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In this letter, we present an extensive analysis on the role of both switching frequency (ranging from 100 kHz to 1 MHz) and duty cycle (from 10% to 90%) on the time-dependent gate breakdown of high electron mobility transistors (HEMTs) with Schottky metal to p-GaN gate. More specifically, results show how the gate lifetime of GaN HEMTs increases by reducing the frequency and the duty cycle of the stressing gate signal (VG). Such behavior is ascribed to the OFF-time, which is responsible to alter the electrostatic potential in the p-GaN layer during the rising phases of VG (from OFF- to ON-state). Findings of this analysis are useful both for further technology improvement and for GaN-based power circuit designers.

TCAD modeling of the dynamic threshold voltage shift (hysteresis) occurring under fast sweeping characterization in Schottky-type p-GaN gate high-electron-mobility transistors (HEMTs) is reported, to the best of our knowledge, for the first time. Dynamic VTH hysteresis has been first experimentally characterized under different sweeping times, temperatures, and AlGaN barrier configurations. Then, TCAD simulations have been carried out, reproducing the experimental evidences and understanding the microscopic mechanisms responsible for such effect. In particular, nonlocal tunneling models implemented in Sentaurus TCAD, defined at the gate Schottky contact and assisted by traps in the AlGaN barrier layer, have been adopted and properly tuned against experiments. Results show that the dynamic VTH hysteresis is mainly caused by the time-dependent hole charging/discharging processes in the floating p-GaN layer, which are governed by the Schottky and AlGaN barrier leakage current components.

This study aimed to verify the applicability of the EN 1787 method for the detection of irradiation in herbal ingredients used in Plant Food Supplements (PFSs). In matrices such as herbs and spices the main limit of the method is the presence of intrinsic radicals responsible for spurious signals leading to complex ESR spectra. To overcome this limit, before ESR measurement a treatment with alcohol has been proposed (Delincee and Soika, 2002; Ahn et al., 2012, 2014). As reported in the literature, this treatment is expected to reduce/eliminate the confounding signals so that the samples may be correctly classified. In this study the efficacy of the pre-treatment was tested on raw herbal ingredients largely used for PFSs, namely Camellia sinensis, Cinnamomum verum, Curcuma longa, Ginkgo biloba, Silybum marianum, Vaccinium myrtillus and Zingiber officinale. Non-irradiated and irradiated (5, 10 kGy) samples were analysed before and after pre-treatment. The results showed a general decrement of signal intensity. In some cases, this was associated with the elimination of some spurious signals, which, however, did not always ensue in an easier interpretation of the ESR spectra. Only for two matrices (Camellia sinensis and Vaccinium myrtillus) was alcoholic extraction crucial for the correct classification of the samples.

The increasing interest on pervasive sensor networks and the steady development of electronic devices with low power consumption motivates the research on electronic systems capable of harvesting energy from the surrounding environment. The use of microelectronic technologies allows a series of circuit optimizations paving the way toward the exploitation of sub‐microwatt power regimes, thanks to the significant reduction of parasitics and to the efficiency of custom designed circuit topologies. This chapter reviews some of the most promising integrated circuits (ICs) for power harvesting, conversion, and management, achieved either by industry or academia, intended for exploiting several different types of energy transducers. The chapter reviews a specific case study consisting in a nanopower IC for harvesting power from multiple energy sources. It focuses on the advantages conferred by nanoelectronic ICs in this specific field. The chapter highlights recent achievements presented in scientific literature, with a special focus on nanopower‐integrated solutions.

International audience; We are today facing a severe power consumption crisis, due to many factors: increase of worldwide energy consumption (by 40% in the last 20 years), cost of energy, climate warming, pollution, and restricted energy reserve. In this global scenario, electronics/information and communication technologies (ICT) is becoming a major player because a signicant part of the energy consumption (15% of electricity consumption today; but it is estimated to increase threefold in the next 20 years) is related to ICT systems. In addition, the battery lifetimes are not sufcient for the increasing needs of new mobile devices, and we need to develop future autonomous ultra-low-power (ULP) systems.

A method for the determination of seven corticosteroids (triamcinolone, prednisolone, prednisone, dexamethasone, betamethasone, flumethasone, triamcinolone acetonide) in the urine of cattle is described. The sample was separated by LC on C18 cartridges and the corticosteroids were determined using tandem mass spectrometric analysis with an atmospheric pressure chemical ionisation (APCI) interface in single reaction monitoring neutral loss mode. For confirmatory use the samples are analysed in multiple reaction ion mode using the typical fragmentation in positive mode for each compound. Data on precision and accuracy for each compound are presented. Neutral loss mode is suitable for the detection of all the corticosteroids that form an adduct with acetonitrile using the APCI interface thus allowing their simultaneous determination with a limit of detection of 1 μg kg−1 and with no need of extensive purification of the sample. The method fully meets the EU legislation requirement for determination of the banned substances.

In this paper, we report an experimental investigation of electron mobility in ultrathin SOI MOSFETs operated in double-gate mode. Mobility is measured for silicon thickness down to approximately 5 nm and for different temperatures. Mobility data in single- and double-gate mode are then compared according to two different criteria imposing either the same total inversion charge density or the same effective field in the two operating modes. Our results demonstrate that for silicon films around 10 nm or thinner and at small inversion densities, a modest but unambiguous mobility improvement for double-gate mode operation is observed even if the same effective field as in the single-gate mode is kept. Furthermore, we also document that the mobility in double-gate mode can improve markedly above single-gate mobility when the comparison is made at the same total inversion density. This latter feature of the double-gate operating mode can be very beneficial in the perspective of very-low voltage operation.

In this paper we present experimental data or electron mobility in Ultra-Thin SOI MOSFETs operating in Single- and Double-Gate Mode. Mobility is measured for silicon thicknesses down to 5nm and for temperatures ranging from 225K to 375K. At large inversion densities (Ninv) ultra-thin SOI exhibit higher mobility than heavily doped bulk MOS and a small dependence of mobility on silicon thickness (TSI). However, at small Ninv the mobility is clearly reduced for decreasing TSI, possibly due to enhanced phonon scattering in the thin quantum well. Compared to Single-Gate, a modest but unambiguous mobility improvement is observed in Double-Gate mode, for silicon films around 10nm and small inversion densities. The mobility increase is more pronounced at low temperatures.

Low-field electron and hole effective mobilities ( μ eff ) of ultra-thin SOI n- and p-MOSFETs, down to a silicon thickness T Si of approximately 5 nm, have been measured at different temperatures using a special test structure able to circumvent parasitic resistance effects. At large inversion densities ( N inv ), ultra-thin SOI exhibit higher mobility than heavily doped bulk MOS and a weak dependence of mobility on silicon thickness. However, at small N inv the mobility is clearly reduced for decreasing T Si , due to enhanced phonon scattering in the thin quantum well.

In this chapter we describe the modeling approaches developed for the simulation of germanium devices. The main focus will be on metal-insulator-semiconductor (MIS) devices, with particular attention on germanium-on-insulator (GOI) structures. Most of the approaches were originally developed for silicon devices, and thus we will describe them briefly, stressing the differences between Si and Ge and how they translate in different modeling requirements. The chapter is organized according to a “bottom-up” structure, beginning with Section 9.2 which describes the main differences between the basic properties of Ge and Si, and then spanning from band-structure calculation up to the determination of the drain current in MIS devices for both n-channel and p-channel transistors. However, so far, most of the models have been developed for n-channel devices and cannot be easily extended to p-channel transistors. This is reflected also in the material presented in this chapter, which is more complete and richer of examples for n-channel than it is for p-channel transistors. Section 9.3 is devoted to band-structure calculation. Since the main interest is in MIS devices, where carriers are quantized in a 2D inversion layer, a relevant fraction of the section is focused on the calculation of the energy states in 2D systems. In the semi-classical physical framework that we will consider hereafter, the transport modeling is essentially based on the Boltzmann transport equation (BTE), whose general solution is very complex because the scattering integrals make the stationary BTE an integral–differential equation in a multi-dimensional space of the phases (which has six dimensions for a bulk semiconductor and four dimensions for a 2D inversion layer). A dramatic simplification is obtained by neglecting the scattering term, which leads to the ballistic transport regime. This simplified approach is mostly useful to investigate the upper-limits of the performance that can be attained with a device structure, so that it can be used for a preliminary investigation of the possible benefits related to new device structures, such as Ge channel Metal-oxidesemiconductor field effect transistor (MOSFETs). This aspect is described in Section 9.4, where comparisons between Si and Ge devices are provided. The solution of the BTE beyond the ballistic approximation is considered in Section 9.5, starting from approximate solutions such as the Drift-Diffusion approach, and then considering more accurate approaches, such as the Monte-Carlo (MC) method. Finally, in Section 9.6 we will draw our conclusion and propose a “roadmap” for the forthcoming activities in the field of the simulation of advanced Ge devices.

In this paper we report experiments and simulations on thin oxide (1.5–3 nm) MOS devices, showing that native traps can play a dominant role in the tunneling characteristics of such oxides. The number of traps, and thus their role on the tunneling current, can be minimized by careful and simple processing: in this case traps affect the tunneling current in relatively thick oxides while their role vanishes at oxide thicknesses of 2 nm and below.

PURPOSE: To describe antidepressant (AD) use in the Emilia-Romagna Region (Italy) and to evaluate adherence to treatment with selective serotonin receptor inhibitors or selective noradrenaline receptor inhibitors (SSRI-SNRI). METHODS: Reimbursed prescriptions of AD were retrieved from the Emilia-Romagna Regional Health Authority Database. The overall AD consumption from the 2006-2011 period was expressed in terms of prevalence and amount of use. Adherence to treatment was assessed in a cohort of patients who received SSRI-SNRI, and was followed throughout a 6-month period from the start of each treatment episode. Adherence was considered according to three parameters: duration of treatment ≥ 120 days, prescription coverage ≥ 80 %, and gaps between prescriptions < 3 months. Determinants of non-adherent regimen, including sociodemographic and clinical variables, were identified by multivariate logistic regression by calculating adjusted Odds Ratio (adjOR) and the relevant 95 % confidence interval (95CI). RESULTS: From 2006 to 2011, the prevalence of use of AD increased by 5 % (from 86 to 90 per 1,000 inhabitants) and the amount of antidepressant consumption increased by 20 % (from 43 to 51 defined daily dose per thousand inhabitants per day [DDD/TID]), with a 14 % rise in the intensity of drug use (from 182 to 208 DDD per patient). Out of 347,615 SSRI-SNRI treatment episodes, only 23.8 % were adherent. Comorbidity (adjOR:0.69; 95CI:0.67-0.72) and recurrence of AD treatment in the previous year (0.91; 0.89-0.92) were associated with better adherence. Moreover, patients treated with duloxetine (0.58; 0.55-0.60), escitalopram (0.64; 0.62-0.66) or sertraline (0.65; 0.64-0.67) showed better adherence in comparison with paroxetine. CONCLUSIONS: Clinical variables resulting in improved adherence seem to identify patients with more severe disorders and who actually need a pharmacological approach, whereas differences in adherence among ADs could in part be caused by channeling and sponsorship bias. Initiatives addressed at improving cooperation between primary care and psychiatrists could decrease AD prescription for cases of sub-threshold or mild depression that easily drop out because of rapid symptom relief or side effects.

International audience

Measured electron injection probabilities (P JN ) into the gate oxide of MOS structures [1] are presented for both liquid nitrogen and room temperature. For the first time P JN has been measured for total voltage drops (V TOT ) in the substrate spanning from well below to well above the value corresponding to the Si-SiO 2 barrier height (V* TOT = Φ B / q = 3.15 V). In contrast to MOSFET data [2], here two different injection regimes can clearly be distinguished. For V TOT < V* TOT a regime occurs in which injection is no longer caused only by the electron energy gained in the electric field but also by the additional energy from phonon absorption. No lucky electron model holds true in this regime and therefore some insight will be given here by means of Monte Carlo simulations of the injection experiment. A simple analysis technique is developed, that explains the observed temperature dependence and injection regimes of P JN .

We describe an approach to the solution of the Boltzmann kinetic equation for the evolution of non- equilibrium electron ensembles in semiconductors under the influence of both phonon scattering and electron-electron interaction. This approach works well when the interaction with optical phonons is the dominant scattering mechanism. In this case, the ensemble evolution can be separated into two stages, the first of which corresponds to the establishment of an intermediate distribution, corresponding to a quasiequilibrium with the optical-phonon subsystem. To describe the subsequent evolution, we assume that this quasiequilibrium is maintained while the ensemble progresses toward the true equilibrium. This assumption implies a certain form of the time-dependent distribution function and renders the full kinetic equation tractable. The solution thus obtained has been checked against Monte Carlo simulations for both polar and nonpolar semiconductors.

A simple and efficient model for first-order simulation of the writing of n-channel erasable programmable ROM (EPROM) cells is presented. It allows the current injected into the gate insulator of the cell transistor to be calculated, accounting (at first order) both for the nonMaxwellian form of the electron energy distribution and for the nonlocal nature of carrier heating. The model is implemented as a postprocessor of a two-dimensional device simulator, and it is validated by means of a comparison with experimental data obtained with devices with effective channel lengths ranging from 1.4 to 0.5 mu m. >

Carrier transport across the semiconductor space-charge region of a silicon triangular barrier diode was investigated by a Monte Carlo simulation. Oscillations of the electron mean kinetic energy are observed as a function of position along the uphill slope of the barrier under bias. At a given point on the uphill slope, the energy distribution function shows an oscillatory behavior, with a periodicity corresponding to the optical phonon energy. These oscillations are shown to be due to the nonequilibrium dynamics of the electron interaction with optical phonons in the situation when other inelastic electron scattering processes are negligible. The energy oscillations are superimposed on a smooth cooling of the distribution in the transport toward the top of the barrier, as current flows through the system. A comparison with the thermionic theory quantifies the importance of nonequilibrium effects in short-range electronic transport. >

A study is presented on the effects of voltage scaling on hot-electron phenomena and intrinsic device performance in submicrometer MOSFETs. A Monte Carlo device simulator featuring a suitable band model for high-energy electrons is used. An interesting finding is that at very short channel lengths the high energy tail of the electron distribution function, the most important quantity in determining hot-carrier reliability, is controlled by the applied bias and not by local electric fields. As confirmed by recently reported experimental work, the results of this study indicate that the conventional, linear voltage scaling can be weakened using a more relaxed voltage reduction law that leads to improved performance without threatening device reliability. >

Experimental data obtained by testing CMOS commercial ICs for latchup by means of automatic test equipment are presented. The results unambiguously show that latchup resistance is strongly influenced by interactions among complex structures within the circuit that are overlooked by widely used testing procedures. In particular, it is shown that both multiple pin excitation and static current loading can significantly decrease the component latchup resistance because of effects taking place within the semiconductor as well as through metal lines. >

In this paper applicability of established semiclassical (SC) simulation techniques to ultra-short gate MOS devices is discussed and comparisons between experimental data of MOS transistors with gate down to 40 nm and simulation results are reported. Finally, examples of applications to the comparison of different device structures are reported. >

The paper presents an historical perspective of the efforts devoted in the past years to achieve efficient but increasingly accurate modeling of hot carrier generation in MOS devices. In addition, new modeling problems raised by recent experiments, and related to the effects of power supply and geometry down-scaling will be discussed.

This paper investigates the relationship between various HALO parameters best suited to achieve short channel effect control in MOSFETs with channel lengths of ≃0.1 μm. New insights into the HALO control upon threshold voltage have been achieved by means of a simple analytical model. The analysis has been refined through extensive drift diffusion simulations based on a parametric representation of the HALO profile.

Developmental anomalies of the appendicular skeleton are among the most common and easily ascertained birth defects. Split hand/split foot malformations, distinctive in having deficiency of the central rays, occur as isolated anomalies and as one component of multisystem syndromes. The clinical and molecular characterization of a new syndrome, found in two unrelated families, consisting of split foot with hearing loss, is presented here. As in other split hand/split foot conditions, variable expression and reduced penetrance is notable. In the larger family, variably expressed split foot malformations were found in 6 of 11 gene carriers. and mild-to-moderate sensorineural hearing loss in 4. Split hand and cleft lip/palate in one individual and tibial deficiency in another suggest that these malformations are uncommon components of the syndrome. Ectodermal abnormalities did not occur. In the second family, variable split foot was observed in 3 of 4 gene carriers, and sensorineural deafness was present in 3. Split hand was only seen in a gene carrier who also had split foot and deafness. One gene carrier only had deafness. The gene for split hand split foot with sensorineural hearing loss was linked to markers in 7q21 in both families, with a combined (maximum LOD score of 4.37 at theta = 0.0 for locus D7S527) at 80% penetrance. Efforts to identify the responsible gene have not yet been successful.

In this paper, we present a comprehensive experimental characterization of electron and hole effective mobility (/spl mu//sub eff/) of ultrathin SOI n- and p-MOSFETs. Measurements have been performed at different temperatures using a special test structure able to circumvent parasitic resistance effects. Our results indicate that, at large inversion densities (N/sub inv/), the mobility of ultrathin SOI transistors is largely insensitive to silicon thickness (T/sub SI/) and is larger than in heavily doped bulk MOS because of a lower effective field. At small N/sub inv/, instead, mobility of SOI transistors exhibits a systematic reduction with decreasing T/sub SI/. The possible explanation for this /spl mu//sub eff/ degradation in extremely thin silicon layers is discussed by means of a comparison to previously published experimental data and theoretical calculations. Our analysis suggests a significant role is played by an enhancement of phonon scattering due to carrier confinement in the thinnest semiconductor films. The experimental mobility data have then been used to study the possible implications for ultrashort SOI transistor performance using numerical simulations.

A solver for the two-dimensional (2-D) Schrodinger equation based on the k-space representation of the solution has been developed and applied to the simulation of 2-D electrostatic quantum effects in nano-scale MOS transistors. This paper presents the mathematical framework of the simulator, addresses the related accuracy and efficiency problems, and discusses the simulations performed to validate it. Furthermore, the 2-D quantum effects observed in the simulation of charge densities in tens-hundreds nanometer scale MOS structures are described.

This paper investigates the use of hot carrier luminescence (HCL) measurements as a mean for the verification of carrier energy distribution functions in submicron silicon devices subject to high electric fields. To this purpose, physically-based two-dimensional (2-D) simulations of the spectral distribution of HCL are compared with extensive experimental data on special purpose n/sup +//n/n/sup +/ test structures that demonstrate lateral field profiles similar to real MOSFETs without the obscuring effects of a gate electrode. Good agreement between measured and simulated data is observed over wide channel length, bias, and temperature ranges, thus providing for the first time a direct verification of simulated electron energy distributions in a MOSFET-like environment.

The multistep analytical procedure routinely applied in our laboratory for the detection of the aryl amine beta-agonists clenbuterol, mabuterol and mapenterol in bovine matrices has been extended to the analysis in urine samples of brombuterol, a new clenbuterol-like compound. In the screening steps, the urine samples were first enzyme-linked immunosorbent assay (ELISA)-tested, then the positive samples were analyzed by thin-layer chromatography (TLC) and the beta-agonists detected with the Bratton-Marshall color reaction. The TLC spots corresponding to the suspected compounds were scraped off the plates, collected and extracted separately with methanol. The beta-agonists in the extracts were detected by HPLC-Vis (limits of detection: 0.5 ng/g). In the confirmatory step the presence and the concentration of the compounds of interest in the samples were established by GC-MS with two different ionization techniques, EI and CI (limits of detection: 1.0 ng/g). The use of this procedure has made possible the detection of brombuterol in officially sampled bovine urine.

In this paper we investigate the role of structure design in determining high effective mobility (µ eff) values in Si/SiGe FETs. To this purpose we have developed a one-dimensional self-consistent Schrodinger-Poisson simulator and applied it to the study of the mobility behavior of different Si/SiGe FET structures. As a result we propose a structure which, despite to its simple design, shows improved theoretical performance.

Device simulation has played a significant role in the evolution of IC technology, providing critical insight into device scaling, leading to the advent of VLSI. Simulators continue to be applied in the analysis of new device concepts and have become an essential component of the technology design process [1]. As scaling continues into the ULSI realm (≤0.25μm), device simulation faces new challenges, necessitating improvements to both physical and numerical capabilities. It is the purpose of this paper to outline these challenges and to suggest algorithmic steps toward the development of a physically-based device simulation tool, predictive into the deep-submicron regime.

A method is presented to extract the bias-dependent series resistances and intrinsic conductance factor of individual MOS transistors from measured I-V characteristics. If applied to groups of scaled channel length devices, it also allows determination of the effective channel length together with the transversal field dependence of the carrier mobility. The method is exactly derived from conventional MOS theory based on the gradual channel approximation, and the deviations from such an ideal case are studied by means of two-dimensional device simulations. Experimental results obtained with n- and p-channel transistors of conventional as well as LDD type are presented to show the correctness of the proposed extraction procedure. >

A shallow n+layer of implanted arsenic is used to lower the effective barrier height of PtSi-n-Si and W-n-Si Schottky-barrier diodes. A device model is presented for metal-semiconductor structures that correctly accounts for physical mechanisms involved in the interface formation and dopant redistribution. Image and dipole barrier lowering as well as silicon consumption and dopant pile,up effects present in metal and silicide contacts are included in the model. A theoretical model is presented to calculate the electric-field dependence of metallic charge penetration into the semiconductor energy gap and experimental results are extracted from the measured electrical characteristics of Schottky-barrier diodes. The barrier height and ideality factor are studied at various temperatures and the theoretical calculations are shown to be in good agreement with the experimental results.

An efficient self-consistent device simulator coupling Poisson equation and Monte Carlo transport suitable for general silicon devices, including those with regions of high doping/carrier densities, is discussed. Key features include an original iteration scheme and an almost complete vectorization of the program. The simulator has been used to characterize nonequilibrium effects in deep submicron nMOSFETs. Substantial overshoot effects are noticeable at gate lengths of 0.25 mu m at room temperatures. >

Based on Monte Carlo (MC) device simulations, an analysis of hot-carrier effects in submicrometer n-MOSFETs is presented that provides detailed insight because the high-energy electrons are treated directly. The DC stress characteristics of both lightly-doped drain (LDD) and conventional As source/drain devices are found to correlate with the surface hot-electron concentration, and agreement with experimental data shows that the electron flux above 3 eV, integrated along the channel, can be used to predict device degradation. The simulations indicate that the whole DC stress characteristic can be attributed to hot electrons, while the holes generated by impact ionization have a very small probability of gaining enough energy to be injected over the oxide barrier. >

This work presents the results of measurements and simulations of n-well C-MOS structures fabricated to study the effect of reduced source-drain doping of p-channel MOSFET's on latchup triggering and holding characteristics. It is shown that lighter dopings, degrading the emitter efficiency of the parasitic p-n-p bipolar transistor, lead to improved latchup resistance that can be conveniently traded off versus the induced decrease of MOSFET transconductance.

This letter presents a novel technique of evaluating Si consumption, dopant segregation, and pile-up effects in metal and silicide contacts on silicide using a newly developed device model based on thermionic-field emission and tunneling phenomena. The field dependence of interface charge penetration into the semiconductor is evaluated from the measured electrical characteristics of Schottky diodes and the theoretical results obtained from the model.

This paper reports experimental data and simulations of low-voltage tunneling in ultrathin oxide MOS devices. When the substrate is very heavily doped, a thermionic barrier is present that opposes the direct tunneling of gate electrons when the applied gate voltage is between 0 V and the flatband voltage. In such conditions, we show that the measured gate current cannot be explained by direct tunneling, but features an additional, dominant component. The temperature dependence of this extra component indicates that it is due to gate electrons tunneling into the anode interface states. By comparing measurements and simulations, it is possible to exploit this extra current to estimate the interface state density within the silicon band gap. In addition, it is shown that this tunneling current component is very sensitive to electrical stress and allows a clear detection of oxide wear out even for stress at very low field. Therefore, it can be adopted as monitor of oxide degradation in ultrathin oxides where the traditional stress induced leakage current due to bulk-oxide traps is not detectable.

The hole impact-ionization coefficient and the hot-electron injection model presently available in the Synopsys TCAD tool have been calibrated, as a necessary step towards the possibility to predict the long-term reliability of the new generation p-channel power LDMOS devices integrated in BCD technology. First, the models have been calibrated on ad-hoc test structures such as p-channel MOSFETs with separated source and body contacts and n-channel MOSFETs with an additional sub-surface emitter region in order to have direct access to the experimental characterization of the impact-ionization under hole avalanche regime and of the hot-electron injection, respectively. Then, the calibrated models have been validated on p-channel power LDMOS featuring the STI architecture. The proposed TCAD approach accurately captures the relevant effects over an extended range of electric fields.

The description of thermal non-uniformity in large area power MOSFETs requires the modeling of a thermal network to account for the thermal interaction between adjacent devices. In this work we propose a methodology to derive an equivalent thermal network which is able to predict the thermal transient as a function of the longitudinal distance from the heat source. The thermal resistances and capacitances are calculated by assuming a cylindrical propagation of the heat. Electro-thermal numerical simulations are performed in order to study the heat propagation inside the device and to verify the accuracy of the proposed model.

a b s t r a c t This paper presents a statistical method for the calibration of an acoustic technique for the real-time eval- uation of fruit firmness. The technique uses an experimental setup based on two standard piezoelectric transducers and exploits two novel stiffness indexes developed in the first part of this paper. Exten- sive experimental measurements show good correlation (r = 0.930, R 2 = 0.865) between the proposed non-destructive test and the traditional destructive Magness-Taylor test. An evaluation of the statistical significance (t-test) of the obtained regression model parameters has been performed and validates the method. The presented sorting analysis complements the physical detection techniques presented in the first part of the paper, allowing to classify individual kiwifruits with high accuracy and high prediction rate (∼90%). The technology is suitable for industrial real-time and in-line applications aiming to improve warehouse stock management and market stock uniformity.