Fast and Accurate Inference on Microcontrollers with Boosted Cooperative Convolutional Neural Networks (BC-Net)

Arithmetic precision scaling is mandatory to deploy Convolutional Neural Networks (CNNs) on resource-constrained devices such as microcontrollers (MCUs), and quantization via fixed-point or binarization are the most adopted techniques today. Despite being born by the same concept of bit-width lowering, these two strategies differ substantially each other, and hence are often conceived and implemented separately. However, their joint integration is feasible and, if properly implemented, can bring to large savings and high processing efficiency. This work elaborates on this aspect introducing a boosted collaborative mechanism that pushes CNNs towards higher performance and more predictive capability. Referred as BC-Net, the proposed solution consists of a self-adaptive conditional scheme where a lightweight binary net and an 8-bit quantized net are trained to cooperate dynamically. Experiments conducted on four different CNN benchmarks deployed on off-the-shelf boards powered with the MCUs of the Cortex-M family by ARM show that BC-Nets outperform classical quantization and binarization when applied as separate techniques (up to 81.49% speed-up and up to 3.8% of accuracy improvement). The comparative analysis with a previously proposed cooperative method also demonstrates BC-Nets achieve substantial savings in terms of both performance (+19%) and accuracy (+3.45%)

Axp: A hw-sw co-design pipeline for energy-efficient approximated convnets via associative matching

The reduction in energy consumption is key for deep neural networks (DNNs) to ensure usability and reliability, whether they are deployed on low-power end-nodes with limited resources or high-performance platforms that serve large pools of users. Leveraging the over-parametrization shown by many DNN models, convolutional neural networks (ConvNets) in particular, energy efficiency can be improved substantially preserving the model accuracy. The solution proposed in this work exploits the intrinsic redundancy of ConvNets to maximize the reuse of partial arithmetic results during the inference stages. Specifically, the weight-set of a given ConvNet is discretized through a clustering procedure such that the largest possible number of inner multiplications fall into predefined bins; this allows an off-line computation of the most frequent results, which in turn can be stored locally and retrieved when needed during the forward pass. Such a reuse mechanism leads to remarkable energy savings with the aid of a custom processing element (PE) that integrates an associative memory with a standard floating-point unit (FPU). Moreover, the adoption of an approximate associative rule based on a partial bit-match increases the hit rate over the pre-computed results, maximizing the energy reduction even further. Results collected on a set of ConvNets trained for computer vision and speech processing tasks reveal that the proposed associative-based hw-sw co-design achieves up to 77% in energy savings with less than 1% in accuracy loss

Marine dual-fuel engines power smart management by hybrid turbocharging systems

The performance of a marine dual-fuel engine, equipped with an innovative hybrid turbocharger producing electric power to satisfy part of the ship’s electric load, is presented by a simulation comparison with the traditional turbocharging technology. The two distinct fuel types, combined with the hybrid turbocharger, involve a substantial change in the engine control modes, resulting in more flexible and efficient power management. Therefore, the investigation requires a numerical analysis depending on the engine load variation, in both fuelling modes, to highlight different behaviours. In detail, a dual-fuel engine simulation model is validated for a particular application in order to perform a complete comparison, reported in tabular and graphical form, between the two examined turbocharging solutions. The simulation analysis is presented in terms of the engine working data and overall energy conversion efficiency

Validation of an Emission Model for a Marine Diesel Engine with Data from Sea Operations

In this study, a model is developed to simulate the dynamics of an internal combustion engine, and it is calibrated and validated against reliable experimental data, making it a tool that can effectively be adopted to conduct emission predictions. In this work, the Ricardo WAVE software is applied to the simulation of a particular marine diesel engine, a four-stroke engine used in the maritime field. Results from the bench tests are used for the calibration of the model. Finally, the calibration of the model and its validation with full-scale data measured at sea are presented. The prediction includes not only the classic engine operating parameters for a comparison with surveys but also an estimate of nitrogen oxide emissions, which are compared with similar results obtained with emission factors. The calibration of the model made it possible to obtain an overlap between the simulation results and real data with an average error of approximately 7% on power, torque, and consumption. The model provides encouraging results, suggesting further applications, such as in the study on transient conditions, coupling of the engine model with the ship model for a complete simulation of the operating conditions, and optimization studies on consumption and emissions. The availability of the emission data during the sea trial and validated simulation results are the strengths and novelties of this work

Experimental estimation of the local heat-transfer coefficient in coiled tubes in turbulent flow regime

Wall curvature is a popular heat transfer enhancement technique since it gives origin to the centrifugal force in the fluid: this phenomenon promotes local maxima in the velocity distribution that locally increase the temperature gradients at the wall by enhancing the heat transfer both in the laminar and in the turbulent flow regime. This geometry produces an asymmetrical distribution of the velocity field over the cross-section of the tube which lead to a significant variation in the convective heat-transfer coefficient along the circumferential angular coordinate: it presents higher values at the outer bend side of the wall surface than at the inner bend side. Although the irregular distribution of the heat transfer coefficient may be critical in some industrial applications, most of the authors did not investigate this aspect, mainly due to the practical difficulty of measuring heat flux on internal wall surface of a pipe. In the present investigation the local convective heat-transfer coefficient is experimentally estimated at the fluid-wall interface in coiled tubes when turbulent flow regime occurs; in particular, temperature distribution maps on the external coil wall are employed as input data of the inverse heat conduction problem in the wall and a solution approach based on the Tikhonov regularisation is implemented. The results, obtained with water as working fluid, are focused on the fully developed region in the turbulent flow regime in the Reynolds number range of 5000 to 12000

Therapeutic sequences in patients with grade 1−2 neuroendocrine tumors (NET): an observational multicenter study from the ELIOS group

Purpose: Many different treatments are suggested by guidelines to treat grade 1−2 (G1−G2) neuroendocrine tumors (NET). However, a precise therapeutic algorithm has not yet been established. This study aims at identifying and comparing the main therapeutic sequences in G1−G2 NET. Methods: A retrospective observational Italian multicenter study was designed to collect data on therapeutic sequences in NET. Median progression-free survival (PFS) was compared between therapeutic sequences, as well as the number and grade of side effects and the rate of dose reduction/treatment discontinuation. Results: Among 1182 patients with neuroendocrine neoplasia included in the ELIOS database, 131 G1–G2 gastroenteropancreatic, lung and unknown primary NET, unresectable or persistent/relapsing after surgery, treated with ≥2 systemic treatments, were included. Four main therapeutic sequences were identified in 99 patients: (A) somatostatin analogs (SSA) standard dose to SSA high dose (n = 36), (B) SSA to everolimus (n = 31), (C) SSA to chemotherapy (n = 17), (D) SSA to peptide receptor radionuclide therapy (PRRT) (n = 15). Median PFS of the second-line treatment was not reached in sequence A, 33 months in sequence B, 20 months in sequence C, 30 months in sequence D (p = 0.16). Both total number and severity of side effects were significantly higher in sequences B and C than A and D (p = 0.04), as well as the rate of dose reduction/discontinuation (p = 0.03). Conclusions: SSA followed by SSA high dose, everolimus, chemotherapy or PRRT represent the main therapeutic sequences in G1−G2 NET. Median PFS was not significantly different between sequences. However, the sequences with SSA high dose or PRRT seem to be better tolerated than sequences with everolimus or chemotherapy

Numerical analysis of flow resistance and heat transfer in the transitional regime of pipe flow with twisted-tape turbulators

In this paper, we present the numerical analysis of the fully developed ow and heat transfer in pipes equipped with twisted-tape inserts in the laminar to transitional flow regime. The flow Reynolds number ranges from 210 to 3100 based on the pipe diameter, whereas the Prandtl number of the working fluid, a 40% mixture of water and ethylene glycol, is about 45 at the average film temperature. The numerical study is carried out via Scale Adaptive Simulations (SAS) where the k-ω SST model is employed for turbulence modeling. Using SAS and low-dissipation discretization schemes, the present study shows that it is possible to capture the transition from the laminar regime to the pulsating or pseudo-laminar flow regime induced by the twisted-tape at low Reynolds numbers, as well as the transition to moderate turbulent regime at the higher, yet non-turbulent for smooth pipes, range of Reynolds numbers. Numerical results, validated against experiments performed in a dedicated test rig, show very good agreement with measured data and an increase of the friction factor and Nusselt number in the range of 4 to 7 times and 6 to 15 times, respectively, of the values for an empty pipe

Organization and implementation of student-centred active learning in science at secondary and university levels: the Qatari experience

Qatar’s National Vision 2030 and Education for New Era emphasise the need to encourage teachers to move from a didactic teacher-led mode of instruction to one that is more student-centred, but also teacher-guided, which encourages the development of critical thinking, problem solving, inquiry, and investigative skills. With an emphasis on an initiative in chemistry, we describe a project that brings together educators from Qatar and Australia to explore the utility and cultural transferability of student inquiry learning approaches that involves improving student conceptual understanding as well as their attitudes and self-efficacy. Process Oriented Guided Inquiry Learning (POGIL) is being applied in foundation chemistry classes at Weill Cornell Medical College in Qatar and studied in parallel with an established learning environment at Curtin University using the same method of instruction. The comparisons are being carried over a number of years to establish longevity of any impact

A lanthanum picrate complex of a 1,2-bisamide substituted calix[4]arene

The synthesis and structural characterization of a lanthanum picrate complex of the proximally-substituted calix[4]arene bisamide, 5,11,17,23-tetra-tert-butyl-25,26- bis(diethylcarbamoylmethoxy)-27,28-dihydroxycalix[4] arene (L), is reported. The complex is formulated as [La(L-H)(picrate)2]2.75CH2Cl2 and crystallises with two inequivalent metal complexes in the unit cell. The differing dispositions of the picrate anions in the two complexes suggest that intramolecular interactions between the aromatic rings of the picrate and calixarene are less significant than the forces involved in the crystal packing of the complexes

Statistical Analysis of Installed Power on Board Modern Cruise Ships

The world fleet of cruise vessels is constantly growing in terms of both tonnage and number of units, with a continuous change in main characteristics. This paper answers to the need for obtaining a reliable prediction of the power installed on modern cruise ships based on data easily accessible on single units. For the purpose, a dataset of 129 cruise ships has been generated. For these vessels, the total power installed was available, together with other more common data including main dimensions, tonnage, speed, number of passengers, etc. The database has been analysed through different statistical formulations by means of a dedicated analysis software. The paper describes and discusses the analyses carried out and provides as a result the regressions with the best characteristics and performances, checked by means of a thorough analysis of residuals and selected statistical indicators