Symbiotic Dynamic Memory Balancing for Virtual Machines in Smart TV Systems

Smart TV is expected to bring cloud services based on virtualization technologies to the home environment with hardware and software support. Although most physical resources can be shared among virtual machines (VMs) using a time sharing approach, allocating the proper amount of memory to VMs is still challenging. In this paper, we propose a novel mechanism to dynamically balance the memory allocation among VMs in virtualized Smart TV systems. In contrast to previous studies, where a virtual machine monitor (VMM) is solely responsible for estimating the working set size, our mechanism is symbiotic. Each VM periodically reports its memory usage pattern to the VMM. The VMM then predicts the future memory demand of each VM and rebalances the memory allocation among the VMs when necessary. Experimental results show that our mechanism improves performance by up to 18.28 times and reduces expensive memory swapping by up to 99.73% with negligible overheads (0.05% on average).     

Poly(diketopyrrolopyrrole‐benzothiadiazole) with Ambipolarity Approaching 100% Equivalency

As a characteristic feature of conventional conjugated polymers, it has been generally agreed that conjugated polymers exhibit either high hole transport property (p‐type) or high electron transport property (n‐type). Although ambipolar properties have been demonstrated from specially designed conjugated polymers, only a few examples have exhibited ambipolar transport properties under limited conditions. Furthermore, there is, as yet, no example with ‘equivalent’ hole and electron transport properties. We describe the realization of an equivalent ambipolar organic field‐effect transistor (FET) by using a single‐component visible–near infrared absorbing diketopyrrolopyrrole (DPP)‐benzothiadiazole (BTZ) copolymer, namely poly[3,6‐dithiene‐2‐yl‐2,5‐di(2‐decyltetradecyl)‐pyrrolo[3,4‐c]pyrrole‐1,4‐dione‐5’,5’’‐diyl‐alt‐benzo‐2,1, 3‐thiadiazol‐4,7‐diyl] ( PDTDPP‐alt‐BTZ ). PDTDPP‐alt‐BTZ shows not only ideally balanced charge carrier mobilities for both electrons (?_e = 0.09 cm²V^?1s^?1) and holes (?_h = 0.1 cm²V^?1s^?1) but also its inverter constructed with the combination of two identical ambipolar FETs exhibits a gain of ～35 that is much higher than usually obtained values for unipolar logic.     

ε‐Branched Flexible Side Chain Substituted Diketopyrrolopyrrole‐Containing Polymers Designed for High Hole and Electron Mobilities

Based on the integrated consideration and engineering of both conjugated backbones and flexible side chains, solution‐processable polymeric semiconductors consisting of a diketopyrrolopyrrole (DPP) backbone and a finely modulated branching side chain (ε‐branched chain) are reported. The subtle change in the branching point from the backbone alters the π?π stacking and the lamellar distances between polymer backbones, which has a significant influence on the charge‐transport properties and in turn the performances of field‐effect transistors (FETs). In addition to their excellent electron mobilities (up to 2.25 cm² V^?1 s^?1), ultra‐high hole mobilities (up to 12.25 cm² V^?1 s^?1) with an on/off ratio (I_on/I_off) of at least 10⁶ are achieved in the FETs fabricated using the polymers. The developed polymers exhibit extraordinarily high electrical performance with both hole and electron mobilities superior to that of unipolar amorphous silicon.     

Ni3(PO4)2-coated Li[Ni0.8Co0.15Al0.05]O2 lithium battery electrode with improved cycling performance at 55 °C

To improve the cycling performance of LiNi_0.8Co_0.15Al_0.05O₂ at 55 °C, a thin Ni₃(PO₄) layer was homogeneously coated onto the cathode particle via simple ball milling. The morphology of the Ni₃(PO₄)₂-coated LiNi_0.8Co_0.15Al_0.05O₂ particle was characterized using SEM and TEM analysis, and the coating thickness was found to be approximately 10-20 nm. The Ni₃(PO₄)₂-coated LiNi_0.8Co_0.15Al_0.05O₂ cell showed improved lithium intercalation stability and rate capability especially at high C rates. This improved cycling performance was ascribed to the presence of Ni₃(PO₄)₂ on the LiNi_0.8Co_0.15Al_0.05O₂ particle, which protected the cathode from chemical attack by HF and thus suppressed an increase in charge transfer resistance. Transmission electron microscopy of extensively cycled particles confirmed that the particle surface of the Ni₃(PO₄)₂-coated LiNi_0.8Co_0.15Al_0.05O₂ remained almost undamaged, whereas pristine particles were severely serrated. The stabilization of the host structure by Ni₃(PO₄)₂ coating was also verified using X-ray diffraction.     

Effect of the valence states of titanium on the lattice structure and ionic conductivity of Li0.33La0.55TiO3 solid electrolyte

Li_0.33La_0.55TiO₃ solid electrolytes with a pure phase were synthesized by the citric acid-supported sol-gel method and then sintered under controlled redox atmospheres of air, argon and hydrogen. Although of similar morphology and relative density, Li_0.33La_0.55TiO₃ samples sintered under reduction atmosphere such as argon and hydrogen exhibited a tetragonal structure with lattice distortion. The distortion and volume expansion of the crystal lattice was identified as originating from the transformation of the Ti valence state, and this was more clearly observed under sintering of the hydrogen atmosphere. The qualitative analysis of the Ti valence state using an X-ray Photoelectron Spectroscopy experiment was performed and indicated that the largest amount of Ti³⁺(18.6%) was formed in the Li_0.33La_0.55TiO₃ samples sintered under hydrogen atmosphere. The relationship between the lattice distortion and the lithium ion conductivity of the Li_0.33La_0.55TiO₃ sintered under different atmospheres is also discussed on the basis of the lattice distortion.     

A study of crystallinity in amorphous Si thin films for silicon heterojunction solar cells

In this work we analyzed the crystallinity of hydrogenated amorphous Si thin films deposited on n-type Si substrates using the effective medium approximation (EMA) method of a spectroscopic ellipsometer (SE) and evaluated their passivation quality by measuring effective carrier lifetime (τ_eff) and implied V_oc using quasi-steady-state photo conductance decay (QSSPC) simultaneously. The crystalline volume fraction of doped a-Si:H layers using RF-PECVD was controlled from ∼0% (nearly full amorphous phase) to above 90% (nearly polycrystalline phase) through varying deposition conditions. The passivation property depended on the crystallinity more strongly for p-a-Si:H than n-a-Si:H of which crystallinity was more sensitive to deposition rate relatively. The implied V_oc above 650 mV was achieved with crystallinity less than about 5% for p-a-Si:H and 20% for n-a-Si:H. The HRTEM images confirmed the reliability of SE analysis with EMA modeling and showed the maximum part of crystalline phase exists at the interface of a-Si:H and c-Si in the form of epitaxial growth configuration. By the optimization of each a-Si:H deposition conditions 17.17% the cell efficiency was accomplished on non-textured substrate.     

N-nitrosodimethylamine formation by free-chlorine-enhanced nitrosation of dimethylamine

The formation of N-nitrosodimethylamine (NDMA) by the nitrosation of dimethylamine (DMA) is greatly enhanced by the presence of free chlorine (HOCl). The effect of HOCl appears at first to be contrary because HOCl rapidly oxidizes nitrite and hence should reduce NDMA formation from a mechanism involving classical nitrosation. The enhanced nitrosation by the presence of HOCl is, however, consistent with a mechanism that involves the formation of a highly reactive nitrosating intermediate such as dinitrogen tetroxide (N2O4) formed during the oxidation of nitrite to nitrate. This mechanism is quite unlike another recently proposed NDMA formation pathway involving the rate-limiting oxidation of DMA directly by monochloramine. NDMA formation by the proposed HOCl-enhanced nitrosation pathway is inhibited by the presence of ammonia and occurs very quickly, only during the short period during which nitrite oxidation occurs. The general importance of this NDMA formation mechanism in actual drinking water appears to be limited by the amount of DMA and nitrite typically present. The mechanism described here, however, suggests the potential involvement of other nitrogen redox reactions that may produce reactive intermediates leading to the indirect and incidental formation of NDMA in the presence of appropriate organic nitrogen precursor.