Modeling and Analysis of Sub-Millimeter-Wave Graphene Switches for On-Wafer Coplanar Transmission Lines

We present an analysis of graphene loaded transmission line switches. Namely, we propose equivalent circuit models for graphene loaded coplanar waveguides and striplines and examine the switching performance under certain design parameters. As such, the models account for the distributed effects of electrically-large shunt switches in coplanar waveguides and we use the Babinet’s principle to derive the respective models for the coplanar stripline transmission lines. Using these models, we identify the optimum design of graphene switches based on transmission line characteristic impedance, scaling factor, graphene shape, and topology (series or shunt). We vary these parameters and obtain the insertion loss and ON/OFF ratio. Τhe extracted results can act as the design roadmap toward an optimum switch topology and emphasize the limitations with respect to fabrication challenges, parasitic effects, and radiation losses. In our models, we use measured graphene values (sheet impedance) instead of theoretical equations, to obtain the actual switching performance. Finally, the proposed equivalent models are crucial for this in-depth study; since, we simulated more than 2,000,000 configurations, a computationally challenging task with the use of full-wave solvers

Modeling and Analysis of Sub-Millimeter-Wave Graphene Switches for On-Wafer Coplanar Transmission Lines

We present an analysis of graphene loaded transmission line switches. Namely, we propose equivalent circuit models for graphene loaded coplanar waveguides and striplines and examine the switching performance under certain design parameters. As such, the models account for the distributed effects of electrically-large shunt switches in coplanar waveguides and we use the Babinet’s principle to derive the respective models for the coplanar stripline transmission lines. Using these models, we identify the optimum design of graphene switches based on transmission line characteristic impedance, scaling factor, graphene shape, and topology (series or shunt). We vary these parameters and obtain the insertion loss and ON/OFF ratio. Τhe extracted results can act as the design roadmap toward an optimum switch topology and emphasize the limitations with respect to fabrication challenges, parasitic effects, and radiation losses. In our models, we use measured graphene values (sheet impedance) instead of theoretical equations, to obtain the actual switching performance. Finally, the proposed equivalent models are crucial for this in-depth study; since, we simulated more than 2,000,000 configurations, a computationally challenging task with the use of full-wave solvers

The Investigation of the Volumetric Strip-Slot Transition with U-Shaped Slot Resonator

The application of volumetric strip-slot transition for the implementationof wireless devices with contactless frequency-selective transmission of microwave signals is relevant. This is due to the compactness of volumetric strip-slot transition achieved by the multilayer arrangement of its functional parts and of its electrical frequency-selective characteristics. At the same time the volumetric-modular design allows the replacement of its individual components which provides high functional flexibility of the device. Reducing of weight and dimensions of the volumetric strip-slot transition while maintaining its electrical characteristics is possible due to well-known methods used in microwave technology: 1) using of substrates with a high value of the relative permittivity, 2) due to the transition to higher frequency ranges. The authors of this paper present the third method for reducing of weight and dimensions of the volumetric stripslot transition by using a U-shaped slot resonator. The development of the equivalent circuit of the volumetric strip-slot transition and calculation of all its lumped elements are also presented. The values of such lumped elements as linear capacitance of the strip line, linear inductance of the strip line, characteristic impedance of the slot transmission line were determined. The value of the inductive inhomogeneity occurred when the slot resonator bends by 90 degrees was calculated and its S-parameters in the frequency range were simulated. Numerical electrodynamics simulation was performed to confirm the validity of the results of circuit simulation. Then the experiment research of the sample of the volumetric strip-slot transition with the U-shaped slot resonator was carried out. The theoretical and experimental results of the conducted researches of volumetric strip-slot transition with the U-shaped slot resonator are in good qualitative and numerical agreement with each other. The use of the U-shaped slot resonator provides an opportunity to achieve a 36% reduction of weight and dimensions parameters of the volumetric stripslot transition while maintaining its electrical characteristics.

Ram cult of funnel beaker culture tribes

Among the variety of clay products of the Funnel beaker culture, there is almost no zoomorphic plastic. Such items include the handle of the vessels in the form of realistically shaped heads of the ram. And it is the only animal in the Funnel beaker culture, which is somehow expressed. Vessels with handles in a shape of rams and their fragments were found in a small amount. On the large territory, occupied by southeastern group of Funnel beaker culture and where hundreds of settlements are known, most of which were excavated only 60-70 figures were found in twenty sites. On some settlements many of such items were collected. For example, in Gródek (about 30), Zymno (18), Ćmielów (over 10) and on the others – only single finds. Also, on the many capitally examined sites such artifacts are absent. The rams decorated only the handles of jugs and pots. These vessels are usually ornamented. The ornament is constructed according to a clear scheme of world tree: rims are decorated with zigzag line, characteristic for ritual zoomorphic vessels of several agricultural cultures and interpreted as symbol of water. Side walls of the body are ornamented by a vertical ladder, which can be interpreted as grain ear. Paired handles in shape of rams, joined by sacred yoke which embodied sacral content of fertility. Most of the products, usually jars, were found in the storage pits, and some of the pots were found in women's graves. On the settlement of Zymno all figures were found in cultural layers and situated in separate concentrations. Such vessels were sacred – intended for the storage and sowing of grain, as well as for the ritual of praying for rain. Among ancient agricultural tribes, some animals, including ram, embodied the fertility cult and identified with certain forces of nature. The origins of the ram cult in the southeastern group of tribes of Funnel beaker culture are obviously can be found among its nearest neighbors, perhaps Trypillians, where such practices were more advanced. Key words: Funnel Beaker culture, ram cult, ritual, ornament, grain, water.

Faulty Line Selection Method for Distribution Network Based on Variable Scale Bistable System

Since weak fault signals often lead to the misjudgment and other problems for faulty line selection in small current to ground system, this paper proposes a novel faulty line selection method based on variable scale bistable system (VSBS). Firstly, VSBS is adopted to analyze the transient zero-sequence current (TZSC) with different frequency variety scale ratio and noise intensity, and the results show that VSBS can effectively extract the variation trends of initial stage of TZSC. Secondly, TZSC is input to VSBS for calculation with Runge-Kutta equations, and the output signal is chosen as the characteristic currents. Lastly, correlation coefficients of every line characteristic current are used as the index to a novel faulty line selection criterion. A large number of simulation experiments prove that the proposed method can accurately select the faulty line and extract weak fault signals in the environment with strong noise.

Improvement of Folded Line Assistance Characteristics Curve for EHPS System

Electro-hydraulic power steering system (EHPS) assistance characteristic curves are generally linear, folded line and curve type. The folded line type combines the advantages of linear and curve type assistance characteristic, but the slope of the characteristic curve changes suddenly, which have an impact on the driver, leading to potentially dangerous. In view of existing problem, the article studies deeply the characteristics of the power system to apply computer simulation technology, and improves the folded line characteristic curve. The simulation analytic results show clearly that the improvements of folded line assistance characteristics curve is reasonable.

Two-dimensional numerical investigations on the termination of bilinear flow in fractures

Bilinear flow occurs when fluid is drained from a permeable matrix by producing it through an enclosed fracture of finite conductivity intersecting a well along its axis. The terminology reflects the combination of two approximately linear flow regimes: one in the matrix with flow essentially perpendicular to the fracture, and one along the fracture itself associated with the non-negligible pressure drop in it. We investigated the characteristics, in particular the termination, of bilinear flow by numerical modeling allowing for an examination of the entire flow field without prescribing the flow geometry in the matrix. Fracture storage capacity was neglected relying on previous findings that bilinear flow is associated with a quasi-steady flow in the fracture. Numerical results were generalized by dimensionless presentation. Definition of a dimensionless time that, other than in previous approaches, does not use geometrical parameters of the fracture permitted identifying the dimensionless well pressure for the infinitely long fracture as the master curve for type curves of all fractures with finite length from the beginning of bilinear flow up to fully developed radial flow. In log–log scale the master curve's logarithmic derivative initially follows a 1/4-slope straight line (characteristic for bilinear flow) and gradually bends into a horizontal line (characteristic for radial flow) for long times. During the bilinear flow period, isobars normalized to well pressure propagate with the fourth and second root of time in fracture and matrix, respectively. The width-to-length ratio of the pressure field increases proportional to the fourth root of time during the bilinear period, and starts to deviate from this relation close to the deviation of well pressure and its derivative from their fourth-root-of-time relations. At this time, isobars are already significantly inclined with respect to the fracture. The type curves of finite fractures all deviate counterclockwise from the master curve instead of clockwise or counterclockwise from the 1/4-slope straight line as previously proposed. The counterclockwise deviation from the master curve was identified as the arrival of a normalized isobar reflected at the fracture tip 16 times earlier. Nevertheless, two distinct regimes were found in regard to pressure at the fracture tip when bilinear flow ends. For dimensionless fracture conductivities TD < 1, a significant pressure increase is not observed at the fracture tip until bilinear flow is succeeded by radial flow at a fixed dimensionless time. For TD > 10, the pressure at the fracture tip has reached substantial fractions of the associated change in well pressure when the flow field transforms towards intermittent formation linear flow at times that scale inversely with the fourth power of dimensionless fracture conductivity. Our results suggest that semi-log plots of normalized well pressure provide a means for the determination of hydraulic parameters of fracture and matrix after shorter test duration than for conventional analysis.