Design of In-phase and Quadrature Two Paths Space-Time-Modulated Metasurfaces

<p>Space-time-modulated metasurfaces can manipulate electromagnetic waves in space and frequency domain simultaneously. In this paper, an analytical design of space-time- modulated metasurfaces with modulation elements composed of two paths, In-phase (I) and Quadrature (Q), is proposed. The model is derived analytically, the space/frequency domain manipulations are achieved by designing the dimension and time sequence of I and Q paths. In the specular reflection direction, an objective frequency shift of the reflected first order harmonic can be obtained. While, in other directions, the opposite first order harmonic can be easily controlled by changing the dimension of I/Q paths and the objective first order harmonic remains unchanged. Furthermore, with a small dimension of I/Q paths, the first order harmonic can be used for beam scanning by pre-designing the start time of the modulation element. To realize the space-time-modulated metasurface with the required periodically time-varying responses, 2-bit unit-cells loaded with dynamically switchable pin diodes are employed as I/Q modulation. Both analytical and numerical results demonstrate that space and frequency domain manipulations of the reflected fields by the first order harmonics can be simultaneously obtained. The proposed designs have potential applications in wireless communications, radar camouflaging, and cloaking.<br></p>

Study of the biology and ecology of the Muscidae Family (Insecta: Diptera): Collections

Adults can be predators, hematophagous and detritivores or feed on numerous types of exudates from plants or animals. They can be attracted to various substances including sugars, sweets, tears, and blood. Larvae appear in a variety of habitats, including decaying vegetation or animals, dry or moist soil, insect, or bird nests, fresh or stagnant water, and droppings. The objective of the mini review consists of bibliographical research on the muscoid dipterans of the Family Muscidae. The research was carried out in studies related to quantitative aspects of the Family and Species (taxonomic groups) and in conceptual. A literature search was carried out containing articles published from 1971 to 2021. The mini review was prepared in Goiânia, Goiás, from August to September 2021, through the Online Scientific Library (Scielo), internet, ResearchGate, Academia.edu, Frontiers, Publons, Qeios, Portal of Scientific Journals in Health Sciences, https://goo.gl/gLTTTs and https://www.growkudos.com/register. Although some species are very common worldwide, such as the housefly and the stablefly due to their synanthropy, most species do not have this behavior, so they are restricted to some territorial areas, sometimes-small dimension.

TOrPEDO: witnessing model correctness with topological proofs

Model design is not a linear, one-shot process. It proceeds through refinements and revisions. To effectively support developers in generating model refinements and revisions, it is desirable to have some automated support to verify evolvable models. To address this problem, we recently proposed to adopt topological proofs, which are slices of the original model that witness property satisfaction. We implemented , a framework that provides automated support for using topological proofs during model design. Our results showed that topological proofs are significantly smaller than the original models, and that, in most of the cases, they allow the property to be re-verified by relying only on a simple syntactic check. However, our results also show that the procedure that computes topological proofs, which requires extracting unsatisfiable cores of LTL formulae, is computationally expensive. For this reason, currently handles models with a small dimension. With the intent of providing practical and efficient support for flexible model design and wider adoption of our framework, in this paper, we propose an enhanced—re-engineered—version of . The new version of relies on a novel procedure to extract topological proofs, which has so far represented the bottleneck of performances. We implemented our procedure within by considering Partial Kripke Structures (PKSs) and Linear-time Temporal Logic (LTL): two widely used formalisms to express models with uncertain parts and their properties. To extract topological proofs, the new version of converts the LTL formulae into an SMT instance and reuses an existing SMT solver (e.g., Microsoft ) to compute an unsatisfiable core. Then, the unsatisfiable core returned by the SMT solver is automatically processed to generate the topological proof. We evaluated by assessing (i) how does the size of the proofs generated by compares to the size of the models being analyzed; and (ii) how frequently the use of the topological proof returned by avoids re-executing the model checker. Our results show that provides proofs that are smaller ($$\approx $$ ≈ 60%) than their respective initial models effectively supporting designers in creating model revisions. In a significant number of cases ($$\approx $$ ≈ 79%), the topological proofs returned by enable assessing the property satisfaction without re-running the model checker. We evaluated our new version of by assessing (i) how it compares to the previous one; and (ii) how useful it is in supporting the evaluation of alternative design choices of (small) model instances in applied domains. The results show that the new version of is significantly more efficient than the previous one and can compute topological proofs for models with less than 40 states within two hours. The topological proofs and counterexamples provided by are useful to support the development of alternative design choices of (small) model instances in applied domains.

Perceptions of Debarking Small-Diameter Stems in the Wood Products Community

Sufficiently valuing small-diameter-stem (diameter &lt; 9 in.) woody material in Pennsylvania forest product markets may incentivize increased utilization of that material, a resource opportunity that would provide economic and ecological benefits to the state's forests and forest products community. Debarking is one primary process that could enhance the value of these small-diameter-stem materials for secondary markets. The wood products community in Pennsylvania was surveyed as to their perceptions of the status and value of economical small-diameter-stem debarking. The largest perceived current market for debarked, small-diameter-stem material identified by respondents is for chips for pulp and paper, and anticipated future demand is expected to be highest for chips for pulp and paper, chips for energy, and small-dimension lumber. Respondents who currently supply a given market tend to be more optimistic about that market than respondents who do not serve that particular market. Shredded wood/hog fuel and mulch are the two markets with the lowest overall scores for anticipated benefit of additional processing by debarking. Seventy-six percent of all respondents indicated that economical small-diameter-stem debarking would benefit their operation.

Some co-tame automorphisms of affine spaces

The investigation of co-tame automorphisms of the affine space [Formula: see text] is helpful to understand the structure of its automorphisms group. In this paper, we show the co-tameness of several classes of automorphisms, including some 3-parabolic automorphisms, power-linear automorphisms, homogeneous automorphisms in small dimension or small transcendence degree. We also classify all additive-nilpotent automorphisms in dimension four and show that they are co-tame.

A Krylov subspace type method for Electrical Impedance Tomography

Electrical Impedance Tomography (EIT) is a well-known imaging technique for detecting the electrical properties of an object in order to detect anomalies, such as conductive or resistive targets. More specifically, EIT has many applications in medical imaging for the detection and location of bodily tumors since it is an affordable and non-invasive method, which aims to recover the internal conductivity of a body using voltage measurements resulting from applying low frequency current at electrodes placed at its surface. Mathematically, the reconstruction of the internal conductivity is a severely ill-posed inverse problem and yields a poor quality image reconstruction. To remedy this difficulty, at least in part, we regularize and solve the nonlinear minimization problem by the aid of a Krylov subspace-type method for the linear sub problem during each iteration. In EIT, a tumor or general anomaly can be modeled as a piecewise constant perturbation of a smooth background, hence, we solve the regularized problem on a subspace of relatively small dimension by the Flexible Golub-Kahan process that provides solutions that have sparse representation. For comparison, we use a well-known modified Gauss-Newton algorithm as a benchmark. Using simulations, we demonstrate the effectiveness of the proposed method. The obtained reconstructions indicate that the Krylov subspace method is better adapted to solve the ill-posed EIT problem and results in higher resolution images and faster convergence compared to reconstructions using the modified Gauss-Newton algorithm.

Recent Advances on Cellulose Nanocrystals and Their Derivatives

Nanocellulose, typically cellulose nanocrystals (CNCs), has excellent properties and is widely used. In particular, CNC has a small dimension, high chemical reactivity, and high sustainability, which makes it an excellent candidate as a starting material to be converted into nanocellulose derivatives. Chemical modification is essential for obtaining the desired products; the modifications create different functional attachment levels and generate novel microstructures. Recent advances on nanocellulose derivatives have not yet been reviewed and evaluated for the last five years. Nanocellulose derivative materials are being used in a wide variety of high-quality functional applications. To meet these requirements, it is essential for researchers to fully understand CNCs and derivative materials, precisely their characteristics, synthesis methods, and chemical modification approaches. This paper discusses CNC and its derivatives concerning the structural characteristics, performance, and synthesis methods, comparing the pros and cons of these chemical modification approaches reported in recent years. This review also discusses the critical physicochemical properties of CNC derivative products, including solubility, wetting performance, and associated impacts on properties. Lastly, this paper also comments on the bottlenecks of nanocellulose derivatives in various applications and briefly discusses their future research direction.

Optimization model in the flexible manufacture

Flexible manufacturing shop is examined. Multilevel control system of the shop is built. The demands to the system construction are listed. The existing input information is insufficient for building of the inventory model, for choice and realization of the optimal model of the manufacture. By this reason the situation of the uncertainties is arise. For the purpose to find needed data and to receive necessary knowledge the following intelligence procedures are suggested: ”Pendulum” – for stock foundation and for construction of the inventory model, “Symmetry in the arithmetical progression” – to define the values of the coefficients with unknown quantities in the aim function of the optimal task. With the help of the procedure “Pendulum” the equal corteges of the quantum of time are building. Cortege of the quantum of time is the unit of the stock and the direction for selection of the kind of the optimization model. The optimization model of location is suggested to use. Building of the indicated models (they are small dimension and equal dimension) give the opportunity to organize the parallel calculations.