A rule-based approach for robust clump splitting

This paper presents a robust rule-based approach for the splitting of binary clumps that are formed by objects of diverse shapes and sizes. First, the deepest boundary pixels, i.e., the concavity pixels in a clump, are detected using a fast and accurate scheme. Next, concavity-based rules are applied to generate the candidate split lines that join pairs of concavity pixels. A figure of merit is used to determine the best split line from the set of candidate lines. Experimental results show that the proposed approach is robust and accurate.     

Towards subject independent continuous sign language recognition: A segment and merge approach

This paper presents a segment-based probabilistic approach to robustly recognize continuous sign language sentences. The recognition strategy is based on a two-layer conditional random field (CRF) model, where the lower layer processes the component channels and provides outputs to the upper layer for sign recognition. The continuously signed sentences are first segmented, and the sub-segments are labeled SIGN or ME (movement epenthesis) by a Bayesian network (BN) which fuses the outputs of independent CRF and support vector machine (SVM) classifiers. The sub-segments labeled as ME are discarded and the remaining SIGN sub-segments are merged and recognized by the two-layer CRF classifier; for this we have proposed a new algorithm based on the semi-Markov CRF decoding scheme. With eight signers, we obtained a recall rate of 95.7% and a precision of 96.6% for unseen samples from seen signers, and a recall rate of 86.6% and a precision of 89.9% for unseen signers.     

Detecting people in dense crowds

We propose a scheme to detect individuals in any image frame of a video sequence showing densely crowded scenes against cluttered backgrounds. The method uses only spatial information, and in an initial pass through the image a trained Viola–Jones-type local detector is used to locate individuals in the densely crowded scene. This yields a large number of false alarms. Hence, in a second step, we seek to reduce the false alarms, and propose two methods for this. In the first, color information from the initially detected windows is passed to a classifier to reduce the false alarms. This classifier consists of a cascade of boosted classifiers with Haar-like features as input and is trained with color information from local windows. In the second method, a weak perspective model of an uncalibrated camera is used to further reduce the false alarm rate while maintaining the detection rate. This is based on the size and locations of the detections in the image frame, without the use of any 3D world information. Results are presented in the form of receiver operating characteristic curves. For instance, at a 79.0% detection accuracy, the false alarm rate is 20.3%.     

Some aspects of surface roughness measurement

The connection between the profile and surface Power Spectral Densities of a rough surface is investigated, and explicit functional relations between the two are obtained for isotropic surfaces. These relations allow the surface Power Spectral Density (PSD) to be obtained from the PSD of a single profile, for isotropic surfaces. For anisotropic surfaces, it is shown how the surface PSD may be obtained from the cross-spectra of several parallel profiles. Techniques for obtaining these cross-spectra are briefly mentioned.A simple example of an isotropic surface is used to show that the profile PSD may seriously distort the spectral content of the surface roughness by giving undue weight to long wavelengths at the expense of short wavelengths.Questions of filtering of the surface and profile PSDs are discussed for isotropic surfaces, and it is shown that removal of all wavelengths smaller than λ₀ on the surface requires their removal on the profile, but in addition requires some attenuation of all wavelengths on the profile greater than λ₀. The question of which profile filters are admissible in the sense that they give rise to physically realizable surface filters (with 0 ? attenuation ? 1) is also examined, and it is shown that all profile filters involving an infinitely sharp cut-off at some wavelength are inadmissible.Based on an examination of the connection between the surface PSD and various surface statistics of interest, four indices of anisotropy involving the moments of this PSD are developed. It is shown how these indices may be evaluated by means of measurements on five nonparallel profiles.     

Smart adaptive optic systems using spatial light modulators

Many factors contribute to the aberrations induced in an optical system. Atmospheric turbulence between the object and the imaging system, physical or thermal perturbations in optical elements degrade the system's point spread function, and misaligned optics are the primary sources of aberrations that affect image quality. The design of a nonconventional real-time adaptive optic system using a micro-mirror device for wavefront correction is presented. The unconventional compensated imaging system presented offers advantages in speed, cost, power consumption, and weight. A pulsed-coupled neural network is used to as a preprocessor to enhance the performance of the wavefront sensor for low-light applications. Modeling results that characterize the system performance are presented.     

Control and enhancement of permselectivity of membrane‐based microcapsules for favorable biomolecular transport and immunoisolation

The success of membrane‐based, cell‐encapsulating microcapsules depends on the membrane permselectivity that provides efficient inward transport of nutrients, therapeutic protein egress, and complete exclusion of immunoglobulins. Microcapsules with a calcium crosslinked alginate core and a genipin‐crosslinked chitosan alginate (GCA) were prepared with good control over size, membrane thickness and density. Importantly, in this study, we report a novel approach of using three relevant biomolecules and investigating the effects of the membrane characteristics (thickness and density) and microcapsule size on biomolecular mass transport across the GCA microcapsules using mathematical models based on a balance of the chemical potential. Scaling analysis was used to interrelate the membrane thickness, chitosan–alginate reaction rate constant, and diffusion coefficient. The resistance to diffusion of the three biomolecules increased with membrane density and thickness. Interestingly, swelling in the large microcapsules resulted in an increase in permeability, allowing larger biomolecules (immunoglobulin and carbonic anhydrase) to diffuse more readily. In the case of the smaller biomolecule, vitamin B₁₂, a shorter diffusion path length in smaller microcapsules allowed better ingress. When compared with other microcapsules, the GCA microcapsules possess improved permselectivity for them to allow diffusion of small nutrient molecules and proteins, whereas completely excluding antibodies. Also, these results elucidate the importance of membrane properties and microcapsule size to realize favorable transport of biomolecules. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Highly scalable wavelet-based video codec for very low bit-rateenvironment

We introduce a highly scalable video compression system for very low bit-rate videoconferencing and telephony applications around 10-30 kbits/s. The video codec first performs a motion-compensated three-dimensional (3-D) wavelet (packet) decomposition of a group of video frames, and then encodes the important wavelet coefficients using a new data structure called tri-zerotrees (TRI-ZTR). Together, the proposed video coding framework forms an extension of the original zero tree idea of Shapiro (1992) for still image compression. In addition, we also incorporate a high degree of video scalability into the codec by combining the layered/progressive coding strategy with the concept of embedded resolution block coding. With scalable algorithms, only one original compressed video bit stream is generated. Different subsets of the bit stream can then be selected at the decoder to support a multitude of display specifications such as bit rate, quality level, spatial resolution, frame rate, decoding hardware complexity, and end-to-end coding delay. The proposed video codec also allows precise bit rate control at both the encoder and decoder, and this can be achieved independently of the other video scaling parameters. Such a scheme is very useful for both constant and variable bit rate transmission over mobile communication channels, as well as video distribution over heterogeneous multicast networks. Finally, our simulations demonstrated comparable objective and subjective performance when compared to the ITU-T H.263 video coding standard, while providing both multirate and multiresolution video scalability     

External-loop fluidized bed airlift bioreactor (EFBAB) for the cometabolic biotransformation of 4-chlorophenol (4-cp) in the presence of phenol

The advantages from a 4-l external-loop inversed fluidized bed airlift bioreactor (EIFBAB) reported by Loh and Liu [2001. Chemical Engineering Science 56, 6171-6176] was synergized with preferential adsorption by granular activated carbon (GAC) for the enhanced cometabolic biotransformation of 4-chlorophenol (4-cp) in the presence of phenol as a growth substrate. This was achieved by incorporating a GAC fluidized bed in the lower part of the riser with the gas sparger relocated above this fluidized bed to avoid the presence of a 3-phase flow in the fluidized bed consequently providing larger gas holdup. Expanded polystyrene beads (EPS) were used as the supporting matrix for immobilizing Pseudomonas putida ATCC 49451, in the downcomer of the bioreactor. The hydrodynamics of the bioreactor system was characterized by studying the effect of the extent of valve opening, under cell-free condition, on gas holdup and liquid circulation velocity at different gas velocities and solids loading (EPS and GAC). The experimental data for gas holdup were modeled using power law correlations, while a Langmuir-Hinshelwood kinetics model was used for the liquid circulation velocity. The bioreactor was tested for batch cometabolic biotransformation of 4-cp in the presence of phenol at various concentration ratios of phenol and 4-cp (ranging from phenol: 4-cp to phenol: 4-cp) at 9% EPS loading and 2.8% (10 g) GAC loading. The 4-cp and phenol biotransformations were achieved successfully in the bioreactor system, which ascertained the feasibility of the bioreactor. Biotransformation of high 4-cp and phenol concentrations, which was oxygen limited, was also effectively achieved by increasing the gas holdup in the riser. This was possible in the current EFBAB system because of the synergistic effect of the GAC fluidized bed, the globe valve and cell immobilization by EPS.     

Durable adhesives based on electrospun poly(vinylidene fluoride) fibers

Herein, the fabrication of poly(vinylidene fluoride) (PVDF) fibrous membrane using electrospinning is reported and its use for dry‐adhesive applications is demonstrated. The shear and normal adhesion performance of the samples was investigated using an Instron tensile tester and an atomic force microscope (AFM) respectively. For shear adhesion measurements, the electrospun membrane was finger pressed on to a glass slide and pulled in shear mode using a tensile tester. The thickness of the electrospun membrane was varied and the effect of thickness on shear adhesion was investigated. The shear adhesion strength increased when the thickness of the samples was reduced. Shear adhesion strength of a 200 µm thick sample was determined to be approximately 0.165 N/cm. For normal adhesion measurements, a flat tipless cantilever was used to indent the sample and then retract back to measure the pull‐off force. High shear adhesion strength and normal pull‐off force recorded are attributed to the fine size of the fibers that conform to the asperities present on the surfaces of the glass slide and the AFM cantilever. The durability of the adhesive was also verified by repeating the AFM adhesion measurements over 1000 consecutive attachment–detachment cycles. The pull‐off force was seen to be constant over 1000 attachment–detachment cycles. Our results indicate that these electrospun fibrous membranes can potentially be used as reusable dry‐adhesives. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44393.     

Effect of differential maturity of paddy grains in a panicle on their milling quality

Branches of paddy panicles were divided into four equal parts and grains collected from each part separately. Moisture content at harvest and milling breakage after shade drying of grains to 12 to 13% moisture were determined. Average moisture content of grains gradually increased while milling quality generally suffered in grains from the top first quarter to the last quarter at the bottom. The same trend was found when the grains in the “top” quarter were compared with those from the “rest” of the panicle. The proportion of sun-checked grains was highest in the “top” fractions at all stages of maturity. The grains at the “top” also had a tendency to shed easily from the panicle. At early stages of maturity milling breakage of grains in lower portions of panicles was high perhaps due to immaturity and softness.