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This study aims to investigate the feasibility and potential of sparse random arrays driven by the particle swarm optimization (PSO) algorithm to generate multiple-focus patterns and a large scanning range without grating lobes, which extends the scanning range of focused ultrasound in the treatment of brain tumors, opening the blood-brain barrier, and neuromodulation. Operating at 1.1 MHz, a random spherical array with 200 square elements (sparseness 58%) and a sparse random array with 660 square elements (sparseness 41%) driven by PSO are employed to simulate different focus patterns. With the same radius of curvature and diameter of transducer and element size, the scanning range of the off-axis single focus of a random 200-element array is two times that of an ordinary array using symmetric arrangement. The focal volume of multiple-focus patterns of the random array is 18 times that of the single focus. The single focus of the sparse random array with 660 elements could steer up to ±23 mm in the radial direction, without grating lobes. The maximum distance between two foci in a multiple-focus "S"-shaped deflection is approximately 25 mm. Simulation results illustrate the capability of a focused beam steered in 3-D space. Multiple-focus patterns could significantly increase the focal volume and shorten the treatment time for large target volumes. Simulation results show the feasibility and potential of the method combining PSO with a sparse random array to generate flexible focus patterns that can adapt to different needs in different tissue treatments.

Objective. Histotripsy is a non-invasive focused ultrasound ablation method that can mechanically disintegrate tissues. This study aims to verify that ultrasound-guided histotripsy using millisecond-length two-stage ultrasound pulses combined with fundamental and second harmonic superposition can enhance treatment in rabbit kidneys in vivo. Approach. Rabbit kidneys (n = 10) were treated using a custom-designed 1.1/2.2 MHz two-element confocal-annular array, with lateral and axial full width at half-maximum pressure dimensions of approximately 1.0 and 6.0 mm. Two-stage ultrasound pulses were applied: stage 1 used 60–80 pulses with a pulse duration of 6 ms and a pulse repetition frequency of 10 Hz. Meanwhile, stage 2 consists of 2–4 periods, each period consists of a concentrated pulse train of localized high DC of 6% and an off-time of 3–5 s, with an average DC of 1%–1.5%. B-mode ultrasound imaging was used to guide and monitor the boiling and cavitation bubbles. Main results. Ultrasound-guided treatment was successful in all rabbits, and the ablation rate is about seven times that of single-frequency combined two-stage pulses, achieving enhanced histotripsy. The regular elliptical lesions with dimensions of 10.6 ± 0.8 mm × 3.9 ± 0.6 mm (axial × lateral) were generated, and a large-volume lesion was generated by multi-point treatment. The size of most lysates was about 2.5 μm. Histologically, lesions were completely homogenized and well demarcated between treated-untreated areas. There was no apparent damage to critical structures surrounding lesions. Nonlinear simulations revealed that it may be the interaction between shock front and the cavitation and boiling bubbles generated by the dual-frequency effect enhanced the treatment efficiency. Significance. The novel histotripsy could improve treatment efficiency and generate regular elliptical lesions with controllable shape and axial dimensions, which may be a useful tool in treating renal cell carcinoma.

We report on our investigation of photo-darkening (PD)-induced thermal load in Yb-doped fiber lasers and the effective suppression by H2-loading. Compared with a quantum defect, the contribution of heat produced by PD was evaluated, indicating PD may become the primary heat source. To reduce the heat generation, the effect of H2-loading on thermal load was quantitatively analyzed. The experimental results showed that 86% of PD loss was mitigated and 82% of PD-induced thermal load was eliminated by H2-loading. In contrast, due to the presence of extra heat source, only 14% heat decreased in the Ce-doped fiber at similar PD loss level. The results indicate that H2-loading is promising for further improving the stable operation of fiber lasers.

Intracerebral hemorrhage is a life-threatening acute cerebrovascular disease characterized by a 30-d mortality rate of 40% and substantial disability for those who survive. The objective of this study is to investigate the feasibility of histotripsy-mediated efficient and fine liquefaction of large-volume hematoma by utilizing a protocol of millisecond-length ultrasound pulse groups combined with fundamental and second harmonic superposition. Experiments were initially performed in an in vitro hematoma phantom, using a two-element confocal-annular array. Results showed that a single ellipsoid shape, histotripsy lesion with major dimensions of 10.8 ± 1.2 mm axially and 4.8 ± 0.2 mm laterally was successfully generated. Controllability of the lesion shape and size could be realized by modulating treatment parameters in single-spot experiments. Large-volume hematomas were efficiently and finely liquefied through multisonications via a treatment strategy under the relatively optimized treatment parameters. Liquefied contents were evacuated and analyzed using a particle sizing system. The size of the lysates for the most part ranged from 4-8 μm, with more than 99% of them being smaller than 10 μm. Experiments were then conducted in an optically transparent tissue phantom to explore the liquefaction mechanisms. The phantom was composed of polyacrylamide hydrogel, embedded with bovine serum albumin (BSA), and a thin phantom layer consisted of red blood cells in the BSA polyacrylamide gel was inlayed in the BSA gel phantom. The related mechanisms, such as the frequent boiling that occurred at multiple positions and the enhanced cavitation, revealed the quick development of the lesion in the phantom and the efficient liquefaction of the clot. These results indicated that the proposed histotripsy approach is feasible for the efficient, precise and fine liquefaction of large-volume hematoma and may be developed as a useful tool for intracerebral hemorrhage treatment.

We propose a novel long-period grating (LPG) based on a ring-core hollow fiber (RCHF) filled with functional liquid as a tunable material. The RCHF structure is simple. The effective refractive index tuning characteristics of the liquid-filled RCHF-LPG are investigated. The RCHF-LPG functions as a tunable device filling with a functional liquid. The temperature sensitivities of three RCHF-LPG samples filled with dimethylacetamide (DMA) or DMA–glycerin mixtures are measured. The results show that the sample with high-RI liquid has higher sensitivity to temperature variation. The maximum linear sensitivity of the temperature can reach −618 pm/°C.

A newly designed and fabricated trench-assisted low-NA (∼0.04) fiber was reported. An output power up to 1.3kW with M2 < 1.1 was achieved in an all-fiber MOPA based on the fabricated low-NA fiber.

We report a novel center-sunken and cladding-trenched Yb-doped fiber. A 456 W laser output was observed in a MOPA structure. The laser slope efficiency was measured to be 79% and the M2 was 1.17.

To observe the clinical effects of acupuncture combined with auricular point sticking based on the western medication for post stroke depression (PSD).Sixty patients with PSD were randomly assigned into an acupuncture plus auricular application group (a combination group) and a medication group, 30 cases in each one. 20 mg paroxetine hydrochloride was prescribed orally in the medication group, once a day for continuous 8 weeks. Based on the above treatment, 30-minute acupuncture was used in the combination group for 8 weeks at Baihui (GV 20), Sishencong (EX-HN 1), Shenting (GV 24), Yintang (GV 29), Shenmen (HT 7), Neiguan (PC 6), Taichong (LR 3), Hegu (LI 4), Zusanli (ST 36), Sanyinjiao (SP 6) and Fenglong (ST 40), once the other day and three times a week. Auricular point sticking therapy for 8 weeks was applied at shenmen (TFAfter treatment, the total HAMD scores of the two groups decreased compared with those before treatment (bothAcupuncture combined with auricular point sticking can improve the clinical symptoms and are effective and safe for PSD.

In this work, Na

In this work, Na+ ions doping into the Yb-doped fiber was proposed to improve the photo-darkening resistance. The results show that the photo-darkening induced excess loss at 702 nm was 37.26dB/m at equilibrium state. More than 50% excess loss was reduced comparing to Yb-doped fiber without Na+ ions.

A gain-tailored Ge-free Yb/Ce codoped aluminosilicate fiber is fabricated by MCVD combined with solution doping technique. Through regulating the temperature in the tube and designing the solution doping process, the refractive index profile of this fiber is close to a step-index without any center dip. The laser performance of this fiber is proved through contrast experiments with conventional fiber in a kW-level MOPA setup. The gain-tailored fiber amplifier presents a beam quality of M2 ~1.43 at 1.2 kW. Its MI threshold is 1.25 kW, about 1.74 times as much as that of the conventional fiber amplifier. The laser slope efficiency of the gain-tailored fiber amplifier is 86.75%. Stabilized at an output power of 1.1 kW for 15 hours, the MI threshold does not decrease after this long-term operation, demonstrating a strong resistance to photodarkening effect. These results have confirmed that MCVD-fabricated gain-tailored Yb/Ce codoped aluminosilicate fibers have great potential in power scaling and output stability of high-power fiber lasers and amplifiers.

We report on the photobleaching effect on photodarkening in an ytterbium (Yb)-doped silica double-cladding fiber by pumping it with 793 nm, 808 nm and 1080 nm lasers. Enlightened by the different recovery processes under 793 nm, 808nm and 1080 nm pumps, it is suggested that the thulium (Tm) plays important roles in the photobleaching of photodarkening in a Yb-doped silica double-cladding fiber. Based on the related reports, a new idea is proposed, stating that the photodarkening and bleaching phenomena in the Yb-doped fiber could be analyzed from the concept of an e− and h+ equilibrium. The photodarkening is due to the electron, ionized by the ultraviolet photon. The bleaching is due to the offset of e− and h+. The Tm ions, existing as a critical factor for photodarkening pumped by its absorbent wavelength, could accelerate the offset of e− and h+. Based on this, the photodarkening phenomenon in Yb-doped fiber lasers could be suppressed by pumping at the wavelengths located at the absorption peaks of the Tm.

In this work, we systematically studied the mitigation of photodarkening (PD) in ytterbium-doped silica fiber co-doped with lithium (Li). Adding a proper concentration of Li+ ions to the core glass composition, the PD-induced excess loss can be reduced by 25%. The results showed that the effect on numerical aperture and laser efficiency was very small. Compared with the sodium (Na) co-doped Yb/Al silica fiber at the same concentration, the mitigation of the PD effect through Li+ and Na+ ions co-doping was analyzed and discussed. Furthermore, a hypothesis was proposed for the mechanism of alkali metal Li and Na co-doping to mitigate the PD effect. More effective core composition and doping concentration were proposed to provide guidance of high output power gain fiber preparation.

We demonstrate a high power 4 cores Yb-doped fiber amplifier which is operated in an in-phase supermode and does not need other mode selection components. The maximum output power is 9.75 W

The internet of things (IoT) technology has great potential in obtaining, analyzing, processing, controlling and feeding back the information of entity properties (location, status, behavior, characteristic, etc.), which will play an active role in promoting the development of smart grid. In this paper, we apply the IoT technology in the smart grid field. A kind of system architecture of smart grid is built according to the IoT system architecture. The system architecture of smart grid is divided into three layers -- the perception layer, the communication layer and the application layer. The application of IoT technology in every layer of the system architecture of the smart grid is analyzed and discussed in detail. Finally, the application prospect and problems which should be solved are forecast. It is found that the IoT technology will make smart grid more efficient, more intelligent, more secure and more convenient.

In this work, Na+ ions doping into the Yb-doped fiber is proposed to improve the photo-darkening resistance. The results show that the photo-darkening induced excess loss at equilibrium state at 633nm, 702 nm, 810 nm, and 1041 nm is 115.54dB/m, 86.87dB/m, 25.51 dB/m, 2.92 dB/m, respectively, when co-doping with Na+ ions. More than 30% excess loss is reduced comparing to the Yb-doped fiber without Na+ ions. The mechanism of Na+ ions doping to mitigate the PD excess loss is discussed. Besides, we measured the laser efficiency of Yb/Al/Na co-doped fiber to be 76.1%. This result remains almost the same with Yb-doped fiber and proves that the addition of Na+ ions do not deteriorate the fiber slope efficiency. The background loss of the two fibers also stays close. The results indicate this method is promising in high power fiber laser development.

We demonstrate a high power four-core Yb-doped fiber amplifier both theoretically and experimentally. An all-fiber MOPA structure without mode selection components was utilized to amplify the 12 m long four-core fiber. An in-phase supermode laser operation was realized in this fiber. The laser slope efficiency is greater than 56.7% with a maximum output power of 11.47 W. The measured M 2 factor of the amplified beam is 1.58, showing the high potential of the fiber.

WCDMA is the most widely used standard of 3rd-generation (3G) mobile communication in the world. The construction of WCDMA wireless network is complex. In order to meet the needs of the network construction in China, as well as the simulation teaching of Communication Profession in college, we designed and developed the software, “WCDMA Project Simulation System”. The software uses geographic information technologies and raster algorithm, and analyses the main processes of wireless network construction, stimulating the key processes such as site location selection, coverage planning, and capacity planning and so on. This software can not only assist the network planning engineers in their works, but also be used in teaching of Communication Profession in a clear way, so it is with a high practical value.

In this paper, by analyzing the shortcomings of existing technologies, we introduced a convenient and flexible smart home system based on Internet of Things. We have developed a demo version of this system and used a cell phone to query and control it locally and remotely. The experimental results show that this system can provide a real-time and reliable management for the smart home. It is believed that with the development of Internet of Things, smart home system will become more intelligent and multiplicity.

3G communication technology has three main wireless interface standards which are WCDMA, CDMA2000 and TD-SCDMA. The 3G devices and software of devices are different between different manufacturers and standards. In order to manage the different devices and many users in the training process of vocational education in communication profession, we designed and developed the software, “comprehensive communication network training platform”. Combining the device controlling software, this software packed the communication devices and users into a platform for unified management with some key technologies such as soft routing, Network Address Translation (NAT). Giving full consideration to the training process, the software can not only meet the requirements of vocational training, but also deploy the communication devices, resources and protect the security of the devices, so it is of great significance to the professional teaching of the mobile communication.

An innovative method based on support vector machines is presented to diagnose the fault of analog circuit. Firstly, in order to get enough fault samples, the circuit program is compiled in MATLAB software to obtain expressions of output signals. Secondly, fault samples are sent into Support Vector Machines to train Support Vector Machines. Thirdly, the test samples are classified by trained Support Vector Machines. Finally, an example of analog circuit fault diagnosis is provided. The result shows that this method has the advantages of simple algorithm, high efficiency, high accuracy, great capability in generalization and classification.