Design Of Macro Research Articles

A Nonvolatile Compute-in-Memory Macro Using Voltage-Controlled MRAM and In Situ Magnetic-to-Digital Converter

Compute-in-Memory (CIM) accelerator has become a popular solution to achieve high energy efficiency for deep learning applications in edge devices. Recent works have demonstrated CIM macros using non-volatile memories (STT-MRAM, RRAM) to take advantages of their non-volatility and high density. However, effective computation dynamic range is far lower than their SRAM-CIM counterparts due to low device ON/OFF ratio. In this work, we combine a non-volatile memory based on a voltage-controlled magnetic tunneling junction (VC-MTJ) device, called voltage-controlled MRAM or VC-MRAM, and accurate switched-capacitor based CIM using a novel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-situ</i> Magnetic-to-Digital Converter (MDC). The VC-MTJ device has demonstrated 10× lower write energy and switching time compared to STT-MRAM device and has comparable density, read energy and read latency. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-situ</i> MDCs embedded inside each VC-MRAM row convert magnetically stored weight information to CMOS logic levels and enable switched-capacitor based multiply–accumulate (MAC) operation with accuracy comparable to state-of-the-art SRAM-CIM. This paper describes the schematic and layout level design of a VC-MRAM CIM macro in 28nm. This is the first non-volatile CIM design to enable analog MAC computation with 256 parallel rows turned ON simultaneously without degradation in dynamic range (< 1 LSB). Detailed circuit simulations including experimentally validated VC-MTJ compact models show 1.5× higher energy efficiency and 2× higher density compared to state-of-the-art SRAM-based CIM.

On the stability of macro–mini robotic systems for physical human–robot interaction

This paper addresses the stability of macro–mini robotic systems in a context of physical human–robot interaction (pHRI). A simple model including a one-degree-of-freedom (one-dof) macro robot and a one-dof mini robot is investigated using a state-space representation in order to assess the controllability and stability of the system. In this work, the stability of the system is analysed in more detail regarding two perspectives of the interaction process, namely the human force input and the human position input. Moreover, physical limits and the frequency response of the macro–mini system are also examined. Therefrom, this study derives a general formula for the constraints of the virtual mass and the virtual damping. Possible choices of these parameters in certain ranges are graphically and visually demonstrated. Simulations are carried out in order to demonstrate the stability and the behaviour of the system with different input signals. The conclusions of the analysis can be used in the design of multi-dof macro–mini systems. An example of a 12-dof macro–mini system is briefly described to illustrate potential applications.

Sensor-based force decouple controller design of macro–mini manipulator

A robotic polishing system includes a force-controlled end-effector (mini manipulator) and a position-controlled industrial robot (macro manipulator). This combination mode has a fast response and a large workspace. However, the force-controlled axis component of the macro motions and the geometric of the workpiece surfaces will affect the contact force response rate and tracking accuracy due to the coupling dynamics between the macro and mini, limiting system performance. A new dynamic decoupling method employing dual force sensors (DFSs) is proposed to address these problems. One of the force sensors installed between the endpoint of the macro and the fixed platform of the mini realizes the dynamic decoupling of the macro and mini. The other one is added at the endpoint of the mini to obtain the interaction force in contact with the environment and feed it back to the control loop. When the disturbances produced by the macro trajectories and the uncertainties coming from the workpiece are introduced into the system, the proposed method can improve force response rate and tracking accuracy without knowing the dynamic models and parameters of the macro and the geometric of the workpiece surface. Several experiments are carried out under various conditions. Experimental results indicate that the contact force response rate and tracking error of DFSs are better than those of the conventional force-controlled and impedance matching methods, proving the proposed method’s effectiveness. In addition, the last comparison experiment verifies that the DFSs method applies to different kinds of end-effectors with various dynamics. • This paper proposes a new dynamic decoupling method based on force sensors. • It can obtain the coupling force to realize dynamic decoupling regardless of models. • It can reduce the disturbance effects of the macro and the workpiece on the force. • The proposed method can improve contact force response rate and tracking accuracy.

Development of Gas Sensor Based on Fractal Substrate Structures

Gas sensor plays a key role in many applications with sensitivity being a critical performance characteristic. Increasing the surface area of gas sensing material is one approach that can increase sensitivity. Fractal geometries, which have large specific surface area and special fractal dimension, have previously been successfully used in the design of macro and microstructures of gas sensors to improve their performance. In this paper, the influence of geometrical structure of the substrate on the gas sensor performance has been investigated. Two fractal structures (Koch snowflake and Menger sponge) and one traditional structure (Cylinder) were fabricated by 3D printing and coated in Ag:MWCNTs based sensing materials. The fabricated sensors were tested with nitrogen dioxide at different temperatures and humidity. Experimental results show that the sensitivity of gas sensors with fractal structures is increased more than twice that of those with traditional geometrical structures.

In-Memory Computing on Resistive RAM Systems Using Majority Operation

Memristors can be used to build nonvolatile memory systems with in-memory computing (IMC) capabilities. A number of prior works demonstrate the design of an IMC-capable memory macro using a memristor crossbar. However, read disturbance limits the use of such memory systems built using a 0-transistor, 1-RRAM (0T1R) structure that suffers from the sneak path problem. In this paper, we introduce a scheme for both memory and logic operations using the 1-transistor, 1-RRAM (1T1R) memristor crossbar, which effectively mitigates the read disturbance problem. The memory array is designed using nMOS transistors and the VTEAM memristor model. The peripheral circuitry like decoders, voltage multiplexers, and sense amplifiers is designed using a 45[Formula: see text]nm CMOS technology node. We introduce a mapping technique to realize arbitrary logic functions using Majority (MAJ) gate operations in the 1T1R crossbar. Through extensive experimentation on benchmark functions, it has been found that the proposed mapping method gives an improvement of 65% or more in terms of the number of time steps required, and 59% or more in terms of energy consumption as compared to some of the recent methods.

3D Printing of Antibacterial, Biocompatible, and Biomimetic Hybrid Aerogel-Based Scaffolds with Hierarchical Porosities via Integrating Antibacterial Peptide-Modified Silk Fibroin with Silica Nanostructure.

Scaffold-mediated tissue engineering has become a golden solution for the regeneration of damaged bone tissues that lack self-regeneration capability. A successful scaffold in bone tissue engineering comprises a multitude of suitable biological, microarchitectural, and mechanical properties acting as different signaling cues for the cells to mediate the new tissue formation. Therefore, careful design of bioactive scaffold macro- and microstructures in multiple length scales and biophysical properties fulfilling the tissue repair demands are necessary yet challenging to achieve. Herein, we have developed an antibacterial and biocompatible silica-silk fibroin (SF) gel-based ink through novel yet simple chemical approaches of sol-gel and self-assembly followed by processing the obtained gels as three-dimensional (3D) hybrid aerogel-based scaffolds exploiting the advanced materials design approaches of micro-extrusion-based 3D printing, and directional freeze-casting/drying approaches. As the main constituent of the hybrid biocompatible scaffold of this study, we used the SF extracted from Bombyx mori silkworm cocoon. However, to increase the cell responsivity and bactericidal efficiency of the final scaffold, thiol-ended antimicrobial and cell adhesive peptide sequence (SH-CM-RGD) was conjugated to silica-SF hybrid gels via covalent attachment using a spacer molecule through either preprint (prior to sol-gel) or during the post-printing steps on the previously printed silica-SF gel. In the next step, the hybrid Silica-SF-CM-RGD hydrogel ink was 3D-printed into the construct with interconnected porous structure with hierarchically organized porosity and a combination of several promising properties. Namely, due to the covalent linkage of the antibacterial peptide to the SF, the scaffold shows potent bactericidal efficiency toward Gram-positive and Gram-negative bacteria. Moreover, nanostructured silica components in the 3D-printed composites could intertwine with SF-CM-RGD to support the mechanical properties in the final scaffold and the final osteoconductivity of the scaffold. This study supports the promising properties of 3D-printed silica-SF-based hybrid aerogels constructs for repairing bone defect.

Application of Fractal Geometry in Gas Sensor: A Review

Increasing the specific superficial area of gas sensing layer is a direction to improve the performance of sensors. Considering the special features, high specific superficial area of fractal geometry and the fractal properties of thin film in the deposition and growth progress, many studies have explored the relationship between fractal geometry and gas sensing characteristics of the sensors. In this paper, the application and development of fractal geometry in gas sensors are reviewed, the superiority of fractal geometry in the application of gas sensors, as well as the formation mechanism and influencing factors of fractal geometry are indicated. The advantages of fractal analysis in the characterization of film morphology and properties are also discussed. This review demonstrates that fractal geometry can be successfully used in the design of macro and micro structure of gas sensors to improve the performance of sensors. Films with appropriate fractal structure and best gas sensing performance can be obtained by controlling the deposition and parameters. 3D printing and MEMS technologies provide an implementation scheme to prepare sensors with fractal structure, such as electrodes and heater based on Hilbert curve and substrates based on Menger sponge.

Hierarchically porous alumina catalyst carrier with biomimetic vein structure prepared by direct ink writing

Biomimetic porous ceramics have great application potential in the petrochemical industry; their biomimetic porous structure is conducive to mass transfer, energy exchange and catalytic reactions. However, it is challenging to produce biomimetic porous ceramics with complex shapes using conventional processes. Herein, we demonstrate a novel structural bionic and 3D printing strategy and a pseudo-boehmite-based slurry for fabricating hierarchical alumina ceramic carriers with biomimetic vein structures. Tuneable hierarchical porosity from nm to mm scales, high specific surface area, and superior strength have been achieved by innovatively combining dehydroxylation and peptisation of pseudo-boehmite, direct ink writing (DIW), and post-sintering processes. The effects of post-sintering temperature and impregnation treatment on the crush strength, porosity, and specific surface area were systematically investigated. The optimised porous ceramics exhibited a crush strength of 54.453 ± 7.359 N/cm, specific surface area of 109.870 ± 0.143 m2/g, and porosity of 60.03 ± 2.72%. The catalytic test for dry reforming of methane was conducted on biomimetic catalysts loaded with nickel (Ni) and phosphorus (P). The biomimetic catalyst had a remarkable methane conversion of 41.27%, in addition to mass transfer and coke inhibition effects. Through the integrated biomimetic design of macro–micro structures, monolithic alumina catalyst carriers with biomimetic vein structures prepared by DIW can potentially be used more efficiently in industrial catalytic reactions.

Design and analysis of 2D/3D negative hydration expansion Metamaterial driven by hydrogel

In this paper, we developed a new design and preparation method of 2D and 3D composite metamaterial with adjustable isotropic negative hydration expansion (NHE) function based on re-entrant auxetic honeycomb. The metamaterial is composed of composite lattice microstructure with hydrogel driving layer and re-entrant framework and prepared by multi-material 3D printer. Experimental, simulation and theoretical investigation were carried out to demonstrate the design method and NHE deformation effects of the metamaterial. It was shown that the effective NHE coefficient depends on the length of the driving layer and the straight bar connecting the lattice microstructures. In addition, a non-monotonic relationship was found between the bandings angle θ2 and the length ratio (s/a) due to the constraint effect on both ends of the composite beam. Through the parameter design of the lattice microstructure, the NHE coefficient of can be adjusted within the range of 0–22.4%. For the 3D sample, the value of the NHE coefficient is among the largest achieved in experiments to date. This work provides a practical method for obtaining 2D and 3D metamaterial with adjustable NHE and can be applied to the design of macro-, micro- and nano-metamaterial.

ANMJ-morph: a simple macro for rapid analysis of neuromuscular junction morphology.

Large-scale data analysis of synaptic morphology is becoming increasingly important to the field of neurobiological research (e.g. ‘connectomics’). In particular, a detailed knowledge of neuromuscular junction (NMJ) morphology has proven to be important for understanding the form and function of synapses in both health and disease. The recent introduction of a standardized approach to the morphometric analysis of the NMJ—‘NMJ-morph’—has provided the first common software platform with which to analyse and integrate NMJ data from different research laboratories. Here, we describe the design and development of a novel macro—‘automated NMJ-morph’ or ‘aNMJ-morph’—to update and streamline the original NMJ-morph methodology. ImageJ macro language was used to encode the complete NMJ-morph workflow into seven navigation windows that generate robust data for 19 individual pre-/post-synaptic variables. The aNMJ-morph scripting was first validated against reference data generated by the parent workflow to confirm data reproducibility. aNMJ-morph was then compared with the parent workflow in large-scale data analysis of original NMJ images (240 NMJs) by multiple independent investigators. aNMJ-morph conferred a fourfold increase in data acquisition rate compared with the parent workflow, with average analysis times reduced to approximately 1 min per NMJ. Strong concordance was demonstrated between the two approaches for all 19 morphological variables, confirming the robust nature of aNMJ-morph. aNMJ-morph is a freely available and easy-to-use macro for the rapid and robust analysis of NMJ morphology and offers significant improvements in data acquisition and learning curve compared to the original NMJ-morph workflow.

Lessons learned from intervertebral disc pathophysiology to guide rational design of sequential delivery systems for therapeutic biological factors.

Intervertebral disc (IVD) degeneration has been associated with low back pain, which is a major musculoskeletal disorder and socio-economic problem that affects as many as 600 million patients worldwide. Here, we first review the current knowledge of IVD physiology and physiopathological processes in terms of homeostasis regulation and consecutive events that lead to tissue degeneration. Recent progress with IVD restoration by anti-catabolic or pro-anabolic approaches are then analyzed, as are the design of macro-, micro-, and nano-platforms to control the delivery of such therapeutic agents. Finally, we hypothesize that a sequential delivery strategy that i) firstly targets the inflammatory, pro-catabolic microenvironment with release of anti-inflammatory or anti-catabolic cytokines; ii) secondly increases cell density in the less hostile microenvironment by endogenous cell recruitment or exogenous cell injection, and finally iii) enhances cellular synthesis of extracellular matrix with release of pro-anabolic factors, would constitute an innovative yet challenging approach to IVD regeneration.

Micro- and macromodels of social networks. I. Theory fundamentals

We consider two approaches to the design and analysis of social networks, namely, macro- and microdescriptions. According to the former approach, the structure of relations in a social network is averaged, and agents' behavior is studied "in the mean." The latter approach takes into account the structural features of the influence graph of agents and their individual decision-making principles. The first and second approaches are compared using the threshold model of collective behavior with a common relative threshold.

Micro porosity analysis in additive manufactured NiTi parts using micro computed tomography and electron microscopy

Long-term fixation of biomedical implants is achievable by using porous materials. These kinds of materials can produce a stable bone-implant interface. A critical aspect in production of porous implants is the design of macro and micro pores. In this research, a micro direct metal deposition process, newly developed as a potential method for implant production, was used to fabricate porous NiTi parts. The effect of process parameters on formation and distribution of micro pores was analysed using micro computed tomography and scanning electron microscopy. The analysis showed that, by increasing the laser scanning speed, inherent micro porosity increases. Also, it was found that there is an optimum temperature to achieve minimum inherent micro porosity by micro direct metal deposition which is 300°C for NiTi powder.

Design of a linear macro–micro actuation stage considering vibration isolation

In microelectronics manufacturing, macro–micro actuation stages are typically applied to obtain a high-precision positioning at a high acceleration. Macro–micro actuation stage comprises a voice coil motor that achieves a high-acceleration motion and a piezoelectric stack actuator which realizes nano-positioning motion. However, high acceleration and nano-positioning are a pair of interacted contradictions. Especially, vibration generated from the high-acceleration motion is the dominating obstacle for enhancement of the nano-positioning implementation. The concentration of the article is a design of a linear macro–micro actuation stage considering vibration isolation. In particular, a floating stator system is proposed to suppress the stage’s vibration and further guarantee a higher precision positioning. Additionally, a flexure hinge mechanism connected to the voice coil motor serially is proposed to achieve a linear motion guide and preload to the piezoelectric stack actuator. The results show that the isolate vibration of the floating stator system is effective in both the time and frequency domain analysis of test. And precision positioning is also further validated experimentally through the flexure hinge mechanism and other components.

Modification and characteristics of biodegradable polymer suitable for selective laser sintering

This paper investigates the methodology to modify biodegradable polymers having random size, shape, and molecular weight into particles appropriate for selective laser sintering (SLS), which is a powerful technique to build arbitrarily complex objects. Polycaprolactone (PCL), which has recently drawn significant attention as biodegradable polymer for potential application in bone and cartilage repair, was used in this study. PCL powders with various sizes, shapes, and molecular weights were modified by chemical processes and resultant shape, size distribution, degree of crystallinity, and thermophysical properties were observed by optical and scanning electron microscopy (OM and SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The modified PCL as well as raw material were sintered by CO2 laser irradiation with 10.6-im wavelength, and specimens for tensile testing were fabricated. By simple design of experiment (DOE) method, macro and micro structures of the fabricated parts were observed depending on various processing parameters related with SLS. Finally, micro tensile tests were conducted, and tensile properties as a function of molecular weight and particle shape were obtained. All the procedures attempted in this study can be extensively applied to other biodegradable polymers. Since SLS has an advantage to deposit multiple materials spatially, the obtained mechanical properties can be referred to generate functionally graded material (FGM), which incorporates deliberately designed transition in materials composition and properties within a component, by SLS.

Robust topology optimization accounting for spatially varying manufacturing errors

This paper presents a robust approach for the design of macro-, micro-, or nano-structures by means of topology optimization, accounting for spatially varying manufacturing errors. The focus is on structures produced by milling or etching; in this case over- or under-etching may cause parts of the structure to become thinner or thicker than intended. This type of error is modeled by means of a projection technique: a density filter is applied, followed by a Heaviside projection, using a low projection threshold to simulate under-etching and a high projection threshold to simulate over-etching. In order to simulate the spatial variation of the manufacturing error, the projection threshold is represented by a (non-Gaussian) random field. The random field is obtained as a memoryless transformation of an underlying Gaussian field, which is discretized by means of an EOLE expansion. The robust optimization problem is formulated in a probabilistic way: the objective function is defined as a weighted sum of the mean value and the standard deviation of the structural performance. The optimization problem is solved by means of a Monte Carlo method: in each iteration of the optimization scheme, a Monte Carlo simulation is performed, considering 100 random realizations of the manufacturing error. A more thorough Monte Carlo simulation with 10000 realizations is performed to verify the results obtained for the final design. The proposed methodology is successfully applied to two test problems: the design of a compliant mechanism and a heat conduction problem.

A 4.5 mW/Gb/s 6.4 Gb/s 22+1-Lane Source Synchronous Receiver Core With Optional Cleanup PLL in 65 nm CMOS

This paper describes the design of a product-level low-power source-synchronous link receiver macro for data rates of 3.2-6.4 Gb/s. The receiver macro consists of 22 data channels plus one forwarded-clock channel, and supports both differential and ground termination. A pulsed CDR with programmable bandwidth is implemented to save power in the CDR. Time dithering is applied to the CDR to avoid notches in the jitter tolerance curve. The receiver clock path incorporates both a clean-up PLL and a polyphase filter for RX clock generation, from which one can be chosen to generate the receive clock. It is shown how jitter in a source-synchronous link is related to skew between clock and data, as well as cross-talk from the data to the clock wires. The jitter performance of the RX using either the polyphase filter or the PLL for clock generation is compared for different loop bandwidths. The RX core was implemented in a 65 nm Bulk CMOS technology. Total power consumption for the 22+1 lane RX PHY core running at 6.4 Gbps with the polyphase filter and in pulsed CDR mode is 635 mW or 4.5 mW/Gbps.

JMD in the New Decade

JMD in the New Decade

Nonlinear Vibrations of Beams, Strings, Plates, and Membranes Without Initial Tension

The subject of this paper is nonlinear vibrations of beams, strings (defined as beams with very thin uniform cross sections), plates and membranes (defined as very thin plates) without initial tension. Such problems are of great current interest in minute structures with some dimensions in the range of nanometers (nm) to micrometers (μm). A general discussion of these problems is followed by finite element method (FEM) analyses of beams and square plates with different boundary conditions. It is shown that the common practice of neglecting the bending stiffness of strings and membranes, while permissible in the presence of significant initial tension, is not appropriate in the case of nonlinear vibrations of such objects, with no initial tension, and with moderately large amplitude (of the order of the diameter of a string or the thickness of a plate). Approximate, but accurate analytical expressions are presented in this paper for the ratio of the nonlinear to the linear natural fundamental frequency of beams and plates, as functions of the ratio of amplitude to radius of gyration for beams, or the ratio of amplitude to thickness for square plates, for various boundary conditions. These expressions are independent of system parameters—the Young’s modulus, density, length, and radius of gyration for beams; the Young’s modulus, density, length of side, and thickness for square plates. (The plate formula exhibits explicit dependence on the Poisson’s ratio.) It is expected that these results will prove to be useful for the design of macro as well as micro and nano structures.

Custom design of CMOS low-power high-performance digital signal-processing macro for hard-disk-drive applications

The design challenges and custom design techniques associated with low-power, small-area, high-performance CMOS digital signal-processing circuits for hard-disk-drive applications are presented. The advantages of custom design are demonstrated by an example custom digital FIR filter macro that provides substantial improvement in performance, area, and power dissipation over standard-cell implementations.