DVB-S2 LDPC Decoding Using Robust Check Node Update Approximations

Broadband satellite services to fixed terminals are currently offered in the forward link by the 2nd generation (2G) digital video broadcasting satellite (DVB-S2) standard. For this standard the use of powerful low-density parity-check (LDPC) error correcting codes has been adopted performing within approximately 1 dB from the Shannon capacity limit. This paper studies and compares for the first time in a systematic manner different approximation methods used in check node update computation of DVB-S2 LDPC decoding with the aim of reducing computational complexity. Various performance evaluation results are presented for a wide range of DVB-S2 parameters, such as LDPC codeword size, coding rate, modulation format and including several decoding algorithms. It is shown that the proposed check node update approximations have a robust behavior, i.e. the resulting performance is quite independent of the DVB-S2 modulation and coding parameters. It is further shown that these approximations perform very close to the optimal sum-product algorithm (SPA) in degradation, which is less than 0.2 dB. Despite this small degradation, the reduction in computational complexity compared to the optimal SPA is significant and can be as high as 40% in computational time savings.     

Microwave measurements - Part III: Advanced non-linear measurements

This work completes the sequence started with articles [1] and [2], previously published in this journal, which presented the most important aspects of RF and microwave linear and non-linear measurements. In [1], some off-the-shelf linear measurement approaches at microwaves were described, whereas [2] showed the conventional characterization of non-linear devices under large-signal conditions, such as active and passive load-pull at fundamental and harmonic frequencies. In basic load-pull systems, the device under test (DUT) is driven by a single tone microwave source while the DUT performance metrics, typically output power and power added effi ciency (PAE), are monitored as a function of the load and/or source terminations. This strategy enables the straight-forward identifi cation of the optimum input and output loads. In this article, we describe two of the most advanced measurement techniques that can provide the required information for power amplifi er design and transistor modeling. The first technique is the multi-tone/complex modulation load-pull. It is useful especially for wireless applications, where conventional single tone excitations do not give suffi cient information for model and design development. The measurement conditions would be too far from the typical working ones. The second measurement technique is the timedomain waveform load-pull. Its applications span from highly accurate and reliable device model extraction to monitoring of actual operating conditions and "waveform engineering" for high-performance design.     

Quantitative Assessment of Affinity Selection Performance by Using DNA-Encoded Chemical Libraries

DNA-encoded chemical libraries are often used for the discovery of ligands against protein targets of interest. These large collections of DNA-barcoded chemical compounds are typically screened by using affinity capture methodologies followed by PCR amplification and DNA sequencing procedures. However, the performance of individual steps in the selection procedures has been scarcely investigated, so far. Herein, the quantitative analysis of selection experiments, by using three ligands with different affinity to carbonic anhydrase IX as model compounds, is described. In the first set of experiments, quantitative PCR (qPCR) procedures are used to evaluate the recovery and selectivity for affinity capture procedures performed on different solid-phase supports, which are commonly used for library screening. In the second step, both qPCR and analysis of DNA sequencing results are used to assess the recovery and selectivity of individual carbonic anhydrase IX ligands in a library, containing 360 000 compounds. Collectively, this study reveals that selection procedures can be efficient for ligands with sub-micromolar dissociation constants to the target protein of interest, but also that selection performance dramatically drops if 10⁴ copies per library member are used as the input.     

Rheological and textural properties of lafun,a stiff dough,from improved cassava varieties

We studied the textural and rheological (viscoelastic) properties of fresh lafun dough, a fermented cassava product, and their changes during storage at 45 °C for 5 and 24 h, in order to determine after-cooking storability. Lafun flours were produced from three types of cassava varieties: seven improved white-fleshed varieties, seven improved provitamin A carotenoids (pVAC) varieties and two local white-fleshed varieties; and processed into lafun doughs. Pasting properties of the flours were assessed. Flours from local varieties had pasting profiles with highest viscosities, while pVAC flours had the lowest. The three types of cassava varieties varied significantly in most of their pasting properties. Four promising improved varieties were identified, based on high peak viscosity (55.8–61.5 P) and stiffer texture than local varieties during storage. Undesirable varieties were also found, which softened during storage instead of hardening. Optimum texture of lafun dough was obtained after 5 h of storage.     

On simple scheme of finite/fixed-time control design*

ABSTRACT

Control laws are designed for stabilisation of a chain of integrators of arbitrary degree in finite and fixed time. Presented control laws are obtained with use of Lyapunov function method and homogeneity concept. The present analysis is based on use of explicitly defined Lyapunov function that is the hallmark with respect to similar works. This analysis allows to get simple procedure of parameters tuning and obtain new estimates for settling-time function. The theoretical results are supported by numerical examples.     

A microservice‐based architecture for (customisable) analyses of Docker images

We introduce Docker Analyser , a microservice‐based tool that permits building customised analysers of Docker images. The architecture of Docker Analyser is designed to crawl Docker images from a remote Docker registry, to analyse each image by running an analysis function, and to store the results into a local database. Users can build their own image analysers by instantiating Docker Analyser with a custom analysis function and by configuring the architecture. More precisely, the steps needed to obtain new analysers are (1) replacing the analysis function used to analyse crawled Docker images, (2) setting the policy for crawling Docker images, and (3) setting the scalability options for obtaining a scalable architecture. In this paper, we also present 2 different use cases, ie, 2 different analysers of Docker images created by instantiating Docker Analyser with 2 different analysis functions and configuration options. The 2 use cases show that Docker Analyser decreases the effort required to obtain new analysers versus building them from scratch.     

Analytical study of a solution-processed diode based on ZnO nanoparticles using multi-walled carbon nanotubes as Schottky contact

Journal of Materials Science: Materials in Electronics - The search for good electrodes processed by solution has interested several niches to produce printed solar cells, lighting emitting diodes,...     

A Parallel Method for Earth Mover’s Distance

We propose a new algorithm to approximate the Earth Mover’s distance (EMD). Our main idea is motivated by the theory of optimal transport, in which EMD can be reformulated as a familiar \(L_1\) type minimization. We use a regularization which gives us a unique solution for this \(L_1\) type problem. The new regularized minimization is very similar to problems which have been solved in the fields of compressed sensing and image processing, where several fast methods are available. In this paper, we adopt a primal-dual algorithm designed there, which uses very simple updates at each iteration and is shown to converge very rapidly. Several numerical examples are provided.