Intelligence Gathering in the Exclusive Economic Zone

The article explores the contours of intelligence gathering in the Exclusive Economic Zone (EEZ) under the international law of the sea. Intelligence gathering in the maritime domain is significant for military and law enforcement purposes and for both coastal States and other States. Intelligence gathering attains even more prominence in the EEZ due to the sensitive location and importance of resources to the coastal State, while the sui generis legal nature of this zone adds further complexity to this inquiry. Indeed, the law of the sea, as reflected in the Law of the Sea Convention, neither explicitly prohibits nor permits the collection of intelligence by other States in the EEZ. Equally, it is silent on the permissibility of intelligence gathering on the part of the coastal State. While acknowledging the complexity of legal issues pertaining to the EEZ, this article asserts that intelligence gathering within the EEZ would fall under a presumption of unlawfulness favoring the coastal State when the intelligence pertains to its economic interests. In contrast, the presumption would favor other States, rather than the coastal State, when the gathering of intelligence is a mere expression of the jus communicationis of the other State. Moreover, other pertinent rules of international law, ranging from the prohibition of the threat of the use of force and the abuse of right to the customary right of approach may find application when deciding whether the intelligence gathering activity violated the rights of the coastal State or other States. Intelligence gathering is certainly a difficult question to address, yet one that international law of the sea affords answers

On the trading volume and time effects on the bid-ask spread components of NYSE and NASDAQ common stocks

The study of the bid-ask spreads of stocks is important since they constitute the mechanism through which trading costs are incorporated into prices and recovered by market-makers. Realized spreads are a measure of the trading costs which private and institutional investors have to cover whereas quoted spreads are important in revealing the price-generating mechanisms involved. A comprehensive trade-indicator model of the bid-ask spread of common stocks has been developed which, unlike previous research, has incorporated trading volume, the depth at the quoted prices, the waiting-time between trades, as well as the fixed-cost-of-trade into equations for the changes in the quoted-spread, the ask, the bid and the transaction prices. The parameters of the models have been estimated using intraday data of NYSE and NASDAQ stocks, split into deciles on the basis of their trading activity as measured by the number of shares traded. For both exchange mechanisms I find that a large adverse-selection cost, which depends on the trading volume and a smaller inventory-holding cost are present in the quoted spread and that the parameters of both of these vary with trading activity. These costs are asymmetric in the bid and ask sides of the quoted spread, a feature not analyzed in previous empirical work. Only a small part of these costs is recovered in the realized spread through trading. My estimates of the adverse-selection cost present in the realized spread are close to the values given by other researchers but the size of the inventory-holding cost is found to be much lower probably owing to the shorter time-horizon of the data employed. The depth at the quotes is found to be symmetric, to affect the size of the spread of both the NYSE and NASDAQ stocks and also to be present in the realized spread. The parameters of the above components, as well as the fixed-cost-of-trade, are estimated and their patterns for the two trading mechanisms examined are compared and contrasted. Weak evidence is found for the waiting-time between trades both in the quoted and the realized spread. The results of this thesis, apart from offering support for recent empirical evidence which indicates that information first enters the price-process through the depths of the quotes and not the spread, also contribute to the formation of a more theoretically sound explanation. Moreover, the finding in this thesis that the adverse-selection cost for NASDAQ is larger compared to that of NYSE stocks is in line with other recent empirical researc

A Variable Impedance Scheme Based on Power-Shaping Signals and Partial Knowledge of Link-Side Dynamics for Flexible-Joint Robot Interaction and Tracking Control

This article proposes a novel scheme - based on power-shaping control (PSC) - that can endow flexible-joint robots with both tracking, and interactional, capabilities. In virtue of relying upon the PSC method, this approach entails modest modeling requirements restricted to computation of the gravitational torque vector, and motor-side dynamics terms (typically available in manufacturer datasheets). Hence, it distinguishes itself by obviating the need for calculation of computationally cumbersome link-side dynamics elements, such as the Coriolis and link inertia matrices. In contrast to analogous schemes, the highest order term required by the proposed design is the third derivative of the motor position vector; it therefore avoids the usage of link-jerk feedback that can be detrimental to interactional performance. Moreover, the propounded framework enables utilisation of noncollocated feedback for enhanced tracking accuracy, as well as variable impedance control for interactional performance augmentation. The aforesaid features are effectuated without any reliance on coordinate transformations; thus, the original dynamical model's structure remains immutable throughout. Also, the proposed design's complexity is dependent solely on the gravitational torque vector's dimension (i.e., not on the link inertia or Coriolis terms). Experimental results involving a flexible-joint robot, namely the Rethink Robotics Baxter, corroborate the theoretical analyses, in addition to demonstrating that interactional performance improvements can be achieved via the proposed methodology.</p

On the trading volume and time effects on the bid-ask spread components of NYSE and NASDAQ common stocks

The study of the bid-ask spreads of stocks is important since they constitute the mechanism through which trading costs are incorporated into prices and recovered by market-makers. Realized spreads are a measure of the trading costs which private and institutional investors have to cover whereas quoted spreads are important in revealing the price-generating mechanisms involved. A comprehensive trade-indicator model of the bid-ask spread of common stocks has been developed which, unlike previous research, has incorporated trading volume, the depth at the quoted prices, the waiting-time between trades, as well as the fixed-cost-of-trade into equations for the changes in the quoted-spread, the ask, the bid and the transaction prices. The parameters of the models have been estimated using intraday data of NYSE and NASDAQ stocks, split into deciles on the basis of their trading activity as measured by the number of shares traded. For both exchange mechanisms I find that a large adverse-selection cost, which depends on the trading volume and a smaller inventory-holding cost are present in the quoted spread and that the parameters of both of these vary with trading activity. These costs are asymmetric in the bid and ask sides of the quoted spread, a feature not analyzed in previous empirical work. Only a small part of these costs is recovered in the realized spread through trading. My estimates of the adverse-selection cost present in the realized spread are close to the values given by other researchers but the size of the inventory-holding cost is found to be much lower probably owing to the shorter time-horizon of the data employed. The depth at the quotes is found to be symmetric, to affect the size of the spread of both the NYSE and NASDAQ stocks and also to be present in the realized spread. The parameters of the above components, as well as the fixed-cost-of-trade, are estimated and their patterns for the two trading mechanisms examined are compared and contrasted. Weak evidence is found for the waiting-time between trades both in the quoted and the realized spread. The results of this thesis, apart from offering support for recent empirical evidence which indicates that information first enters the price-process through the depths of the quotes and not the spread, also contribute to the formation of a more theoretically sound explanation. Moreover, the finding in this thesis that the adverse-selection cost for NASDAQ is larger compared to that of NYSE stocks is in line with other recent empirical researchEThOS - Electronic Theses Online ServiceGBUnited Kingdo

Online impedance regulation techniques for compliant humanoid balancing

This paper presents three distinct techniques, aimed at the online active impedance regulation of compliant humanoid robots, which endeavours to induce a state of balance to the system once it has been perturbed. The presence of passive elastic elements in the drives powering this class of robots leads to under-actuation, thereby rendering the control of compliant robots an intricate task. Consequently, the impedance regulation procedures proposed in this paper directly account for these elastic elements. In order to acquire an indication of the robot’s state of balance in an online fashion, an energy (Lyapunov) function is introduced, whose sign then allows one to ascertain whether the robot is converging to or diverging from, a desired equilibrium position. Computing this function’s time derivative unequivocally gives the energy-injecting nature of the active stiffness regulation, and reveals that active damping regulation has no bearing on the system’s state of stability. Furthermore, the velocity margin notion is interpreted as a velocity value beyond which the system’s balance might be jeopardized, or below which the robot will be guaranteed to remain stable. As a result, the unidirectional and bidirectional impedance optimization methods rely upon the use of bounds that have been defined based on the energy function’s derivative, in addition to the velocity margin. Contrarily, the third technique’s functionality revolves solely around the use of Lyapunov Stability Margins (LSMs). A series of experiments carried out using the COmpliant huMANoid (COMAN), demonstrates the superior balancing results acquired when using the bidirectional scheme, as compared to utilizing the two alternative techniques

The Boltzmann–Hamel equations for the optimal control of mechanical systems with nonholonomic constraints

In this paper, we generalize the Boltzmann–Hamel equations for nonholonomic mechanics to a form suited for the kinematic or dynamic optimal control of mechanical systems subject to nonholonomic constraints. In solving these equations one is able to eliminate the controls and compute the optimal trajectory from a set of coupled first-order differential equations with boundary values. By using an appropriate choice of quasi-velocities, one is able to reduce the required number of differential equations by m and 3 m for the kinematic and dynamic optimal control problems, respectively, where m is the number of nonholonomic constraints. In particular we derive a set of differential equations that yields the optimal reorientation path of a free rigid body. In the special case of a sphere, we show that the optimal trajectory coincides with the cubic splines on SO (3). Copyright © 2010 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79427/1/1598_ftp.pd

Stiffness evaluation of a novel ankle rehabilitation exoskeleton with a type-variable constraint

This paper presents a novel ankle rehabilitation exoskeleton with two rotational degrees of freedom, which is suitable for dynamical rehabilitation for patients with neurological impairments. Its stiffness performance is assessed in consideration that the interaction between the footplate and the ground may deflect the mechanism away from the desired/predefined motion patterns. The novel design employs a universal-prismatic-universal (U-P-U) joint link, whose constraint type changes between a couple and a line vector during manipulation of the exoskeleton. To conduct a stiffness analysis of such a mechanism with a type-variable constraint – for the first time – a modified screw-based method (SBM) is proposed. Comparisons with the results obtained from finite element analysis verified that, the modified SBM provides reliable estimates of the exoskeleton's stiffness within the complete workspace (covering the constraint-type transition configurations). The stiffness of the exoskeleton is further evaluated by acquiring the minimum/maximum stiffness values, after computing the distribution of the most crucial linear and angular stiffness parameters within the workspace. Moreover, the influence of the architectural parameters on the stiffness properties is considered for further design optimization

Progress in Classical and Quantum Variational Principles

We review the development and practical uses of a generalized Maupertuis least action principle in classical mechanics, in which the action is varied under the constraint of fixed mean energy for the trial trajectory. The original Maupertuis (Euler-Lagrange) principle constrains the energy at every point along the trajectory. The generalized Maupertuis principle is equivalent to Hamilton's principle. Reciprocal principles are also derived for both the generalized Maupertuis and the Hamilton principles. The Reciprocal Maupertuis Principle is the classical limit of Schr\"{o}dinger's variational principle of wave mechanics, and is also very useful to solve practical problems in both classical and semiclassical mechanics, in complete analogy with the quantum Rayleigh-Ritz method. Classical, semiclassical and quantum variational calculations are carried out for a number of systems, and the results are compared. Pedagogical as well as research problems are used as examples, which include nonconservative as well as relativistic systems

A²ML: A general human-inspired motion language for anthropomorphic arms based on movement primitives

The recent increasing demands on accomplishing complicated manipulation tasks necessitate the development of effective task-motion planning techniques. To help understand robot movement intention and avoid causing unease or discomfort to nearby humans toward safe human–robot interaction when these tasks are performed in the vicinity of humans by those robot arms that resemble an anthropomorphic arrangement, a dedicated and unified anthropomorphism-aware task-motion planning framework for anthropomorphic arms is at a premium. A general human-inspired four-level Anthropomorphic Arm Motion Language (A²ML) is therefore proposed for the first time to serve as this framework. First, six hypotheses/rules of human arm motion are extracted from the literature in neurophysiological field, which form the basis and guidelines for the design of A²ML. Inspired by these rules, a library of movement primitives and related motion grammar are designed to build the complete motion language. The movement primitives in the library are designed from two different but associated representation spaces of arm configuration: Cartesian-posture-swivel-angle space and human arm triangle space. Since these two spaces can be always recognized for all the anthropomorphic arms, the designed movement primitives and consequent motion language possess favorable generality. Decomposition techniques described by the A²ML grammar are proposed to decompose complicated tasks into movement primitives. Furthermore, a quadratic programming based method and a sampling based method serve as powerful interfaces for transforming the decomposed tasks expressed in A²ML to the specific joint trajectories of different arms. Finally, the generality and advantages of the proposed motion language are validated by extensive simulations and experiments on two different anthropomorphic arms