Hydrolysis of titanium alkoxide and effects of hydrolytic polycondensation parameters

Titanium alkoxides hydrolyse vigorously with water producing polycondensates whose equivalent oxide content varies from 70% to over 90%. This variation reflects the average molecular size and the nature of the terminal bonds. Hydrolysis conditions also affect the molecular and particle morphologies modifying the crystallization and sintering behaviour of oxide materials derived from polycondensates. It is also possible to form clear polymer solutions under excess water hydrolysis with the addition of certain acids. Investigations show that there is a window in the acid concentration which provides long-term solution stability. The gels formed from these clear solutions shrink in their liquor under certain conditions and the introduction of hydrogen peroxide into the liquor (surrounding the gel) causes vigorous gel shrinkage.     

Managing knowledge on communication and information flow in global software projects

Communication is a key success factor of distributed software projects. Poor communication has been identified as a main obstacle to successful collaboration. Global projects are especially endangered by information gaps between collaborating sites. Different communication styles, technical equipment, and missing awareness of each other can cause severe problems. Knowledge about actual and desired channels, paths, and modes of communication is required for improving communication in a globally distributed project. However, many project participants know little about communication and information flow in their projects. In this contribution, we focus on knowledge about communication and information flow. It is acquired by modelling on‐going and desired flows of information, including documented and non‐documented channels of information flow. We analyzed a distributed software project from the information flow perspective. Based on the findings, we developed specific techniques to improve information flow in distributed software development according to the FLOW Method. In a second distributed project, we evaluated one of the techniques. We found the FLOW mapping technique to be suitable for effectively spreading knowledge about communication and information flow in global software projects.     

Activity coefficients of Na2O in molten NaCl,Na2SO4, and Na2CO3

Measurements of the cell

have been used to determine activity coefficients of Na₂O in molten NaCl, Na₂SO₄ and Na₂CO₃. Extreme negative deviations from Raoult's law were observed (γ < 10^?3). In NaCl and Na₂SO₄, γ is independent of concentration below 1 m/o Na₂O, but in Na₂CO₃, the activity is nearly independent of concentration, probably because the oxide reacts with dissolved O₂ to form superoxide (O^?₂).     

Features of a Scan and Clock Resource chip for providing access to board-level test functions

The architecture and some of the specific features of a Scan and Clock Resource (SCR) chip are described. This chip is currently being used in a high-end workstation product to provide access to the testability features of the individual chips and/or printed circuit boards. Using a board-level controller to gain access to the testability features of system components and interfacing the controller to a diagnostics processor (or external tester) is emerging as a common strategy for designing testable digital systems. Based upon experience gained from such an application, controller features that are deemed useful are discussed.This paper is an enhanced version of the author's earlier paper titled Towards a Standard Approach for Controlling Board-Level Test Functions, presented at the IEEE International Test Conference, ITC'90, Washington D.C., September 1990.     

A logarithmic complexity divide-and-conquer algorithm for multi-flexible-body dynamics including large deformations

A new algorithm is presented for the modeling and simulation of multi-flexible-body systems. This algorithm is built upon a divide-and-conquer-based multibody dynamics framework, and it is capable of handling arbitrary large rotations and deformations in articulated flexible bodies. As such, this work extends the current capabilities of the flexible divide-and-conquer algorithm (Mukherjee and Anderson in Comput. Nonlinear Dyn. 2(1):10–21, 2007), which is limited to the use of assumed modes in a floating frame of reference configuration. The present algorithm utilizes the existing finite element modeling techniques to construct the equations of motion at the element level, as well as at the body level. It is demonstrated that these equations can be assembled and solved using a divide-and-conquer type methodology. In this respect, the new algorithm is applied using the absolute nodal coordinate formulation (ANCF) (Shabana, 1996). The ANCF is selected because of its straightforward implementation and effectiveness in modeling large deformations. It is demonstrated that the present algorithm provides an efficient and robust method for modeling multi-flexible-body systems that employ highly deformable bodies. The new algorithm is tested using three example systems employing deformable bodies in two and three spatial dimensions. The current examples are limited to the ANCF line or cable elements, but the approach may be extended to higher order elements. In its basic form, the divide-and-conquer algorithm is time and processor optimal, yielding logarithmic complexity O(log(N _b )) when implemented using O(N _b ) processors, where N _b is the number of bodies in the system.     

An extended divide-and-conquer algorithm for a generalized class of multibody constraints

An extension to the divide-and-conquer algorithm (DCA) is presented in this paper to model constrained multibody systems. The constraints of interest are those applied to the system due to the inverse dynamics or control laws rather than the kinematically closed loops which have been studied in the literature. These imposed constraints are often expressed in terms of the generalized coordinates and speeds. A set of unknown generalized constraint forces must be considered in the equations of motion to enforce these algebraic constraints. In this paper dynamics of this class of multibody constrained systems is formulated using a Generalized-DCA. In this scheme, introducing dynamically equivalent forcing systems, each generalized constraint force is replaced by its dynamically equivalent spatial constraint force applied from the appropriate parent body to the associated child body at the connecting joint without violating the dynamics of the original system. The handle equations of motion are then formulated considering these dynamically equivalent spatial constraint forces. These equations in the GDCA scheme are used in the assembly and disassembly processes to solve for the states of the system, as well as the generalized constraint forces and/or Lagrange multipliers.