Jitter Tolerant Hybrid Sigma-Delta Modulator

Commonly used in wireless applications and consumer products, Continuous-time (CT) Sigma Delta (Σ∆) Analog to Digital Converter (ADC) stands out for its high resolution, less input signal conditioning and large incorporating with digital signal processing. The clock jitter impact on CT Σ∆ ADC is a critical issue as it will directly increase the noise floor within signal bandwidth. Thus, reducing jitter sensitivity is beneficial for improving the performance of CT Σ∆ ADC. This thesis presents a novel idea of reducing CT Σ∆ ADC jitter sensitivity by splitting one stage of continuous-time integrator into two parts - a gain stage and a digital low-pass filter. The gain stage remains prior to quantizer for compensating the loss of loop gain when removing the original continuous-time integrator. The digital filter is placed at the output of quantizer to suppress the out-of-band noise level. This hybrid Σ∆ ADC is implemented with two configurations in system level with TSMC 40nm CMOS technology at 20 MHz bandwidth and 640 MHz sampling frequency. The maximum SNR of the hybrid Σ∆ ADC is 69.18 dB. The proposed ADC achieves the maximum of 14 dB better SQNR than the conventional CT Σ∆ ADC at RMS jitter as high as 10% of the clock period. A negative resistor gain boosting single stage amplifier is also presented in this thesis

Jitter Tolerant Hybrid Sigma-Delta Modulator

Commonly used in wireless applications and consumer products, Continuous-time (CT) Sigma Delta (Σ∆) Analog to Digital Converter (ADC) stands out for its high resolution, less input signal conditioning and large incorporating with digital signal processing. The clock jitter impact on CT Σ∆ ADC is a critical issue as it will directly increase the noise floor within signal bandwidth. Thus, reducing jitter sensitivity is beneficial for improving the performance of CT Σ∆ ADC. This thesis presents a novel idea of reducing CT Σ∆ ADC jitter sensitivity by splitting one stage of continuous-time integrator into two parts - a gain stage and a digital low-pass filter. The gain stage remains prior to quantizer for compensating the loss of loop gain when removing the original continuous-time integrator. The digital filter is placed at the output of quantizer to suppress the out-of-band noise level. This hybrid Σ∆ ADC is implemented with two configurations in system level with TSMC 40nm CMOS technology at 20 MHz bandwidth and 640 MHz sampling frequency. The maximum SNR of the hybrid Σ∆ ADC is 69.18 dB. The proposed ADC achieves the maximum of 14 dB better SQNR than the conventional CT Σ∆ ADC at RMS jitter as high as 10% of the clock period. A negative resistor gain boosting single stage amplifier is also presented in this thesis

Numerical simulation and tool parameters optimization of aluminum alloy transmission intermediate shell

Abstract Due to its challenging manufacturing and intricate morphology, the aluminum alloy transmission intermediate shell used in vehicle transmission has been the focus of many academic studies. In this study, the three-dimensional cutting model is condensed to a two-dimensional cutting model and utilized to simulate the finishing process of an aluminum alloy workpiece using the finite element modeling program DEFORM-3D. Through orthogonal testing and range analysis, the impact of integral end mill side edge parameters on cutting performance was investigated. It is determined that tool chamfering has a greater impact on cutting performance than tool rake and relief angles, that chamfering width has the most impact on cutting force, and that chamfering angle has the greatest impact on cutting temperature. The workpiece's surface roughness is tested during a cutting experiment, and an analysis of the data reveals that the finite element simulation model is accurate and the orthogonal test method is reasonable. The tool chamfer has a greater impact on roughness than the tool rake angle and relief angle. The tool settings are further optimized using the firefly method. By examining the data, it is determined that the prediction model is correct and the optimization model is reasonable. The cutting efficiency is higher and the surface quality is better when the chamfer width is 0.17 mm and the chamfer angle is 7.3° or 18.3°. Therefore, optimizing the side edge parameters of the integral end mill during the finishing process of a thin-walled aluminum alloy shell has practical technical value

Study of Mask Electrochemical Machining for Ring Narrow Groove under the Action of Multiple Physical Fields

Deep and narrow groove structures are widely used in aviation, aerospace, weapons, and other industries, and play a very important role. In order to solve the problems of machining tool deformation, machining flying edge, burr in traditional Computerized Numerical Control (CNC) milling for deep and narrow grooves, and the problems of serious motor loss and low machining efficiency in non-contact electrical discharge machining (EDM), electrochemical mask machining through the mask treatment of the non-processed part mask processing, and with no loss of the processing cathode tool, was suggested as an efficient way to solve these problems. Considering that the corrosion removal of the anodic workpiece is mainly subject to the multi-physical field coupling action between the electric field, the flow field, and the temperature field, it is necessary to construct a multi-physical field coupling model of electrochemical mask machining and combine this with the numerical simulation analysis to realize the distribution state of the multi-physical field, so as to realize the optimization guidance of the overall processing process

Clinical value of contrast-enhanced ultrasound in improving diagnostic accuracy rate of transthoracic biopsy of anterior-medial mediastinal lesions

Objective: To evaluate the clinical value of contrast-enhanced ultrasound (CEUS) in transthoracic biopsy of anterior-medial mediastinal lesions. Methods: A total of 123 patients with anterior or middle mediastinum lesions required ultrasound guided transthoracic biopsy for pathological diagnosis. Among them, 72 patients received CEUS examinations before biopsy. After CEUS, 8 patients were excluded from biopsy and the rest 64 patients underwent biopsy (CEUS group). During the same period, 51 patients received biopsy without CEUS examination (US group). The ultrasonography characteristics, the number of biopsy puncture attempts, diagnostic accuracy rate and the incidence of complications were recorded and compared between the two groups. Results: A large portion of necrosis area or superficial large vessels was found in 8 patients, so the biopsy was cancelled. The internal necrosis was demonstrated in 43.8% of the lesions in CEUS group and in 11.8% of US group (P>0.001). For thymic carcinoma, CEUS increased the detection rate of internal necrosis and pericardial effusion than conventional ultrasound (62.5% vs. 18.8%, P=0.012; 56.3% vs. 12.5%, P=0.023). The average number of punctures in CEUS group and US group was 2.36 +/- 0.70 and 2.21 +/- 0.51 times, respectively (P>0.05). The diagnostic accuracy rate of biopsy in CEUS group (96.9%, 62/64) was significantly higher than that in US group (84.3%, 43/51) (P=0.022). In US group, 2 patients suffered from mediastinal bleeding (3.9%), while no major complications occurred in CEUS group. Conclusions: CEUS examination provided important information before transthoracic mediastinum biopsy and improved diagnostic accuracy rate in biopsy of anterior and middle mediastinum lesions than conventional ultrasound.Beijing Municipal Health System Special Funds of High-Level Medical Personnel Construction [2013-3-086]; Natural Science Foundation of Beijing [7152031]; Beijing Baiqianwan Talents ProjectSCI(E)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)ARTICLE6617-6252

Antitumor Activity of Chinese Propolis in Human Breast Cancer MCF-7 and MDA-MB-231 Cells

Chinese propolis has been reported to possess various biological activities such as antitumor. In present study, anticancer activity of ethanol extract of Chinese propolis (EECP) at 25, 50, 100, and 200 μg/mL was explored by testing the cytotoxicity in MCF-7 (human breast cancer ER(+)) and MDA-MB-231 (human breast cancer ER(−)) cells. EECP revealed a dose- and time-dependent cytotoxic effect. Furthermore, annexin A7 (ANXA7), p53, nuclear factor-κB p65 (NF-κB p65), reactive oxygen species (ROS) levels, and mitochondrial membrane potential were investigated. Our data indicated that treatment of EECP for 24 and 48 h induced both cells apoptosis obviously. Exposure to EECP significantly increased ANXA7 expression and ROS level, and NF-κB p65 level and mitochondrial membrane potential were depressed by EECP dramatically. The effects of EECP on p53 level were different in MCF-7 and MDA-MB-231 cells, which indicated that EECP exerted its antitumor effects in MCF-7 and MDA-MB-231 cells by inducing apoptosis, regulating the levels of ANXA7, p53, and NF-κB p65, upregulating intracellular ROS, and decreasing mitochondrial membrane potential. Interestingly, EECP had little or small cytotoxicity on normal human umbilical vein endothelial cells (HUVECs). These results suggest that EECP is a potential alternative agent on breast cancer treatment

A helitron-induced RabGDIα variant causes quantitative recessive resistance to maize rough dwarf disease

Maize rough dwarf disease (MRDD), caused by various species of the genus Fijivirus, threatens maize production worldwide. We previously identified a quantitative locus qMrdd1 conferring recessive resistance to one causal species, rice black-streaked dwarf virus (RBSDV). Here, we show that Rab GDP dissociation inhibitor alpha (RabGDIα) is the host susceptibility factor for RBSDV. The viral P7-1 protein binds tightly to the exon-10 and C-terminal regions of RabGDIα to recruit it for viral infection. Insertion of a helitron transposon into RabGDIα intron 10 creates alternative splicing to replace the wild-type exon 10 with a helitron-derived exon 10. The resultant splicing variant RabGDIα-hel has difficulty being recruited by P7-1, thus leading to quantitative recessive resistance to MRDD. All naturally occurring resistance alleles may have arisen from a recent single helitron insertion event. These resistance alleles are valuable to improve maize resistance to MRDD and potentially to engineer RBSDV resistance in other crops

Preparation of a new superhydrophobic/superoleophilic corn straw fiber used as an oil absorbent for selective absorption of oil from water

Abstract Background Oil leakages frequently occur during oil product development and oil transportation. These incidents are a vital factor in water contamination, thus leading to serious environmental destruction. Therefore, superhydrophobic/superoleophilic material is one of the solutions to treat oily wastewater. Results This study aimed to develop a simple, fast and low-cost method to treat oily wastewater by synthesizing a new superhydrophobic/superoleophilic corn straw fiber via conventional impregnation. The corresponding results illustrate that abundant homogeneous silica (SiO2) granules evenly accreted on the surface of the prepared fiber were conducive to high surface roughness. Meanwhile, (Heptadecafluoro-1,1,2,2-tetradecyl) trimethoxysilane, a sort of silane coupling agent, could greatly reduce surface free energy by grafting with SiO2 particles on the corn straw fiber surface. The obtained superhydrophobic/superoleophilic corn straw fiber exhibited a water contact angle of 152° and an oil contact angle of 0° for various oils, strongly demonstrating its considerable application as an oil absorbent that can be applied for oil cleanup. In addition, the prepared fiber displayed a great chemical stability and environmental durability. Conclusions Due to its high absorption capacity and absorption efficiency, the prepared fiber has great potential as a new oil absorbent for treatment of oily water

Hadamard product-based in-memory computing design for floating point neural network training

Deep neural networks (DNNs) are one of the key fields of machine learning. It requires considerable computational resources for cognitive tasks. As a novel technology to perform computing inside/near memory units, in-memory computing (IMC) significantly improves computing efficiency by reducing the need for repetitive data transfer between the processing and memory units. However, prior IMC designs mainly focus on the acceleration for DNN inference. DNN training with the IMC hardware has rarely been proposed. The challenges lie in the requirement of DNN training for high precision (e.g. floating point (FP)) and various operations of tensors (e.g. inner and outer products). These challenges call for the IMC design with new features. This paper proposes a novel Hadamard product-based IMC design for FP DNN training. Our design consists of multiple compartments, which are the basic units for the matrix element-wise processing. We also develop BFloat16 post-processing circuits and fused adder trees, laying the foundation for IMC FP processing. Based on the proposed circuit scheme, we reformulate the back-propagation training algorithm for the convenience and efficiency of the IMC execution. The proposed design is implemented with commercial 28 nm technology process design kits and benchmarked with widely used neural networks. We model the influence of the circuit structural design parameters and provide an analysis framework for design space exploration. Our simulation validates that MobileNet training with the proposed IMC scheme saves $91.2\%$ in energy and $13.9\%$ in time versus the same task with NVIDIA GTX 3060 GPU. The proposed IMC design has a data density of 769.2 Kb mm ^−2 with the FP processing circuits included, showing a 3.5 × improvement than the prior FP IMC designs