The home-made Nd-YAG laser with the wavelength of 1 064 nm was used as the solid sam- ple introduction system of inductively coupled plasma-atomic emission spectrometry (ICP-AES).Ac- cording to the influence of Fe intensity and other elements relative intensity on stability,analytical conditions were optimized and the results obtained were as follows:laser frequency of 10 Hz,laser voltage of 760 V,argon flush rate of 0.7 L/min,RF power of 1 350 W,and defocus distance of 10 mm.Under the optimum conditions,eight elements including Cr,Cu,Mn,Mo,Ni,Si,V and Ti in middle-low alloy steel were analyzed.It was found that the correlation coefficients of the elements ex- cept Si were more than 0.999 0 and the detection limits of the elements were less than 50μg/g except Ni of 79μg/g.The results indicated that the home-made laser sample ablation system can be success- fuly used to analyze solid samples without pre-treatment.The determination results of standard sam- ples are agreement with the certified values,with RSD of below 7 % except low content Si,Ti.
To achieve real-time and high-sensitive humidity sensing, four classical metal-organic framework (MOF) materials (ZIF-8, UiO-66, HKUST-1, MIL-101) are connected to the end of a single-mode optical fiber by a universal connection method to form humidity sensors. According to the Fabry−Perot interference principle, the change of humidity causes the optical path difference of Fabry−Perot cavity, which further shifts the interference spectral peaks. By monitoring the spectral change in relation to humidity, high-sensitive humidity sensing can be achieved. The best performing optical-fiber sensor based on MIL-101 exhibits the sensitivity of 5.30 nm/%RH and shows good circulation and stability. This tiny integrated structure is of great importance for real-time and sensitive humidity detection in extreme environments.
Accurate segmentation of organs at risk (OARs) is a key step in treatment planning system (TPS) of image guided radiation therapy. We are developing three classes of methods to segment 17 organs at risk throughout the whole body, including brain, brain stem, eyes, mandible, temporomandibular joints, parotid glands, spinal cord, lungs, trachea, heart, livers, kidneys, spleen, prostate, rectum, femoral heads, and skin. The three classes of segmentation methods include (1) threshold-based methods for organs of large contrast with adjacent structures such as lungs, trachea, and skin; (2) context-driven Generalized Hough Transform-based methods combined with graph cut algorithm for robust localization and segmentation of liver, kidneys and spleen; and (3) atlas and registration-based methods for segmentation of heart and all organs in CT volumes of head and pelvis. The segmentation accuracy for the seventeen organs was subjectively evaluated by two medical experts in three levels of score: 0, poor (unusable in clinical practice); 1, acceptable (minor revision needed); and 2, good (nearly no revision needed). A database was collected from Ruijin Hospital, Huashan Hospital, and Xuhui Central Hospital in Shanghai, China, including 127 head scans, 203 thoracic scans, 154 abdominal scans, and 73 pelvic scans. The percentages of "good" segmentation results were 97.6%, 92.9%, 81.1%, 87.4%, 85.0%, 78.7%, 94.1%, 91.1%, 81.3%, 86.7%, 82.5%, 86.4%, 79.9%, 72.6%, 68.5%, 93.2%, 96.9% for brain, brain stem, eyes, mandible, temporomandibular joints, parotid glands, spinal cord, lungs, trachea, heart, livers, kidneys, spleen, prostate, rectum, femoral heads, and skin, respectively. Various organs at risk can be reliably segmented from CT scans by use of the three classes of segmentation methods.
A wideband magneto-electric (ME) dipole array antenna fed by substrate integrated waveguide (SIW) is proposed in this paper. By combining the bowtie-shaped slot on the top surface of the SIW as a magneto dipole, and a shorted patch as an electric dipole, the ME-dipole element is realized. Then a $1\times 8$ array operating at 28GHz is formed with eight ME-dipole elements and a wideband SIW feed network. Simulation results show that the array antenna can achieve an impedance bandwidth of 31.4% (24.2-33GHz) and a peak gain of 14dB. Moreover, stable radiation patterns, low cross-polarization levels and low front-to-back ratio are obtained over the wide band, which makes the proposed antenna a good candidate for the 5G millimeter-wave wireless communication system.
A novel coil with alternative clockwise and counterclockwise winding has been proposed and employed to construct inductive power transfer (IPT) systems. After establishing the equivalent circuit of the proposed IPT system, the coil-to-coil, source-to-load, and optimum transfer efficiency are analyzed mathematically. Then, comprehensive expressions for accurate estimation of transfer efficiency of a realizable structure are deduced. Theoretical analyses indicate that it is not always mandatory to use extremely low-loss material to fabricate the coils for high-efficiency mid-range wireless power transfer (WPT) systems. To validate the proposed IPT system, a prototype is designed, fabricated, and measured. Good agreements are achieved between calculated and experimental results. It is demonstrated that the adoption of the present coil can enhance the IPT systems' performance significantly. Compared with traditional IPT systems, the present system can operate properly without surplus and complex compensating networks. Further, an IPT system at 13.56 MHz employing proposed coils without any matching networks is designed, fabricated, and tested. This system is then used to drive a LED monitor wirelessly to demonstrate the feasibility of the proposed system in commercial applications. Owing to its design simplicity and demonstrated benefits, the proposed configuration endeavors to replace traditional approach to design high-efficiency optimized WPT systems.
In this letter, a dual-frequency reflectionless absorber based on the subwavelength helical structures is presented. The proposed structure is composed of two sets of subwavelength helical structures with different sizes, designed to achieve dual-frequency absorption performance. For the subwavelength helical structures, their electric and magnetic responses are simultaneously excited under the same resonant mode. To eliminate the bianisotropy of a single subwavelength helical structure and achieve the dual-polarized performance, eight different subwavelength helical units are used to construct an absorber unit, among which four units achieve dual polarization through rotation, and the other four units are mirror images of them to form a combined arrangement of left-handed and right-handed structures. Consequently, the proposed structure demonstrates a narrow peak of nearly full absorption, while remaining nearly invisible in reflection across a wide frequency range. Specifically, the overall structure exhibits two absorption bands with absorptive peaks above 90% at 2.31 and 2.8 GHz, respectively, while the out-of-band reflection is kept very low. Moreover, the absorber achieves an ultralow profile of $ 0.023\,{\lambda }_{L}$ and exhibits dual-polarization characteristics. A prototype of the proposed absorber is fabricated and measured. A good agreement between the results of the experiment and simulation can verify the effectiveness of the presented idea.
InN thin films were grown on Si(1 0 0) substrates by plasma-enhanced atomic layer deposition (PEALD). In this work, It is found that the island growth of InN on Si(1 0 0) easily happens at the initial PEALD period. The PEALD parameters have been systematically investigated to optimize the size, density, coalescence and distribution uniformity of InN grains with good crystallinity and no metallic indium clustering. Especially, indium segregation of PEALD-grown InN has a direct dependence on the deposition temperature (T), the supply of trimethylindium (TMIn) precursor and nitrogen plasma (NP) source. Based on our proposed PEALD mechanism of InN, a polycrystalline hexagonal InN thin film in the thickness of 24.2 nm has been well deposited at the growth per cycle (GPC) of 0.8 Å/cycle. And it shows a (0 0 2) preferential orientation and no any structural phase of metallic indium segregation. As a result, it may provide a useful guide for deeply understanding the PEALD growth mechanism of InN and In-rich nitrides, which further extends the promising applications in high-efficiency photovoltaics and high speed electronic devices.
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