Search

The effect of Pt content dispersed in Ag-CuO fillers on the interfacial microstructure and properties of Al2O3 ceramic joints brazed in air was investigated. Pt addition did not influence the variety of phases formed during reactive air brazing of Al2O3 joints. The position and morphology of CuO phase changed with Pt content which varied from 0 to 13.6 wt. %. Pt dissolved into Ag matrix completely. The typical interfacial sequence of brazed joints was Al2O3/CuAl2O4/CuO/Ag(s, s)/CuO/CuAl2O4/Al2O3. The addition of Pt to the Ag-CuO filler enhanced significantly the strength of Al2O3 joint from room temperature and up to 600℃. The joints brazed with Ag-CuO-9.0 wt. % Pt had the highest average strength at room temperature and at 600℃. The strength increased by 17 % and almost 100 %, respectively, compared with the Pt-free joint.

9 p., Background: Stroke disproportionately affects people in low-income and middle-income countries. Although improvements in stroke care and outcomes have been reported in high-income countries, little is known about practice and outcomes in low and middle-income countries. We aimed to compare patterns of care available and their association with patient outcomes across countries at different economic levels. Methods: We studied the patterns and effect of practice variations (ie, treatments used and access to services) among participants in the INTERSTROKE study, an international observational study that enrolled 13 447 stroke patients from 142 clinical sites in 32 countries between Jan 11, 2007, and Aug 8, 2015. We supplemented patient data with a questionnaire about health-care and stroke service facilities at all participating hospitals. Using univariate and multivariate regression analyses to account for patient casemix and service clustering, we estimated the association between services available, treatments given, and patient outcomes (death or dependency) at 1 month. Findings: We obtained full information for 12 342 (92%) of 13 447 INTERSTROKE patients, from 108 hospitals in 28 countries; 2576 from 38 hospitals in ten high-income countries and 9766 from 70 hospitals in 18 low and middle-income countries. Patients in low-income and middle-income countries more often had severe strokes, intracerebral haemorrhage, poorer access to services, and used fewer investigations and treatments (p

The multiphase emplacements of granitoids and well-developed depositional sequences from Neoproterozoic to Mesozoic are exposed widely in the Wugongshan domain of South China provide important keys for the reconstruction of the pre-Mesozoic tectonic evolution of the Cathaysia Block. Here we present the results from geological investigations, detrital zircon U–Pb geochronology, in situ Hf-isotope and REE composition of the Ordovician meta-sandstones, together with the U–Pb age data on a Mesozoic pluton with an attempt to evaluate the petrogenesis and crustal evolution history. A group of 276 detrital zircon U–Pb ages are reported from four meta-sandstones which show five major age populations: 2630–2350 Ma with a peak of 2440 Ma, 1890–1540 Ma (peak of 1680 Ma), 1120–870 Ma (peak of 980 Ma), 810–700 Ma (peak of 760 Ma) and 660–510 Ma (peak of 550 Ma). Among these, the most prominent age at 980 Ma fits well with the collisional event of Yangtze and Cathaysia Blocks. The second prominent age at 760 Ma correlates with a breakup of Rodinia, and the third one at 1680 Ma corresponds to the initial breakup of Columbia. For the fourth (peak of 2440 Ma) and fifth (peak of 550 Ma) ages, no corresponding magmatic rocks are exposed in the study area or in the adjacent regions, although the age populations broadly correspond to the global continental growth in the early Paleoproterozoic and the latest Neoproterozoic ‘Pan-African’ orogeny. We obtained 132 in situ Hf isotope compositions, among which 98 show negative eHf(t) values (− 36.88 to − 0.3) with two-stage model ages (T DM2 ) of 3.5–1.7 Ga (peak of 2.2 Ga), and 34 display positive eHf(t) values (+ 0.3 to + 9.89) with crystallization ages of 1.5–1.1 Ga (peak of 1.4 Ga). Zircons from two Mesozoic granitic samples yield rather similar late Jurassic ages of 158.1 ± 2.1 Ma and 154.0 ± 3.9 Ma. All the corresponding eHf(t) values of zircons are negative (− 24.2 to − 4.2) and the Hf two-stage model ages range from 1.5 to 3.0 Ga with a peak of 1.68 Ga. Combined with previous age data on 120 Ma massive granitoids and 230 Ma on ductile sheared plutons, we consider that the magmatism in the Wugong complex started from the late Triassic, and reached a peak in the late Jurassic, but was gradually weakened since the early Cretaceous (130 Ma) and culminated at 120 Ma. Almost all the Wugongshan granitic plutons were derived from the partial melting of Mesoproterozoic crustal material, with little mantle components. We also discuss the provenance of the metasedimentary rocks and pre-Mesozoic crustal evolution of Cathaysia.

Two compact dual-band bandpass filters based on open complementary split-ring resonators (OCSRRs) with stub loaded are presented. Both of the stub-loaded open-loop resonators can achieve two resonant modes, and each of the resonators generate a passband. Thus, a small ratio of two passbands central frequencies can be obtained. Moreover, the two resonant modes of the outer ring are λ /4 resonators, so the OCSRR exhibits a compact size. Meanwhile, the characteristics of dual-mode resonators can be discussed by using even-/odd-mode analysis. The proposed filters exhibit four transmission zeros, one or two of which can be introduced between the two passbands. To verify the theory, two filters with zeros of different locations are designed, fabricated and measured. The test results indicate good agreement with simulated ones.

In this article, a compact dual-mode tunable wide bandstop filter with controllable bandwidth is presented. The proposed filter consists of an open-loop stepped-impedance resonator with a T open stub loaded. Varactor diodes Cv1 and Cv2 are loaded at two ends of the stepped-impedance resonator and the loaded T stub, respectively. By properly adjusting the capacitances Cv1 and Cv2 of the varactor diodes, the constant fractional bandwidth and constant absolute bandwidth can be achieved, respectively. A new dual-mode tunable wide bandstop filter with 61.0% constant fractional bandwidth and 2.0-GHz constant absolute bandwidth has been designed and fabricated to verify the validity of the proposed method. The measured results are in good agreement with the electromagnetic simulation.

A novel lowpass filter (LPF) with a sharp roll-off and a wide stopband is presented. The proposed LPF is based on a dual-plane structure with an interdigital shape defected ground structure (DGS). The DGS exhibits a sharp roll-off and three transmission zeros. By tuning the length of the fingers, the resonant frequency can be easily changed. Based on the proposed DGS, a LPF has been designed, fabricated and measured. The transition band is from 3.11 (f c) to 3.23 GHz with −3.02 and −22.5 dB, respectively. The stopband with rejection better than 25 dB can be extended to 3.4 f c.

A novel microstrip lowpass filter (LPF) with a wide stopband is presented. The basic resonator is composed of two stepped impedance hairpin units with one embedded in another, which can obtain two more transmission zeros and extend a wide stopband. Based on the proposed resonator, a demonstration LPF of compact size, sharp transition and wide stopband has been designed, fabricated and measured. The proposed filter exhibits a small size of 0.081λg × 0.113λg, where λg is the waveguide length at the cutoff frequency of 1.6 GHz. Results show good agreement with simulations and the 20 dB rejection stopband can be extended to more than 15 GHz.

A miniaturized dual-band bandpass filter with high frequency selectivity using stepped-impedance hairpin resonators is presented. The proposed filter consists of two sets of short-circuit centered stepped-impedance hairpin resonators, one of which is embedded in the other one to obtain two passbands. Multiple transmission zeros are employed via introducing mixed electric/magnetic coupling and source-load coupling simultaneously for high frequency selectivity. A 2.4-/5.2-GHz dual-band bandpass filter is designed and fabricated to demonstrate the proposed method. The measurement results show six finite transmission zeros in the stopband, located at 2.04, 3.67, 4.58, 5.89, 10.63, and 15.73 GHz, respectively. And the circuit only occupies 6.70 × 10.25 mm2.

In this paper, a compact bandpass filter (BPF) with improved stopband characteristics using stepped impedance resonators (SIRs) is proposed. The filter consists of two quarter-wavelength SIRs with radial stubs and a PI-network of capacitance, which is used to suppress the upper frequency spurious signals. An odd- and even-mode analysis is adopted considering the structure’s symmetry. A new BPF centered at 1.57 GHz has been designed and fabricated to verify the validity of the proposed method. Measured results are in good agreement with the electromagnetic simulation. The frequency selectivity was enhanced via introducing two finite transmission zeros (TZs) near the passband, located at 1.21 GHz with 43.5 dB rejection and 3.10 GHz with 62.3 dB rejection, respectively. The spurious frequencies of the upper stopband are suppressed better than 20 dB from 2.07 to 16.25 GHz. And the circuit only occupies 0.09 λ g × 0.09 λ g.

A multi-layer modified trisection and its applications to substrate-integrated waveguide filters is presented in this article. By using source or load to replace a resonator of a conventional trisection filter, the multi-layer modified trisection could reduce one resonator but still reserves a transmission zero, which can be flexibly controlled either below or above the passband through adjusting the coupling manner and strength in the multi-layer structure. Moreover, based on low-temperature co-fired ceramic technology, the resonators in a multi-layer modified trisection can be embedded into ceramic substrate to achieve a more compact area. Two substrate-integrated waveguide filters are designed with a single transmission zero below or above the passband by introducing electric or magnetic coupling between the source and the resonator, respectively. Both are constructed by the multi-layer modified trisection. The impacts of coupling manner and level on the position of transmission zero are inves...

A novel multilayer substrate integrated hexagonal cavity filter with mixed coupling (MC) is proposed. Based on the substrate integrated waveguide techniques, the filter configuration is composed of hexagonal resonators which combine flexibility of rectangular cavities and performance of circular cavities. Meanwhile, by introducing MC into two adjacent resonators in the middle layer, the proposed filter has not only good selectivity due to the controllable transmission zeros, but also a compact size by profit from low-temperature co-fired ceramic technology. A fourth-order bandpass filter with three transmission zeros has been designed and fabricated. The measured results validate the feasibility of the proposed design, with its high selectivity demonstrated.

A compact substrate integrated waveguide symmetric filter with source–load coupling using low temperature cofired ceramic (LTCC) technology for high-selectivity application is presented. The proposed filter with second-order resonators has two transmission zeros which can be controlled flexibly by adjusting the coupling strength and modifying coupling style. With the assistance of the multilayer LTCC structure and refined coupling manner, the proposed filter has a more compact size while maintaining high selectivity. A demonstration filter is designed, fabricated, and measured to validate the proposed structure. Measured results are provided to show good performance and in agreement with the simulated results. Moreover, thanks to the vertical LTCC multilayer structure, the overall size of the proposed filter is only mm3.

A novel substrate integrated waveguide (SIW) hexagonal resonator structure and its applications to bandpass filters are presented. Based on the SIW techniques, the resonance characteristic of proposed resonator is investigated. The hexagonal SIW resonators, which can combine flexibility of rectangular cavities and performance of circular cavities, are convenient for bandpass filters design. Since any of the six sides of a hexagonal resonator can be utilized for coupling, the filter configurations are flexible and adaptable. By changing the coupling sides of the hexagonal resonators, two types of experimental circuit configuration at the same central frequency of 10 GHz but with different fractional bandwidths of 3 and 6%, including third-order Chebyshev and crossed-coupling trisection, are constructed, fabricated, and measured. Measured results show a good agreement with simulated ones and validate the proposed configurations.

A compact second-order substrate integrated waveguide (SIW) filter using low-temperature co-fired ceramic (LTCC) technology with two transmission zeros for high-selectivity application is presented. The proposed filter is composed of a Modified Doublet (MD) and input/output (I/O) SIW. The MD comprises two resonators that are not coupled to each other, whereas the two resonators are placed below and above the I/O SIW, respectively. The input and output SIW are directly coupled in order to generate up to two finite transmission zeros. The filter not only has good selectivity owing to the controllable transmission zeros by tuning the coupling manner and strength between the I/O SIWand two resonators, but also has a small size by profit from LTCC structure. A demonstration filter having a center frequency of 10 GHz and a 3 dB fractional bandwidth of 2.5% is designed and fabricated to validate the proposed structure. The measured results exhibit high selectivity, minimum passband insertion loss of 2.0...

Flat and steep subduction are end-member modes of oceanic subduction zones with flat subduction occurring at about 10% of the modern convergent margins and mainly around the Pacific. Continental (margin) subduction normally follows oceanic subduction with the remarkable event of formation and exhumation of high- to ultrahigh-pressure (HP–UHP) metamorphic rocks in the continental subduction/collision zones. We used 2D thermo-mechanical numerical models to study the contrasting subduction/collision styles as well as the formation and exhumation of HP–UHP rocks in both flat and steep subduction modes. In the reference flat subduction model, the two plates are highly coupled and only HP metamorphic rocks are formed and exhumed. In contrast, the two plates are less coupled and UHP rocks are formed and exhumed in the reference steep subduction model. In addition, faster convergence of the reference flat subduction model produces extrusion of UHP rocks. Slower convergence of the reference flat subduction model results in two-sided subduction/collision. The higher/lower convergence velocities of the reference steep subduction model can both produce exhumation of UHP rocks. A comparison of our numerical results with the Himalayan collisional belt suggests two possible scenarios: (1) A spatially differential subduction/collision model, which indicates that steep subduction dominates in the western Himalaya, while flat subduction dominates in the extensional central Himalaya; and (2) A temporally differential subduction/collision model, which favors earlier continental plate (flat) subduction with high convergence velocity in the western Himalaya, and later (flat) subduction with relatively low convergence velocity in the central Himalaya.

It is well recognized that the linear mark is one of the quality defects on the tube surface in the stretch reducing process. However, among previous literatures, the problems of the non-homogeneous wall thickness and the internal polygonization have been given more attention, while the research on the linear mark generating in the stretch reducing is ignored to a certain extent. In this paper, the simulation study was carried out for the rolling process when the pass is over full through the thermo-mechanical coupling FEM. The problem of the mesh distortion in the small roll gap was solved by means of applying local dense meshes and Euler method. The distribution of deformation and temperature of the tube were then obtained. The reasons of the linear mark generating and the cracks initiating on the tube surface can be found in the obtained results.

This research develops an innovative free-form surface scanning system using laser triangulation for 3D dental data required for crown reconstruction. This novel design employs double laser diodes to produce two 45° structured-light lines projecting onto the plaster tooth models and three CCD cameras to capture deformed fringes to achieve fast and accurate 3D surface measurement of plaster tooth models. Effective strategies were implemented to overcome problems such as potential measurement occlusion and data registration inaccuracy, commonly encountered by other data scanning methods. The developed system has distinctive features such as laser projecting angles for complete surface measurement coverage, digitizing accuracy, and compact scanner volume for potential applications on 3D surface digitization of tiny industrial components. Experimental results verified that the proposed system achieves a 20µm digitizing accuracy and possesses fast scanning capability. Maximum one minute is used for a single-tooth model and 30 minutes are used for scanning the whole jaw.

This paper presents a principle and a method of color 3D laser scanning measurement, based on the fundamental of monochrome 3D measurement study. A new color 3D measurement model was derived, and a rapid calibrating method to measure the system parameters was proposed—the optical plane equation calibrating method. A calibrating drone was made. This paper also advances an auto-merging method for multi-frame, i.e. several frames of measured color 3D digital images are merged quickly according to their curvature characteristics and RGB information, in order to accomplish the complete color 3D digital model of the object. The system can be broadly used in the fields of product design, mold manufacture, multi-media, game development, animation, medical engineering, antique digitization, etc.

A 2–5 GHz MMIC double-balanced Gilbert mixer (DBGM) with a lumped-elements LO balun and IF buffer has been designed, fabricated in GaN-on-Si HEMT MMIC technology and characterized with on-board measurements. This proposed mixer uses on-chip capacitively coupled resonating elements to isolate the dc currents of RF and LO route, which could help to realize low voltage and improve the noise figure (NF). Compared with other conventional baluns, the proposed lumped-element passive LO input balun can reduce chip size. The mixer demonstrates a 3 dB IF bandwidth from DC to 0.5 GHz and the maximum conversion gain (CG) of 9.3 dB at RF input of 3.5 GHz.

A novel multilayer dual-mode filter based on substrate integrated hexagonal cavity (SIHC) that supports two degenerated modes is demonstrated. The proposed filter is composed of a modified extended-doublet. By profit from two coupled dual-mode hexagonal cavity and asymmetry feeding structure, three transmission zeros (TZs) are generated. Accordingly, the filter not only has good selectivity due to three controllable TZs, but also has a small size by the virtue of multilayer structure. Example filter at X-band is designed and presented to demonstrate the validity of the proposed structure. Measured Results agree well with the simulated ones, with its good performance predicted.

A compact cavity filter using multilayer Low Temperature Co-fired Ceramic (LTCC) technology is proposed for millimetre-wave (MMW) transceiver module application. According to full-wave electro-magnetic (EM) comparing simulation, the length and the width of filter's structure has been determined by optimizing and extracting quality factor and coupling coefficient of the cavity resonators. A Ka-band cavity filter of the proposed prototype is fabricated and measured. Measurement results show good performance and agree with EM full wave simulation. The minimum measured insertion loss is 2.21 dB at 34.4 GHz, and return loss is lower than 18 dB over the passband. The size of the filter is only 8.5 mm×3.2 mm×1.2 mm including microstrips I/O ports and via fences structure. The cavity filter exhibits advantages of small size and high reliability compared to conventional planar filter structure, which makes it suitable for MMW wireless communication applications.

A compact substrate integrated waveguide (SIW) filter with an improved stopband using multilayer embedded mixed coupling (MC) is presented. By implementing MC into the input/output SIW, the filter not only exhibits good rejection for the upper stopband, owing to an additional controllable transmission zero, but also has a miniature size of 18 × 12 mm2 by profiting from its low-temperature co-fired ceramic structure. An experimental second-order filter with three TZs has been designed and fabricated. The measured results show good agreement with the simulated ones.

Proposed is a compact dual-band bandpass filter (BPF) using stepped impedance resonators (SIRs). To improve the upper-stopband of the proposed filter, tri-section folded SIRs are used. By adjusting the impedance ratio and electronical length ratio of the tri-section SIR, the out-of-band of the filter can be improved. A 2.09/2.62 GHz dual-band experimental BPF has been designed and fabricated to demonstrate the proposed method. The measured results are in good agreement with the electromagnetic simulation. The spurious frequencies of the upper-stopband are suppressed below 20 dB from 2.79 to 22.13 GHz. The circuit only occupies 0.29 λg × 0.13 λg.

A novel multilayer substrate integrated waveguide (SIW) filter with an improved stopband using mixed coupled modified trisections (MCMTs) is presented. The proposed filter is composed of two cascade MCMTs embedded in LTCC substrate. Four transmission zeros (TZs) can be generated with only three resonators, where two TZs near the passband are utilised to achieve sharper skirt selectivity, and another two TZs for the upper wide stopand. A 10 GHz experimental filter has been designed, fabricated and measured to validate the proposed method.

A compact dual-band bandpass filter with an improved stopband using short-circuit centred stepped impedance resonators (SCSIRs) is presented. The proposed filter consists of two SCSIRs, one of which is embedded in the other one to obtain two passbands. Multiple transmission zeros can be generated by the proposed SCSIR for high passband selectivity and upper wide stopband bandwidth. The centre frequencies and bandwidths of the two passbands can be controlled by adjusting the geometric dimensions of the SCSIRs, respectively. A 2.4/5.2 GHz dual-band experimental BPF has been designed and fabricated to demonstrate the proposed method.

A compact DC-DC convertor is proposed and fabricated in multilayer ferrite substrate using LTCC technology. The spiral conductors are buried into the ferrite substrate with a multilayer 3-D structure to reduce the volume of convertor. The passive integration of magnetic components and surface circuitry are achieved in a whole substrate and the size of module can be reduced markedly. The whole height of module is only 3mm, 1/3 of the height of conventional modules. Testing results indicate that the performance of the module is excellent in Point-of-Load (POL) field. The step-down DC-DC converter converts input voltage of 5V to output voltage of 3.3V. It is confirmed that the maximum conversion efficiency of 93.2% is sufficient for actual DC-DC converter application. Such a compact DC-DC convertor provides a compact, low cost and high reliability approach for power supply and magnetic integration application.