Tracking 3-D body motion for docking and robot control

An advanced method of tracking three-dimensional motion of bodies has been developed. This system has the potential to dynamically characterize machine and other structural motion, even in the presence of structural flexibility, thus facilitating closed loop structural motion control. The system's operation is based on the concept that the intersection of three planes defines a point. Three rotating planes of laser light, fixed and moving photovoltaic diode targets, and a pipe-lined architecture of analog and digital electronics are used to locate multiple targets whose number is only limited by available computer memory. Data collection rates are a function of the laser scan rotation speed and are currently selectable up to 480 Hz. The tested performance on a preliminary prototype designed for 0.1 in accuracy (for tracking human motion) at a 480 Hz data rate includes a worst case resolution of 0.8 mm (0.03 inches), a repeatability of plus or minus 0.635 mm (plus or minus 0.025 inches), and an absolute accuracy of plus or minus 2.0 mm (plus or minus 0.08 inches) within an eight cubic meter volume with all results applicable at the 95 percent level of confidence along each coordinate region. The full six degrees of freedom of a body can be computed by attaching three or more target detectors to the body of interest

Electronic heat current rectification in hybrid superconducting devices

In this work, we review and expand recent theoretical proposals for the realization of electronic thermal diodes based on tunnel-junctions of normal metal and superconducting thin films. Starting from the basic rectifying properties of a single hybrid tunnel junction, we will show how the rectification efficiency can be largely increased by combining multiple junctions in an asymmetric chain of tunnel-coupled islands. We propose three different designs, analyzing their performance and their potential advantages. Besides being relevant from a fundamental physics point of view, this kind of devices might find important technological application as fundamental building blocks in solid-state thermal nanocircuits and in general-purpose cryogenic electronic applications requiring energy management.Comment: 9 pages, 5 color figure

A review of modular strategies and architecture within manufacturing operations

This paper reviews existing modularity and modularization literature within manufacturing operations. Its purpose is to examine the tools, techniques, and concepts relating to modular production, to draw together key issues currently dominating the literature, to assess managerial implications associated with the emerging modular paradigm, and to present an agenda for future research directions. The review is based on journal papers included in the ABI/Inform electronic database and other noteworthy research published as part of significant research programmes. The research methodology concerns reviewing existing literature to identify key modular concepts, to determine modular developments, and to present a review of significant contributions to the field. The findings indicate that the modular paradigm is being adopted in a number of manufacturing organizations. As a result a range of conceptual tools, techniques, and frameworks has emerged and the field of modular enquiry is in the process of codifying the modular lexicon and developing appropriate modular strategies commensurate with the needs of manufacturers. Modular strategies and modular architecture were identified as two key issues currently dominating the modular landscape. Based on this review, the present authors suggest that future research areas need to focus on the development and subsequent standardization of interface protocols, cross-brand module use, supply chain power, transparency, and trust. This is the first review of the modular landscape and as such provides insights into, first, the development of modularization and, second, issues relating to designing modular products and modular supply chains

Racial Disparity in Federal Criminal Sentences

Using rich data linking federal cases from arrest through to sentencing, we find that initial case and defendant characteristics, including arrest offense and criminal history, can explain most of the large raw racial disparity in federal sentences, but significant gaps remain. Across the distribution, blacks receive sentences that are almost 10 percent longer than those of comparable whites arrested for the same crimes. Most of this disparity can be explained by prosecutors’ initial charging decisions, particularly the filing of charges carrying mandatory minimum sentences. Ceteris paribus, the odds of black arrestees facing such a charge are 1.75 times higher than those of white arrestee

Mandatory Sentencing and Racial Disparity, Assessing the Role of Prosecutors and the Effects of Booker

This Article presents new empirical evidence concerning the effects of United States v. Booker, which loosened the formerly mandatory U.S. Sentencing Guidelines, on racial disparities in federal criminal cases. Two serious limitations pervade existing empirical literature on sentencing disparities. First, studies focus on sentencing in isolation, controlling for the “presumptive sentence” or similar measures that themselves result from discretionary charging, plea-bargaining, and fact-finding processes. Any disparities in these earlier processes are excluded from the resulting sentence-disparity estimates. Our research has shown that this exclusion matters: pre-sentencing decision-making can have substantial sentence-disparity consequences. Second, existing studies have used loose causal inference methods that fail to disentangle the effects of sentencing-law changes, such as Booker, from surrounding events and trends. In contrast, we use a dataset that traces cases from arrest to sentencing, allowing us to assess Booker’s effects on disparities in charging, plea-bargaining, and fact-finding, as well as sentencing. We disentangle background trends by using a rigorous regression discontinuity-style design. Contrary to other studies (and in particular, the dramatic recent claims of the U.S. Sentencing Commission), we find no evidence that racial disparity has increased since Booker, much less because of Booker. Unexplained racial disparity remains persistent, but does not appear to have increased following the expansion of judicial discretion

On Estimating Disparity and Inferring Causation: Sur-Reply to the U.S. Sentencing Commission Staff

In this Essay, Professors Starr and Rehavi respond to the U.S. Sentencing Commission’s empirical staff’s criticisms of their recent article, which found, contrary to the Commission’s prior work, no evidence that racial disparity in sentences increased in response to United States v. Booker. As Starr and Rehavi suggest, their differences with the Commission perhaps relate to differing objectives. The Commission staff’s reply expresses a lack of interest in identifying Booker’s causal effects; in contrast, that is Starr and Rehavi’s central objective. In addition, Starr and Rehavi’s approach also accounts for disparities arising throughout the post-arrest justice process, extending beyond the Commission’s narrower focus on disparities in adherence to the Sentencing Guidelines. Beyond these core disagreements, Starr and Rehavi point to several ways in which the reply’s other criticisms inaccurately describe their claims, their methods, and the scope of their study’s sample

Racial Disparity in Federal Criminal Sentences

Using rich data linking federal cases from arrest through to sentencing, we find that initial case and defendant characteristics, including arrest offense and criminal history, can explain most of the large raw racial disparity in federal sentences, but significant gaps remain. Across the distribution, blacks receive sentences that are almost 10 percent longer than those of comparable whites arrested for the same crimes. Most of this disparity can be explained by prosecutors’ initial charging decisions, particularly the filing of charges carrying mandatory minimum sentences. Ceteris paribus, the odds of black arrestees facing such a charge are 1.75 times higher than those of white arrestee

Ratcheting Heat Flux against a Thermal Bias

Merely rocking the temperature in one heat bath can direct a steady heat flux from cold to hot against a non-zero thermal bias in stylized nonlinear lattice junctions that are sandwiched between two heat baths. Likewise, for an average zero-temperature difference between the two contacts a net, ratchet-like heat flux emerges. Computer simulations show that this very heat flux can be controlled and reversed by suitably tailoring the frequency ($\lesssim$ 100 MHz) of the alternating temperature field.Comment: 5 pages, 6 figure