Electric drive subsystem for a low-storage requirement hybridelectric vehicle

Integrating an electric machine drive system into the powertrain of a hybrid electric vehicle (HEV) represents a challenging exercise in packaging complex electromechanical and power electronic subsystems. The Ford combined alternator starter (FCAS) and its attendant power and control electronics are physically partitioned because power electronics has not yet evolved to the stage in which fully packaged drives can be realized. A similar situation exists for the control and sensor subsystems necessary for a fully functional high-performance drive. Hardware partitioning requires that more attention be given to installation issues and to mitigating system interactions. The FCAS system consists of an integrated starter/alternator (S/A), an S/A module (SAM), and a vehicle electrical infrastructure that can support the power and energy levels demanded. Our field experience with the FCAS system is presented along with test results obtained from vehicle operation     

Investigation of Gold Nanoparticle Inks for Low-Temperature Lead-Free Packaging Technology

Gold nanoparticle inks were investigated as a potential candidate for lead-free packaging applications. Inks consisted of surfactant-passivated nanoparticles dissolved in a solvent. Optimized gold inks are able to sinter at temperatures as low as 120°C and achieve conductivities of up to 70% of bulk. Once sintered, the metallic structure reverts to bulk-like properties and approaches bulk reliability and performance. Thus nanoparticle-based solders would operate at much lower homologous temperatures as compared with alloy-based solders. Nanoparticle inks under investigation were sintered at 180°C. The resulting material exhibited a resistivity of 5 μΩ cm, which is significantly lower than those of Pb-Sn and Sn-Ag-Cu. Electromigration studies were carried out and time to failure was investigated as a function of temperature. Electromigration activation energy was calculated through Black’s equation to be 0.52 eV, which is consistent with surface/grain boundary diffusion. These studies suggest that nanoparticle-ink-based films show excellent robustness, due to their irreversible conversion to bulk-like materials. Nanoparticle inks are thus promising candidates for next-generation lead-free solders.     

Comparative performance of some polynomial-based lowpass filters for microwave/digital transmission applications

This paper reports on the comparative performances of some polynomial based lowpass filters in the lumped elements, microstrip and defected ground structure (DGS) environment. The microwave designers are normally familiar with Butterworth, Chebyshev and Bessel filters. However, many more polynomials based, ripple and non-ripple types LPF have been suggested for the low-frequency applications. Some of these LPF, such as L-opt, H-type, Transitional Butterworth-Legendre (TBL), Pascal, Legendre group of LPF, are compared for their applications in analog microwaves, digital transmission, efficiency enhancement of the linear power amplifiers and five level partial response modulations. A method is reported to compute the ripple frequency for the Legendre group of LPF and Pascal LPF. Further, a design is suggested to significantly improve group delay performance of high selectivity filters.     

Effects of reflow on wettability, microstructure and mechanical properties in lead-free solders

Solder joints used in electronic applications undergo reflow operations. Such operations can affect the solderability, interface intermetallic layer formation and the resultant solder joint microstructure. These in turn can affect the overall mechanical behavior of such joints. In this study the effects of reflow on solderability and mechanical properties were studied. Nanoindentation testing (NIT) was used to obtain mechanical properties from the non-reflow (as-melted) and multiple reflowed solder materials. These studies were carried out with eutectic Sn-3.5Ag solders, with or without mechanically added Cu or Ag reinforcements, using Cu substrates. Microstructural analysis was carried out on solder joints made with the same solders using copper substrate.     

Precious‐Metal‐Free Electrocatalysts for Activation of Hydrogen Evolution with Nonmetallic Electron Donor: Chemical Composition Controllable Phosphorous Doped Vanadium Carbide MXene

The insufficient strategies to improve electronic transport, the poor intrinsic chemical activities, and limited active site densities are all factors inhibiting MXenes from their electrocatalytic applications in terms of hydrogen production. Herein, these limitations are overcome by tunable interfacial chemical doping with a nonmetallic electron donor, i.e., phosphorization through simple heat‐treatment with triphenyl phosphine (TPP) as a phosphorous source in 2D vanadium carbide MXene. Through this process, substitution, and/or doping of phosphorous occurs at the basal plane with controllable chemical compositions (3.83–4.84 at%). Density functional theory (DFT) calculations demonstrate that the P? C bonding shows the lowest surface formation energy (ΔG_Surf) of 0.027 eV Å^?2 and Gibbs free energy (ΔG_H) of –0.02 eV, whereas others such as P‐oxide and P? V (phosphide) show highly positive ΔG_H. The P3–V₂CT_x treated at 500 °C shows the highest concentration of P? C bonds, and exhibits the lowest onset overpotential of –28 mV, Tafel slope of 74 mV dec^?1, and the smallest overpotential of ‐163 mV at 10 mA cm^?2 in 0.5 m H₂SO₄. The first strategy for electrocatalytically accelerating hydrogen evolution activity of V₂CT_x MXene by simple interfacial doping will open the possibility of manipulating the catalytic performance of various MXenes.     

A cross-layer design: energy efficient multilevel dynamic feedback scheduling in wireless sensor networks using deadline aware active time quantum for environmental monitoring

Recently, Packet scheduling plays a vital role in Wireless Sensor Networks (WSNs). The major key challenges include delay, packet dropping, energy consumption and lifetime due to constraints in energy and computing resources. All the research works on packet scheduling scheme in WSN uses only First Come First Served (FCFS) and Dynamic Multilevel Priority (DMP) schemes. FCFS works based on packet arrival time, it leads to starvation and high processing overhead for real-time packets. DMP works in multilevel with dynamic priority reduces the transmission overhead and bandwidth; it consumes more resources for real-time task leads to deadlock. To solve these problems, this work presents Multilevel Dynamic Feedback Scheduling (MDFS) algorithm. The sensor node classifies the emergency and normal data into three different ready queues named as high, medium and low priority, respectively. The queues are connected with a feedback mechanism; each packet from the sensor node has its own time quantum value based on the deadline. The updated time quantum value is compared with the boundary value of the queues, depends on the updated value the data packets are moved between queues with help of feedback mechanism. The simulation result proves that the projected MDFS outperforms in WSN environment.     

Cell‐Tethered Ligands Modulate Bone Remodeling by Osteoblasts and Osteoclasts

The goals of the present study are to establish an in vitro co‐culture model of osteoblast and osteoclast function and to quantify the resulting bone remodeling. The bone is tissue engineered using well‐defined silk protein biomaterials in 2D and 3D formats in combination with human cells. Parathyroid hormone (PTH) and glucose‐dependent insulinotropic peptide (GIP) are selected because of their roles in bone remodeling for expression in tethered format on human mesenchymal stem cells (hMSCs). The cell‐modified biomaterial surfaces are reconstructed from scanning electron microscopy images into 3D models for quantitative measurement of surface characteristics. Increased calcium deposition and surface roughness are found in 3D surface models of silk protein films remodeled by co‐cultures containing tethered PTH, and decreased surface roughness is found for the films remodeled by tethered GIP co‐cultures. Increased surface roughness is not found in monocultures of hMSCs expressing tethered PTH, suggesting that osteoclast‐osteoblast interactions in the presence of PTH signaling are responsible for the increased mineralization. These data point towards the design of in vitro bone models in which osteoblast‐osteoclast interactions are mimicked for a better understanding of bone remodeling.     

Exploring online virtual networks mapping with stochastic bandwidth demand in multi-datacenter

Network virtualization serves as a promising technique for providing a flexible and highly adaptable shared substrate network to satisfy the diversity of demands and overcoming the ossification of Internet infrastructure. As a key issue of constructing a virtual network (VN), various state-of-the-art algorithms have been proposed in many research works for addressing the VN mapping problem. However, these traditional works are efficient for mapping VN which with deterministic amount of network resources required, they even deal with the dynamic resource demand by using over-provisioning. These approaches are obviously not advisable, since the network resources are becoming more and more scarce. In this paper, we investigate the online stochastic VN mapping (StoVNM) problem, in which the VNs are generated as a Poisson process and each bandwidth demand x _i follows a normal distribution, i.e., x _i ~ N(μ _i , σ _i ²). Firstly, we formulate the model for StoVNM problem by mixed integer linear programming, which with objective including minimum-mapping-cost and load balance. Then, we devise a sliding window approach-based heuristic algorithm w-StoVNM for tackling this NP-hard StoVNM problem efficiently. The experimental results achieved from extensive simulation experiments demonstrate the effectiveness of the proposed approach and superiority than traditional solutions for VN mapping in terms of VN mapping cost, blocking ratio, and total net revenue in the long term.     

Thermomechanical fatigue behavior of Sn-Ag solder joints

Microstructural studies of thermomechanically fatigued actual electronic components consisting of metallized alumina substrate and tinned copper lead, soldered with Sn-Ag or 95.5Ag/4Ag/0.5Cu solder were carried out with an optical microscope and environmental scanning electron microscope (ESEM). Damage characterization was made on samples that underwent 250 and 1000 thermal shock cycles between −40°C and 125°C, with a 20 min hold time at each extreme. Surface roughening and grain boundary cracking were evident even in samples thermally cycled for 250 times. The cracks were found to originate on the free surface of the solder joint. With increased thermal cycles these cracks grew by grain boundary decohesion. The crack that will affect the integrity of the solder joint was found to originate from the free surface of the solder very near the alumina substrate and progress towards and continue along the solder region adjacent to the Ag₃Sn intermetallic layer formed with the metallized alumina substrate. Re-examination of these thermally fatigued samples that were stored at room temperature after ten months revealed the effects of significant residual stress due to such thermal cycles. Such observations include enhanced surface relief effects delineating the grain boundaries and crack growth in regions inside the joint.     

Steganalysis of Network Packet Length Based Data Hiding

Recently, data hiding by modifying network parameters like packet header, payload, and packet length has become popular among researchers. Different algorithms have been proposed during the last few years which have altered the network packets in different ways to embed the data bits. Some of these algorithms modify the network packet length for embedding. Although most of the packet length based embedding schemes try to imitate the normal network traffic distribution, they have altered the statistical distribution of network packet lengths during embedding. These statistical anomalies can be exploited to detect such schemes. In this paper, a second order detection scheme for packet length based steganography has been proposed. A comprehensive set of experiments have been carried out to show that the proposed detection scheme can detect network packet length based steganography with a considerably high accuracy.