The French model and water challenges in developing countries: evidence from Jakarta and Manila

10.1016/j.polsoc.2013.05.004Policy and Society322103-11

Monolithic silicon opto-electro-mechanical light modulator

A Fabry-Perot light beam modulator of the reflection-type has been designed with process and performance parameters optimized. This design takes advantage of the economies of surface micromaching using silicon substrates and selected thin films. High performance with a low drive voltage are achieved using electrostatic actuation of a thin polysilicon diaphragm. The diaphragm is a novel corrugated structure which has maximum compliance and maintains planarity during actuation. In addition, the corrugationsuspension used provides an improved linearity of amplitude modulation response as a function of the actuation voltage. A preliminary version of this device has been fabricated through a contract foundry using some industry- standard film thicknesses. The preliminary version of the device confirms the physical mask design without optimal film processing. The optimized Fabry-Perot structure is designed for operation at a wavelength of 1.3 nm. Using a thin, corrugated diaphragm of 190 nm thickness a 48.90% modulation index is obtained with an actuation voltage of 5 volts based on detailed simulation results. The final optimized device will be fabricated at NJIT at a future date. The proposed optimized device contains a titanium-tungsten metal film deposited into a cavity of half wavelength depth and insulated from the monolithic silicon substrate. An additional quarter wavelength film of silicon nitride is deposited over the metal to increase the modulation index. In the fabrication process a 325 nm sacrificial film of spinon glass is deposited to fill the cavity and form the spacer between the Fabry-Perot etalon entrance and reflecting surfaces. The optical entrance surface is obtained next in the fabrication process by depositing an infrared-transmissive film of polysilicon. The selected polysilicon thickness is 190 nm or any odd integer multiple of a half wavelength. This device can be used as an economical light modulator in near-infrared communications and control systems. This device suitable for relatively low bandwidth applications is expected to provide cost and reliability advantages over competing torsion mirror and macro-sized modulators

Novel dip-pen nanolithography strategies for nanopatterning

Dip-pen nanolithography (DPN) is an atomic force microscopy (AFM)-based\ud lithography technique offering the possibility of fabricating patterns with feature sizes\ud ranging from micrometers to tens of nanometers, utilizing either top-down or bottom-up\ud strategies. Although during its early development stages the serial nature of operation of\ud DPN restricted the patterning efficiency, the successful design and fabrication of AFM\ud probe arrays have increased the throughput of DPN dramatically by enabling generation\ud of patterns in parallel. Several advantages of DPN including (1) ease of generation of\ud arbitrary patterns, (2) application to a variety of ink-substrate combinations, and (3) lower\ud cost relative to other lithographic techniques, have led to many applications in different\ud fields and the establishment of DPN as a popular tool for nanofabrication.\ud This thesis contributes to the continuing development of the DPN technique, mainly\ud focusing on two aspects. The first aspect, presented in Chapters 3-5, is to use DPN to\ud fabricate metal-ion and (bio)-molecular patterns at micrometer or sub-micrometer scale\ud onto monolayer-functionalized solid surfaces with different chemical immobilization\ud strategies. Before performing all DPN experiments, microcontact printing (μCP), a\ud well-known and understood simple and rapid soft lithography technique, was used first to\ud confirm the usefulness of the ink-substrate interactions. The second aspect of interest is to\ud develop an AFM tip surface-modification method for long-term DPN writing, as described\ud in Chapters 6 and 7

Performance of epoxy-coated reinforcement in Iowa bridge decks

Concrete bridge decks subjected to corrosive environment, due to the application of de-icing chemical, could deteriorate at a rapid rate. In an effort to minimize corrosion of the reinforcement and the corresponding delaminations and spalls, the Iowa Department of Transportation (IADOT) started using epoxy-coated rebars (ECR) in the top mat of reinforcing around 1976 and in both mats about 10 years later. The ultimate objective of this research was to determine the impact of deck cracking on durability and estimate the remaining functional service life of a bridge deck. The overall objectives of this work were obtained by conducting a literature review, visually inspecting several bridge decks, collecting and sampling test cores from cracked and uncracked areas of bridge decks, determining the extent to which epoxy coated rebars deteriorate at the site of cracks, and evaluating the impact of cracking on service life. Overall, 81 bridges constructed with ECR were sampled. Fick\u27s Second Law was applied in this study to estimate the time required to reach the corrosive threshold of chloride concentration at the rebar level i.e., the time length of the corrosion initiation stage. No signs of corrosion were observed on the rebars collected from uncracked locations. Rebars that had surface corrosion undercutting the epoxy coating were those collected from cores that were taken from cracked locations. In general, no delaminations or spalls were found on the decks where these bars were cored. The surface chloride concentration at 1/2 below the deck surface and the diffusion constant were found to be 14.0 lb/yd3 and 0.05 in 2/yr respectively. The predicted service life for Iowa bridge decks constructed with ECR was calculated to be approximately between 53 and 141 years. This illustrates that ECR can significantly extend the service life when compared to bridges constructed with black rebars

Detect-and-Avoid: Flight Test 6 Scripted Encounters Data Analysis

The Unmanned Aircraft System (UAS) in the National Airspace System (NAS) project conducted Flight Test 6 (FT6) in 2019. The ultimate goal of this flight test was to produce data to inform RTCA SC-228's Phase II Minimum Operational Performance Standards (MOPS) for Detect and Avoid (DAA) and Low Size, Weight, and Power Sensors. This report documents the analysis of scripted encounters' data. Scripted encounters own were analyzed and categorized based on the outcome of alert, maneuver guidance, and effectiveness of pilots' maneuver in resolving conflicts. Results indicate that UAS pilots' decisions as well as intruder maneuvers are leading factors that contribute to ineffective DAA maneuvers. Results also show that adding buffers to the DAA's suggested minimum turn angle improves effectiveness of the DAA maneuvers

Current steering and electrode spanning with partial tripolar stimulation mode in cochlear implants

Cochlear implants (CIs) partially restore hearing sensation to profoundly deaf people by electrically stimulating the surviving auditory neurons. However, CI users perform poorly in challenging listening tasks such as speech recognition in noise and Cochlear implants (CIs) partially restore hearing sensation to profoundly deaf people by electrically stimulating the surviving auditory neurons. However, CI users perform poorly in challenging listening tasks such as speech recognition in noise and music perception, possibly due to the small number of implanted electrodes and the large current spread of electric stimulation. Although current spread may be reduced using partial tripolar (pTP) stimulation mode, the number of electrodes may not be sufficient to preserve fine spectral details. Here, we propose to introduce current steering and electrode spanning to pTP mode to create additional spectral channels for CI users. Loudness and pitch perception with steered and spanned pTP modes were simulated using a computational model of CI stimulation and were tested in CI users. The excitation pattern of each stimulation mode was also measured at the physical (i.e., intra-cochlear electrical potential distribution), neural (i.e., spatial profile of evoked compound action potential), and perceptual levels (i.e., psychophysical forward masking pattern). Consistent with the model predictions, pitch-ranking results verified the feasibility and efficacy of the proposed stimulation modes in eliciting distinctive pitches for CI users. Pitch increased when the centroid of excitation pattern was shifted basally. When the centroid of excitation pattern did not move, higher pitches were perceived for narrower excitation patterns. These results suggest that in pTP-mode CI processing strategies, current steering and electrode spanning may provide additional spectral channels for better coding of spectral fine structures and for handling the cochlear dead region and defective electrode contact

Fractal analyses of some natural systems

Fractal dimensions are estimated by the box-counting method for real world data sets and for mathematical models of three natural systems. 1 he natural systems are nearshore sea wave profiles, the topography of Shei-pa National Park in Taiwan, and the normalised difference vegetation index (NDV1) image of a fresh fern. I he mathematical models which represent the natural systems utilise multi-frequency sinusoids for the sea waves, a synthetic digital elevation model constructed by the mid-point displacement method for the topography and the Iterated Function System (IFS) codes for the fern leaf. The results show that similar fractal dimensions are obtained for discrete sub-sections of the real and synthetic one-dimensional wave data, whilst different fractal dimensions are obtained for discrete sections of the real and synthetic topographical and fern data. The similarities and differences are interpreted in the context of system evolution which was introduced by Mandelbrot (1977). Finally, the results for the fern images show that use of fractal dimensions can successfully separate void and filled elements of the two-dimensional series