Continuous-Time Switched H∞ Proportional-Integral observer: Application for sideslip and road bank angles estimation

International audience— In this work, a Continuous-Time Switched H ∞ Proportional-Integral (CTSH ∞ PI) observer is presented. The estimation method is based on a proportional-integral observer introduced by [13], [11], [12]. The estimation method is used to estimate simultaneously the state variables and unknown inputs of switched systems. A design method is established using a common Lyapunov function and H ∞ norm. Its stability and global convergence conditions are proved and expressed in term of LMIs. All conditions are established under given switching signals. The estimation method is applied in vehicle dynamics to estimate simultaneously the vehicle sideslip angle and road bank angle. Moreover, the switching signal is deduced from measured premise variables. Simulation tests with experimental data are included to demonstrate the advantage of this method

Simple Tracking Output Feedback H ∞ Control for Switched Linear Systems: Lateral Vehicle Control Application

International audienceIn this paper, the problem of the switched H ∞ tracking output feedback control problem is studied. The control design problem is addressed in the context of discrete-time switched linear systems. Then, the design of continuous-time case becomes trivial. Linear Matrix Inequality (LMI) and Linear Matrix Equality (LME) representations are used to express all sufficient conditions to solve the control problem. Some transformations leading to sufficient conditions for the control problem are also used. All conditions are established for any switching using a switched Lyapunov function and a common Lyapunov function. The effectiveness of the proposed control approach is shown through a steering vehicle control implementation. Interesting simulation results are obtained using real data acquired by an instrumented car

Simple Discrete-Time Switched H ∞ Optimal Control: Application for Lateral Vehicle Control

International audienceThis paper presents a switched H ∞ optimal control for a class of discrete-time switched linear systems. All sufficient conditions of the existence of the control law are proved and given in terms of LMI for any switching. Moreover, the proofs are established using an H ∞ norm and switched Lyapunov functions. Its performances are shown through a steering vehicle control application. In fact, the vehicle models are affected by several parameter variations like longitudinal speed, cornering stiffnesses coefficients. The validation step is conducted using real data acquired by a laboratory car under high lateral loads

Low-temperature thin film encapsulation for MEMS with silicon nitride/chromium cap

In this work, a low-temperature fabrication process of thin film encapsulation (TFE) with silicon nitride/chromium cap is proposed for large-size (750 μm x 300 μm) packaging of microelectromechanical systems (MEMS). A FEM model was developed to evaluate the shape of TFE as a function of the residual stress and the thickness of the sealing layer, providing useful guidelines for the fabrication process. The low temperature of 200 °C, which was used in the plasma-enhanced chemical vapor deposition of the silicon nitride capping layer, allowed an organic sacrificial material to be employed for the definition of the encapsulation area. Silicon nitride/chromium (1 μm/20 nm) bilayer was demonstrated to be successful to overcome the technological limitations that affect the creation of cap holes with size of ~2 μm on high topography substrates, as in the case of MEMS. Plasma focused ion beam (PFIB) and scanning electron microscopy (SEM) techniques were used in combination to gain deeper insight into the sealing process of cap holes. Specifically, a PFIB-SEM serial section procedure was developed, resulting to be a powerful tool to directly observe the sealing profile above cap holes. Hence, the presented results greatly contribute to overcome the main technological/reliability issues of TFE, paving the way for the widespread application of the proposed encapsulation methodology to the most used MEMS devices, as radio-frequency (RF) switches, transducers, actuators, sensors and resonators

Host markers in Quantiferon supernatants differentiate active TB from latent TB infection: preliminary report

<p>Abstract</p> <p>Background</p> <p>Interferon gamma release assays, including the QuantiFERON^®TB Gold In Tube (QFT) have been shown to be accurate in diagnosing <it>Mycobacterium tuberculosis </it>infection. These assays however, do not discriminate between latent TB infection (LTBI) and active TB disease.</p> <p>Methods</p> <p>We recruited twenty-three pulmonary TB patients and 34 household contacts from Cape Town, South Africa and performed the QFT test. To investigate the ability of new host markers to differentiate between LTBI and active TB, levels of 29 biomarkers in QFT supernatants were evaluated using a Luminex multiplex cytokine assay.</p> <p>Results</p> <p>Eight out of 29 biomarkers distinguished active TB from LTBI in a pilot study. Baseline levels of epidermal growth factor (EGF) soluble CD40 ligand (sCD40L), antigen stimulated levels of EGF, and the background corrected antigen stimulated levels of EGF and macrophage inflammatory protein (MIP)-1β were the most informative single markers for differentiation between TB disease and LTBI, with AUCs of 0.88, 0.84, 0.87, 0.90 and 0.79 respectively. The combination of EGF and MIP-1β predicted 96% of active TB cases and 92% of LTBIs. Combinations between EGF, sCD40L, VEGF, TGF-α and IL-1α also showed potential to differentiate between TB infection states. EGF, VEGF, TGF-α and sCD40L levels were higher in TB patients.</p> <p>Conclusion</p> <p>These preliminary data suggest that active TB may be accurately differentiated from LTBI utilizing adaptations of the commercial QFT test that includes measurement of EGF, sCD40L, MIP-1β, VEGF, TGF-α or IL-1α in supernatants from QFT assays. This approach holds promise for development as a rapid diagnostic test for active TB.</p

Strengthening of Wood-like Materials via Densification and Nanoparticle Intercalation

Recently, several chemical and physical treatments were developed to improve different properties of wood. Such treatments are applicable to many types of cellulose-based materials. Densification leads the group in terms of mechanical results and comprises a chemical treatment followed by a thermo-compression stage. First, chemicals selectively etch the matrix of lignin and hemicellulose. Then, thermo-compression increases the packing density of cellulose microfibrils boosting mechanical performance. In this paper, in comparison with the state-of-the-art for wood treatments we introduce an additional nano-reinforcemeent on densified giant reed to further improve the mechanical performance. The modified nanocomposite materials are stiffer, stronger, tougher and show higher fire resistance. After the addition of nanoparticles, no relevant structural modification is induced as they are located in the gaps between cellulose microfibrils. Their peculiar positioning could increase the interfacial adhesion energy and improve the stress transfer between cellulose microfibrils. The presented process stands as a viable solution to introduce nanoparticles as new functionalities into cellulose-based natural materials

Augmenting forearm crutches with wireless sensors for lower limb rehabilitation

Forearm crutches are frequently used in the rehabilitation of an injury to the lower limb. The recovery rate is improved if the patient correctly applies a certain fraction of their body weight (specified by a clinician) through the axis of the crutch, referred to as partial weight bearing (PWB). Incorrect weight bearing has been shown to result in an extended recovery period or even cause further damage to the limb. There is currently no minimally invasive tool for long-term monitoring of a patient's PWB in a home environment. This paper describes the research and development of an instrumented forearm crutch that has been developed to wirelessly and autonomously monitor a patient's weight bearing over the full period of their recovery, including its potential use in a home environment. A pair of standard forearm crutches are augmented with low-cost off-the-shelf wireless sensor nodes and electronic components to provide indicative measurements of the applied weight, crutch tilt and hand position on the grip. Data are wirelessly transmitted between crutches and to a remote computer (where they are processed and visualized in LabVIEW), and the patient receives biofeedback by means of an audible signal when they put too much or too little weight through the crutch. The initial results obtained highlight the capability of the instrumented crutch to support physiotherapists and patients in monitoring usage

Distinct host-immune response toward species related intracellular mycobacterial killing : a transcriptomic study

CITATION: Madhvi Abhilasha et al. 2020. Distinct host-immune response toward species related intracellular mycobacterial killing : a transcriptomic study. Virulence, 11(1):170-182, doi:10.1080/21505594.2020.1726561.The original publication is availablle at: https://www.ncbi.nlm.nih.govThe comparison of the host immune response when challenged with pathogenic and nonpatho- genic species of mycobacteria can provide answers to the unresolved question of how pathogens subvert or inhibit an effective response. We infected human monocyte derived macrophages (hMDMs) with different species of mycobacteria, in increasing order of pathogenicity, i.e. M. smegmatis, M. bovis BCG, and M. tuberculosis R179 that had been cultured in the absence of detergents. RNA was isolated post-infection and transcriptomic analysis using amplicons (Ampliseq) revealed 274 differentially expressed genes (DEGs) across three species, out of which we selected 19 DEGs for further validation. We used qRT-PCR to confirm the differential expression of 19 DEGs. We studied biological network through Ingenuity Pathway Analysis® (IPA) which revealed up-regulated pathways of the interferon and interleukin family related to the killing of M. smegmatis. Apart from interferon and interleukin family, we found one up-regulated (EIF2AK2) and two down-regulated (MT1A and TRIB3) genes as unique potential targets found by Ampliseq and qRT-PCR which may be involved in the intracellular mycobacterial killing. The roles of these genes have not previously been described in tuberculosis. Multiplex ELISA of culture supernatants showed increased host immune response toward M. smegmatis as compared to M. bovis BCG and M.tb R179. These results enhance our understanding of host immune response against M.tb infection.Publisher's versio

Experimental feedback linearisation of a vibrating system with a non-smooth nonlinearity

Input-output partial feedback linearisation is demonstrated experimentally for the first time on a system with non-smooth nonlinearity, a laboratory three degrees of freedom lumped mass system with a piecewise-linear spring. The output degree of freedom is located away from the nonlinearity so that the partial feedback linearisation possesses nonlinear internal dynamics. The dynamic behaviour of the linearised part is specified by eigenvalue assignment and an investigation of the zero dynamics is carried out to confirm stability of the overall system. A tuned numerical model is developed for use in the controller and to produce numerical outputs for comparison with experimental closedloop results. A new limitation of the feedback linearisation method is discovered in the case of lumped mass systems e that the input and output must share the same degrees of freedom