GA Optimisation of Crossed Dipole FSS Array Geometry

Crossed dipoles are used as dual polarised elements in frequency selective surface arrays but the transmission response is angle of incidence dependent. A genetic algorithm has been used to minimise the drift of the reflection band, stabilising it for a wide range of angles, to beyond 60°, even on thin substrates

A Novel Reconfigurable EBG Structure and Its Potential Use as Liquid Sensor

A novel reconfigurable antenna using a modified electromagnetic band gap (EBG) structure is introduced. The EBG is made of an array of square patches with a series of cuts and grooves in the dielectric material between the patches. These grooves allow for the deposition of liquids that can be used to change the resonant frequency of the antenna. The variation in the dielectric permittivity of the liquids produces a change in the reflected phase of the EBG. This change in phase is detected using a planar antenna placed at a short distance from the EBG structure. The change in phase in the EBG produces a change in the reflection coefficient of the antenna. This relationship is shown to be linear for lossless liquids. The reconfigurable structure could also be used as a sensor or detector. In order to assess the use as a sensor, Butan-1-ol, propan-2-ol, ethanol and methanol have been tested. The reflection coefficients and the radiation patterns were measured. Simulations were carried out simulated and measured results

3D printing technique for the development of non-planar electromagnetic bandgap structures for antenna applications

The use of 3D printing for the development of non-planar electromagnetic bandgap (EBG) structures for antenna applications is proposed. A coplanar waveguide (CPW) fed antenna is tested on a non-planar EBG substrate, fabricated using additive manufacturing techniques. Inexpensive fuse filament fabrication is used as the fabrication process. Silver-loaded conducting ink is employed for the metallic components of the EBG. The CPW antenna on the non-planar EBG structure has a satisfactory reflection coefficient at 2.45 GHz, which is suitable for Bluetooth/WLAN communications. The radiation patterns have reduced back lobes and improved gain compared with the antenna in free space

A Liquid Sensor based on Frequency Selective Surfaces

A novel, simple and easy-to-fabricate liquid sensor using frequency selective surfaces (FSS) is proposed. The new sensor concept is based on modifying the capacitance between adjacent FSS elements when materials of different electrical characteristics are inserted. The change in capacitance produces a change in resonant frequency. The FSS design consists of a 9 x 9 array of square loops on 0.31λ x 0.31λ square unit cells with trenches between the loops. The trenches are filled with liquids under test (LTU). The structure operates at 4.6 GHz without any liquid. When liquids are inserted in the trenches, the resonance frequency varies in relation to the dielectric constant of the liquid. This is observed by measuring the transmission coefficient (S 21 ). Butan-1-ol, ethanol, methanol, propan-2-ol, and Xylene are used to demonstrate the sensing function. A maximum sensitivity of 8.65 % for Xylene was achieved. Further, very low differences were observed between the measured and expected dielectric constant and loss tangent, thus validating the design. The device is inexpensive, compact, and easy to make and scalable for large area operations in liquid detection for microwave sensing applications. This technique has potential applications in reconfigurable FSS

3D Frequency Selective Surface Displacement Sensor using Complementary Dielectrics

A novel displacement sensor using a frequency selective surface (FSS) with a removable substrate complement is proposed. The new concept sensor is based on modifying the effective permittivity of the FSS when the substrate complement is gradually withdrawn. The change in the effective permittivity produces a change in capacitance, and thus in the resonant frequency. The FSS consists of an array of square loops elements in a square lattice. A 3D convoluted version of the FSS sensor improves the angle of incident behavior and increases the displacement range. The dielectric layers of the 3D FSS sensor were 3D printed while the metal layers were painted using silver conductive paint. The transmission response, S 21 , has been employed as the validation parameter. The proposed sensor operates in a frequency range between 2.0 GHz and 2.8 GHz and has achieved a 0.052 GHz/mm sensitivity and 12 mm dynamic range and has a dimension of 207mm by 207mm. The sensor is passive, compact, inexpensive, and easy to operate. The envisaged application is the wireless detection of structural movement, which can be critical in civil structures such as bridges or buildings or earthquake monitoring

The genetic hallmarks of dog breed development reveal shared patterns of historical human-dog interactions

Each Approximately 15,000 years ago, the wild grey wolf gave rise to the first domestic dogs. Multiple domestication events likely took place throughout modern day Eurasia, though the precise times and locations are a hotly debated topic among researchers. Distinct populations of dogs, varying in physical appearance and behavior, developed to reflect the needs or desires of the human cultures in which they were formed. Rich in history, Italy is home to at least 24 unique dog breeds. Genetic analysis of these breeds, in relation to global dog breeds, has highlighted key technological advancements and movements of the region\u2019s people. We have analyzed DNA from 1,609 dogs, representing 182 breeds, and 16 wild canids, on a panel of 142,840 markers genomewide. Twenty-four of these breeds are native to Italy, with 3 represented by both Italian and American populations. Through analysis of phylogeny and identity-by-descent haplotype sharing, patterns of breed formation have emerged that parallel the developmental progression of humans. Selection for common physical and behavioral phenotypes in hunting sighthounds, without evidence of recent shared genetic history, reveals shared human needs and biologically ideal forms. Identification of breed relationships to the isolated Fonni\u2019s Dog of Sardinia exposes geographic regions of development and tracks shared migration with human cultures. Finally, molecular evidence of historic agricultural practices is observed in the shared genetics of livestock guardian breeds

Making things happen : a model of proactive motivation

Being proactive is about making things happen, anticipating and preventing problems, and seizing opportunities. It involves self-initiated efforts to bring about change in the work environment and/or oneself to achieve a different future. The authors develop existing perspectives on this topic by identifying proactivity as a goal-driven process involving both the setting of a proactive goal (proactive goal generation) and striving to achieve that proactive goal (proactive goal striving). The authors identify a range of proactive goals that individuals can pursue in organizations. These vary on two dimensions: the future they aim to bring about (achieving a better personal fit within one’s work environment, improving the organization’s internal functioning, or enhancing the organization’s strategic fit with its environment) and whether the self or situation is being changed. The authors then identify “can do,” “reason to,” and “energized to” motivational states that prompt proactive goal generation and sustain goal striving. Can do motivation arises from perceptions of self-efficacy, control, and (low) cost. Reason to motivation relates to why someone is proactive, including reasons flowing from intrinsic, integrated, and identified motivation. Energized to motivation refers to activated positive affective states that prompt proactive goal processes. The authors suggest more distal antecedents, including individual differences (e.g., personality, values, knowledge and ability) as well as contextual variations in leadership, work design, and interpersonal climate, that influence the proactive motivational states and thereby boost or inhibit proactive goal processes. Finally, the authors summarize priorities for future researc

Large-scale magnetic fields from inflation in dilaton electromagnetism

The generation of large-scale magnetic fields is studied in dilaton electromagnetism in inflationary cosmology, taking into account the dilaton's evolution throughout inflation and reheating until it is stabilized with possible entropy production. It is shown that large-scale magnetic fields with observationally interesting strength at the present time could be generated if the conformal invariance of the Maxwell theory is broken through the coupling between the dilaton and electromagnetic fields in such a way that the resultant quantum fluctuations in the magnetic field has a nearly scale-invariant spectrum. If this condition is met, the amplitude of the generated magnetic field could be sufficiently large even in the case huge amount of entropy is produced with the dilution factor $\sim 10^{24}$ as the dilaton decays.Comment: 28 pages, 5 figures, the version accepted for publication in Phys. Rev. D; some references are adde

Fluctuations and Dissipation of Coherent Magnetization

A quantum mechanical model is used to derive a generalized Landau-Lifshitz equation for a magnetic moment, including fluctuations and dissipation. The model reproduces the Gilbert-Brown form of the equation in the classical limit. The magnetic moment is linearly coupled to a reservoir of bosonic degrees of freedom. Use of generalized coherent states makes the semiclassical limit more transparent within a path-integral formulation. A general fluctuation-dissipation theorem is derived. The magnitude of the magnetic moment also fluctuates beyond the Gaussian approximation. We discuss how the approximate stochastic description of the thermal field follows from our result. As an example, we go beyond the linear-response method and show how the thermal fluctuations become anisotropy-dependent even in the uniaxial case.Comment: 22 page

Scalable and accurate causality tracking for eventually consistent stores

Lecture Notes in Computer Science 8460, 2014In cloud computing environments, data storage systems often rely on optimistic replication to provide good performance and availability even in the presence of failures or network partitions. In this scenario, it is important to be able to accurately and efficiently identify updates executed concurrently. Current approaches to causality tracking in optimistic replication have problems with concurrent updates: they either (1) do not scale, as they require replicas to maintain information that grows linearly with the number of writes or unique clients; (2) lose information about causality, either by removing entries from client-id based version vectors or using server-id based version vectors, which cause false conflicts. We propose a new logical clock mechanism and a logical clock framework that together support a traditional key-value store API, while capturing causality in an accurate and scalable way, avoiding false conflicts. It maintains concise information per data replica, only linear on the number of replica servers, and allows data replicas to be compared and merged linear with the number of replica servers and versions.(undefined