Ultrasound Imaging by Thermally Tunable Phononic Crystal Lens

This work demonstrates the detections and mappings of a solid object using a thermally tunable solid-state phononic crystal lens at low frequency for potential use in future long-distance detection. The phononic crystal lens is infiltrated with a polyvinyl alcohol-based poly n-isopropyl acrylamide (PVA-PNIPAm) bulk hydrogel polymer. The hydrogel undergoes a volumetric phase transition due to a temperature change leading to a temperature-dependent sound velocity and density. The temperature variation from 20 °C to 39 °C changes the focal length of the tunable solid-state lens by 1 cm in the axial direction. This thermo-reversible tunable focal length lens was used in a monostatic setup for one- and two-dimensional mapping scans in both frequency domain echo-intensity and temporal domain time-of-flight modes. The experimental results illustrated 1.03 ± 0.15λ and 2.35 ± 0.28λ on the lateral and axial minimum detectable object size. The experiments using the tunable lens demonstrate the capability to detect objects by changing the temperature in water without translating an object, source, or detector. The time-of-flight mode modality using the tunable solid-state phononic lens increases the signal-to-noise ratio compared to a conventional phononic crystal lens.     

NONLINEAR ELASTODIFFUSION AT SMALL DEFORMATIONS IN POLYMER MEMBRANES

Sorption in glassly polymer accompanied by strong concentration effects, is investigated theoretically. Asymptotic solutions for the concentration profiles are obtained and show that the fronts are very sharp, but advance with a square root of time type of dependence. The system is subdivided into two regions, a swollen gel and dry polymer regions using theories from interfacial phenomena. The dynamics are shown to be stable to small perturbations. The stress effects from swelling are shown to be negligible under this model.     

Exciton localization in vertically and laterally coupled GaN/AlN quantum dots

Near-field and time-resolved photoluminescence measurements show evidence of exciton localization in vertically and laterally coupled GaN quantum dots (QDs). The binding energies in multiple period QDs (MQDs) are observed to be stronger by more than six times compared to single period QDs (SQDs). Excitons in MQDs have a short (450 ps) lifetime and persist at room temperature, while SQDs exhibit extraordinarily long (>5 ns) lifetime at 10 K due to reduced spatial overlap of electron and hole wave functions in strained QDs.     

A comparative study on the intensity and harmfulness of late propagation in near-miss code clones

Exact or nearly similar code fragments in a software system’s source code are referred to as code clones. It is often the case that updates (i.e., changes) to a code clone will need to be propagated to its related code clones to preserve their similarity and to maintain source code consistency. When there is a delay in propagating the changes (possibly because the developer is unaware of the related cloned code), the system might behave incorrectly. A delay in propagating a change is referred to as ‘late propagation,’ and a number of studies have investigated this phenomenon. However, these studies did not investigate the intensity of late propagation nor how late propagation differs by clone type. In this research, we investigate late propagation separately for each of the three clone types (Type 1, Type 2, and Type 3). According to our experimental results on thousands of revisions of eight diverse subject systems written in two programming languages, late propagation occurs more frequently in Type 3 clones compared with the other two clone types. More importantly, there is a higher probability that Type 3 clones will experience buggy late propagations compared with the other two clone types. Also, we discovered that block clones are more involved in late propagation than method clones. Refactoring and tracking of Similarity Preserving Change Pattern (SPCP) clones (i.e., the clone fragments that evolve following a SPCP) can help us minimize the occurrences of late propagation in clones.     

Deep structured residual encoder-decoder network with a novel loss function for nuclei segmentation of kidney and breast histopathology images

To improve the process of diagnosis and treatment of cancer disease, automatic segmentation of haematoxylin and eosin (H & E) stained cell nuclei from histopathology images is the first step in digital pathology. The proposed deep structured residual encoder-decoder network (DSREDN) focuses on two aspects: first, it effectively utilized residual connections throughout the network and provides a wide and deep encoder-decoder path, which results to capture relevant context and more localized features. Second, vanished boundary of detected nuclei is addressed by proposing an efficient loss function that better train our proposed model and reduces the false prediction which is undesirable especially in healthcare applications. The proposed architecture experimented on three different publicly available H&E stained histopathological datasets namely: (I) Kidney (RCC) (II) Triple Negative Breast Cancer (TNBC) (III) MoNuSeg-2018. We have considered F1-score, Aggregated Jaccard Index (AJI), the total number of parameters, and FLOPs (Floating point operations), which are mostly preferred performance measure metrics for comparison of nuclei segmentation. The evaluated score of nuclei segmentation indicated that the proposed architecture achieved a considerable margin over five state-of-the-art deep learning models on three different histopathology datasets. Visual segmentation results show that the proposed DSREDN model accurately segment the nuclear regions than those of the state-of-the-art methods.

     

A framework for development and evaluation of a dynamic subchannel allocation scheme in an OFDMA system

This paper presents a framework for allocating radio resources to the Access Points (APs) introducing an Access Point Controller (APC). Radio resources can be either time slots or subchannels. The APC assigns subchannels to the APs using a dynamic subchannel allocation scheme. The developed framework evaluates the dynamic subchannel allocation scheme for a downlink multicellular Orthogonal Frequency Division Multiple Access (OFDMA) system. In the considered system, each AP and the associated Mobile Terminals (MTs) are not operating on a frequency channel with fixed bandwidth, rather the channel bandwidth for each AP is dynamically adapted according to the traffic load. The subchannels assignment procedure is based on quality estimations due to the interference measurements and the current traffic load. The traffic load estimation is realized with the measurement of the utilization of the assigned radio resources. The reuse partitioning for the radio resources is done by estimating mutual Signal to Interference Ratio (SIR) of the APs. The developed dynamic subchannel allocation ensures Quality of Service (QoS), better traffic adaptability, and higher spectrum efficiency with less computational complexity.

A simple nonlinear PD controller for integrating processes

Many industrial processes are found to be integrating in nature, for which widely used Ziegler–Nichols tuned PID controllers usually fail to provide satisfactory performance due to excessive overshoot with large settling time. Although, IMC (Internal Model Control) based PID controllers are capable to reduce the overshoot, but little improvement is found in the load disturbance response. Here, we propose an auto-tuning proportional-derivative controller (APD) where a nonlinear gain updating factor α continuously adjusts the proportional and derivative gains to achieve an overall improved performance during set point change as well as load disturbance. The value of α is obtained by a simple relation based on the instantaneous values of normalized error (e_N) and change of error (Δe_N) of the controlled variable. Performance of the proposed nonlinear PD controller (APD) is tested and compared with other PD and PID tuning rules for pure integrating plus delay (IPD) and first-order integrating plus delay (FOIPD) processes. Effectiveness of the proposed scheme is verified on a laboratory scale servo position control system.     

Performance analysis of an RSVP-capable router

RSVP is a bandwidth reservation protocol that allows distributed real-time applications such as videoconferencing software to make bandwidth reservations over packet-switched networks. Coupled with real-time scheduling mechanisms built into packet routers, the network guarantees to provide the reserved bandwidth throughout the lifetime of the applications. Although guaranteed services are of great value to both end users and carrier providers, their performance cost, due to additional control and data processing overhead, can potentially have a negative impact on the packet throughput and latency of RSVP-capable routers. The goal of this article is to examine the performance cost of RSVP based on measurements from an industrial-strength RSVP implementation on a commercial IP router. The focus is on the detailed evaluation of the performance implications of various architectural decisions in RSVP. We found that RSVP's control messages do not incur significant overhead in terms of processing delay and bandwidth consumption. However, the performance overhead of real-time packet scheduling is noticeable in the presence of a large number of real-time connections. In extreme cases, the performance guarantees of existing real-time connections may not be kept, and some best-effort packets are actually dropped, although the overall bandwidth requirement from these connections is smaller than the available link bandwidth     

Effect of long-term application of organic amendment on C storage in relation to global warming potential and biological activities in tropical flooded soil planted to rice

The impact of long term organic amendments on the functional microbial activities, soil carbon (C) storage in relation to greenhouse gas (GHG) emission from rice field was investigated in a tropical Aeric Endoaquept. The treatments included unamended control, farmyard manure (FYM), green manure (GM) (Sesbania aculeata), FYM?+?GM and rice straw (RS)?+?GM combination. Our results suggest that the FYM?+?GM treatment has increased the global warming potential (GWP) by 110?% as well decreased the C efficiency ratio by 24?% in comparison to control. On the other hand, under RS?+?GM treatment the soil organic C and total C contents were significantly higher to the tune of 34 and 53?%, respectively. Our studies clearly reveal that the application of RS?+?GM at 1:1 [Nitrogen (N) basis] could probably be the best soil amendment to sequester the soil organic C. Such amendments may not only have practical application value but also lead to higher yield capacity and minimize emission of GHG under flooded tropical rice soil systems.