An efficient current-based logic cell model for crosstalk delay analysis

Logic cell modelling is an important component in the analysis and design of CMOS integrated circuits, mostly due to nonlinear behaviour of CMOS cells with respect to the voltage signal at their input and output pins. A current-based model for CMOS logic cells is presented, which can be used for effective crosstalk noise and delta delay analysis in CMOS VLSI circuits. Existing current source models are expensive and need a new set of Spice-based characterisation, which is not compatible with typical EDA tools. In this article we present Imodel, a simple nonlinear logic cell model that can be derived from the typical cell libraries such as NLDM, with accuracy much higher than NLDM-based cell delay models. In fact, our experiments show an average error of 3% compared to Spice. This level of accuracy comes with a maximum runtime penalty of 19% compared to NLDM-based cell delay models on medium-sized industrial designs.     

A coupled Thermal‐mechanical FE Model of Flow Localization during the Hot Torsion Test

The hot torsion test (HTT) has been extensively used to analyse and physically model the flow behaviour and microstructure evolution of materials and alloys during hot deformation processes. The geometry of the specimen is a key factor for obtaining reliable results. In the present work, a thermo‐rigid viscoplastic FE code, THORAX.FOR, was developed to describe the interaction of thermal‐mechanical conditions and geometries of the HTT specimens. This was used to recommend the conditions for avoiding flow localization during HTT of API‐X70 microalloyed steel. The simulation results show how an inappropriate choice of both test specimen geometry and twist rate of deformation could lead to a significant temperature raise in the middle of the gauge section and temperature gradient in the radial and longitudinal direction of the specimen. This consequently causes flow localization during the test. Therefore, assumptions of isothermal forming conditions or uniform strain softening may not be valid in many test scenarios. These assumptions could introduce significant errors in the post results of the test such as flow curve and interpretation of microstructure evolution. Recommendations on proper specimen geometry for a specified strain rate will be given to avoid flow localization during the hot torsion test.     

Preemptive cloud resource allocation modeling of processing jobs

Cloud computing allows execution and deployment of different types of applications such as interactive databases or web-based services which require distinctive types of resources. These applications lease cloud resources for a considerably long period and usually occupy various resources to maintain a high quality of service (QoS) factor. On the other hand, general big data batch processing workloads are less QoS-sensitive and require massively parallel cloud resources for short period. Despite the elasticity feature of cloud computing, fine-scale characteristics of cloud-based applications may cause temporal low resource utilization in the cloud computing systems, while process-intensive highly utilized workload suffers from performance issues. Therefore, ability of utilization efficient scheduling of heterogeneous workload is one challenging issue for cloud owners. In this paper, addressing the heterogeneity issue impact on low utilization of cloud computing system, conjunct resource allocation scheme of cloud applications and processing jobs is presented to enhance the cloud utilization. The main idea behind this paper is to apply processing jobs and cloud applications jointly in a preemptive way. However, utilization efficient resource allocation requires exact modeling of workloads. So, first, a novel methodology to model the processing jobs and other cloud applications is proposed. Such jobs are modeled as a collection of parallel and sequential tasks in a Markovian process. This enables us to analyze and calculate the efficient resources required to serve the tasks. The next step makes use of the proposed model to develop a preemptive scheduling algorithm for the processing jobs in order to improve resource utilization and its associated costs in the cloud computing system. Accordingly, a preemption-based resource allocation architecture is proposed to effectively and efficiently utilize the idle reserved resources for the processing jobs in the cloud paradigms. Then, performance metrics such as service time for the processing jobs are investigated. The accuracy of the proposed analytical model and scheduling analysis is verified through simulations and experimental results. The simulation and experimental results also shed light on the achievable QoS level for the preemptively allocated processing jobs.     

Cellulose-reinforced bioglass composite as flexible bioactive bandage to enhance bone healing

Low mechanical strength of cellulose nanofiber (CNF) and its lack of osseoconductivity in physiological media limit its application for bone tissue regeneration. To resolve these limitations, the densely packed cellulosic layers with thickness of ~50 μm impregnated by 58S bioglass (BG) nanoparticles was made-up (via the simple method of vacuum filtration) in this study. The developed fabrics showed uniform distribution of BG nanoparticles and effectively wrapped between CNF layers which caused sustained ion release into the SBF × 5 solution. The FTIR spectrum of the fabric after the SBF test was illustrated the presence of newly formed HA on the fabric. Also, no significant difference in the hydrophilicity of pure CNF and the developed fabric was presented by AFM results. Alkaline phosphatase activity (ALP) and cytotoxicity evaluation were performed to investigate cell treatment of the fabric which indicated its superior osteogenic potential of developed fabric compared with pure CNF. The increase in osseoconductivity of the developed fabric caused better cell attachment thanks to the interconnected CNFs network. Effective integration of BG nanoparticles between CNF interlayers increased Young's modulus of the developed fabric by 50% that mitigated swelling and enhanced structural stability of CNFs in the SBF × 5 solution. Thus, developed fabric could be considered as an appropriate biomaterial such as a bandage around cracked bone before metallic implantation with good mechanical integrity of the layered constructs obtained as well as strength and swelling.     

P75 and S100 gene expression induced by cell-imprinted substrate and beta-carotene to nerve tissue engineering

Here we aimed to differentiate adipose derived stem cells (ADSCs) to Schwann cells (SCs), as one of the major and instrumental cell sources in nerve regeneration, by synergistic application of imprinting method and β-carotene. Accordingly, the topography of Schwann cells was imprinted on poly dimethyl siloxane (PDMS) substrates via mold casting and human ADSCs seeded on substrates; moreover, β-carotene was added to induce hADSCs differentiation. Physiochemical evaluations of PDMS by FTIR spectra presented its silicon-methyl bond (Si CH₃) at 1260 cm⁻¹. Morphology analysis by crystal violet, picrosirus red staining, and SEM images illustrated that MSCs seeded on imprinted substrates have formed SC-like morphology. Furthermore, according to q-PCR and ICC evaluations, SCs specific markers; S100 and P75 in addition of 5 μl β-carotene (BC) were upregulated (p-value<0.001). Also, the expression was detected on the imprinted surfaces without β-carotene to a lesser degree. Our study revealed that Schwann cell imprinted substrates can mimic the morphology and topography of SCs and induce differentiation signals in mesenchymal stem cells (MSCs). In addition, the potency of β-carotene as an organic substance in boosting and stimulating the neural differentiation was demonstrated. Relevantly, the reports have confirmed the synergistic pivotal roles of β-carotene and patterned surfaces in directing MSCs into SC-like cells differentiation without applying expensive and less safe chemical growth factors.     

A novel numerical modeling paradigm for bio particle tracing in non-inertial microfluidics devices

Microsystem Technologies - In this work, we report on the design and implementation of a new method for the two dimensional (2D) simulation of rigid spherical particles trajectory which are to be...     

Dynamics and vibrations of particle-sensing MEMS considering thermal and electrostatic actuation

Microsystem Technologies - The dynamic behavior of micro-cantilevers and micro-bridges under electrostatic and thermal&nbsp;base actuations is investigated in this paper. To solve the equation...     

Thermal actuation and confinement of water droplets on paper-based digital microfluidics devices

In this paper, the thermocapillary actuation is implemented to manipulate and confine the fluid droplets in a paper-based digital microfluidics (PB-DMF) device. The main advantage of using the thermocapillary actuation over the traditional electrowetting-on-dielectric actuation in the DMF devices is its ability to work with lower operating DC voltages. The proposed device is fabricated by the low-cost screen printing method using very low-cost materials. In order to overcome the weak controllability of the device over the droplets, a new thermal confinement technique is proposed which simply embedded in the device electrode pattern. A new thermally actuated valve is also designed to work based on thermocapillary actuation for switching on or off the droplets. The fabricated DMF device and the thermal valve are both combined with a microfluidics paper-based analytical device to form a hybrid paper chip in which the droplets are driven by both channel-based and droplet-based devices. The device operation is tested by using a biochemical glucose colorimetric detection assay.