Electrical Disconnection Research Articles

Fluctuation statistics in the scrape-off layer of Alcator C-Mod

We study long time series of the ion saturation current and floating potential, sampled by Langmuir probes dwelled in the outboard mid-plane scrape-off layer and embedded in the lower divertor baffle of Alcator C-Mod. A series of ohmically heated L-mode plasma discharges is investigated with line-averaged plasma density ranging from to 0.42, where nG is the Greenwald density. All ion saturation current time series that are sampled in the far scrape-off layer are characterized by large-amplitude burst events. Coefficients of skewness and excess kurtosis of the time series obey a quadratic relationship and their histograms coincide partially upon proper normalization. Histograms of the ion saturation current time series are found to agree well with a prediction of a stochastic model for the particle density fluctuations in scrape-off layer plasmas.The distribution of the waiting times between successive large-amplitude burst events and of the burst amplitudes are approximately described by exponential distributions. The average waiting time and burst amplitude are found to vary weakly with the line-averaged plasma density. Conditional averaging reveals that the radial blob velocity, estimated from floating potential measurements, increases with the normalized burst amplitude in the outboard mid-plane scrape-off layer. For low density discharges, the conditionally averaged waveform of the floating potential associated with large amplitude bursts at the divertor probes has a dipolar shape. In detached divertor conditions the average waveform is random, indicating electrical disconnection of blobs from the sheaths at the divertor targets.

Si nanoparticles/graphene composite membrane for high performance silicon anode in lithium ion batteries

Silicon is an exciting anode material with high specific capacity of 4200 mAh g−1, which is more than ten times the theoretical capacity of the commercialized graphite anode. However, successful applications of Si anode have been impeded by rapid capacity fading caused by large volume expansion (pulverization and subsequent electrical disconnection) during lithiation/delithiation and low ionic/electronic conductivity. Tackling the Si anode problems require a multifaceted design, which can simultaneously address the above-mentioned problems of Si-based anode. Herein, we present a facile approach to fabricate the freestanding Si/graphene composite membrane for Si anode in a large scale, allowing control over uniformly inserting Si nanoparticles into the pores between graphene sheets from nanoscale to macroscale. We demonstrate its high specific discharge capacities and excellent capacity retention. Over a long-term cycling of 1300 cycles at 400 mA g−1, a capacity decay as low as 0.06% per cycle and an average Coulombic efficiency of 99.8% was achieved.

Radiofrequency Catheter Ablation for Atrial Fibrillation Elicited "Jackhammer Esophagus": A New Complication Due to Vagal Nerve Stimulation?

Radiofrequency catheter ablation (RFCA) is a potentially curative method for treatment of highly symptomatic and drug-refractory atrial fibrillation (AF). However, this technique can provoke esophageal and nerve lesion, due to thermal injury. To our knowledge, there have been no reported cases of a newly described motor disorder, the Jackhammer esophagus (JE) after RFCA, independently of GERD. We report a case of JE diagnosed by high-resolution manometry (HRM), in whom esophageal symptoms developed 2 weeks after RFCA, in absence of objective evidence of GERD. A 65-year-old male with highly symptomatic, drug-refractory paroxysmal AF was candidate to complete electrical pulmonary vein isolation with RFCA. Prior the procedure, the patient underwent HRM and impedance-pH to rule out GERD or hiatal hernia presence. All HRM parameters, according to Chicago classification, were within normal limits. No significant gastroesophageal reflux was documented at impedance pH monitoring. Patient underwent RFCA with electrical disconnection of pulmonary vein. After two weeks, patient started to complain of dysphagia for solids, with acute chest-pain. The patient repeated HRM and impedance-pH monitoring 8 weeks after RFCA. HRM showed in all liquid swallows the typical spastic hypercontractile contractions consistent with the diagnosis of JE, whereas impedance-pH monitoring resulted again negative for GERD. Esophageal dysmotility can represent a possible complication of RFCA for AF, probably due to a vagal nerve injury, and dysphagia appearance after this procedure must be timely investigated by HRM.

Dimensionally Stable and Fast-Charging Graphite-Silicon Planar Composite Anode for Li-Ion Batteries

Advanced Li-ion batteries (LIBs) have been developed to have high capacity density, long cycle life, and high-rate performance for portable electronics, electric vehicles (EVs), and renewable energy storage. Graphite is currently the predominant anode material for commercial LIBs because it has a low cost, low charge/discharge plateau potential, satisfactory specific capacity (372 mAh/g), and substantially high dimensional stability; its essential role in high-energy LIBs is expected to continue. Si is a potential Li-insertion anode material that has a substantially higher capacity than graphite but is susceptible to large (>300% when fully lithiated) volume expansion. The cyclic dimensional variations during charge/discharge cycles result in pulverization and electrical disconnection from the conductive paths of the Si active materials, leading to rapid capacity reduction during the cycles. In spite of a large amount of literature devoted to solving this issue in the past years, long-lasting Si anode up to now remains as a formidable challenge. On the other hand, composite anodes comprising graphite and limited amount of Si or Si oxide may be attractive transient products for advanced high-energy LIBs before viable Si-dominant anodes are realized. Moreover, improvement in the rate capability of Si-based anodes is needed for meeting the power requirements of various applications. In this presentation, a planar graphite-silicon composite Li-ion battery anode showing substantially higher capacities than graphite, fast-charging capability, and exceptional cycle stability will be described. The Si oxide-coated graphite flake (SGF) composite anode for Li-ion batteries (LIBs) synthesized by a unique microwave-heating process of graphite flakes (GFs) in a solution made of liquid polysiloxanes as the Si-containing precursor. Microwave-heating of the GFs induces the deposition of a conformal Si-containing conformal layer on the GF surfaces, which subsequently turns into oxide-graphite-oxide sandwiched planar composite structure. The resulting SGF exhibits a reversible specific capacity of nearly 480 mAh/g, 97% capacity retention at the current density of 2.5 A/g (~5C-rate), and 95% capacity retention after 400 cycles with an average Coulombic efficiency > 99.9%. The data suggest new strategies for both designing and synthesizing high-performance anode materials for LIB applications. Figure 1

Characterisation of Si-Based Anodes for Li-Ion Batteries By Operando Dilatometry and Acoustic Emission Measurements

The replacement of graphite by silicon as the active material in negative electrodes of Li-ion batteries is very attractive since the specific capacity of Si is 10 times higher than that of graphite. However, Si suffers from huge volume variation (up to ~300% vs 10% for C) during its lithiation. This leads to the electrode cracking which induces electrical disconnections in addition to cause an instability of the solid electrolyte interface (SEI), resulting in poor cycle life and low coulombic efficiency. A precise evaluation of the electrode volume variation and cracking upon cycling is thus crucial to develop more efficient Si-based anodes. To date, the study of their morphological changes is usually limited to post mortemexaminations by microscopy. This does not allow a detailed analysis of the morphological degradation process, which can significantly vary depending on the electrode composition and processing, and the charge/discharge conditions. In the present study, the volume change with cycling of Si-based anodes is monitored by operando dilatometry experiments. For that purpose, a specific displacement transducer is used, which allows measuring expansion or shrinkage of the electrode during cycling down to the sub-micrometer range. Operando acoustic emission (AE) measurements are also performed to study the electrode cracking [1]. The AE technique is based on the detection and analysis of transient elastics waves generated by stress events. The influence of the cycling conditions and electrode formulation on the volume variation and cracking of Si-based electrodes is highlighted, and correlated to their electrochemical performance. [1] A. Tranchot, A. Etiemble, P-X. Thivel, H. Idrissi, L. Roué In-situ acoustic emission study of Si-based electrodes for Li-ion batteries, J. Power Sources 279 (2015) 259-266.

Heterostructure of SnO2/TiO2 Nanotubes with Precise Wall Thickness Control As Anodes for Lithium Ion Battery

Devices of energy storage and conversion draw much attention recently, among the devices, secondary lithium-ion batteries for energy storage will play an increasingly important role. SnO2 as anode materials have attracted a lot of attention and are regarded as one of the most promising candidates for lithium-ion battery, with the theoretical reversible capacity of 782 mAhg- 1 and low enough discharge potential of 0.01V. Like to other alloy-type anode materials, its practical application has been impeded by the poor cycling performance owing to the pulverization and subsequent electrical disconnection of the electrode caused by extremely large volume change (about 300%) during the insertion and extraction processes of lithium ions. Li2O phases, produced by the reaction of SnO2 and lithium ions, are electrochemically inactive, which is the main reason for the large initial irreversible capacity. To overcome this problem, feasible strategy is to design the nanostructure. 1-dimensional nanotubular structures exhibit enhanced cyclability due to the short diffusion path of lithium ions within the wall of nanotubes and the local empty space in the core of tubular structures can accommodate its volume expansion. SnO2 and TiO2 nanotubes as well as their heterostructures were synthesized by anodic aluminum oxide (AAO) template-directed ALD (Atomic Layer Deposition) process. Nanotubes and their heterostructures were characterized by thermogravimetric/differential thermal analysis (TG/DTA), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray diffraction (XRD). The wall thickness of nonotubes can be easily controlled by the number of cycles during ALD processes. The porous nanotubes and their heterostructures exhibit high lithium ion storage capacity, fairly high rate performance, and high cyclability when evaluated as anode materials. As expected, the nanotubes of SnO2 with the wall thickness of about 10 nm show the initial capacity of 900 mAhg-1 and reduces down to 300 mAhg-1 after 50 cycle. The conversion reaction of SnO2 to Sn and further Li and Sn alloys were clealy observed by ex sity TEM. Composite heterostructures of TiO2/SnO2 show much improved cycle performance without any degradation during Li insertion and di-insertion. Advantages of using heterostructure of TiO2/SnO2 nanotubes as anode materials will be further discussed. Figure 1

Compliance Driven Cost Control for Telecom Infrastructure Operation Management

For a major telecom infrastructure company operating pan India including the state of Haryana, over 400 of their telecom infrastructure operation sites in Haryana had connected running power load more than the load sanctioned by the Haryana State Electricity Board (HSEB). As per the Standard Operating Procedure of this telecom infrastructure company (SOP), these 400 plus sites did not qualify under load upgrade category since the load had been increased without attracting any new tenancy i.e. Base Transceiver Station (BTS) of other telecom operators (service providers). Power load at these 400 sites had increased because of additional load due to sector expansion, cabinet expansion and 3G additions.Since running power load for a BTS cannot be more than the sanctioned load, these 400 sites were non compliant as per HSEB norms. If these sites were to be inspected by State Electricity Board inspectors and identified for non-conformity, it would have lead to heavy commercial penalties and even permanent disconnection of electricity to these sites. This inturn would entail using 24x7 diesel generators to keep sites active, increasing the operation cost manifold and also threatening environment pollution.A business case was prepared for this problem using the Define, Measure, Analyze, Improve and Control (DMAIC) methodology, a Six-Sigma approach. Cause of power overload and its effect was detailed out using root cause analysis and possible optimal remedial solution was arrived at for this project. The total penalties calculated as per the HSEB guidelines came out to be Rs.35 million whereas the total expenditure being involved in complying and coming out of this issue came out to be Rs.12 million approximately, thus making it a net saving of Rs.23 million for the telecom company. It was also observed that for the sites where the sanctioned load was 35%-50% of the required load, net saving potential was more compared to the sites where the sanctioned load was 55%-80% of the required load. A similar business case was carried out by the same company in the state of Himachal Pradesh and found that net saving potential was more compared to the state of Haryana.This was practically achieved by calling different partners (vendors) to discuss this project in an open forum. Non compliant site allocation was carried out on the basis of partner's confidence, band width and operational capabilities to deliver these sites. A reward per site was declared to motivate the partners for quick achievement of the desired results (compliance) with a gate criterion of ≥80% of the total site allocation done. The partners provided power usage receipts from HSEB as a proof of job done and payments were released accordingly. The change in power load was reflected in the subsequent electricity bills. The target set for the change over to the HSEB compliance was three months during which rigorous monitoring and review mechanism was put in place including circulation of Daily Progress Report to all internal and external stakeholders. To ensure that this issue does not repeat in future, the technical guidelines (SOP) was amended in terms of the power load to be upgraded for every new asset being deployed at site.

Large-sized out-of-plane stretchable electrodes based on poly-dimethylsiloxane substrate

This paper describes a reliable fabrication method of stretchable electrodes based on poly-dimethylsiloxane (PDMS) substrate. The electrode traces and pads were formed in out-of-plane structures to improve the flexibility and stretchability of the electrode array. The suspended traces and pads were attached to the PDMS substrate via parylene posts that were located nearby the traces and under the pads. As only conventional micro-electro-mechanical systems techniques were used, the out-of-plane electrode arrays were clearly fabricated at wafer level with high yield and reliability. Also, bi-layer out-of-plane electrodes were formed through additional fabrication steps in addition to mono-layer out-of-plane electrodes. The mechanical characteristics such as the stretchability, flexibility, and foldability of the fabricated electrodes were evaluated, resulting in stable electrical connection of the metal traces with up to 32.4% strain and up to 360° twist angle over 25 mm. The durability in stretched condition was validated by cyclic stretch test with 10% and 20% strain, resulting in electrical disconnection at 8600 cycles when subjected to 20% strain. From these results, it is concluded that the proposed fabrication method produced highly reliable, out-of-plane and stretchable electrodes, which would be used in various flexible and stretchable electronics applications.

Elastic a-silicon nanoparticle backboned graphene hybrid as a self-compacting anode for high-rate lithium ion batteries.

Although various Si-based graphene nanocomposites provide enhanced electrochemical performance, these candidates still yield low initial coloumbic efficiency, electrical disconnection, and fracture due to huge volume changes after extended cycles lead to severe capacity fading and increase in internal impedance. Therefore, an innovative structure to solve these problems is needed. In this study, an amorphous (a) silicon nanoparticle backboned graphene nanocomposite (a-SBG) for high-power lithium ion battery anodes was prepared. The a-SBG provides ideal electrode structures-a uniform distribution of amorphous silicon nanoparticle islands (particle size <10 nm) on both sides of graphene sheets-which address the improved kinetics and cycling stability issues of the silicon anodes. a-Si in the composite shows elastic behavior during lithium alloying and dealloying: the pristine particle size is restored after cycling, and the electrode thickness decreases during the cycles as a result of self-compacting. This noble architecture facilitates superior electrochemical performance in Li ion cells, with a specific energy of 468 W h kg(-1) and 288 W h kg(-1) under a specific power of 7 kW kg(-1) and 11 kW kg(-1), respectively.

Hybrid Polyvinyl Alcohol/Silicon Nanofiber Anodes with High Concentrated Graphene Nanoribbons for Rechargeable Lithium-ion Batteries

Despite the highest theoretical capacity of 3579 mAh/g in lithium–ion batteries,[1,2] silicon (Si) anodes have been still suffered from severe capacity fading, because of two kinds of drawbacks such as (i) dramatic volume expansion called pulverization leading to electrical disconnection as well as (ii) formation of solid–electrolyte interface on their surfaces.Herein, we prepared an organic/inorganic hybrid anode of polyvinyl alcohol (PVA)/Si nanoparticles (NPs)/graphene nanoribbons (GNRs) nanofibers via electrospinning process. Since PVA polymer could be dissolved in water, our hybrid nanofibers have been made via water‒based electrospinning, which means that toxic solvents like N–Methyl–2–pyrrolidone (NMP) do not need to be used for preparing the electrodes. Furthermore, the PVA polymer as a good dispersant can effectively help to disperse high‒concentrated GNRs (20 mg/ml) under water, which are unzipped from multiwall carbon nanotubes for better dispersion ability. The battery cells using the hybrid PVA/Si/GNRs nanofibers exhibited an initial high discharge capacity of over 5000 mAh/g at 0.1C because of the contribution of well–dispersed GNRs and Si NPs, while only Si NPs have the first discharge capacity of ca. 2500 mAh/g. At even 1C (3.6 A/g), they showed a high reversible capacity of around 1800 mAh/g owing to highly–conductive GNRs within the hybrid nanofibers. Moreover, the nanofibers retained very stable cycle retention of over 90% during 200 cycles. Such excellent cycle retention should be attributed by cross–linked and stabilized PVA nanofibers covering Si NPs, available to not only prohibit the volume expansion but also alleviate the formation of SEI layers. In terms of electrochemical properties, the hybrid nanofibers represented much less charge transport resistance from electrochemical impedance spectroscopy and higher peak current density from cyclic voltammetry than only Si NPs, because the GNRs as electrical conductors in the electrodes must be well–distributed between Si NPs. As a result, we demonstrated an outstanding battery performance through a novel hybrid PVA/Si/GNRs nanofibers directly fabricated via water–based spinning.

In-Situ Characterization of Si-Based Electrodes By Dilatometry and Acoustic Emission

The replacement of carbon by silicon as active material in negative electrodes of Li-ion batteries is very attractive since the gravimetric and volumetric capacities of silicon are much higher than those of carbon. However, silicon suffers from huge volume variation (up to ~300% versus 10% for C) upon cycling. This leads to the electrode pulverization inducing electrical disconnections in addition to cause an instability of the solid electrolyte interface (SEI), resulting in poor cycle life and coulombic efficiency. A precise evaluation of the volume variation and cracking processes is thus crucial to develop more efficient Si-based electrodes. For that purpose, in the present study, the volume change of Si-based anodes during cycling is monitored by in situ dilatometry. In addition, in situ acoustic emission (AE) measurements are performed to study the electrode pulverization process with cycling. For a better identification of the origin of the different populations of detected AE signals, a detailed study of their energetic and temporal characteristics (amplitude, rise time, frequency...) is conducted. The influence of the cycling conditions (discharge capacity, cycle number, C-rate), electrode formulation (Si particle size…) and processing (calendar pressure) and electrolyte composition on the electrode volume variation and cracking is highlighted and correlated to its electrochemical performance.

TSV Cu Filling Failure Modes and Mechanisms Causing the Failures

In this paper, we report through-silicon via (TSV) Cu filling failure modes and categorize them into three major regions based on their causes. First, Si etch-related region for the TSV defining. Si etch defects, such as bottom corner notch, Si grass at the bottom, surface roughness, and sponge-like defect, cause Cu seed layer loss at the defect areas. It causes electrical disconnection resulting in the TSV Cu filling failure. Second, Cu seed layer-related region. Defects include poor Cu seed layer step coverage and oxidation of the Cu seed layer from the Cu seed layer deposition until the TSV Cu electroplating from the Cu seed layer deposition. They result in aggrandizing terminal effect, which makes Cu ion reduction at the TSV bottom difficult. Third, Cu electroplating-related region. The most important factor in this region is chemical concentration control because the TSV Cu filling by bottom up filling mainly depends on the cooperation of three additives of suppressor, accelerator, and leveler. Another important factor in the region is current density ramp up rate. It is critical to ramp up the current density with an appropriate rate to prevent pinchoff plating causing voids inside the TSVs. These regions are closely connected with each other and the relationship needs to be understood to overcome the TSV Cu filling failure.

Highly–stable Ternary Si/Carbon Nanotube/Carbon Nanofiber Anodes for Li-Ion Batteries

Despite the highest theoretical capacity, silicon anodes for Li-ion batteries have two critical drawbacks of (i) severe volume expansion leading to electrical disconnection and (ii) formation of poor electronic conductive solid–electrolyte interface caused by deformation of electrolyte at low potential,[1,2 ] leading to a poor cycle performance. Herein, we fabricated ternary silicon nanoparticles (Si NPs) /carbon nanotube (CNTs) /carbon nanofibers (CNFs) via water-based electrospinning process, followed by carbonization. Since CNTs provide excellent electrical and electronic properties from their one–dimensional (1–D) feature, they could be easily assembled with Si NPs into nanofibers and improve the charge conductivity and structural stability for our anodes. Furthermore, the carbon nanofibers made from polyvinyl alcohol polymer can make Si NPs connected each other to form networking electrodes. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge tests of this ternary anode demonstrated better activity and smaller charge transport resistance than pure SiNPs and our previous Si rich carbon nanofibers[3]. Furthermore, more than two-fold increase in the capacity retention was achieved for the ternary anode compared to that of Si rich carbon nanofibers after 100 cycles. In addition, our ternary anodes exhibited about 1,000 mAh/g even at high charging rates after 150 cycles. This improvement of cycle life should be attributed to facilitating charge transport and distribution of Si NPs by employing 1–D CNTs and carbon nanofibrous networks, and our ternary SiNPs/CNTs/CNFs system provided by scalable water-based spinning should overcome current barriers to commercializing Si-based anodes such as pulverization and low production rate.

A wireless intraocular pressure monitoring device with a solder-filled microchannel antenna

This paper presents the prototype of an intraocular pressure sensor as a major step toward building a device that can be permanently implanted during cataract surgery. The implantation will proceed through an incision of 2–3 mm using an injector, during which the complete device must be folded into a cross-section of 2 mm × 1 mm. The device uses radio frequency (RF) for wireless power and data transfer. The prototype includes an antenna, an RF chip and a pressure sensor assembled on a printed circuit board with several circuit components used for testing and calibration. The antenna is fabricated and integrated with the circuit using a fabrication method employing solder-filled microchannels embedded in an elastomer. The monitoring device is powered at 2.716 GHz from a distance of 1–2 cm. The prototype has undergone electrical and mechanical tests for antenna and sensor performance. The flexible antenna can withstand a stress of 33.4 kPa without any electrical disconnection. It did not show a significant increase in electrical resistance after 50 bending cycles with a maximum applied stress of 116 kPa. Transmitted pressure data shows an averaged sensitivity of 16.66 Hz (mm-Hg)–1.

1C15 Development of Full Active Seismic Isolator via Mechanical Control(The 12th International Conference on Motion and Vibration Control)

Reducing collapse damages of buildings and constructions by earthquakes is an important issue for human lives. Hydraulic active vibration suppression is made by mobilizing cylinders with the most suitable command signals through servo valves after computing data. These data are collected by various measuring instruments. However unforeseeable contingency takes place in natural disasters such as electric power failure or disconnection by sharp vibration. If any of such disaster should occurs, the system does not function. The excess power would rather cause out of control. The system itself contains potential for harm. This study is to propose the simple and reliable control system for hydraulic cylinder using robust mechanical structure instead of electronic measurement and control. The results of model experiments and simulations presented in our previous works show good results. But it is necessary to raise the precision of simulation to put it into practical use. For the purpose of improving accuracy, we made experiments and simulations for various parameters such as inertial load mass, link ratio for control sensibility, and coefficient of oil switching flow and so on. Then, the control performance is evaluated.

Formation of Sn@C Yolk–Shell Nanospheres and Core–Sheath Nanowires for Highly Reversible Lithium Storage

As one promising anode material with high theoretical capacity, metallic tin has attracted much research interest in the field of lithium‐ion batteries. Here, two types of tin/carbon (Sn@C) core–shell nanostructures with inner buffering voids are fabricated from SnO2 hollow nanospheres via a facile chemical vapor deposition (CVD) method. The crystallinity and surface topography of SnO2 hollow nanospheres are found to affect the morphology of resultant Sn@C materials. Sn@C yolk–shell nanospheres and core–sheath nanowires are obtained from the as‐prepared SnO2 and high‐temperature annealed SnO2 nanospheres, respectively. The unique Sn@C nanostructures can mitigate the agglomeration/pulverization of Sn nanoparticles and electrical disconnection from the current collector caused by the large volume change during the lithium alloying/dealloying process. Both Sn@C yolk–shell and core–sheath nanostructures show stable cycling performance up to 500 cycles with specific capacities of ca. 430 and 520 mA h g−1, respectively.

An electrochemically roughened Cu current collector for Si-based electrode in Li-ion batteries

An electrochemically roughened copper foil was evaluated as a current collector for micrometric Si powder (ball-milled) based electrodes prepared by the conventional slurry-coating method. The formation of a bunch of copper nanowires on the current collector provides a rough surface, which enhances the adhesion of the Si composite electrode as confirmed from scratch tests. This produces a major decrease of the irreversible capacity associated with the electrical disconnection of the Si particles with cycling, which results in a great improvement of the electrode cycle life. With such a roughened Cu current collector, the micrometric Si-based electrode is able to maintain a discharge capacity of 1200mAhg−1 for at least 1000 cycles.

Novel Titanium Dioxide Based Nanocomposite Anodes for Li-Ion Batteries

The graphite anode electrode in commercial lithium ion batteries has several disadvantages such as its electrical disconnection, structural deformation, and initial loss of capacity [1 3]. Especially, TiO2 is regarded as a promising active lithium intercalation material with low production cost and high capacity, low-voltage (below ca. 2.0 V vs. Li/Li) for lithium intercalation. More recently, much attention has been paid to fabricate TiO2-based hybrid nanostructures as anode materials with enhanced lithium storage performance. One of the strategy is to introduce a bu ering matrix that can prevent the breaking down of TiO2-based hybrid nanostructures during cycling. Since the landmark paper by Iijima [4], carbon nanotubes (CNTs) have attracted considerable research interest due to their unique combination of mechanical, electrical and thermal properties. Forms of CNTs in the macroscopic level, such as forests, yarns and lms have been reported providing a practical venue to utilize and manipulate the remarkable properties of CNTs for broad applications [5, 6]. Paper-like CNT lms, also called buckypapers, are self-supporting networks of entangled CNT assemblies arranged in a random fashion and held together by van der Waals interactions at the tube tube junctions. In this study, CNTs-TiO2 nanocomposite structures are studied, which integrates both electronic conductivity and bu ering matrix design strategies. The CNTs-TiO2 nanostructured electrodes have been prepared and applied as anode materials for lithium-ion batteries, which exhibit higher lithium storage capacities and better cycling performance compared to single CNTs and TiO2 electrodes.

Formulation and heuristic algorithms for multi-chip module substrate testing

Multi-chip module (MCM) substrates are designed for packing two or more semiconductor chips. On these substrates, there are open faults in the wiring, which are electrical disconnections. We must therefore test the substrates to detect open faults, and it is essential to establish an efficient method of testing them. One type of test method uses two probes. Two probes, each touching one edge (end) of an inter-chip wiring, are used to check for the presence of faults. Testing is complete when we have confirmed that no faults exist on the MCM substrate. The objective is to minimize the time to complete testing, that is, our aim is to design efficient routes for the two probes. In this paper, we propose a novel approach of formulating the routing problem as a shortest path problem with covering constraints (SPCC) and we also propose three algorithms for the SPCC. In computational experiments, we show that our formulation and algorithms outperform the existing method.

Pulmonary Vein Isolation Requiring Ablation on the Intervenous Ridge to Achieve Electrical Disconnection: Impact on Acute and Long Term Outcome

Pulmonary Vein Isolation Requiring Ablation on the Intervenous Ridge to Achieve Electrical Disconnection: Impact on Acute and Long Term Outcome