INTERCONNECT STRUCTURE TO IMPROVE CHIP SIGNAL INTEGRITY AND MECHANICAL RELIABILITY

Techniques are presented herein that support a novel chip interconnect structure, encompassing convex- and concave-shaped copper joint pillars, for connecting a chip (that follows the Optical Internetworking Forum (OIF) next generation (NG) common electrical input/output (CEI)-224 gigabit per second (G) framework) to a printed circuit board (PCB). Aspects of the presented techniques provide excellent signal integrity (SI) performance (including return loss, insertion loss, and impedance discontinuity) in support of, for example, a 102.4 terabit (T) per second switch comprising, among other things, an application-specific integrated circuit (ASIC) having 512 lanes of 224G Serializer/Deserializer (SerDes) capacity. Under further aspects of the techniques, mechanical performance and long-term reliability are significantly improved

The Sihailongwan Maar Lake, northeastern China as a candidate Global Boundary Stratotype Section and Point for the Anthropocene Series

Sihailongwan Maar Lake, located in Northeast China, is a candidate Global boundary Stratotype Section and Point (GSSP) for demarcation of the Anthropocene. The lake’s varved sediments are formed by alternating allogenic atmospheric inputs and authigenic lake processes and store a record of environmental and human impacts at a continental-global scale. Varve counting and radiometric dating provided a precise annual-resolution sediment chronology for the site. Time series records of radioactive (239,240Pu, 129I and soot 14C), chemical (spheroidal carbonaceous particles, polycyclic aromatic hydrocarbons, soot, heavy metals, δ13C, etc), physical (magnetic susceptibility and grayscale) and biological (environmental DNA) indicators all show rapid changes in the mid-20th century, coincident with clear lithological changes of the sediments. Statistical analyses of these proxies show a tipping point in 1954 CE. 239,240Pu activities follow a typical unimodal globally-distributed profile, and are proposed as the primary marker for the Anthropocene. A rapid increase in 239,240Pu activities at 88 mm depth in core SHLW21-Fr-13 (1953 CE) is synchronous with rapid changes of other anthropogenic proxies and the Great Acceleration, marking the onset of the Anthropocene. The results indicate that Sihailongwan Maar Lake is an ideal site for the Anthropocene GSSP

Influencing factors analyses and matching design of ultimate bearing capacity of external pressure tank

ObjectivesThis paper aims to discuss the relationship between the ultimate bearing capacity of a pressure hull and pressure tank under the same strength margin, and obtain a matching design with the equivalent ultimate bearing capacity and strength margins accordingly. MethodsTo this end, a typical external pressure tank is taken as the research object. On the basis of evaluating the stability and ultimate bearing capacity of the initial structural scheme, the influences of the thicknesses of the pressure tank shell, solid floor and transverse bulkhead on the ultimate bearing capacity are studied. The initial scheme is then adjusted to obtain a scheme with the equivalent strength margins of the pressure hull and pressure tank. In this context, the relationship between the ultimate bearing capacity of the pressure hull and pressure tank is discussed. By strengthening the pressure hull to match the ultimate bearing capacities of the pressure tank and pressure hull, the corresponding strength margins are obtained. ResultsThe results show that thinning the pressure tank shell by 30%, solid floor shell by 33.3% and transverse bulkhead shell by 30% reduces the ultimate bearing capacity of the tank by 16.5%, 36.4% and 0.17% respectively. ConclusionsAs further analyses show, under the condition of the same strength margin, the ultimate bearing capacity of the pressure hull is much lower than that of the pressure tank. When the strength margin of the pressure tank is about 25% and that of the pressure hull is about 40%, the ultimate bearing capacities of the pressure hull and pressure tank are roughly the same

Study on oxidation behaviors of Zr–Sn–Nb alloy in water steam at 1250 °C

To investigate the effect of different oxidation times on the oxidation behavior of Zr–Sn–Nb alloy in a high-temperature steam environment at 1250 °C, steam oxidation tests were conducted on the Zr–Sn–Nb alloy at 1250 °C for durations ranging from 100 to 5000 s. Microstructural and elemental composition analyses of the Zr–Sn–Nb alloy were carried out using scanning electron microscopy, energy-dispersive x-ray spectroscopy, and optical microscopy. The results showed that in the initial stages of oxidation (0–1000 s), the weight gain per unit area followed a parabolic trend. After 2500 s of oxidation, the weight gain rate significantly increased. In the later stages of oxidation (after 4000 s), the weight gain curve transitioned from a parabolic shape to a linear law. With increasing oxidation time, the thickness of the oxide layer gradually increased. In the early stages (0–2500 s), the growth rate of the oxide layer thickness was relatively slow, but the appearance of micro-pores and cracks was observed. However, after 2500 s, the steam oxidation rate of the Zr–Sn–Nb alloy significantly accelerated, leading to fracture and failure of the alloy specimens. The change in oxide layer thickness over time followed a parabolic law before 2500 s and a linear law after 2500 s. The growth curve of the α-Zr(O) layer within 5000 s also followed a parabolic law

Finite element simulation of high-speed finish milling of SKD11 hardened steel based on modified constitutive equation

High precision parts have been widely used in automobile, aerospace, medical and other fields. Conventional machining methods are difficult to meet the requirements of the high-quality requirements of components, including shape precision, dimensional accuracy, surface finish and surface integrity. Using milling instead of grinding can significantly improve machining efficiency of ultra-precision parts for difficult cut materials, especially high hardness SKD11 hardened steel. To improve the surface quality and the processing surface integrity of the parts, high-speed milling (HSM) can be able to meet the high-quality requirements of components. However, the quality of finish HSM is difficult to control through experiments. Therefore, the modified flow stress model of SKD11 hardened steel based on SHPB experimental is adopted to simulate the high-speed finish milling in this paper. The effect of cutting parameters on chip formation, cutting temperature, stress and cutting force of SKD11 are analyzed. Compared with the experimental data of cutting force of different cutting parameters, the simulation results are the same as the measured data. The results show that the model can predict the performance of the SKD11 high-speed finish milling process accurately

WASTE PRINTED CIRCUIT BOARDS DISASSEMBLY DEVICE DESIGN AND CUTTER PARAMETER OPTIMIZATION

According to the characteristics of waste PCB（ Printed Circuit Board）,an energy-efficient disassembly device was designed in this paper. PCB was heated by high temperature and high speed gas. And then the THD（ Through Hole Device）and SMD（ Surface Mount Devices） on PCB were removed by spiral hob. The cutter parameters were optimized for the optimization goal the minimum damage of THD. The research results showed that: When the diameter of the knife roller is 30 mm,the helix angle is 26°,the blade pressure angle of 0°,spiral line number is 4,the dismantling effect of THD is the best.New methods and technologies are provided for the efficient,green waste PCB recycling processing

Towards BCI-actuated smart wheelchair system

Abstract Background Electroencephalogram-based brain–computer interfaces (BCIs) represent novel human machine interactive technology that allows people to communicate and interact with the external world without relying on their peripheral muscles and nervous system. Among BCI systems, brain-actuated wheelchairs are promising systems for the rehabilitation of severely motor disabled individuals who are unable to control a wheelchair by conventional interfaces. Previous related studies realized the easy use of brain-actuated wheelchairs that enable people to navigate the wheelchair through simple commands; however, these systems rely on offline calibration of the environment. Other systems do not rely on any prior knowledge; however, the control of the system is time consuming. In this paper, we have proposed an improved mobile platform structure equipped with an omnidirectional wheelchair, a lightweight robotic arm, a target recognition module and an auto-control module. Based on the you only look once (YOLO) algorithm, our system can, in real time, recognize and locate the targets in the environment, and the users confirm one target through a P300-based BCI. An expert system plans a proper solution for a specific target; for example, the planned solution for a door is opening the door and then passing through it, and the auto-control system then jointly controls the wheelchair and robotic arm to complete the operation. During the task execution, the target is also tracked by using an image tracking technique. Thus, we have formed an easy-to-use system that can provide accurate services to satisfy user requirements, and this system can accommodate different environments. Results To validate and evaluate our system, an experiment simulating the daily application was performed. The tasks included the user driving the system closer to a walking man and having a conversation with him; going to another room through a door; and picking up a bottle of water on the desk and drinking water. Three patients (cerebral infarction; spinal injury; and stroke) and four healthy subjects participated in the test and all completed the tasks. Conclusion This article presents a brain-actuated smart wheelchair system. The system is intelligent in that it provides efficient and considerate services for users. To test the system, three patients and four healthy subjects were recruited to participate in a test. The results demonstrate that the system works smartly and efficiently; with this system, users only need to issue small commands to get considerate services. This system is of significance for accelerating the application of BCIs in the practical environment, especially for patients who will use a BCI for rehabilitation applications

Structural hysteresis of dilute fluorine salt aqueous solutions

In contrast with the generally accepted picture for most of the dilute salt aqueous solutions, which defaults that only one structural state/form exists at the given values of system/thermodynamic parameters, in this work, combining characterization of 19F nuclear magnetic resonance, ultraviolet-visible spectroscopies with theoretical calculations, we found that the F−-bearing aqueous solutions with identical component, but prepared by both different pathways, one of which is by mixing subsaturated MF2 solutions and Na//ClO4−(SO42−) solutions (path 1) and another is by mixing concentrated M2+//ClO4−(SO42−) solutions (M = Zn, Cd, Co and Cu) and NaF solution (path 2), can long-termly exist spectrographic distinguishable different thermodynamic steady states, in which the F− in the former preferentially exists in the form of more M2+-F− contact ion pairs (CIP), whereas in the form of more, even all M2+-F− solvent-separated/shared ion pairs (SIP) for the latter. This results from the different solution initial states, where path 1 solutions contain certain amounts of CIPs, whereas there is no CIPs initially in path 2 solutions, the high energy barrier of conversion between SIP and CIP, coupling with the low concentration gradient and thereby small conversion driving force. This makes the solutions exhibit an unusual “apparent” structural hysteresis. Due to the universality of the causes, present findings can expand to other sparingly soluble salts and enhance the significance of solution preparation bias on the thermodynamic studies in solution chemistry domain of sparingly soluble salts

High-fidelity dynamics of piezoelectric covered metamaterial Timoshenko beams using the spectral element method

Piezoelectric metamaterial beams have received enormous research interest for the applications of vibration attenuation and/or energy harvesting in recent years. This paper presents a generic modelling approach for predicting the high-frequency dynamics of piezoelectric metamaterial beams. The spectral element method (SEM) is used to derive the dynamic stiffness matrix of a composite piezoelectric beam segment. Boundary condition implementations are demonstrated. Both band structure and transmittance analyses are realized. Several case studies for piezoelectric metamaterial beams configured in different geometric/electrical forms are carried out. The corresponding finite element (FE) models are built for verification, and a comparison study with the transfer matrix method (TMM) is conducted. For the uniform configurations, an almost indistinguishable difference is noted between the theoretical and FE results. For the stepped configurations, only minor discrepancies are observed in the high-frequency responses. The improved robustness and stability of the SEM method compared to the TMM method are demonstrated. A further discussion has been provided to explain the cause of the high-frequency discrepancies: sudden changes in the cross-section of the beam result in the stress concentration effect and reduce the bending stiffness at the junction connection. Finally, the value of the high-fidelity modelling approach is reflected through a parametric-based optimization study towards merging the Bragg scattering and locally resonant band gaps in an example piezoelectric metamaterial beam to achieve a wide band gap.This work was financially supported by the State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, China (GZ21114, S22311)

Sputtering parameters effect on microstructural parameters of TiN coating via the Williamson-Hall analysis

Titanium nitride (TiN) coatings were deposited on Zr-4 substrate by direct current magnetron sputtering. The microstructural property of the as-deposited coating was studied by means of x-ray diffraction (XRD). The microstructural parameters, such as crystal size, lattice strain, lattice deformation stress and lattice deformation energy density, were investigated in detail by employed modified Debye–Scherrer method (MDS) and Williamson-Hall methods by assuming three models namely uniform deformation model, uniform stress deformation model and uniform energy density deformation model. And the effects of sputtering power, substrate temperature and substrate bias on microstructural parameters were investigated. The results show that TiN coating deposited by magnetron sputtering presents lattice compressive strain, except for sample X3 - 1 which is prepared by substrate bias of −50 V. It is also shown that sputtering power, substrate temperature and substrate bias have great influence on crystal size, lattice strain, lattice deformation stress and lattice deformation energy density of the as-deposited TiN coating. Especially the influence of substrate bias is very significant