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The improvement of the robustness of the performance of electrical machines in presence of neglected features, such as manufacturing tolerances and deviations in material properties and parameters, is increasingly demanded. The available optimization procedures do not account for manufacturing tolerances, leaving the decision process incomplete. The article proposes a methodology for the selection of the more robust design towards manufacturing tolerances among the best candidates, detected by an optimization procedure. Statistical tools for tolerance analysis and worst-case analysis are discussed and adopted for the scope. The proposed methodology is used to select a robust design with respect to torque ripple deviations due to geometric tolerances in the laminations of a Synchronous Reluctance Motor with fluid shaped barriers. The statistical performance analysis and the worst-case analysis provide an estimation of the performance deterioration in the presence of the tolerances in the manufacturing process.

Platinum is a promising candidate for the realization of blocking electrical contacts on cadmium-zinc-telluride (CdZnTe or CZT) radiation detectors. However, the poor mechanical adhesion of this metal often shortens the lifetime of the final device. In this work, a simple and effective procedure to obtain robust platinum contacts by electroless deposition is presented. Microscopical analysis revealed the final thickness and composition of the contact layer and its adhesion to the bulk crystal. The blocking nature of the Pt-CdZnTe junction, essential to obtain low noise devices, was confirmed by current–voltage measurements. The planar Pt-CdZnTe-Pt detectors showed good room temperature spectroscopic performance with energy resolution of 4% (2.4 keV) and 3% (3.7 keV) FWHM at 59.5 and 122.1 keV, respectively. Finally, we showed, for the first time, that platinum contacts allow the estimation of the carrier lifetime and mobility of both holes and electrons by using current transient measurements. This demonstrated the optimal hole extraction capability of such contacts.

The use of quantum dots (QDs) is widespread and as such, the potential risk associated with their dispersion in the environment has stimulated research on their interaction with potential sensitive receptors. To this end, the model plant Arabidopsis thaliana wild type (wt) and two mutant lines known to be tolerant to cadmium-based CdS QDs but not to CdSO4 were exposed to CdS QDs or CdSO4 at sub-inhibitory concentrations for 20 days. X-ray absorption spectroscopy (XAS) was employed to investigate cadmium speciation in the cellular environment of the plants after treatment. After exposure to CdS QDs and CdSO4, differences in biomass were observed between the wt and mutants, but the form of Cd in the treatment had a marked influence on the cadmium atomic environment. The spectra of whole plant samples were found to be compatible with a mixed O/S coordination; while Cd–S distances did not show much variation, Cd–O distances varied from ≈2.16 A in samples grown with QDs to ≈2.22 A in those grown with CdSO4. In addition, the number of Cd–S bonds in plants grown with QDs was higher than Cd–O bonds. XAS data showed that CdS QDs were bio-transformed after their uptake; the particle original structure was modified but not totally eliminated, and Cd atoms were not released as Cd(II) ions. These findings show the nanoscale specific response of plants to QDs, provide important insight into understanding the nanoparticle fate in plants and in the environment, and have implications for both risk assessment and design of appropriate remediation strategies.

The paper presents a sustainable electric powertrain for a transit city bus featuring an electrochemical battery-free power unit consisting of a hydrogen fuel cell stack and a kinetic energy storage system based on high-speed flywheels. A rare-earth free high-efficiency motor technology is adopted to pursue a more sustainable vehicle architecture by limiting the use of critical raw materials. A suitable dynamic energetic model of the full vehicle powertrain has been developed to investigate the feasibility of the traction system and the related energy management control strategy. The model includes losses characterisation, as a function of the load, of the main components of the powertrain by using experimental tests and literature data. The performance of the proposed solution is evaluated by simulating a vehicle mission on an urban path in real traffic conditions. Considerations about the effectiveness of the traction system are discussed.

The Theory of the Adjacent Possible (TAP) equation has been proposed as an appropriate description of super-exponential growth phenomena, where a phase of slow growth is followed by a rapid increase, leading to a “hockey stick” curve. This equation, initially conceived to describe the growth in time of the number of new types of artifacts, has also been applied to several natural phenomena. A possible drawback is that it may overestimate the number of new artifact types, since it does not take into account the fact that interactions, among existing types, may produce types which have already been previously discovered. We introduce here a Binary String World (BSW) where new string types can be generated by interactions among (at most two) already existing types. We introduce a continuous limit of the TAP equation for the BSW; we solve it analytically and show that it leads to divergence in finite time. We also introduce a criterion to distinguish this type of behavior from the familiar exponential growth, which diverges only as t → ∝. In the BSW, it is possible to directly model the generation of new types, and to check whether the newborns are actually novel types, thus discarding the rediscoveries of already existing types. We show that the type of growth is still TAP-like, rather than exponential, although of course in simulations one never can observes true divergence. We also show that this property is robust with respect to some changes in the model, as long as it deals with types (and not with individuals).

Ovarian cancer is a highly lethal gynecological malignancy. Drug resistance rapidly occurs, and different therapeutic approaches are needed. So far, no biomarkers have been discovered to predict early response to therapies in the case of multi-treated ovarian cancer patients. The aim of our investigation was to identify a protein panel and the molecular pathways involved in chemotherapy response through a combination of studying proteomics and network enrichment analysis by considering a subset of samples from a clinical setting. Differential mass spectrometry studies were performed on 14 serum samples from patients with heavily pretreated platinum-resistant ovarian cancer who received the FOLFOX-4 regimen as a salvage therapy. The serum was analyzed at baseline time (T0) before FOLFOX-4 treatment, and before the second cycle of treatment (T1), with the aim of understanding if it was possible, after a first treatment cycle, to detect significant proteome changes that could be associated with patients responses to therapy. A total of 291 shared expressed proteins was identified and 12 proteins were finally selected between patients who attained partial response or no-response to chemotherapy when both response to therapy and time dependence (T0, T1) were considered in the statistical analysis. The protein panel included APOL1, GSN, GFI1, LCATL, MNA, LYVE1, ROR1, SHBG, SOD3, TEC, VPS18, and ZNF573. Using a bioinformatics network enrichment approach and metanalysis study, relationships between serum and cellular proteins were identified. An analysis of protein networks was conducted and identified at least three biological processes with functional and therapeutic significance in ovarian cancer, including lipoproteins metabolic process, structural component modulation in relation to cellular apoptosis and autophagy, and cellular oxidative stress response. Five proteins were almost independent from the network (LYVE1, ROR1, TEC, GFI1, and ZNF573). All proteins were associated with response to drug-resistant ovarian cancer resistant and were mechanistically connected to the pathways associated with cancer arrest. These results can be the basis for extending a biomarker discovery process to a clinical trial, as an early predictive tool of chemo-response to FOLFOX-4 of heavily treated ovarian cancer patients and for supporting the oncologist to continue or to interrupt the therapy.

This paper proposes a rapid and analytical approach to evaluate the steady-state eddy-current losses in hairpin wound induction motors fed by pulse width modulated inverter. The method is based on a custom frequency-dependent lumped parameter circuit, useful to evaluate the steady-state harmonic content of the phase current considering the modulation. Furthermore, simplifying hypotheses, suitably described and justified, allow the definition of an analytical model for the calculation of the Joule losses contribution for each harmonic considering the effect of eddy-currents. This proposed approach is compared with the computationally more expensive transient finite element method and applied, as test-case, to a 200kW induction motor designed for an electric vehicle. A realistic estimation of the method accuracy and computational time is provided in a practical case, as well as a quantitative evaluation of the eddy current losses due to the modulation.

This paper presents a preliminary sizing procedure for a fluid shaped rotor of a Synchronous Reluctance motor and the design refinement by an optimization step. Starting from the definition of the fluid shaped barrier based on the Joukosky equation and on the analogy between the magnetic and mechanical equations, the preliminary design can be defined. The method uses the same approach of the other rotor shapes accurately changed to match the features of the fluid shaped rotor. This procedure is applied to a case study where the stator core is already defined. After the definition of the preliminary design a further optimization is carried out which involves an optimization algorithm linked to the Finite Element analysis. The preliminary and the optimized designs are then compared and discussed.

This study investigates the cooling performance of a passive cooling system for electric motor cooling applications. The metal-based phase change materials are used for cooling the motor and preventing its temperature rise. As compared to oil-based phase change materials, these materials have a higher melting point and thermal conductivity. The flow field and transient heat conduction are simulated using the finite volume method. The accuracy of numerical values obtained from the simulation of the phase change materials is validated. The sensitivity of the numerical results to the number of computational elements and time step value is assessed. The main goal of adopting the phase change material based passive cooling system is to maintain the operational motor temperature in the allowed range for applications with high and repetitive peak power demands such as electric vehicles by using phase change materials in cooling channels twisted around the motor. Moreover, this study investigates the effect of the phase change material container arrangement on the cooling performance of the under study cooling system.

We fabricated gold nanoparticles on nanoporous silicon microparticles using electroless deposition in a hydrofluoric acid solution containing gold chloride. The reaction was followed by UV spectrometer analysis of the absorbance of the solution (proportional to the nanoparticle concentration) for two temperatures (20 and 50 degrees C). The results indicate that the process is autocatalytic, described by a pseudo-first-order reaction, the apparent rate constant k(obs) of which was determined by utilizing UV spectrometer data. We found that the reaction rate constant at 20 degrees C is 7 x 10(-3) s(-1) and that at 50 degrees C is 2.9 x 10(-2) s(-1). Scanning electron microscope (SEM) analysis of samples and diffusion-limited aggregation (DLA) simulations were used to validate the results. This study aims to resolve the kinetics of the electroless deposition of gold on silicon at the nanoscale, in the present state of art missing a quantitative characterization, for certain conditions of growth and given values of temperature and concentration of the reagents. Results may have applications to the synthesis of gold nanoparticles and their use as nanosensors, drug delivery systems, or metal nanometamaterials with advanced optical properties.

Executive Summary corresponding to the ReFreeDrive project deliverable D6.8: "PM Synchronous Reluctance Motor for 200 kW of operation"

This report describes the progresses and achievements of ReFreeDrive project in the period from 01.07.2018 (M10) to 31.07.2019 (M22). In this period several management procedures have been carried out, such as risk management, open data management, reporting to the EC, monitoring of the project progress, etc. Design of induction motor, pure synchronous reluctance motor and permanent magnets assisted reluctance motor has been carried out, ensuring the accomplishment of the Key Performance Indicators defined in the project proposal. Power electronics and control algorithm for all motor topologies have been developed. Some integration activities have also been made. The first draft of the techno-economic evaluation and results exploitation is summed up, as well as the first iterations of the Life Cycle Analysis. Although the information is individualized for each Work Package, interactions between them are also considered. All the Work Package Leaders have participated in the writing of this report

Executive Summary corresponding to the ReFreeDrive project deliverable D6.7: "Pure Synchronous Reluctance Motor for 200kW of operation"

In previous work, two independent Arabidopsis thaliana Ac/Ds transposon insertional mutant lines, atnp01 and atnp02, were identified that showed a higher level of tolerance than the wild type (wt) line to cadmium sulfide quantum dots (CdS QDs). The tolerance response was characterized at physiological, genetic and transcriptomic levels. In this work, a comparative analysis was performed on protein extracts from plantlets of the two mutants and of wt, each treated with 80 mg L-1 CdS QDs. A comparative protein analysis was performed by 2D-PAGE, and proteins were characterized by MALDI-TOF/TOF mass spectrometry. Of 250 proteins identified from all three lines, 98 showed significant changes in relative abundance between control and CdS QD-treated plantlets. The wt, atnp01, and atnp02 control-treated pairs respectively showed 61, 31, and 31 proteins with differential expression. The two mutants had a different response to treatment in terms of type and quantity of up- and downregulated proteins. This difference became more striking when compared to wt. A network analysis of the proteins differentially expressed in atnp01 and atnp02 included several of those encoded by putative genes accommodating the transposons, which were responsible for regulation of some proteins identified in this study. These included nifu-like protein 3 (Nfu3), involved in chloroplast assembly, elongator complex 3 (Elo3), involved in transcriptional elongation, magnesium-chelate subunit-2 (Chli2), involved in chlorophyll biosynthesis, and protein phosphatase 2C (PP2C) which mediates abiotic stress response.

Plasmon-exciton coupling is gaining increasing interest for enhancing the performance of optoelectronic, photonic and photo-catalytic devices. Herein we evaluate the interaction of excitons in zinc oxide tetrapods with surface plasmons of gold nanostructures with different morphologies. The gold nanostructures are grown in situ on ZnO tetrapods by means of a photochemical process, resulting in clean interfaces. The modification of the synthesis parameters results in different morphologies, as isolated nanoparticles, nano-domes or nanoparticles aggregates. Plasmon-exciton interaction is evaluated by means of cathodoluminescence spectroscopy and mapping at the nanoscale. The ZnO excitonic emission is strongly blue-shifted and broadened in close proximity of the gold nanostructures. This effect is explained by the formation of a Schottky barrier that is strongly mediated by the morphology of metal nanostructures.

The demand for energy saving and the new policies on the efficiency of motors for constant speed applications have shifted the interest of designers from conventional induction motors (IMs) towards alternative high-efficiency motors such as the line-start synchronous reluctance motor (LSSynRM). This type of motor is very cost-effective and can compete with the robustness and the low price of the IM. LSSynRM critical aspects are the rough starting transient, limitations in terms of pull-in (synchronization) capability and low power factor. In this chapter, a specific design procedure for LSSynRMs has been used in order to reach the desired balance between the pull-in capability, starting behaviour, and steady-state performance. It is the combination between finite-element (FE) analyses and optimization algorithms. The procedure is applied to design two LSSynRMs, 3 kW-2 pole and 4 kW-4 pole, 400 V, 50 Hz. The simulation results are compared with those of the IMs of the same size. A prototype of the 4 kW-4pole motor has been realized and tested. Then, its performance is presented in comparison with the IM counterpart. The LSSynRM proved to be a cost-effective, mass production-ready solution for super-premium efficiency IE4 motors, and it can effectively replace the conventional IM in a vast panorama of industrial applications.

The ability to produce distributed sensors by tailoring materials readily available on the market is becoming an emerging strategy for Internet of Things applications. Embedding sensors into functional substrates allows one to reduce costs and improve integration and gives unique functionalities inaccessible to silicon or other conventional materials used in microelectronics. In this paper, we demonstrate the functionalization of a commercial polyurethane (PU) foam with the conductive polymer PEDOT:PSS: the resulting material is a modified all-polymeric foam where the internal network of pores is uniformly coated with a continuous layer of PEDOT:PSS acting as a mechanical transducer. When an external force causes a modification of the foam microstructure, the conductivity of the device varies accordingly, enabling the conversion of a mechanical pressure into an electric signal. The sensor provides a nearly linear response when stimulated by an external pressure in the range between 0.1 and 20 kPa. Frequency-dependent measurements show a useful frequency range up to 20 Hz. A simple micromechanical model has been proposed to predict the device performance based on the characteristics of the system, including geometrical constrains, the microstructure of the polymeric foam, and its elastic modulus. By taking advantage of the simulation output, a flexible shoe in sole prototype has been developed by embedding eight pressure sensors into a commercial PU foam. The proposed device may provide critical information to medical teams, such as the real-time bodyweight distribution and a detailed representation of the walking dynamic.

In this work, we explore the properties of a control mechanism exerted on random Boolean networks that takes inspiration from the methylation mechanisms in cell differentiation and consists in progressively freezing (i.e. clamping to 0) some nodes of the network. We study the main dynamical properties of this mechanism both theoretically and in simulation. In particular, we show that when applied to random Boolean networks, it makes it possible to attain dynamics and path dependence typical of biological cells undergoing differentiation.

Random Boolean networks are a widely acknowledged model for cell dynamics. Previous studies have shown the possibility of achieving Boolean networks with given characteristics by means of evolutionary techniques. In this work we make a further step towards more biologically plausible models by aiming at evolving networks with a given fraction of active nodes along the attractors, while constraining the evolutionary process to move across critical networks. Results show that this path along criticality does not impede to climb the mount of improbable, yet biologically realistic requirements.

This paper presents different approaches proposed to evaluate eddy-current losses in hairpin wound motor fed by pulse width modulated inverter, underlining strengths and weaknesses of everyone and applying them, as test-case, to a 200kW induction motor designed for a premium electric vehicle. The first three approaches are based on the finite element analysis: the first, the more accurate one, use a transient analysis that request long execution time and high memory usage, the second is based on tool that permits rapidly to evaluate the steady state conditions imposing a sinewave current and the third uses a single-slot simplified model. The fourth approach proposes a rapid monodimensional analytic method based on hypotheses that permit to consider the superposition effects of the Eddy Current Losses of every current harmonic component. The fifth approach makes uses of the proposed analytic method by leveraging a rapid investigation of current harmonic content due to pulse width modulation based on a lumped parameter motor model. In addition, the paper discusses important considerations about the use of the hairpin technology fed by pulse width modulation that can be drawn from the analysis of the obtained results

The properties of most systems composed of many interacting elements are neither determined by the topology of the interaction network alone, nor by the dynamical laws in isolation. Rather, they are the outcome of the interplay between topology and dynamics. In this paper, we consider four different types of systems with critical dynamic regime and with increasingly complex dynamical organization (loosely defined as the emergent property of the interactions between topology and dynamics) and analyze them from a structural and dynamic point of view. A first noteworthy result, previously hypothesized but never quantified so far, is that the topology per se induces a notable increase in dynamic organization. A second observation is that evolution does not change dramatically the size distribution of the present dynamic groups, so it seems that it keeps track of the already present organization induced by the topology. Finally, and similarly to what happens in other applications of evolutionary algorithms, the types of dynamic changes strongly depend upon the used fitness function.

This work describes a new technique for the induction machine analysis using finite element method. It is based on magneto-static simulations, in which both stator and rotor current are imposed as field sources. The rotor current is set in the bars using an equivalent poly-phase winding and the amplitude is derived the main concepts of the machine analytical model in the rotor field oriented reference frame. The main part of the work is the comparison with the time-domain analysis results, considered to be the benchmark, as a very accurate and exhaustive approach. The great advantage of using the new method, based on the magneto-static finite element formulation, is the dramatic reduction of the computation time, for deriving steady-state machine performance.

This work explores several cooling system topologies for permanent magnet machines with hairpin winding configurations in automotive traction applications. A common cooling system such as a housing water jacket is initially utilized and subsequently compared to a slot water jacket one. Four different in-slot cooling arrangements are considered, leading to four different stator designs, keeping the same machine volume. The impact of the different loss components on the machine performance both electromagnetically and thermally is analyzed. The work aims to show and prove the goodness of the slot water jacket for hairpin windings in addition to the selection of the optimal solution among the proposed ones.

This paper presents the design and the verification of a brushless DC motor integrated in an actuator for aircraft application and can be inserted in the field of so called More Electric Aircraft line of though. Main challenge of More Electric Aircraft concepts is the complete substitution of traditional actuator with Electro-Mechanical Actuator, ensuring the same performance and reliability. In this paper, a brushless DC motor for primary flight surface actuator has been designed and analyzed and the comparison on performance of different motor solutions has been presented. Before the sizing of the motor, an accurate selection of the active material has been performed the actuator architecture has been deeply evaluated to identify the best compromise between performance and reliability. After the electromagnetic design, a thermal analysis has been carried out in order to verify the brushless DC motor temperatures during its operation

This article deals with the design of high-speed synchronous reluctance motors for electric vehicle applications. The need to enhance the power density and to lower the cost leads to research on high-speed motors with a reduced amount of rare earth. Pure synchronous reluctance motors potentially operate at high speed and exhibit a cost-effective rotor compared to permanent magnets and induction motors. Nevertheless, they present reduced performances in deep flux weakening operations, in particular when the so-called radial ribs are introduced to increase the mechanical robustness of the rotor. In this article, the introduction of the radial ribs and the related design challenges are investigated and discussed. The adoption of the topology optimization tool that is able to optimize the amount, the positioning, and the sizing of suitable structural ribs is presented. A design flow integrating the topology optimization is presented. The approach leads to an original positioning of the radial ribs able to preserve the performance of the motor at high operating speed enhancing the mechanical integrity of the rotor.

The data included in this paper are associated with a research article entitled 'Differences in toxicity, mitochondrial function and miRNome in human cells exposed in vitro to Cd as CdS quantum dots or ionic Cd' [1]. The article concerns the use of miRNAs as biomarkers for engineered nanomaterials (ENMs) risk assessment. Two different type of human cells, HepG2 and THP-1, were exposed to different forms of Cadmium: nanoscale, as CdS quantum dots (CdS QDs), and ionic, as CdSO4 8/3 -hydrate (Cd(II)). The cells were treated with sub-toxic doses of CdS QDs; 3 µg ml-1 in HepG2 and 6.4 µg ml-1 and 50 µg ml-1 in THP-1, as well as equivalent cadmium doses as Cd(II). In this dataset, changes in expression levels of miRNAs are reported. In addition, GO enrichment analyses of target genes of miRNAs modulated by Cd stress, network analysis of the microRNome and an in silico pathway analysis are also reported. These data enhance and also summarize much of the data independently presented in the research article and therefore, must be considered as supplementary.

This paper presents the results obtained by the finite elements model co-simulation technique in the transient analysis of an electric drive for advanced traction applications. The case study refers to a 200kW induction motor drive designed for a premium electric vehicle in the frame of the Horizon 2020 “ReFreeDrive” project (Rare earth Free e-Drives featuring low cost manufacturing). The transient performance and the operating limits are evaluated when a field-oriented control strategy based on the lumped parameters model of the machine is used. The co-simulation involves the ANSYS/Simplorer and MATLAB/Simulink environments. The finite element motor model developed in ANSYS is controlled by the rotor flux-oriented controller with axes decoupling built in Simulink. A lumped parameters motor model is also derived to design the control parameters and implemented in Simulink for comparison respect to the co-simulation approach. The results highlight the influence of the controller detuning for the correct prediction of the voltage limit operation at steady state.

Background The increasing use of cadmium sulphide (CdS) quantum dot (QD)-enabled products is expected to be accompanied by their release into the environment. In this study, the whole organism Saccharomyces cerevisiae was used as a model eukaryote to study protein modulations employing 2D- gel electrophoresis and gel-free iTRAQ (Isobaric Tags for Relative and Absolute Quantitation) proteomics following cell exposure to CdS QDs for 9 and 24 h. From both biotechnological and ecotoxicological perspectives, the use of S. cerevisiae as a model organism sheds light on the impact nanomaterials have on the biochemical responses of the exposed organism. Results Key proteins involved in essential biological pathways were downregulated, in particular after 24 h exposure. These include the major proteins of the glycolytic pathway, the components of mitochondrial respiratory chain complexes III, IV and V involved in the oxidative phosphorylation chain, the ATP-dependent molecular chaperone Hsc82 as well as other proteins responsible for protein folding and ubiquitination in the endoplasmic reticulum. Some of the proteins whose expression was altered have previously been described as strongly-adsorbed by CdS QD nanomaterial surfaces as hard corona, and involved in the cytotoxicity of this class of engineered nanomaterials. These data may be extrapolated to broader contexts and a wider range of organisms by allowing the identification of robust biomarkers of exposure to CdS QDs. Conclusions The work shows the power of the model organisms S. cerevisiae in biotechnology to ensure high levels of health and environmental safety. In fact, the double proteomic approach allowed to identify early markers of exposure to CdS QDs among all the proteins reprogrammed by the treatment.

Random Boolean networks are a widely acknowledged model for cell dynamics. Previous studies have shown the possibility of achieving Boolean Networks (BN) with given characteristics by means of evolutionary techniques. In this work we show that it is possible to evolve BNs exhibiting more positive than negative reactions to knock-out stresses. It is also interesting to observe that in the observed runs (i) the evolutionary processes can guide the BNs toward different dynamic regimes, depending on their internal structure and that (ii) the BNs forced to evolve by maintaining a critical dynamical regime achieve better results than those that do not have this characteristic; this observation supports the idea that criticality may be beneficial to an evolving population of dynamical systems.

Living beings share several common features at the molecular level, but there are very few large-scale &ldquo, operating principles&rdquo, which hold for all (or almost all) organisms. However, biology is subject to a deluge of data, and as such, general concepts such as this would be extremely valuable. One interesting candidate is the &ldquo, criticality&rdquo, principle, which claims that biological evolution favors those dynamical regimes that are intermediaries between ordered and disordered states (i.e., &ldquo, at the edge of chaos&rdquo, ). The reasons why this should be the case and experimental evidence are briefly discussed, observing that gene regulatory networks are indeed often found on, or close to, the critical boundaries. Therefore, assuming that criticality provides an edge, it is important to ascertain whether systems that are critical can further evolve while remaining critical. In order to explore the possibility of achieving such &ldquo, always-critical&rdquo, evolution, we resort to simulated evolution, by suitably modifying a genetic algorithm in such a way that the newly-generated individuals are constrained to be critical. It is then shown that these modified genetic algorithms can actually develop critical gene regulatory networks with two interesting (and quite different) features of biological significance, involving, in one case, the average gene activation values and, in the other case, the response to perturbations. These two cases suggest that it is often possible to evolve networks with interesting properties without losing the advantages of criticality. The evolved networks also show some interesting features which are discussed.

A well-known hypothesis, with far-reaching implications, is that biological evolution should preferentially lead to critical dynamic regimes. Useful information about the dynamical regime of gene regulatory networks can be obtained by studying their responses to small perturbations. The interpretation of these data requires the use of suitable models, where it is usually assumed that the system is homogeneous. On the other hand, it is widely acknowledged that biological networks display some degree of modularity, so it is interesting to ascertain how modularity can affect the estimation of their dynamical properties. In this study we introduce a well-defined degree of modularity and we study how it influences the network dynamics. In particular, we show how the estimate of the Derrida parameter from “avalanche” data may be affected by strong modularity.