Simultaneous inversion method of thermal barrier coating parameters based on electromagnetic/capacitive dual-module sensor.

Thermal barrier coating (TBC) of turbine blades can prevent aeroengine damage resulting from high temperature. TBC exhibits a multilayer complex structure of ceramic and bonding layers. The ceramic layer is dielectric, whereas the bonding layer is conductive. Disabling either layer can endanger aircraft safety. Changes in TBC parameters are indicative of failure. This study proposed a neural-network-based method to inverse the three key parameters of TBC simultaneously based on electromagnetic/capacitive dual-module sensor. Thus, this method can be used for monitoring the status of aeroengines. The experimental results revealed that the inversion error of thickness and permittivity of the ceramic layer and the conductivity of the bonding layer is less than 2%. Therefore, the proposed method can satisfy application requirements.

Controlled Epitaxial Growth and Atomically Sharp Interface of Graphene/Ferromagnetic Heterostructure via Ambient Pressure Chemical Vapor Deposition.

The strong spin filtering effect can be produced by C-Ni atomic orbital hybridization in lattice-matched graphene/Ni (111) heterostructures, which provides an ideal platform to improve the tunnel magnetoresistance (TMR) of magnetic tunnel junctions (MTJs). However, large-area, high-quality graphene/ferromagnetic epitaxial interfaces are mainly limited by the single-crystal size of the Ni (111) substrate and well-oriented graphene domains. In this work, based on the preparation of a 2-inch single-crystal Ni (111) film on an Al2O3 (0001) wafer, we successfully achieve the production of a full-coverage, high-quality graphene monolayer on a Ni (111) substrate with an atomically sharp interface via ambient pressure chemical vapor deposition (APCVD). The high crystallinity and strong coupling of the well-oriented epitaxial graphene/Ni (111) interface are systematically investigated and carefully demonstrated. Through the analysis of the growth model, it is shown that the oriented growth induced by the Ni (111) crystal, the optimized graphene nucleation and the subsurface carbon density jointly contribute to the resulting high-quality graphene/Ni (111) heterostructure. Our work provides a convenient approach for the controllable fabrication of a large-area homogeneous graphene/ferromagnetic interface, which would benefit interface engineering of graphene-based MTJs and future chip-level 2D spintronic applications.

Quantitative detection of thermal barrier coating parameters based on electromagnetic/capacitive dual modality sensor.

A thermal barrier coating (TBC), which is composed of a top coating (TC) and bond coating (BC), can keep a turbine engine working in high temperature. The TC is an insulated ceramic layer, and the BC is a conductive layer between the TC and engine blade. Owing to poor working conditions, some failures such as sintering, thinning of coating thickness, and oxide layer initiation will occur in the TBC. Once any part of the TBC fails, it will seriously threaten the safety of the aircraft. The quantitative detection of TBC parameters is realized with the electromagnetic/capacitive dual modality sensor in this paper. The measurement grid algorithm is used to inverse the thickness of the TC layer and the conductivity of the BC layer, and an analytical method is proposed to inverse the relative permittivity of the TC layer. According to the experiment, the inversion errors of these parameters are all less than 4%, which can meet the industry needs well.

Removal of pediatric stage IV neuroblastoma by robot-assisted laparoscopy: A case report and literature review.

BACKGROUND: Neuroblastoma (NB) is the most common extracranial solid tumor in children, with an incidence of approximately 1/10000. Surgical resection is an effective treatment for children with NB. Robot-assisted laparoscopic surgery is a new method and is superior to conventional laparoscopic surgery, since it has been preliminarily applied in clinical practice with a significant curative effect. This paper discusses significance and feasibility of complete resection of stage IV NB using robot-assisted laparoscopic surgery, while comparing its safety and effectiveness with conventional laparoscopic surgery. CASE SUMMARY: In June 2018, a girl with stage IV retroperitoneal NB, aged 3 years and 5 mo, was admitted. Her weight was 15 kg, and her height was 100 cm. Robot-assisted, five-port laparoscopic resection of NB was performed. Starting from the middle point between the navel and the anterior superior iliac spine to the left lower abdomen, the pneumoperitoneum and observation hole (10 mm) were established using the Hasson technique. Operation arm #1 was located between the left anterior axillary line, the navel, and the costal margin (8 mm); operation arm #2 was located at the intersection of the right anterior axillary line and Pfannenstiel line (8 mm); one auxiliary hole was located between arm #2 (on the Pfannenstiel line) and the observation hole (12 mm); and another auxiliary hole (5 mm) was located slightly below the left side of the xiphoid. Along the right line of Toldt and the hepatic flexure of the transverse colon, the colon was turned to the left and below with a hook electrode. Through Kocher's incision, the duodenum and the pancreatic head were turned to the left to expose the inferior vena cava and the abdominal aorta. The vein was separated along the right external iliac, and the inferior vena cava was then lifted to expose the right renal vein from the bottom to the top. The tumor was transected horizontally below the renal vein, and it was first cut into pieces and then resected. The right renal artery and the left renal vein were also exposed, and the retrohepatic inferior vena cava was isolated. The tumor was resected along the surface of the psoas muscle, the back of the inferior vena cava, and the right side of the abdominal aorta. Finally, the lymph node metas-tases in front of the abdominal aorta and left renal vein were completely removed. The specimens were loaded into a disposable specimen retrieval bag and removed from the enlarged auxiliary hole. T-tube drainage was placed and brought out through a hole in the right lower quadrant of the abdomen. The operative time was 389 min, the time of pneumoperitoneum was 360 min, the intraoperative blood loss was approximately 200 mL, and the postoperative recovery was smooth. There were no complications, such as lymphatic fistula, diarrhea, bleeding, and paralytic ileus. Two months after discharge, there were no other complications. The literature on the application of robot-assisted laparoscopic surgery in the treatment of NB in children was reviewed. CONCLUSION: The robot has the advantages of a three-dimensional view and flexible operation, and it can operate finely along blood vessels. The successful experience of this case confirmed that robot-assisted laparoscopic surgery can skeletonize the abdominal blood vessels in the tumor and cut the tumor into pieces, indicating that robot-assisted laparoscopic surgery is feasible.

Retroperitoneoscopic approach for partial nephrectomy in children with duplex kidney: A case report.

BACKGROUND: Renal duplication is a common deformity of the urinary system, with an incidence of approximately 1/125 in children. Symptomatic patients with hydronephrosis, vesicoureteral reflux, or incontinence may require surgical interventions. Laparoscopy and retroperitoneoscopy are the two main accesses for partial nephrectomy. CASE SUMMARY: A 9-year-old child was admitted to the hospital for hydronephrosis of the left kidney. Ultrasonography showed that the left kidney was larger, approximately 12.6 cm × 6.3 cm × 5.5 cm in size, with visible separation of the pelvis and an obviously separated lower portion. The upper segment of the left ureter was dilated (approximately 2.6 cm in width), and no significant dilation was observed in the middle and upper segments. The right kidney and ureter were normal. Primary diagnosis was left renal duplication malformation and hydronephrosis. Retroperitoneal laparoscopic nephrectomy and ureterectomy were performed. Intraoperative exploration revealed a dilated pelvis and thin renal parenchyma at the lower pole of the left kidney. The upper left kidney was smaller than normal, and the pelvis and ureter were larger than normal. The renal artery was blocked for 40 min. A hemolock was used to clamp down the kidney ureter, and a drainage tube was retained in the retroperitoneal cavity. The operation was uneventful, and the estimated amount of blood loss was 100 mL. Total abdominal drainage amount was 116 mL. The drainage tube was removed on postoperative day (POD) 3 and the patient was discharged on POD6. The pathological diagnosis confirmed the atrophy of the renal parenchyma, the dilation of the renal pelvis, hydronephrosis, and ureteral cystic dilation. CONCLUSION: The retroperitoneoscopic approach for partial nephrectomy is feasible and effective in selective pediatric patients with a duplex kidney.

Robot-assisted gallbladder-preserving hepatectomy for treating S5 hepatoblastoma in a child: A case report and review of the literature.

BACKGROUND: Hepatoblastoma (HB) is the most common hepatic malignant tumour in children, accounting for approximately 50%-60% of primary hepatic malignant tumours in children, mostly in children under 3 years old. In Western countries, the incidence of hepatoblastoma is approximately 1-2/100000. Da Vinci surgical system is fast becoming a key instrument in microinvasive surgery. The past decade has seen the rapid development of robot-assisted laparoscopy, which expends many fields including the liver surgery. This paper discusses the significance and feasibility of robot-assisted gallbladder-preserving hepatectomy for treating S5 hepatoblastoma in children. The aim of this essay is to compare the safety and effectiveness of robotic surgery with conventional laparoscopic surgery, and explore the meaning of preservation of the gallbladder by sharing this case. CASE SUMMARY: A 3-year-old child with a liver mass in the 5th segment was treated using the Da Vinci surgical system, and the gallbladder was retained. The child was admitted to the hospital for 20 d for the discovery of the right hepatic lobe mass. Ultrasonography revealed a low echo mass, 46 mm × 26 mm × 58 mm in size, indicating hepatoblastoma in the right lobe, and enhanced computed tomography showed continuous enhancement of iso-low-density lesions with different sizes and nodules and unclear boundaries, without the dilation of the intrahepatic bile duct, no enlargement of the gallbladder, and uniform thickness of the wall. The diagnosis was "liver mass, hepatoblastoma". It was decided to perform S5 liver tumour resection. During surgery, the tumour and gallbladder were isolated first, and the gallbladder could be completely separated from the tumour surface without obvious infiltration; therefore, the gallbladder was preserved. The cutting line was marked with an electric hook. The hepatic duodenal ligament was blocked with a urethral catheter using the Pringle method, and the tumour and part of the normal liver tissue were completely resected with an ultrasound knife along the incision. The hepatic portal interdiction time was approximately 25 min. An abdominal drainage tube was inserted. The auxiliary hole was connected to the lens, and the specimen was removed. The patient's status was uneventful, and the operation time was 166 min. The robotic time was 115 min, and the bleeding amount was approximately 200 mL. In total, 300 mL of red blood cell suspension and 200 mL of plasma were injected. No serious complications occurred. Pathological findings confirmed fetal hepatoblastoma and R0 resection. A gallbladder contraction test was performed two weeks after surgery. CONCLUSION: Robot-assisted S5 hepatectomy with gallbladder preservation is safe and feasible for specific patients.

Robotic-assisted surgery for pediatric choledochal cyst: Case report and literature review.

Our paper describes the key surgical points of pediatric choledochocystectomy performed completely by Da Vinci robotic system. A choledochocystectomy was safely carried out for a girl at our hospital, and without any complication. Then systematic literature review was done to discuss the methods of intestine surgery and intestinal anastomosis, the use of 3rd robotic arm, the surgical safety and advantages comparing open and laparoscopic surgery. We systematically reviewed choledochocystectomy for children performed by robotic surgery. We included a total of eight domestic and foreign reports and included a total of 86 patients, whose average age was 6.3 (0.3-15.9) years; the male-to-female ratio was 1:3.5 (19:67). Seven patients experienced conversion to open surgery, and the surgery success rate was 91.9% (79/86). The average total operation time was 426 (180-520) min, the operation time on the machine was 302 (120-418) min, 11 cases used the number 3 arm, and the remaining mainly used the hitch-stitch technique to suspend the stomach wall and liver. Forty-seven patients underwent pull-through intestine and intestinal anastomosis, and 39 patients underwent complete robotic intestine surgery and intestinal anastomosis. The hospitalization time of robotic-assisted choledochocystectomy was 8.8 d. Eight patients had biliary fistula and were all cured by conservative treatment and continuous observation. One patient had anastomotic stenosis, and one patient had wound dehiscence, both cured by surgery. Choledochocystectomy for children performed by completely robotic surgery and Roux-en-Y hepaticojejunostomy is safe and feasible. The initial experience shows that this surgical approach has a clearer field than the traditional endoscopy, and its operation is more flexible, the surgery is more accurate, and the injury is smaller. With the advancement of technology and the accumulation of surgeons' experience, robotic surgery may become a new trend in this surgical procedure.

Calibration of micro-capacitance measurement system for thermal barrier coating testing.

In order to comprehensively evaluate the thermal barrier coating system of an engine blade, an integrated planar sensor combining electromagnetic coils with planar capacitors is designed, in which the capacitance measurement accuracy of the planar capacitor is a key factor. The micro-capacitance measurement system is built based on an impedance analyzer. Because of the influence of non-ideal factors on the measuring system, there is an obvious difference between the measured value and the actual value. It is necessary to calibrate the measured results and eliminate the difference. In this paper, the measurement model of a planar capacitive sensor is established, and the relationship between the measured value and the actual value of capacitance is deduced. The model parameters are estimated with the least square method, and the calibration accuracy is evaluated with experiments under different dielectric conditions. The capacitance measurement error is reduced from 29% ∼ 46.5% to around 1% after calibration, which verifies the feasibility of the calibration method.

An Electromagnetic/Capacitive Composite Sensor for Testing of Thermal Barrier Coatings.

Thermal barrier coatings (TBCs) can significantly reduce the operating temperature of the aeroengine turbine blade substrate, and their testing technology is very urgently demanded. Due to their complex multi-layer structure, it is hard to evaluate TBCs with a single function sensor. In this paper, an electromagnetic/capacitive composite sensor is proposed for the testing of thermal barrier coatings. The dielectric material is tested with planar capacitor, and the metallic material is tested with electromagnetic coils. Then, the comprehensive test and evaluation of thermal barrier coating system can be realized. The sensor is optimized by means of theoretical and simulation analysis, and the interaction between the planar capacitor and the electromagnetic coil is studied. The experimental system is built based on an impedance analyser and multiplex unit to evaluate the performance of the composite sensor. The transimpedances and capacitances are measured under different coating parameters, such as thickness and permittivity of top coating as well as bond layer conductivity. The experimental results agree with the simulation analysis, and the feasibility of the sensor is proved.

Resolution improvement of low frequency AC magnetic field detection for modulated MR sensors.

Magnetic modulation methods especially Micro-Electro-Mechanical System (MEMS) modulation can improve the sensitivity of magnetoresistive (MR) sensors dramatically, and pT level detection of Direct Current (DC) magnetic field can be realized. While in a Low Frequency Alternate Current (LFAC) magnetic field measurement situation, frequency measurement is limited by a serious spectrum aliasing problem caused by the remanence in sensors and geomagnetic field, leading to target information loss because frequency indicates the magnetic target characteristics. In this paper, a compensation field produced with integrated coils is applied to the MR sensor to remove DC magnetic field distortion, and a LFAC magnetic field frequency estimation algorithm is proposed based on a search of the database, which is derived from the numerical model revealing the relationship of the LFAC frequency and determination factor [defined by the ratio of Discrete Fourier Transform (DFT) coefficients]. In this algorithm, an inverse modulation of sensor signals is performed to detect jumping-off point of LFAC in the time domain; this step is exploited to determine sampling points to be processed. A determination factor is calculated and taken into database to figure out frequency with a binary search algorithm. Experimental results demonstrate that the frequency measurement resolution of the LFAC magnetic field is improved from 12.2 Hz to 0.8 Hz by the presented method, which, within the signal band of a magnetic anomaly (0.04-2 Hz), indicates that the proposed method may expand the applications of magnetoresistive (MR) sensors to human healthcare and magnetic anomaly detection (MAD).

A fast and accurate frequency estimation algorithm for sinusoidal signal with harmonic components.

Frequency estimation is a fundamental problem in many applications, such as traditional vibration measurement, power system supervision, and microelectromechanical system sensors control. In this paper, a fast and accurate frequency estimation algorithm is proposed to deal with low efficiency problem in traditional methods. The proposed algorithm consists of coarse and fine frequency estimation steps, and we demonstrate that it is more efficient than conventional searching methods to achieve coarse frequency estimation (location peak of FFT amplitude) by applying modified zero-crossing technique. Thus, the proposed estimation algorithm requires less hardware and software sources and can achieve even higher efficiency when the experimental data increase. Experimental results with modulated magnetic signal show that the root mean square error of frequency estimation is below 0.032 Hz with the proposed algorithm, which has lower computational complexity and better global performance than conventional frequency estimation methods.

Surgical treatment of pediatric retroperitoneal tumors with invasion of major blood vessels: a single-center experience.

BACKGROUND: This study assessed operative experiences with common pediatric retroperitoneal tumors invading major blood vessels. METHODS: Forty-seven pediatric patients with retroperitoneal tumors were enrolled. They included 22 neuroblastomas, 6 gangliocytomas and 19 Wilms' tumors, and underwent primary surgical resection after vascular skeletonization and manipulations of involved vessels. RESULTS: In the above tumors, the one-stage gross total resection rates of, respectively, 95.45%, 100% and 100% were obtained. There was only one complication, namely post-operational early acute renal failure that recovered with dialysis. There were no deaths. CONCLUSIONS: Vascular skeletonization and other vessel manipulations prior to surgery improve the gross total resection rates of pediatric retroperitoneal tumors.

Fatigue Crack Length Sizing Using a Novel Flexible Eddy Current Sensor Array.

The eddy current probe, which is flexible, array typed, highly sensitive and capable of quantitative inspection is one practical requirement in nondestructive testing and also a research hotspot. A novel flexible planar eddy current sensor array for the inspection of microcrack presentation in critical parts of airplanes is developed in this paper. Both exciting and sensing coils are etched on polyimide films using a flexible printed circuit board technique, thus conforming the sensor to complex geometric structures. In order to serve the needs of condition-based maintenance (CBM), the proposed sensor array is comprised of 64 elements. Its spatial resolution is only 0.8 mm, and it is not only sensitive to shallow microcracks, but also capable of sizing the length of fatigue cracks. The details and advantages of our sensor design are introduced. The working principal and the crack responses are analyzed by finite element simulation, with which a crack length sizing algorithm is proposed. Experiments based on standard specimens are implemented to verify the validity of our simulation and the efficiency of the crack length sizing algorithm. Experimental results show that the sensor array is sensitive to microcracks, and is capable of crack length sizing with an accuracy within ±0.2 mm.

Flux concentration and modulation based magnetoresistive sensor with integrated planar compensation coils.

1∕f noise is one of the main noise sources of magnetoresistive (MR) sensors, which can cause intrinsic detection limit at low frequency. To suppress this noise, the solution of flux concentration and vertical motion modulation (VMM) has been proposed. Magnetic hysteresis in MR sensors is another problem, which degrades their response linearity and detection ability. To reduce this impact, the method of pulse magnetization and magnetic compensation field with integrated planar coils has been introduced. A flux concentration and VMM based magnetoresistive prototype sensor with integrated planar coils was fabricated using microelectromechanical-system technology. The response linearity of the prototype sensors is improved from 0.8% to 0.12%. The noise level is reduced near to the thermal noise level, and the low-frequency detection ability of the prototype sensor is enhanced with a factor of more than 80.

Magnetostatic detection using magnetoresistive sensors with vertical motion flux modulation.

Recently, the flux modulation has been presented to deal with the 1/f noise of magnetoresistive (MR) sensors. However, the efficiency of most flux modulation schemes with simple micro- electromechanical-system (MEMS) actuators is not satisfying yet. In this paper, the vertical motion flux modulation (VMFM) is proposed to improve the modulation efficiency. In VMFM, the soft magnetic film driven by a MEMS actuator vibrates vertically above the MR sensors with a pair of flux concentrators. Consequently, the detected magnetostatic field is modulated to the higher frequency where the 1/f noise is much lower. A VMFM prototype based on AA002 (multi-layered giant magnetoresistive sensors) was fabricated and its flux modulation efficiency can reach 18.7%, which exceeds most achieved efficiency with other schemes. Also, the magnetostatic detection ability is improved to 530 pT/√Hz.

Study on electrodynamic sensor of multi-modality system for multiphase flow measurement.

Accurate measurement of multiphase flows, including gas/solids, gas/liquid, and liquid/liquid flows, is still challenging. In principle, electrical capacitance tomography (ECT) can be used to measure the concentration of solids in a gas/solids flow and the liquid (e.g., oil) fraction in a gas/liquid flow, if the liquid is non-conductive. Electrical resistance tomography (ERT) can be used to measure a gas/liquid flow, if the liquid is conductive. It has been attempted to use a dual-modality ECT/ERT system to measure both the concentration profile and the velocity profile by pixel-based cross correlation. However, this approach is not realistic because of the dynamic characteristics and the complexity of multiphase flows and the difficulties in determining the velocities by cross correlation. In this paper, the issues with dual modality ECT/ERT and the difficulties with pixel-based cross correlation will be discussed. A new adaptive multi-modality (ECT, ERT and electro-dynamic) sensor, which can be used to measure a gas/solids or gas/liquid flow, will be described. Especially, some details of the electrodynamic sensor of multi-modality system such as sensing electrodes optimum design, electrostatic charge amplifier, and signal processing will be discussed. Initial experimental results will be given.