Synthesis,characterization and properties of functionalized styrene–maleimide copolymers

New functionalized styrene–maleimide copolymers were prepared by free radical copolymerization of styrene (St) and N‐4‐carboxybutylmaleimide (NBMI) in chloroform, using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. Monomer and copolymer characterization was carried out by ¹H‐ and ¹³C‐NMR. Copolymer composition was determined by elemental analysis and Fourier‐transform infrared (FTIR) spectroscopy. The glass transition temperature (from DSC) and the thermogravimetric analysis (TGA) of the copolymers were consistent with the thermal behavior and stability observed for alternating St–maleimide copolymers. St–NBMI copolymers crosslinked with divinylbenzene (DVB) were also synthesized and their cation exchange properties evaluated in order to assess the capacity of the new copolymers to bind metallic ions. Copyright © 2005 Society of Chemical Industry     

Use of the Precipitation Method in the Synthesis of Ceramic Pigments

The results of the synthesis of ceramic pigments using coprecipitation of hydroxides and difficultly soluble salts of multivalent metal ions are described. The specifics of the coprecipitation process and the effect of various factors on the production of the initial precipitates for subsequent synthesis of ceramic pigments are analyzed. The technology of pigment production is described. __________ Translated from Steklo i Keramika, No. 6, pp. 37 – 39, June, 2005.     

The Metaflow architecture

The Metaflow architecture, a unified approach to maximizing the performance of superscalar microprocessors, is introduced. The Metaflow architecture exploits inherent instruction-level parallelism in conventional sequential programs by hardware means, without relying on optimizing compilers. It is based on a unified structure, the DRIS (deferred-scheduling, register-renaming instruction shelf), that manages out-of-order execution and most of the attendant problems. Coupling the DRIS with a speculative-execution mechanism that avoids conditional branch stalls results in performance limited only be inherent instruction-level parallelism and available execution resources. Although presented in the context of superscalar machines, the technique is equally applicable to a superpipelined implementation. Lightning, the first implementation of the Metaflow architecture, which executes the Sparc RISC instruction set is described     

Tracking and force control for a class of robotic manipulators

The increasing utilization of robotic manipulators in industrial tasks, such as assembly, forming or shaping of surfaces, and handling hazardous materials, depends greatly on available hybrid force and position control schemes. Since the robot and its environment are often subject to parameter uncertainties that cannot be neglected, it is necessary to design controllers that are robust with respect to these uncertainties. In addition, the dynamics of the robot are nonlinear, requiring consideration of nonlinear control concepts. Another aspect to be taken into account is the relative stiffness of the robot, the force sensor, and the manipulated surface. That is, the behavior of the system normal to the surface is relatively stiff, while that tangential to the surface is relatively free. Separation of the controller for these two directions is therefore indicated. We propose a controller design that accounts for this point of view and demonstrate its efficacy with respect to robustness and accuracy of position and force tracking by means of numerical simulations. The design is based on the control concept of Corless and Leitmann [l]. The example considered is a Manutecr3 robot with three degrees of freedom. In addition, we account for the dynamics of the actuator, which also possesses three degrees of freedom. The considered parameter uncertainties are friction moments in the links and friction between the end effector and the manipulated object, as well as nonlinear dynamics, which are difficult to characterize.Recommended by J. Skowronski     

Transformational approach to program concretization

This paper focuses on the problem of program concretization by applying correctness-preserving transformations of annotated programs. According to the approach presented, a general-purpose program can be annotated by known information about a specific context of its applications and correctly transformed into a specialized program which is equivalent to the original one on the context-defined ranges of inputs and outputs and is better than it by quality criteria given by the context. Tools for program concretizations via annotated program transformations are considered.