Wireless data: Systems,standards, services

Wireless data products and services being proposed today include exotic mixes of services and technologies: packet transport over cellular circuits, facsimile service over Cellular Digital Packet Data (CDPD), voice and video over wireless LANs, and everything in between. Data networking terms that seem to have a clear meaning-data-link, network and transport layers; circuit-mode and datagram; connection-less and connection-oriented-in fact have meaning only in context. Thus TCP, a reliable packet transport protocol, is being used in CDMA circuit-mode data to provide a reliable data-link layer for the error-prone wireless link. IP datagrams will be transported over cellular links using dedicated channels with call establishment, possibly per packet. Market demands for timely solutions, competition between alternative technologies and the plethora of alternative fora for standards development are driving wireless data into fragmented directions. The primary constraints come from the limited spectrum, the need for security in the presence of mobility and the size and weight of mobile terminals and devices. Often the optimization for the latter constraints is sacrificed at the altar of the former drivers. Based upon our experience and work with standards and systems we attempt to put wircless data into perspective. We compare and contrast major services and products and identify the choices that were made and why.We acknowledge the contributions of our colleagues at AT&T Bell Laboratories: Ken Budka, Mooi Choo Chuah, Bharat Doshi, Subra Dravida, Richard Ejzak and On-Ching Yue.     

Communication interface in a physical simulator for robotic palletization

This paper addresses the issues relating to the communication channels in a physical simulator for flexible automation of a palletization task. The simulator used in our work involves an IBM-7545 robot, a personal computer and an Allen-Bradley Programmable Logic Controller (PLC). The communications relating to the Robot/PC interface and the PLC/PC interface are discussed.

The palletization station design requires that decisions on pallet pattern are made dynamically by a program running on the personal computer. The Robot/PC communication interface is necessary to transmit these decisions to the robot controller for execution. This communication is to be achieved using BASIC language and AML 4.1 as the software platforms.

The PLC has the task of controlling the transport of the boxes coming to the palletization station. The program for deciding the pallet pattern, running on the personal computer, needs real-time information on the counts of boxes of different sizes that are arriving for palletization. The PLC/PC interface serves to provide this information.     

Effects of cola drinks on the morphology and elastic modulus of dentin

The mechanical and morphological degradation that human dentin undergoes after prolonged exposure in cola drinks was examined using nanoindentation and AFM. The elastic modulus of the dentin prior cola exposure was 18.28 ± 1.7 GPa, while after exposure it had decreased to 4.25 ± 1.4 GPa on the surface that was in direct contact with the drink, and to 13.38 ± 2.9 GPa on the surface that was in indirect contact with the drink. AFM documented the corrosion effects of the cola through topography images and histograms of the RMS roughness.     

Design and development of a physical simulator for robotic palletization

This paper discusses the design and development of a physical simulator for robotic palletization. The design is aimed at two objectives. One, to provide a test bed for studying issues relating to automation of palletization and second, to provide a teaching tool for some common elements of material handling automation. The major hardware components of the system are an IBM 7545 robot, a Personal Computer, an Allen-Bradley Programmable Logic Controller (PLC), Conveyors and a Bar Code Reader. The software components include the IBM AML 4.1 language, PLC Software and BASIC software for the BASIC Module of the PLC.     

An Approach for Establishing Enterprise Data Standards

Avoid the common pitfalls experienced by many organizations that have established enterprise data standards by following a straightforward process. Standards should be defined around a simple framework and be borrowed from third parties or vendors wherever possible to save time. It is better to reuse, rather than reinvent or create standards. To be used successfully, standards must be easy to understand, have a proven track record, be easy to use, and be readily available. Standards should be maintained in a central repository such as Lotus Notes or on an intranet Web site so that they are readily accessible to project teams.     

Harvesting of Saccharomyces cerevisiae using colloidal gas aphrons

Adsorptive bubble separation using Colloidal Gas Aphrons (CGA) can be used for harvesting of microorganisms. The effect of various operating parameters, for example pH, biomass loading, dispersed and continuous phase velocity, surfactant type and concentration, has been studied on the recovery of Saccharomyces cerevisiae. The operating conditions were optimised for maximum separation. The results obtained have been compared with the prediction of an model earlier.     

Smart‐Dust‐Nanorice for Enhancement of Endogenous Raman Signal,Contrast in Photoacoustic Imaging,and T2‐Shortening in Magnetic Resonance Imaging

Raman microspectroscopy provides chemo‐selective image contrast, sub‐micrometer resolution, and multiplexing capabilities. However, it suffers from weak signals resulting in image‐acquisition times of up to several hours. Surface‐enhanced Raman scattering (SERS) can dramatically enhance signals of molecules in close vicinity of metallic surfaces and overcome this limitation. Multimodal, SERS‐active nanoparticles are usually labeled with Raman marker molecules, limiting SERS to the coating material. In order to realize multimodal imaging while acquiring the rich endogenous vibronic information of the specimen, a core–shell particle based on “Nanorice”, where a spindle‐shaped iron oxide core is encapsulated by a closed gold shell, is developed. An ultrathin layer of silica prevents agglomeration and unwanted chemical interaction with the specimen. This approach provides Raman signal enhancement due to plasmon resonance effects of the shell while the optical absorption in the near‐infrared spectral region provides contrast in photoacoustic tomography. Finally, T2‐relaxation of a magnetic resonance imaging (MRI) experiment is altered by taking advantage of the iron oxide core. The feasibility for Raman imaging is evaluated by nearfield simulations and experimental studies on the primate cell line COS1. MRI and photoacoustics are demonstrated in agarose phantoms illustrating the promising translational nature of this strategy for clinical applications in radiology.     

A Robotic Excavator for Autonomous Truck Loading

Excavators are used for the rapid removal of soil and other materials in mines, quarries, and construction sites. The automation of these machines offers promise for increasing productivity and improving safety. To date, most research in this area has focussed on selected parts of the problem. In this paper, we present a system that completely automates the truck loading task. The excavator uses two scanning laser rangefinders to recognize and localize the truck, measure the soil face, and detect obstacles. The excavator's software decides where to dig in the soil, where to dump in the truck, and how to quickly move between these points while detecting and stopping for obstacles. The system was fully implemented and was demonstrated to load trucks as fast as human operators.