Performance Of Portable Devices Research Articles

77 Aerosolized Particulate Matter from Fragmentation of Carbon Nanotube-Enhanced Concrete

Abstract Construction and demolition workers are exposed to high levels of particulate matter (PM) from building materials throughout their working life. Although nano-enabled building materials (NEBMs) may improve the performance and functionality of buildings, concerns are being raised regarding health risks from occupational exposure to PM from NEBMs. In this work, an experimental set-up for integrated resuspension and characterization of PM from NEBMs was developed and tested using three types of concrete (low density, normal, high strength), each enhanced with Carbon Nanotubes (CNTs) at different concentrations (0, low, high). The performance of portable devices used in occupational exposure assessments (DustTrak and NanoTracer) was compared with stationary instruments and gravimetric filter techniques. 40-70% of the mass and 90-98% of the number of particles were within the respirable fraction, with primary modes at 150 nm and 2-3 µm. Addition of CNTs significantly decreased mean particle number concentrations (PNCs) across the entire characterized size range (7 nm - 20 µm) for low density concrete, whereas the opposite was the case for normal strength and high strength concrete. It was hypothesised that the concrete matrix primarily governs the PM formation, which is in turn modulated by CNT-matrix interactions either suppressing or supporting fragmentation during crushing. SEM imaging could display partially submerged CNTs protruding from concrete fragments. Fundamental interactions at the interface of the nanomaterial and the surrounding matrix needs to be investigated to determine how the PM generated from NEBMs differ from their non-nano counterparts and how to prevent future exposure during demolition.

LOW POWER VLSI TECHNIQUES FOR PORTABLE DEVICES

In the present day scenario, designing a circuit with low power has become very important and challenging task. The designing of any processor for portable devices demands low power. This can be achieved by incorporating low power design strategies and rules at various stages of design. To increase the performance of portable devices, the power backup should be taken in consideration, which is extremely desirable from the users prospective. As we approaches towards the sub-micron technology the requirement of low power devices increases significantly. But at the same time leakage current and dynamic power dissipation play a vital role to diminish the performance of portable devices. This paper presents techniques to reduce the power dissipation and various methodologies to increase the speed of device. That is very beneficial for designing of future VLSI circuits.

Micro fuel cell utilizing fuel cell water recovery and pneumatic valve

Micro fuel cells (MFCs) defined by an average power output of less than 10 W offer the potential to improve the runtime and performance of portable devices by providing significantly higher energy density (energy per unit volume) than batteries. However, despite several decades of intense research and development, MFCs have yet to realize this potential, and no MFC technology has achieved broad market adoption. We report in this article an MFC which utilizes water-vapor-driven hydride hydrolysis, fuel cell water recovery, and a self-regulating pneumatic valve to achieve higher energy density than conventional batteries. Integrated MFC prototypes were developed and tested, and achieved 987 Wh L−1. Further improvements in energy density are possible by optimizing the fuel pellet configuration (density, geometry, particle size and distribution, etc.). Energy density greater than 2000 Wh L−1 may be possible in optimized MFCs discharged at low power.

Direct Share: Photo Management System Based on Round-robin Concept-driven User Preference Feedback

As the size of camera modules is decreasing and as the computing performance of portable devices is improving, taking photos has become a part of daily life. However, existing photo management programs and products that manage such photos still require extensive user effort to facilitate the sharing and browsing of images. It is especially difficult for novice users to manage and share photos. In this paper, we develop a round-robin concept-driven user preference feedback mechanism for achieving direct photo sharing, instant display, and easy management using optimized user controls and user preference-driven classification. Compared with commercial photo management systems, our proposed solution provides new features: optimized user controls, direct sharing and instant display, and user preference feedback driven classification. These new features boost the round-robin concept-driven user preference feedback. This paper proposes a photo finder that automatically searches for photos in storage spaces or cameras. The proposed photo finder relies on user preference feedback to share photos by leveraging user preferences, and the round-robin connection transmits photos to the family?s digital photo frame or web album by arbiter. The proposed method saves time and spares users the effort required for photo management. Moreover, this method does not merely direct photo sharing and simple photo management, but it also increases the satisfaction level of users viewing the photos.