Modeling of Flexible Bodies for the Study of Control in the Simulink Environment

When studying complex mechatronic systems, it is useful to build models able to simulate both the dynamics of the phenomenon and the control system applied. Typically, the bodies involved are modeled as rigid bodies. In this work, a technique for modeling flexible bodies in Simulink environment is presented. Simulink is a powerful instrument where it is quite easy to integrate control algorithms with complex systems. The solution developed is presented and applied to a machining center. Modern machining centers ensure a level of accuracy that traditional manual machines cannot reach. Simulations of the working process considering vibrations are needed to obtain high precision machining. These simulations aim to determine the error in the position of the tool and to help designers in finding the optimal solution in terms of machining velocity and precision. This work is focused on the carriage of a machine tool moving along horizontal guides, typically named Z-axis. The axis is actuated and borne by a linear motor; therefore, movable constraints must be modeled. A finite-element (FE) model of the carriage was reduced with a Craig-Bampton reduction to provide the mass and stiffness matrices for an in-house Matlab simulation code. The rigid constraints of the carriage were implemented in the model as moving stiffnesses, and their value was set to obtain continuity of the constraints in the discrete model. In the end, a map of different vibrational configurations is proposed to visualize the possible errors that a machining process can generate

Design of a Spherical UGV for Space Exploration

The paper presents the design of a spherical UGV (Unmanned Ground Vehicle) for exploration of critical, unknown or extended areas, such as planetary surfaces. Spherical robots are an emerging class of devices whose shape brings many advantages, e.g. omni-directionality, sealed internal environment and protection from overturning. Many dedicated sensors can be safely placed inside the sphere and the robot can roll in any direction without getting stuck in singular configurations. Specifically, the proposed UGV is thought to collect images and environmental data, so required sensors are firstly discussed to evaluate in sequence of the payload in terms of size and energy consumption. The most effective drive mechanism is selected considering several possible concepts and carrying a trade-off process based on the requirements for a space mission. The optimal solution involves the use of a single pendulum: a hanging mass, attached to the central shaft of the sphere, is shifted to produce rolling. The design issues due to the selected mechanism are discussed, showing the effect of design parameters on the expected performance. For instance, the barycenter offset from the center of the sphere plays a crucial role and affects the maximum step or inclines that can be overcomed. Therefore, the pre-design phase is conducted by discussing the functional design of the robot and introducing a differential mechanism for driving and steering. A quasi omni-directionality is achieved and the mechanical components, opportunely designed according to the loads acting on the device, are arranged to match the mission requirements. Moreover, the mechatronic integration is discussed: microcontrollers, drive electronics, sensors and batteries are sized in order to reach 3 hours of continuous operation. The multibody system is finally modelled in Matlab-Simscape to verify the mechanism for the UGV testing in specific cases. Results show that a suitable layout is a 0.5 m diameter spherical UGV with a steel main structure, mounting 2 DC motors that activate a bevel gear by means of pulleys and timing belts. The spherical shell, with the internal mechanism and electronics, has a total mass of 25 kg and from standstill it can climb up to 15 degrees inclines or steps up to 25 mm, as proved by Matlab simulations. Future works will focus on the realization of the physical prototype, as well as navigation and control strategies

The effect of moxidectin 0,1% vs ivermectin 0,08% on milk production in sheep naturally infected by gastrointestinal nematodes

BACKGROUND: Gastrointestinal nematode (GIN) infection is one of the main constraints to sheep production both in temperate and tropical countries. Economic losses caused by GIN are related to decreased production, treatment costs and even animal death. The present paper was aimed at assessing the anthelmintic efficacy (based on faecal egg count reduction) of moxidectin and ivermectin both admistered per os at dose rate of 0.2 mg/Kg body weight and the benefit of anthelmintic treatments on milk production in a commercial dairy sheep farms in central Italy whose animals were naturally infected by GIN. RESULTS: The treatment with moxidectin was highly effective (> 98%) from day 7 until day 75, and effective (90-98%) until day 105. The treatment with ivermectin was highly effective (> 98%) from day 7 until day 14, effective (90-98%) at day 28 and moderately effective (80-89%) on day 45. The milk productions in the treated groups were significantly higher than those of the control group. CONCLUSION: In conclusion, the results of the present study demonstrated that moxidectin and ivermectin adminstered per os according to the manufacturer's instructions were both effective and safe anthelmintics in sheep. The total milk production was higher in the treated groups than the control group. Overall, animals treated with moxidectin had a milk production 40.8% higher than control group; whereas animals treated with ivermectin had a milk production 32.2% higher than control group

A deployable and inflatable robotic arm concept for aerospace applications

The interest in soft systems for space missions represents a growing trend in recent years. The development of inflatable robots, combined with the improvement of deployment mechanisms, allows to build novel lightweight and deployable robotic manipulators. In several space applications, the use of soft robots could minimize bulk and mass, reducing space mission costs. The main challenges in soft robotics are the control of the system and the exertion of high forces. In this manuscript, the concept of an inflatable manipulator with two inflatable links and three degrees of freedom is proposed. After a review about the possible materials to be used for the inflatable parts, the robot mechanical structure, the deploying strategy and the pneumatic line are presented. Then, an elastostatic approach is proposed to model the robot with the aim of developing its control. The last section shows preliminary experimental tests performed on the link prototype with the purpose to evaluate a static characterization in relation to the supplied pressure. Results suggest the validity of the adopted approach to model the system and clarify the pressure influence about the system performances. The study puts the basis for the development of the first prototype of the robotic system

Fatality rate and predictors of mortality in an Italian cohort of hospitalized COVID-19 patients

Clinical features and natural history of coronavirus disease 2019 (COVID-19) differ widely among different countries and during different phases of the pandemia. Here, we aimed to evaluate the case fatality rate (CFR) and to identify predictors of mortality in a cohort of COVID-19 patients admitted to three hospitals of Northern Italy between March 1 and April 28, 2020. All these patients had a confirmed diagnosis of SARS-CoV-2 infection by molecular methods. During the study period 504/1697 patients died; thus, overall CFR was 29.7%. We looked for predictors of mortality in a subgroup of 486 patients (239 males, 59%; median age 71 years) for whom sufficient clinical data were available at data cut-off. Among the demographic and clinical variables considered, age, a diagnosis of cancer, obesity and current smoking independently predicted mortality. When laboratory data were added to the model in a further subgroup of patients, age, the diagnosis of cancer, and the baseline PaO2/FiO2 ratio were identified as independent predictors of mortality. In conclusion, the CFR of hospitalized patients in Northern Italy during the ascending phase of the COVID-19 pandemic approached 30%. The identification of mortality predictors might contribute to better stratification of individual patient risk

Case Study of the Use of a Digital Twin for Leak Detection and Quantification in Underground Gas Storage Wells

Underground gas storage (UGS) wells are essential components in energy security. However, UGS wells present a complicated and delicate combination of elements where ensuring safe and secure functionality over long periods is paramount. This paper showcases how a digital twin is used to evaluate and forecast the link between leaks and temperature and pressure trends in a UGS well, allowing the identification and quantification of defects and, subsequently, well barrier integrity. The digital twin used for this application presents advantages compared with other solutions present on the market with regard to the simplified configuration; that is, with minimal input data, the system can produce an accurate and useful output, which is then used in the well integrity decision-making process. UGS wells present additional criticalities with respect to normal production wells due to their longer life span and the repetitive production and injection cycles. This makes early and accurate leak detection essential for the safe management of the well barriers. The proposed digital twin simulates the trends of pressure and temperature within each annulus and compares results with data from the field, allowing the identification of the position and size of leaks. A genetic algorithm is applied to optimize the placement of leaks on their specific barriers. Once a leak is identified, a risk assessment is conducted to evaluate the overall integrity of the well. If the status of the well is found to be critical enough, an intervention may be planned. The studies presented show how the digital twin has been used on two wells with similar problems. At first, it has confirmed the necessity to put the well out of service as opposed to planning maintenance, thereby saving both time and cost. In the second case, it allowed the validation of a solution that led to a 60% reduction in failure consequence, allowing the well to continue operating without major costs or risks. The errors of the resulting simulations were always confined within the 0.5 bar limit highlighting its accuracy. The system has been in use for over a year and has shown great potential in accurate and efficient identification of leaks. This has accelerated the process of well integrity evaluation and allowed timely interventions on wells that required it. On the other hand, the process has highlighted cases where previous assumptions about leak location and size were corrected using the digital twin, therefore reducing the costs of interventions. Finally, the model showcases a clear readiness for predictive capabilities aimed to select, plan, and design fit for purpose mitigating actions

Case Study of the Use of a Digital Twin for Leak Detection and Quantification in Underground Gas Storage Wells

Underground gas storage (UGS) are essential components in energy security. However, UGS wells present a complicated and delicate combination of elements where ensuring safe and secure functionality over long periods is paramount. Today, with the advancement of continuous remote monitoring and digitalization, evaluating the integrity of UGS wells has become quicker and more efficient. This paper showcases how a digital twin is used to evaluate and forecast the link between leaks and temperature and pressure trends in a UGS well, allowing the identification and quantification of defects and, subsequently, well barrier integrity. UGS wells present additional criticalities with respect to normal production wells due to its longer life span and the repetitive production and injection cycles. This makes early and accurate leak detection essential for a safe management of the well barriers. The proposed digital twin has been developed using material and energy balances and considering each annulus as a separate control volume. Each control volume can exchange heat and mass through predesigned barriers. Simulating evolution in time of pressure and temperature in the control volumes., and comparing results with data from field, allows the identification of position and size of leaks. A genetic algorithm is applied to optimize placement of leaks on their specific barriers. The system aims to identify the position and dimension of possible leaks by matching historical pressure, temperature, and flow data. Once a leak is identified, a risk assessment is conducted to evaluate the overall integrity of the well. If the status of the well is found to be critical enough, an intervention may be planned. The system has been in use for little over a year and has shown great potential in accurate and efficient identification of leaks. This has accelerated the process of well integrity evaluation and allowed timely interventions on wells that required it. On the other hand, the process has highlighted cases where previous assumptions about leak location and size were corrected using the digital twin, therefore reducing the costs of interventions. Finally, the model showcased a clear readiness for predictive capabilities aimed to select, plan and design fit for purpose mitigating actions. This paper highlights the power that a digital twin can present leveraging field data with advanced algorithms. The paper also showcases workflows that allow convenient, efficient, and timely evaluation of well integrity, which leads to safer operating conditions and lower operational costs

An Inflatable Robotic Assistant for Onboard Applications

In recent years, robots are evolving to collaborate with humans sharing the same workspace. In space missions, human and robotic partnership is now essential, especially in onboard activities. Collaborative robots have the possibility to work in strict contact with humans, thanks to their gentle design and the limitations on the speed. In limited working areas, soft robots are considered an interesting possibility because the intrinsic feature of softness of their structure allows to work with users more safely. In this paper, the concept of an inflatable and lightweight onboard robotic assistant is proposed. The robot consists of two inflatable links and three actuated joints. It can be stored in a relatively small package, if compared to its extended configuration, to be deployed on demand for working activities. The links are expected to have built-in sensors, as flex sensors, inertial measurement units and cameras, that are used to estimate the robot state, using sensor fusion techniques. The behavior of the inflatable links is described through a pseudo-rigid body model, considering non-linearities introduced by the presence of possible wrinkles. A prototype of the link is realized and characterized throughout static and dynamic tests, analyzing the effect of internal pressure. Evaluations about achievable payloads, weights and dimensions of the robot are exhibited. Results suggest the feasibility of the project, putting the basis for the development of the overall system

Helicobacter pyloriperiplasmic receptor CeuE (HP1561) modulates its nickel affinity via organic metallophores

In Gram-negative bacteria, nickel uptake is guaranteed by multiple and complex systems that operate at the membrane and periplasmic level. Helicobacter pylori employs other yet uncharacterized systems to import the nickel required for the maturation of key enzymes, such as urease and hydrogenase. H. pylori CeuE protein (HP1561), previously annotated as the periplasmic component of an ATP-binding cassette (ABC)-type transporter apparatus responsible of haem/siderophores or other Fe(III)-complexes uptake, has been recently proposed to be on the contrary involved in nickel/cobalt acquisition. In this work, the crystal structure of H. pylori CeuE has been determined at 1.65 \uc5 resolution using the single anomalous dispersion (SAD) method. It comprises two structurally similar globular domains, each consisting of a central five-stranded \u3b2-sheet surrounded by \u3b1-helices, an arrangement commonly classified as a Rossmannlike fold. Structurally, H. pylori CeuE belongs to the class III periplasmic substrate-binding protein. Both crystallographic data and fluorescence binding assays allow to exclude a role of the protein in the transport of Vitamin B12, enterobactin, haem and isolated Ni2+ ions. On the contrary, the crystal structure and plasmon resonance studies about CeuE/Ni-(LHis) 2 complex indicate that in H. pylori nickel transport is supported by CeuE protein and requires the presence of a natural nickelophore, analogously to what has been recently demonstrated for NikA from Escherichia coli