Design of high speed folding and interpolating analog-to-digital converter

High-speed and low resolution analog-to-digital converters (ADC) are key elements in the read channel of optical and magnetic data storage systems. The required resolution is about 6-7 bits while the sampling rate and effective resolution bandwidth requirements increase with each generation of storage system. Folding is a technique to reduce the number of comparators used in the flash architecture. By means of an analog preprocessing circuit in folding A/D converters the number of comparators can be reduced significantly. Folding architectures exhibit low power and low latency as well as the ability to run at high sampling rates. Folding ADCs employing interpolation schemes to generate extra folding waveforms are called "Folding and Interpolating ADC" (F&I ADC). The aim of this research is to increase the input bandwidth of high speed conversion, and low latency F&I ADC. Behavioral models are developed to analyze the bandwidth limitation at the architecture level. A front-end sample-and-hold unit is employed to tackle the frequency multiplication problem, which is intrinsic for all F&I ADCs. Current-mode signal processing is adopted to increase the bandwidth of the folding amplifiers and interpolators, which are the bottleneck of the whole system. An operational transconductance amplifier (OTA) based folding amplifier, current mirror-based interpolator, very low impedance fast current comparator are proposed and designed to carry out the current-mode signal processing. A new bit synchronization scheme is proposed to correct the error caused by the delay difference between the coarse and fine channels. A prototype chip was designed and fabricated in 0.35μm CMOS process to verify the ideas. The S/H and F&I ADC prototype is realized in 0.35μm double-poly CMOS process (only one poly is used). Integral nonlinearity (INL) is 1.0 LSB and Differential nonlinearity (DNL) is 0.6 LSB at 110 KHz. The ADC occupies 1.2mm2 active area and dissipates 200mW (excluding 70mW of S/H) from 3.3V supply. At 300MSPS sampling rate, the ADC achieves no less than 6 ENOB with input signal lower than 60MHz. It has the highest input bandwidth of 60MHz reported in the literature for this type of CMOS ADC with similar resolution and sample rate

Cyclic axial compressive performance of hybrid double-skin tubular square columns

This paper presents an experimental study on the cyclic axial compressive behavior of FRP-concrete-steel hybrid double-skin tubular columns. The square column specimens were cast with an external Fiber Reinforced Polymer jackets, inner steel tube and concrete in between. The height of the columns was 500 mm and the side dimension was 150 mm. The effects of loading scheme, void ratio and diameter-thickness ratio on axial compression behavior were investigated. A total of eight columns were tested under monotonic and cyclic axial compression. The experimental results show that the effect of loading scheme on axial stress-strain envelope curve and the peak load were not significant, and the ultimate state of the square columns subjected to cyclic axial compression was very similar to that of specimens subjected to monotonic axial compression. Besides, compared with void ratio, the diameter-thickness ratio of the inner steel tube has significant influence on the peak load of the columns when subjected to cyclic axial compression

Silicon Micro-ring Resonator Device Design for Optical Interconnect Systems

Optical interconnect systems is one of the most promising solutions to surpass the speed bottleneck of CPU from the electrical interconnects. To realize this idea, one of the key topics is to design compact photonic devices suitable for building the optical interconnects. The use of silicon microring resonators is an attractive technology for the integrated photonics pursuing optical interconnect applications, highly exciting due to the high integration density, low power consumption, and versatile functionalities. The platform technologies available for silicon microring resonators can be categorized by their structures, functions in optical interconnect systems, etc. Specific designs are in great needed to break off some critical tradeoffs in these silicon microring-based devices performances. In this dissertation, the design and simulations of silicon microring based photonic devices for optical interconnects are presented. Utilizing the proposed technologies, various types of optical elements such as resonance-switching/coupling-switching OOK modulators, DPSK modulators and filters are designed. The systematic performance is studied as well. The data have shown that, by employing our unique designs critical tradeoffs in the device performance can be successfully broken and great data quality at ultra-high data transmission speed can be obtained

Exploration of treatment technology for heavy metal wastewater

Among the current pollutants in our water bodies, the one that has the greatest degree of pollution and impact on the water environment is heavy metal wastewater. Various heavy metal ions in water bodies can seriously disrupt the ecological balance of water bodies and spread throughout the biosphere through the natural material cycle and other means. Excess heavy metal ions not only seriously endanger the health of aquatic organisms, but can also enrich in animals and even humans, posing a serious threat to human health and causing failure or damage to vital organs such as the human internal organs and brain. The common heavy metal ions in existing water bodies are Cu2+, Hg2+, Pb2+ etc. Due to their inherent difficulty in degradation, enrichment and persistence, heavy metal ions make heavy metal wastewater treatment different from other traditional pollutant treatment methods. This paper examines the two main techniques currently used to remove heavy metals from water bodies: physical, chemical and biological techniques, and summarises the advantages and disadvantages of both methods. It is proposed that future treatment methods for heavy metal wastewater should develop an environmentally friendly and efficient systematic approach based on biotechnology and synergistic multi-technologies

A risk assessment method of the energy supply chain based on combination weights and Technique for Order Preference by Similarity to an Ideal Solution

Nowadays, the energy supply chain (ESC) with the coupling of multiple energy systems is able to promote the complementation between various energy types. However, due to a more complex structure, ESCs are facing more risks from the internal major links and external environment. Hence, an risk assessment method of the ESC based on combination weights and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) is proposed. First, a multi-level risk index system with 4 main indices and 16 sub-level indices is established. Next, methods of Criteria Importance Though Intercriteria Correlation (CRITIC) and entropy weighting are presented for determining the initial weights of each sub-level index respectively, in which the CRITIC method considers the conflicts between the indices, and the entropy method focuses on the variation of the index values. After that, a combination weighting approach based on relative entropy is used to assign the final combination weight to each index. Then, considering the final combination weights, the TOPSIS method is adopted to assess the risk level of an ESC. Finally, case studies of 4 regional ESCs are carried out to verify the effectiveness of the proposed method, while the final risk level score of region B’s ESC is the lowest which indicates the best performance in predicting, controlling, and mitigating its internal and external risks

Radiative Transfer Model Simulations for Ground-Based Microwave Radiometers in North China

Ground-based microwave radiometer profilers (MWRPs) are widely used to provide high-temporal resolution atmospheric temperature and humidity profiles. The quality of the observed brightness temperature (TB) from MWRPs is key for retrieving accurate atmospheric profiles. In this study, TB simulations derived from a radiative transfer model (RTM) were used to assess the quality of TB observations. Two types of atmospheric profile data (conventional radiosonde and ERA5 reanalysis) were combined with the RTM to obtain TB simulations, then compared with corresponding observations from three MWRPs located in different places in North China to investigate the influence of input atmospheric profiles on TB simulations and evaluate the quality of TB observations from the three MWRPs. The comparisons of the matching samples under clear-sky conditions showed that TB simulations derived from both radiosonde and ERA5 profiles were very close to the TB observations from most of the MWRP channels; however, the correlation was lower and the bias was obvious at 51.26 GHz and 52.28 GHz, which indicates that the oxygen absorption component in the RTM needs to be improved for lower-frequency temperature channels. The difference in location of the radiosonde and MWRP sites affected the TB simulations for the water vapor channels, but had little impact on temperature channels that are insensitive to humidity. Comparisons of both simulations (ERA5 and Radiosonde) and the corresponding TB observations from the three sites indicated that the water vapor channels observation quality for the MWRP located in southern Beijing needs improvement. For the two types of profile data, ERA5 profiles have a more positive effect on TB simulations in the water vapor channels, such as enhanced consistence, reduced bias and standard deviation between simulations and observations for those MWRPs located away from the radiosonde station. Therefore, hourly ERA5 data are an optimal option in terms of compensating for limited radiosonde measurements and enhancing the monitoring quality of MWRP observations within 24 h

Planning with Spatial-Temporal Abstraction from Point Clouds for Deformable Object Manipulation

Effective planning of long-horizon deformable object manipulation requires suitable abstractions at both the spatial and temporal levels. Previous methods typically either focus on short-horizon tasks or make strong assumptions that full-state information is available, which prevents their use on deformable objects. In this paper, we propose PlAnning with Spatial-Temporal Abstraction (PASTA), which incorporates both spatial abstraction (reasoning about objects and their relations to each other) and temporal abstraction (reasoning over skills instead of low-level actions). Our framework maps high-dimension 3D observations such as point clouds into a set of latent vectors and plans over skill sequences on top of the latent set representation. We show that our method can effectively perform challenging sequential deformable object manipulation tasks in the real world, which require combining multiple tool-use skills such as cutting with a knife, pushing with a pusher, and spreading the dough with a roller.Comment: Published at the Conference on Robot Learning (CoRL 2022

Low-Cost 400 Gbps DR4 Silicon Photonics Transmitter for Short-Reach Datacenter Application

Targeting high-speed, low-cost, short-reach intra-datacenter connections, we designed and tested an integrated silicon photonic circuit as a transmitter engine. This engine can be packaged into an optical transceiver module which meets the QSFP-DD Form Factor, together with other electrical/optical components. We first present the design and performance of a high-speed silicon modulator, which had a 3-dB EO bandwidth of >40 GHz and an ER of >5 dB. We then incorporated the engine onto a test board and injected a 53.125 Gbaud PAM4 signal. Clear eye patterns were observed at the receiver with TDECQ ~3 dB for all four lanes