$ and a delivery time $$q_j$$. The machines are available at time $$t=0$$ and each of them can process at most one job at a given time. This paper proposes an exact algorithm (based on a dynamic programming) to generate the complete Pareto Frontier in a pseudo-polynomial time. Then, we present a polynomial time approximation scheme (PTAS) to generate an approximate Pareto Frontier. In this scheme, we use a simplification technique based on the merging of jobs. Furthermore, we present two fully polynomial time approximation scheme (FPTAS) to generate an approximate Pareto Frontier, the first one is based on the conversion of the dynamic programming, the second one is applied to the simplified instances given by the PTAS. The proposed FPTAS algorithms are strongly polynomial. Finally, some numerical experiments are provided in order to compare the four proposed approaches.

Clustering mining blocks in presence of geological uncertainty

ABSTRACTA major trend in mine production planning research is incorporating geological uncertainty in the processes of planning. Many mathematical models and heuristic approaches are proposed to deal with the uncertainty. Although there have been advances in exact methods to solve simpler instances of the mine production scheduling problem more complex instances of the model, especially when incorporating uncertainty, remain intractable and aggregation of blocks can help to decrease solution times. In this paper, we present four variations of the agglomerative hierarchical clustering algorithm, one based on deterministic estimates of properties and three based on possible worlds approach which use Geostatistical realizations to form aggregates with regard to the geological properties and the existing uncertainties. We show, through case studies, that uncertainty-based algorithms can result in aggregates that are less susceptible to uncertainties, and at the same time, the proposed algorithm can produce aggregates that are within a controlled size and have minable shapes.

On index policies for stochastic minsum scheduling

Minimizing the sum of completion times when scheduling jobs on m identical parallel machines is a fundamental scheduling problem. Unlike the well-understood deterministic variant, it is a major open problem how to handle stochastic processing times. We show for the prominent class of index policies that no such policy can achieve a distribution-independent approximation factor. This strong lower bound holds even for simple instances with deterministic and two-point distributed jobs. For such instances, we give an O(m)-approximative list scheduling policy.

Multi-objective evolutionary algorithm on simplified bi-objective minimum weight minimum label spanning tree problems

As general purpose optimisation methods, evolutionary algorithms have been efficiently used to solve multi-objective combinatorial optimisation problems. However, few theoretical investigations have been conducted to understand the efficiency of evolutionary algorithms on such problems, and even fewer theoretical investigations have been conducted on multi-objective combinatorial optimisation problems coming from real world. In this paper, we analyse the performance of a simple multi-objective evolutionary algorithm on two simplified instances of the bi-objective minimum weight minimum label spanning tree problem, which comes from real world. Though these two instances are similar, the analysis results show that the simple multi-objective evolutionary algorithm is efficient for one instance, but it may be inefficient for the other. According to the analysis on the second instance, we think that the restart strategy may be useful in making the multi-objective evolutionary algorithm more efficient for the bi-objective problem.

An attribute value frequency-based instance weighting filter for naive Bayes

ABSTRACTDue to its simplicity, efficiency and efficacy, naive Bayes (NB) continues to be one of the top 10 data mining algorithms. A mass of improved approaches to NB have been proposed to weaken its conditional independence assumption. However, there has been little work, up to the present, on instance weighting filter approaches to NB. In this paper, we propose a simple, efficient, and effective instance weighting filter approach to NB. We call it attribute (feature) value frequency-based instance weighting and denote the resulting improved model as attribute value frequency weighted naive Bayes (AVFWNB). In AVFWNB, the weight of each training instance is defined as the inner product of its attribute value frequency vector and the attribute value number vector. The experimental results on 36 widely used classification problems show that AVFWNB significantly outperforms NB, yet at the same time maintains the computational simplicity that characterizes NB.

Theories of class F and anomalies

We consider the 6d (2, 0) theory on a fibration by genus g curves, and dimensionally reduce along the fiber to 4d theories with duality defects. This generalizes class S theories, for which the fibration is trivial. The non-trivial fibration in the present setup implies that the gauge couplings of the 4d theory, which are encoded in the complex structures of the curve, vary and can undergo S-duality transformations. These monodromies occur around 2d loci in space-time, the duality defects, above which the fiber is singular. The key role that the fibration plays here motivates refering to this setup as theories of class F. In the simplest instance this gives rise to 4d mathcal{N}=4 Super-Yang-Mills with space-time dependent coupling that undergoes SL(2, ℤ) monodromies. We determine the anomaly polynomial for these theories by pushing forward the anomaly polynomial of the 6d (2, 0) theory along the fiber. This gives rise to corrections to the anomaly polynomials of 4d mathcal{N}=4 SYM and theories of class S. For the torus case, this analysis is complemented with a field theoretic derivation of a U(1) anomaly in 4d mathcal{N}=4 SYM. The corresponding anomaly polynomial is tested against known expressions of anomalies for wrapped D3-branes with varying coupling, which are known field theoretically and from holography. Extensions of the construction to 4d mathcal{N}=0 and 1, and 2d theories with varying coupling, are also discussed.