Strip Structure Research Articles

Selective deposition on block copolymer film by thermal evaporation of silver

Selective deposition of Ag onto nanostructured block copolymer film template of poly(ethylene oxide) and poly(methacrylate) with azobenzene mesogen (PEO-b-PMA(Az)) has been done by thermal evaporation technique. A hexagonally arranged pattern or ordered strip structure of the PEO nanocylinders dispersed in the PMA(Az) matrix appears on the pure copolymer film surface after thermal annealing at 140°C or 110°C, respectively. Atomic force microscopy confirms that the deposited Ag atoms prefer to wet PMA(Az) matrix domains on the film surface, and finally aggregate into discrete nanoparticles in both cases. An ordered porous metallic layer is created on the hexagonally patterned copolymer template surface due to the preferential interaction of Ag toward the PMA(Az) phase. Alternatively, ordered array of metallic chains is formed on the template featured with strip structure. While the nominal layer thickness of the deposited Ag is 50nm, the ordered metallic nanostructure disappears, indicating the host copolymer template cannot guide the spatial distribution of the deposited metal any more.

Algorithm Design and Application of Laminar Cooling Feedback Control in Hot Strip Mill

Feedback control is one of the most important ways to improve coiling temperature control precision during laminar cooling process. Laminar cooling equipments of a hot strip mill and structure of the control system were introduced. Feedback control algorithm based on PI controller and that based on Smith predictor were designed and tested in a hot strip mill respectively. Practical application shows that the feedback control system based on PI controller plays a limited role in improving coiling temperature control precision. The feedback control system based on Smith predictor runs stable and reliable. When the measured coiling temperature deviates from the target value, it can be adjusted to the required range quickly and steadily by Smith predictor feedback control, which improves the coiling temperature control precision greatly, and qualities of hot rolled strips are improved significantly.

Geometrically optimum ultra wide band 180° hybrids

This article presents two rat-race 180° ring hybrid couplers that operate on ultra wide band at the frequency range of 3 to 10 GHz. All pass coplanar strip structure, based on one of the ten canonical coupled line circuits, is proposed for the λ/4 sections [1, 2], and two-metal structure on suspended substrate [3] is used to improve the return-losses of hybrid. Besides the two end-shorted coupled lines for the 3λ/4 section, which is already known to broaden the narrowband behaviour of the traditional rat-race ring [4], a three-coupled lines structure [5] was studied as a design alternative. This hybrid could be used in a UWB low cost passive mixer with the advantage of maximizing the available space for the mixing devices and their associated circuitry, leaving free the internal area of the hybrid on the both sizes of the substrate. Consequently, the total size of the complete mixer is minimised and the compactness improved. The low coast approach is remarked by the use of standard FR-4 laminate. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:909–915, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26718

FIB‐SEM investigation of trapped intermetallic particles in anodic oxide films on AA1050 aluminium

PurposeThe purpose of this investigation is to understand the structure of trapped intermetallics particles and localized composition changes in the anodized anodic oxide film on AA1050 aluminium substrates.Design/methodology/approachThe morphology and composition of Fe‐containing intermetallic particles incorporated into the anodic oxide films on industrially pure aluminium (AA1050, 99.5 per cent) has been investigated. AA1050 aluminium was anodized in a 100 ml/l sulphuric acid bath with an applied voltage of 14 V at 20°C ±2°C for 10 or 120 min. The anodic film subsequently was analyzed using focused ion beam‐scanning electron microscopy (FIB‐SEM), SEM, and EDX.FindingsThe intermetallic particles in the substrate material consisted of Fe or both Fe and Si with two different structures: irregular and round shaped. FIB‐SEM cross‐sectioned images revealed that the irregular‐shaped particles were embedded in the anodic oxide film as a thin strip structure and located near the top surface of the film, whereas the round‐shaped particles were trapped in the film with a spherical structure, but partially dissolved and were located throughout the thickness of the anodic film. The Fe/Si ratio of the intermetallic particles decreased after anodizing.Originality/valueThis paper shows that dual beam FIB‐SEM seems to be an easy, less time consuming and useful method to characterize the cross‐sectioned intermetallic particles incorporated in anodic film on aluminium.

Angular response of thin-film organic solar cells with periodic metal back nanostrips

We theoretically study the angular response of thin-film organic solar cells with periodic Au back nanostrips. In particular, the equation of the generalized Lambert's cosine law for arbitrary periodic nanostructure is formulated. We show that the periodic strip structure achieves wide-angle absorption enhancement compared with the planar nonstrip structure for both the s- and p-polarized light, which is mainly attributed to the resonant Wood's anomalies and surface plasmon resonances, respectively. The work is important for designing and optimizing high-efficiency photovoltaic cells.

Highly Miniaturized On-Chip 180° Hybrid Employing Periodic Ground Strip Structure for Application to Silicon RFIC

A highly miniaturized on-chip 180° hybrid employing periodic ground strip structure (PGSS) was realized on a silicon radio frequency integrated circuit. The PGSS was placed at the interface between SiO2 film and silicon substrate, and it was electrically connected to top-side ground planes through the contacts. Owing to the short wavelength characteristic of the transmission line employing the PGSS, the on-chip 180° hybrid was highly miniaturized. Concretely, the on-chip 180° hybrid exhibited good radio frequency performances from 37 GHz to 55 GHz, and it was 0.325 mm2, which is 19.3% of a conventional 180° hybrid. The miniaturization technique proposed in this work can be also used in other fields including compound semiconducting devices, such as high electron mobility transistors, diamond field effect transistors, and light emitting diodes.

Toward a high granularity and high counting rate, differential readout timing MRPC

Abstract A new differential architecture of a resistive plate counter based on high granularity strip structure readout electrodes, symmetric relative to the central anode, is proposed. Details of its design and construction are introduced. Results of the 60Co source tests and of the in-beam investigations using minimum ionizing particles are discussed. A time resolution of 50–60 ps and a cluster size of ∼ 1.4 strips were obtained. These results together with previous ones based on low resistivity glass electrodes [1] open the perspective to built large area time-of-flight (TOF) detectors with a very good time resolution and high granularity for high intensity fixed target experiments.

Characteristics of a novel biaxial capacitive MEMS accelerometer

A novel MEMS accelerometer with grid strip capacitors is developed. The mechanical and electrical noise can be reduced greatly for the novel structure design. ANSOFT-Maxwell software was used to analyze the fringing electric field of the grid strip structure and its effects on the designed accelerometer. The effects of the width, thickness and overlapping width of the grid strip on the sensing capacitance are analyzed by using the ANSOFT-Maxwell software. The results show that the parameters have little effect on the characteristics of the presented accelerometer. The designed accelerometer was fabricated based on deep RIE and silicon–glass bonding processes. The preliminary tested sensitivities are 0.53 pF/g and 0.49 pF/g in the x and y axis directions, respectively. A resonator with grid strip structure was also fabricated whose tested quality factor is 514 in air, which proves that the grid strip structure can reduce mechanical noise.

A comprehensive study for the plasmonic thin-film solar cell with periodic structure

A comprehensive study of the plasmonic thin-film solar cell with the periodic strip structure is presented in this paper. The finite-difference frequency-domain method is employed to discretize the inhomogeneous wave function for modeling the solar cell. In particular, the hybrid absorbing boundary condition and the one-sided difference scheme are adopted. The parameter extraction methods for the zeroth-order reflectance and the absorbed power density are also discussed, which is important for testing and optimizing the solar cell design. For the numerical results, the physics of the absorption peaks of the amorphous silicon thin-film solar cell are explained by electromagnetic theory; these peaks correspond to the waveguide mode, Floquet mode, surface plasmon resonance, and the constructively interference between adjacent metal strips. The work is therefore important for the theoretical study and optimized design of the plasmonic thin-film solar cell.

A spline approximation applied for solving the problem of diffraction by a periodic grating located over a chiral half-space

The method of extended boundary conditions is modified for solving the problem of scattering a plane wave by a periodic grating consisting of thin metal screens. The grating is located over a chiral half-space. The method is tested for the case of scattering by a strip structure and for the parabolic and circular shapes of the grating’s elements.

Effect of hydrogenation on the microstructure of Ti-5.6Al-4.8Sn-2.0Zr alloy

The hydride phase in the Ti-5.6Al-4.8Sn-2.0Zr alloy after hydrogenation was investigated through TEM and XRD analysis. The experimental results show that the phase transition temperature of the hydrogenated Ti-5.6Al-4.8Sn-2.0Zr alloy is decreased approximately by 150–200°C. XRD analysis verifies that the hydrogenation treatment accelerates the phase transition process from α phase to β phase of the Ti-5.6Al-4.8Sn-2.0Zr alloy, so as to decrease the phase transition temperature of the alloy. Meanwhile, TiH2 hydride (δ phase) with strip structure appears in α phase and β phase.

Broadband dual frequency sleeve monopole antenna for DTV/GSM applications

A broadband dual frequency sleeve monopole antenna for application in Digital Tele-Vision (DTV) systems and Global System for Mobile communications (GSM) is presented. A parasitic inverted L-shaped strip and dual planar sleeve structure are introduced in the back ground plane for expanding the frequency band. The simulated and measured results show that the impedance bandwidth covers the DTV (470-862-MHz) band and GSM (824-960 and 1710-2170-MHz) band with VSWR less than 2.5. An omnidirectional radiation property is also shown.

Atomic scale study of strain relaxation in Sn islands on Sn-induced Si(111)-(23×23) surface

Surface structure of the Sn islands 5 ML high, prepared on Si(111)-(23×23)-Sn substrate, is investigated by low temperature scanning tunneling microscopy/spectroscopy. Due to the elastic strain relaxation in the islands, the in-plane unit cell structure distorts and the apparent height of the surface atoms varies regularly to form an overall modulated strip structure. The quantum well states are observed to depend on the relative position within this structure, which implies the change of the surface chemical potential induced by the elastic strain relaxation as well.

Effect of Polydispersity on the Self-Assembly Structure of Diblock Copolymers under Various Confined States: A Monte Carlo Study

We studied the self-assembly of polydisperse diblock copolymers under various confined states by Monte Carlo simulation. When the copolymers were confined within two parallel walls, it was found that the ordered strip structures appeared alternately with the increase in wall width. Moreover, the wall width at which the ordered structure appeared tended to increase with an increase in the polydispersity index (PDI). On the other hand, the simulation results showed that the copolymers were likely to form ordered concentric strip structures when they were confined within a circle wall. An increase in the PDI led to a change in structure from an ordered concentric strip structure to a newly ordered concentric strip structure. It is interesting to note that one strip was lost while the center was replaced by the other component as the PDI increased. Similar results were obtained in the case of three dimensions. That is, the copolymers were confined in a spherical or cylindrical space. Further along, one layer ...

The phase dynamics and wetting layer formation mechanisms in two-step surface-directed spinodal decomposition

The two-step quench process of surface-directed spinodal decomposition is numerically investigated by coupling the Flory-Huggins-de Gennes equation with the Cahn-Hilliard-Cook equation. The phase dynamics and formation mechanisms of the wetting layer in two-step surface-directed spinodal decomposition have been concerned in detail. The results demonstrate that a parallel strip structure forms near the wetting layer and propagates into the bulk, when the first quench depth is very shallow and the bulk does not undergo phase separation, and the second quench depths are various points with deeper quench depths. In this case, the wetting layer turns to be unchangeable at the intermediate and later stages of the second quench process, compared to the growth with a time exponent 1/2 during the first quench process. When the first quench depth is deeper and phase separation occurs in the bulk during the first quench process, it is found that a deeper second quench depth can stimulate a more obvious secondary domain structure, and the formation mechanism of the wetting layer changes from logarithmic growth law to Lifshitz-Slyozov growth law.

Response to annealing treatment of a twin-roll cast thin AlFeMnSi strip

Twin-roll cast AlFeMnSi thin strips show some marked differences with respect to conventional strips in their response to an annealing treatment. When annealed as-cast, the grain structure is rearranged by a growth process starting at 525 °C. The surface as well as the interior of the strip recrystallizes starting at 420 °C, when the thin strip is annealed after a cold rolling pass. Recrystallization of the surface relies entirely on the growth of the grains which have nucleated in the interior of the strip. The final strip structure in both cases is a coarse one with large grains across the section of the strip.

THE FORM EFFECTS OF MAGNETORESISTIVITY IN p-TYPE DIAMOND FILMS

The geometric form effects of magnetoresistivity (MR) from chemical vapor deposited p-type diamond films were investigated. The MR patterns (width/length ratio = 1, 2, 3, 4, 5, 6) were produced on p-type diamond films by photolithography and ion etching in oxygen plasma. The experimental results showed that the MR in diamond films with the strip structure changed with width–length ratio at magnetic field intensity of 3 T. The changes of MR strongly depended on the geometric form of the samples. With the width–length ratio increasing from 1 to 6, the MR increases from 0.08 to 1.0. It was almost changing linearly with the increase of width-to-length ratio. The geometric form effect is closely related to the Hall effect. A calculation formula of form effect of MR was presented.

Effect of weld thermal cycle on microstructure and fracture toughness of simulated heat-affected zone for a 800 MPa grade high strength low alloy steel

In the present investigation, thermal simulated specimens were used to investigate the effect of welding cooling time and peak temperature on characteristic fracture toughness and microstructure feature of heat-affected zone (HAZ) for an 800 MPa grade high strength low alloy (HSLA) steel. It is found that the fracture toughness is the best for the simulated coarse-grained HAZ, when the cooling time of t 8/5 is 18 s. In addition, the size of prior austenite grain, and the volume fraction of bainitic ferrite and M/A constituent increase with increasing the cooling time. However, the volume fraction of martensite decreases with increasing the cooling time. Remarkable decrease of toughness is observed with increasing the size of austenite grain and the volume fraction of M/A constituent. Moreover, there exists the effect of orientation on fracture toughness for the specimens subjected to weld thermal cycle. Generally, the fracture toughness of simulated HAZ with L–T orientation is higher than that with T–L orientation. The reason may be related to that the strip structure formed during rolling is remained after the thermal simulation. Furthermore, the investigation shows that the toughness of coarse-grained zone is higher than that of fine-grained zone for the simulated HAZ. The reason may be related with the microstructure evolution of the HAZ during the complete thermal cycle used in the simulation. For the fine-grained HAZ, the shorter cooling time of t 8/5 may be not benefit for the self-tempering and decomposition of M/A constituents, then the toughness of the fine-grained HAZ is lower. For the coarse-grained HAZ, however, the longer cooling time of t 8/5, may promote the decomposition of M/A constituents, then the toughness of coarse-grained HAZ is improved. The fracture toughness deteriorated drastically for the partly phase transformed HAZ may be related with the formation of mixture microstructure, in which the M/A constituent is distributed in shape of network.

The influence of riparian buffer strips on carabid beetle (Coleoptera, Carabidae) assemblage structure and diversity in intensively managed grassland fields

The use of riparian buffer strips as a means of reducing diffuse pollution in European grassland systems is becoming more common and consequently there is a need for comprehensive research on the influence of buffer strip management, placement and structure on biodiversity. Carabid assemblages were examined in a range of riparian zones in intensively managed grassland in Scotland. Carabids were monitored by pitfall trapping in riparian zones open to grazing, wide riparian buffer strips (>5 m wide), narrow boundary strips (<2 m wide) and adjacent fields in order to determine factors influencing carabid diversity and assemblage structure. While carabid diversity was greater in open riparian zones and narrow boundary strips when compared to the adjacent fields, it was actually poorer in wide riparian buffers when compared to open zones thus indicating wide buffers may actually be detrimental to carabid diversity. Carabid assemblages in wide riparian buffers were, however, more distinct from the adjacent field than narrow boundary strips or riparian zones open to grazing. Consequently, while the presence of wide riparian buffers may not promote carabid diversity within the actual buffer strips, by adding an additional habitat that supports a distinct carabid assemblage, riparian buffer strips may promote diversity at the landscape level. Carabid assemblage structure was driven by a combination of soil and vegetation characteristics in addition to physical attributes including distance from the watercourse and width of the strip. Only when we have a better understanding of the factors influencing biodiversity within riparian buffer strips can we start to formulate effective management prescriptions that fuse their dual function of pollution mitigation and biodiversity promotion.

Spin-current-induced charge accumulation and electric current in semiconductor nanostructures with Rashba spin-orbit coupling

We demonstrate that the flow of a longitudinal spin current with different spin polarization will induce different patterns of charge accumulation in a two-terminal strip, or electric current distribution in a four-terminal Hall-bar structure, of two-dimensional electron gas with Rashba spin-orbit coupling (RSOC). For an in-plane polarized spin current, charges will accumulate either by the two lateral edges or around the center of the strip structure while, for an out-of-plain polarized spin current, charge densities will show opposite signs by the two lateral edges leading to a Hall voltage. Our calculation offers a new route to experimentally detect or differentiate pure spin currents with various spin polarization.