Ab␣Initio Study of Aluminium Impurity and Interstitial-Substitutional Complexes in Ge Using a Hybrid Functional (HSE)

The results of an ab?initio modelling of aluminium substitutional impurity (\({\hbox {Al}}_{\rm Ge}\)), aluminium interstitial in Ge [\({\hbox {I}}_{\rm Al}\) for the tetrahedral (T) and hexagonal (H) configurations] and aluminium interstitial-substitutional pairs in Ge (\({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\)) are presented. For all calculations, the hybrid functional of Heyd, Scuseria, and Ernzerhof in the framework of density functional theory was used. Defects formation energies, charge state transition levels and minimum energy configurations of the \({\hbox {Al}}_{\rm Ge}\), \({\hbox {I}}_{\rm Al}\) and \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) were obtained for ?2, ?1, 0, \(+\)1 and \(+\)2 charge states. The calculated formation energy shows that for the neutral charge state, the \({\hbox {I}}_{\rm Al}\) is energetically more favourable in the T than the H configuration. The \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) forms with formation energies of ?2.37 eV and ?2.32 eV, when the interstitial atom is at the T and H sites, respectively. The \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) is energetically more favourable when the interstitial atom is at the T site with a binding energy of 0.8 eV. The \({\hbox {I}}_{\rm Al}\) in the T configuration, induced a deep donor (\(+\)2/\(+1\)) level at \(E_{\mathrm {V}}+0.23\) eV and the \({\hbox {Al}}_{\rm Ge}\) induced a single acceptor level (0/?1) at \(E_{\mathrm {V}}+0.14\) eV in the band gap of Ge. The \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) induced double-donor levels are at \(E_{\rm V}+0.06\) and \(E_{\rm V}+0.12\) eV, when the interstitial atom is at the T and H sites, respectively. The \({\hbox {I}}_{\rm Al}\) and \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) exhibit properties of charge state-controlled metastability.     

Key-Recovery Attacks on <Emphasis FontCategory="SansSerif">ASASA</Emphasis>

The \(\mathsf {ASASA}\) construction is a new design scheme introduced at Asiacrypt 2014 by Biryukov, Bouillaguet and Khovratovich. Its versatility was illustrated by building two public-key encryption schemes, a secret-key scheme, as well as super S-box subcomponents of a white-box scheme. However, one of the two public-key cryptosystems was recently broken at Crypto 2015 by Gilbert, Plût and Treger. As our main contribution, we propose a new algebraic key-recovery attack able to break at once the secret-key scheme as well as the remaining public-key scheme, in time complexity \(2^{63}\) and \(2^{39}\), respectively (the security parameter is 128 bits in both cases). Furthermore, we present a second attack of independent interest on the same public-key scheme, which heuristically reduces the problem of breaking the scheme to an \(\mathsf {LPN}\) instance with tractable parameters. This allows key recovery in time complexity \(2^{56}\). Finally, as a side result, we outline a very efficient heuristic attack on the white-box scheme, which breaks instances claiming 64 bits of security under one minute on a laptop computer.     

An Accurate Performance Analysis for Regenerative Multi-hop Relaying in Wireless Networks Over Composite Multipath/Shadowed Fading

This paper presents and evaluates the performance of wireless networks that utilize the decode-and-forward relay. This multi-hop relaying scheme communicates over Extended Generalized-\({\mathcal {K}}\) (\(\hbox {EG}{\mathcal {K}}\)) composite fading channels to create performance evaluation. To this effect, new exact and easy to compute formulas for several performance metrics are derived. More specifically, new and exact-form mathematical formulas are derived for the cumulative distribution function, the generalized moments of the overall end-to-end signal-to-noise ratio, the outage probability (\({\hbox {P}}_{\text{out}}\)), the ergodic capacity (\({\mathcal {C}}_{\text{Ergodic}}\)), the moment generating function, and the average error probability (\({\hbox {Pr(e)}}\)) for different modulation schemes. Moreover, we carried out a series of computer simulation experiments in order to testify the accuracy of the derived framework. Finally, we discussed the impact of different parameters including fading/shadowing parameters, transmitted power and the number of hops on the derived expressions.     

High-Accuracy Time-Mode Duty-Cycle-Modulation-Based Temperature Sensor for Energy-Efficient System Applications

This paper presents a new time-mode duty-cycle-modulation-based high-accuracy temperature sensor. Different from the well-known \({\varSigma }{\varDelta }\) ADC-based readout structure, this temperature sensor utilizes a temperature-dependent oscillator to convert the temperature information into temperature-related time-mode parameter values. The useful output information of the oscillator is the duty cycle, not the absolute frequency. In this way, this time-mode duty-cycle-modulation-based temperature sensor has superior performance over the conventional inverter-chain-based time domain types. With a linear formula, the duty-cycle output streams can be converted into temperature values. The design is verified in 65nm standard digital CMOS process. The verification results show that the worst temperature inaccuracy is kept within 1\(\,^{\circ }\mathrm{C}\) with a one-point calibration from \(-\)55 to 125 \(^{\circ }\mathrm{C}\). At room temperature, the average current consumption is only 0.8 \(\upmu \)A (1.1\(\,\upmu \)A in one phase and 0.5 \(\upmu \)A in the other) with 1.2 V supply voltage, and the total energy consumption for a complete measurement is only 0.384 \({\hbox {nJ}}\).     

Study on the Effect of Mn,Zn, and Sb on Undercooling Behavior of Sn-Ag-Cu Alloys Using Differential Thermal Analysis

Differential thermal analysis (DTA) has been conducted on directionally solidified near-eutectic Sn-3.0 wt.%Ag-0.5 wt.%Cu (SAC), SAC \(+\) 0.2 wt.%Sb, SAC \(+\) 0.2 wt.%Mn, and SAC \(+\) 0.2 wt.%Zn. Laser ablation inductively coupled plasma mass spectroscopy was used to study element partitioning behavior and estimate DTA sample compositions. Mn and Zn additives reduced the undercooling of SAC from 20.4\(^\circ \hbox {C}\) to \(4.9^\circ \hbox {C}\) and \(2^\circ \hbox {C}\), respectively. Measurements were performed at cooling rate of \(10^\circ \hbox {C}\) per minute. After introducing 200 ppm \(\hbox {O}_2\) into the DTA, this undercooling reduction ceased for SAC \(+\) Mn but persisted for SAC \(+\) Zn.     

A Low-Voltage Fully Differential Pure Current Mode Current Operational Amplifier

In this paper a novel high-frequency fully differential pure current mode current operational amplifier (COA) is proposed that is, to the authors’ knowledge, the first pure MOSFET Current Mode Logic (MCML) COA in the world, so far. Doing fully current mode signal processing and avoiding high impedance nodes in the signal path grant the proposed COA such outstanding properties as high current gain, broad bandwidth, and low voltage and low-power consumption. The principle operation of the block is discussed and its outstanding properties are verified by HSPICE simulations using TSMC \(0.18\,\upmu \hbox {m}\) CMOS technology parameters. Pre-layout and Post-layout both plus Monte Carlo simulations are performed under supply voltages of \(\pm 0.75\,\hbox {V}\) to investigate its robust performance at the presence of fabrication non-idealities. The pre-layout plus Monte Carlo results are as; 93 dB current gain, \(8.2\,\hbox {MHz}\,\, f_{-3\,\text {dB}}, 89^{\circ }\) phase margin, 137 dB CMRR, 13 \(\Omega \) input impedance, \(89\,\hbox {M}\Omega \) output impedance and 1.37 mW consumed power. Also post-layout plus Monte Carlo simulation results (that are generally believed to be as reliable and practical as are measuring ones) are extracted that favorably show(in abovementioned order of pre-layout) 88 dB current gain, \(6.9\,\hbox {MHz} f_{-3\text {db}} , 131^{\circ }\) phase margin and 96 dB CMRR, \(22\,\Omega \) input impedance, \(33\,\hbox {M}\Omega \) output impedance and only 1.43 mW consumed power. These results altogether prove both excellent quality and well resistance of the proposed COA against technology and fabrication non-idealities.     

On the ratio of independent complex Gaussian random variables

In this paper, we derive a closed form equation for the joint probability distribution \({{f_{{R}_{z}}},{\varTheta _{z}}}({r_{z}},{\theta _{z}})\) of the amplitude \({R_{z}}\) and phase \({\varTheta _{z}}\) of the ratio \({Z=\frac{X}{Y}}\) of two independent non-zero mean Complex Gaussian random variables \(X\sim CN(\nu _{x} \mathrm {e}^{j\phi _{x}},{\sigma ^{2}_{x}})\) and \(Y\sim CN(\nu _{y} \mathrm {e}^{j\phi _{y}},{\sigma ^{2}_{y}})\). The derived joint probability distribution only contains a confluent hypergeometric function of the first kind \({_1F_{1}}\) without infinite summations resulting in computational efficiency. We further derive the probability distribution for the ratio of two non-zero mean independent real Rician random variables containing an infinite summation generated by the estimation of the Cauchy product of equivalent series of two modified Bessel functions.     

An efficient resource management scheme in light-trail networks

Light-trail, a framework proposed in the past few years, is generalized from the concept of lightpath, and its distinguishing features include bandwidth sharing and efficient bandwidth utilization. Performance of light-trail networks depends on the routing algorithm and the dynamic bandwidth allocation (DBA) scheme, and the former issue has been discussed extensively. In this work, we aim at the design of an efficient DBA scheme, named Demand and Delay-latency Aware with Two-round Deliberation \((\hbox {D}^{2}\hbox {ATD})\), to allocate bandwidth more accurately and efficiently in light-trail networks. In addition to DBA issue, \(\hbox {D}^{2}\hbox {ATD}\) includes a light-trail setup/release mechanism as well. As expected, the simulation results reveal superiority of \(\hbox {D}^{2}\hbox {ATD}\) in both blocking performance and delay performance. Although \(\hbox {D}^{2}\hbox {ATD}\) pays a price of control overhead for performance gain, it is still reasonable since the amount of control messages does not exceed the capacity of the control channel. It verifies that \(\hbox {D}^{2}\hbox {ATD}\) can properly employ the control channel to achieve excellent performance.     

A PAPR reduction scheme based on a new spreading code in optical direct detection OFDM system

In this paper, we propose and experimentally demonstrate a peak-to-average power ratio (PAPR) reduction scheme based on a new spreading code in direct detection optical orthogonal frequency division multiplexing (OFDM) system. The new spreading code with low cross correlation and high auto-correlation can support \(2N+1\) users. Thus, \(2N+1\) users or data symbols can be transmitted over only N subcarriers. The experimental results show that, after transmission over 70 km single-mode fiber, at the bit error rate of \(10^{-3}\), with fiber launch power of 2.75 dBm, the receiver sensitivity can be improved 2.1 dB by using the proposed scheme based on new spreading code. The PAPR can be reduced about 4.6 dB, compared with the original OFDM signal at a complementary cumulative distribution function of \(10^{-4}\).     

New Efficient Algorithms for Multiplication Over Fields of Characteristic Three

In this paper, we first present an enhancement of the well-known Karatsuba 2-way and 3-way algorithms for characteristic three fields, denoted by \(\mathbb {F}_{3^{n}}\) where n≥1. We then derive a 3-way polynomial multiplication algorithm with five 1/3 sized multiplications that use interpolation in \(\mathbb {F}_{9}\). Following the computation of the arithmetic and delay complexity of the proposed algorithm, we provide the results of our hardware implementation of polynomial multiplications over \(\mathbb {F}_{3}\) and \(\mathbb {F}_{9}\). The final proposal is a new 3-way polynomial multiplication algorithm over \(\mathbb {F}_{3}\) that uses three polynomial multiplications of 1/3 of the original size over \(\mathbb {F}_{3}\) and one polynomial multiplication of 1/3 of the original size over \(\mathbb {F}_{9}\). We show that this algorithm represents about 15% reduction of the complexity over previous algorithms for the polynomial multiplications whose sizes are of practical interest.     

Electrical Transport Mechanisms and Photoconduction in Undoped Crystalline Flash-Evaporated Lead Iodide Thin Films

The flash-evaporation technique was utilized to fabricate undoped 1.35-μm and 1.2-μm thick lead iodide films at substrate temperatures \( T_{\rm{s}} = 150 \)°C and 200°C, respectively. The films were deposited onto a coplanar comb-like copper (Cu-) electrode pattern, previously coated on glass substrates to form lateral metal–semiconductor–metal (MSM-) structures. The as-measured constant-temperature direct-current (dc)-voltage (\( I\left( {V;T} \right) - V \)) curves of the obtained lateral coplanar Cu-PbI₂-Cu samples (film plus electrode) displayed remarkable ohmic behavior at all temperatures (\( T = 18 - 90\,^\circ {\hbox{C}} \)). Their dc electrical resistance \( R_{\rm{dc}} (T \)) revealed a single thermally-activated conduction mechanism over the temperature range with activation energy \( E_{\rm{act}} \approx 0.90 - 0.98 \,{\hbox{eV}} \), slightly less than half of room-temperature bandgap energy \( E_{\rm{g}} \) (\( \approx \,2.3\, {\hbox{eV}} \)) of undoped 2H-polytype PbI₂ single crystals. The undoped flash-evaporated \( {\hbox{PbI}}_{\rm{x}} \) thin films were homogeneous and almost stoichiometric (\( x \approx 1.87 \)), in contrast to findings on lead iodide films prepared by other methods, and were highly crystalline hexagonal 2H-polytypic structure with c-axis perpendicular to the surface of substrates maintained at \( T_{\rm{s}} { \gtrsim }150^\circ {\hbox{C}} \). Photoconductivity measurements made on these lateral Cu-PbI₂-Cu-structures under on–off visible-light illumination reveal a feeble photoresponse for long wavelengths (\( \lambda > 570\,{\hbox{nm}} \)), but a strong response to blue light of photon energy \( E_{\rm{ph}} \) \( \approx \,2.73 \, {\hbox{eV}} \) (\( > E_{\rm{g}} \)), due to photogenerated electron–hole (e–h) pairs via direct band-to-band electronic transitions. The constant-temperature/dc voltage current–time \( I\left( {T,V} \right) - t \) curves of the studied lateral PbI₂ MSM-structures at low ambient temperatures (\( T < 50^\circ {\hbox{C}} \)), after cutting off the blue-light illumination, exhibit two trapping mechanisms with different relaxation times. These strongly depend on \( V \) and \( T \), with thermally generated charge carriers in the PbI₂ mask photogenerated (e–h) pairs at higher temperatures.     

$$\ell _{1/2,1}$$ group sparse regularization for compressive sensing

Recently, the design of group sparse regularization has drawn much attention in group sparse signal recovery problem. Two of the most popular group sparsity-inducing regularization models are \(\ell _{1,2}\) and \(\ell _{1,\infty }\) regularization. Nevertheless, they do not promote the intra-group sparsity. For example, Huang and Zhang (Ann Stat 38:1978–2004, 2010) claimed that the \(\ell _{1,2}\) regularization is superior to the \(\ell _1\) regularization only for strongly group sparse signals. This means the sparsity of intra-group is useless for \(\ell _{1,2}\) regularization. Our experiments show that recovering signals with intra-group sparse needs more measurements than those without, by the \(\ell _{1,\infty }\) regularization. In this paper, we propose a novel group sparsity-inducing regularization defined as a mixture of the \(\ell _{1/2}\) norm and the \(\ell _{1}\) norm, referred to as \(\ell _{1/2,1}\) regularization, which can overcome these shortcomings of \(\ell _{1,2}\) and \(\ell _{1,\infty }\) regularization. We define a new null space property for \(\ell _{1/2,1}\) regularization and apply it to establish a recoverability theory for both intra-group and inter-group sparse signals. In addition, we introduce an iteratively reweighted algorithm to solve this model and analyze its convergence. Comprehensive experiments on simulated data show that the proposed \(\ell _{1/2,1}\) regularization is superior to \(\ell _{1,2}\) and \(\ell _{1,\infty }\) regularization.     

A deterministic auto-regressive STAP approach for nonhomogenerous clutter suppression

Direct data domain (DDD) space-time adaptive processing methods avoid nonhomogenerous training samples and can effectively suppress the clutter within the test range cell. However, it suffers inevitable performance loss due to the spatial and temporal smoothing process. Furthermore, the clutter suppression ability of these methods sharply degrades when applied to non-uniform and non-linear array for airborne radar. In this paper, a novel clutter suppression approach in the direct data domain is proposed, which describes clutter characteristic of the test range cell with AR model. For convenience, the novel method is referred to as \(\hbox {D}^{3}\hbox {AR}\). It utilizes the most system DOF. Hence, it suffers less aperture loss, compared to conventional DDD methods, e.g., the direct data domain least squares (\(\hbox {D}^{3}\hbox {LS}\)). More importantly, \(\hbox {D}^{3}\hbox {AR}\) can achieve much better clutter suupression prformance than \(\hbox {D}^{3}\hbox {LS}\) when applied to conformal array airborne radar because it does not need the spatial smoothing. The effectiveness of the \(\hbox {D}^{3}\hbox {AR}\) is verified by numerical examples for the case of a circular array.     

A 0.36 μW/channel recorder for external ambulatory ECG recorders

There is an increasing demand for long-term ECG monitoring applications which are very low power, small size and capable of wireless data transmission. This paper presents an analog front-end and also modulator for long-term ECG recording purpose. The fully integrated system features three independent channels and a modulator. The analog front-end includes a voltage-to-time conversion and a tunable modulator to achieve a very low power consumption for wireless transmission of the data without analog to digital converter. The proposed system is designed and simulated in a \(0.18\,\upmu \hbox {m}\) CMOS technology and occupies only \(0.245\,\mathrm{mm}^{2}\). It can record ECG signal with 9.2-bit resolution while consuming only \(0.36\,\upmu {\mathrm{W}}\) per channel from a 0.9 V supply. Also, it can transmit data consuming just \(0.72\,{\upmu }\mathrm{W}\) per channel from a 0.9 V supply. The input referred noise of the readout channel is \(2.01\,\upmu {\mathrm{V}}_{{{\rm rms}}}\).     

New refractive index profiles of dispersion-flattened highly nonlinear fibers for future all-optical signal processing in wdm optical networks

In this paper, we demonstrate new dissimilar refractive index profiles for highly nonlinear ultra-flattened dispersion fibers with noteworthy effective area \((A_\mathrm{eff})\) for future optical signal processing. The newly proposed fibers named from Type 1 to Type 5 have a flattened dispersion over S, C, L and U bands. Predominantly, few-mode HNL-UFF fiber of Type 3 yields dispersion-flattened characteristics over a range of 250 nm of optical communication spectrum with a mere 0.2 ps/nm km variation in dispersion and a dispersion slope of \(0.0057\hbox { ps}/\hbox {nm}^{2}\) km due to the contribution of higher-order modes to the dispersion characteristics of the fiber. Moreover, it has a moderate nonlinear coefficient of \(8.03\hbox { W}^{-1}\,\hbox {km}^{-1}\). By modifying the refractive index profile of Type 3 fiber, Type 4 and Type 5 fibers are obtained in order to ensure single-mode operation, while the zero flattened dispersion characteristics of the fiber are compromised. Among the newly proposed fibers, Type 4 fiber offers a very low ITU-T cutoff wavelength of \(1.33~\upmu \hbox {m}\), whereas in the case of Type 5 fiber it is \(1.38~\upmu \hbox {m}\). Moreover, Type 4 and Type 5 fibers have good nonlinear coefficients of \(12.26\hbox { W}^{-1}\,\hbox {km}^{-1}\) and \(11.45\hbox { W}^{-1}\,\hbox {km}^{-1}\), respectively. By virtue of the proposed optimized index profile, an insensitive behavior toward bending is displayed by Type 3, Type 4 and Type 5 fibers. In addition, Type 4 fiber provides a better splice loss of 0.25 dB.     

The $$\mathbb {}$$-curve Construction for Endomorphism-Accelerated Elliptic Curves

We give a detailed account of the use of \(\mathbb {Q}\)-curve reductions to construct elliptic curves over \(\mathbb {F}_{p^2}\) with efficiently computable endomorphisms, which can be used to accelerate elliptic curve-based cryptosystems in the same way as Gallant–Lambert–Vanstone (GLV) and Galbraith–Lin–Scott (GLS) endomorphisms. Like GLS (which is a degenerate case of our construction), we offer the advantage over GLV of selecting from a much wider range of curves and thus finding secure group orders when \(p\) is fixed for efficient implementation. Unlike GLS, we also offer the possibility of constructing twist-secure curves. We construct several one-parameter families of elliptic curves over \(\mathbb {F}_{p^2}\) equipped with efficient endomorphisms for every \(p > 3\), and exhibit examples of twist-secure curves over \(\mathbb {F}_{p^2}\) for the efficient Mersenne prime \(p = 2^{127}-1\).     

The Security of Tandem-DM in the Ideal Cipher Model

We prove that Tandem-DM, one of the two “classical” schemes for turning an n-bit blockcipher of 2n-bit key into a double-block-length hash function, has birthday-type collision resistance in the ideal cipher model. For \(n=128\), an adversary must make at least \(2^{120.87}\) blockcipher queries to achieve chance 0.5 of finding a collision. A collision resistance analysis for Tandem-DM achieving a similar birthday-type bound was already proposed by Fleischmann, Gorski and Lucks at FSE 2009. As we detail, however, the latter analysis is wrong, thus leaving the collision resistance of Tandem-DM as an open problem until now. Our analysis exhibits a novel feature in that we introduce a trick never used before in ideal cipher proofs. We also give an improved bound on the preimage security of Tandem-DM. For \(n=128\), we show that an adversary must make at least \(2^{245.99}\) blockcipher queries to achieve chance 0.5 of inverting a randomly chosen point in the range. Asymptotically, Tandem-DM is proved to be preimage resistant up to \(2^{2n}/n\) blockcipher queries. This bound improves upon the previous best bound of \({{\varOmega }}(2^n)\) queries and is optimal (ignoring log factors) since Tandem-DM has range of size \(2^{2n}\).     

On the Ergodic Capacity of Distributed MIMO Antenna Systems

We consider distributed multiple-input–multiple-output (MIMO) antenna systems, along with their certain generalizations. We show that distributed MIMO configuration can be mapped to a semicorrelated (one side correlated) Wishart model. For a given set of large-scale fading parameters, associated with the path loss and shadow fading, we derive exact and closed-form results for the marginal density of eigenvalues of \(\mathbf{H}^\dag \mathbf{H}\) (or \(\mathbf{H} \mathbf{H} ^\dag\)), where \(\mathbf{H}\) is the channel matrix. We also obtain exact and closed-form expressions for the ergodic channel capacity with the aid of Meijer G-function. The ergodic capacity of semicorrelated Rayleigh fading channel follows as a special case. All analytical results are validated by comparison with Monte-Carlo simulations.