Advanced Control Strategies for Mobile Hydraulic Applications

Mobile hydraulic machines are affected by numerous undesired dynamics, mainly discontinuous motion and vibrations. Over the years, many methods have been developed to limit the extent of those undesired dynamics and improve controllability and safety of operation of the machine. However, in most of the cases, today\u27s methods do not significantly differ from those developed in a time when electronic controllers were slower and less reliable than they are today. This dissertation addresses this aspect and presents a unique control method designed to be applicable to all mobile hydraulic machines controlled by proportional directional valves. In particular, the proposed control method is targeted to hydraulic machines such as those used in the field including construction (wheel loaders, excavators, and backhoes, etc.), load handling (cranes, reach-stackers, and aerial lift, etc.), agriculture (harvesters, etc.), forestry, and aerospace. For these applications the proposed control method is designed to achieve the following goals: A. Improvement of the machine dynamics by reducing mechanical vibrations of mechanical arms, load, as well as operator seat; B. Reduction of the energy dissipation introduced by current vibration damping methods; C. Reduction of system slowdowns introduced by current vibration damping methods. Goal A is generally intended for all machines; goal B refers to those applications in which the damping is introduced by means of energy losses on the main hydraulic transmission line; goal C is related to those applications in which the vibration attenuation is introduced by slowing down the main transmission line dynamics. Two case studies are discussed in this work: 1. Hydraulic crane: the focus is on the vibrations of the mechanical arms and load (goals A and B). 2. Wheel loader: the focus is on the vibrations of the driver\u27s seat and bucket (goals A and C). The controller structure is basically unvaried for different machines. However, what differs in each application are the controller parameters, whose adaptation and tuning method represent the main innovations of this work. The proposed controller structure is organized so that the control parameters are adapted with respect to the instantaneous operating point which is identified by means of feedback sensors. The Gain Scheduling technique is used to implement the controller whose set of parameters are function of the specific identified operating point. The optimal set of control parameters for each operating point is determined through the non-model-based controller tuning. The technique determines the optimal set of controller parameters through the optimization of the experimental machine dynamics. The optimization is based on an innovative application of the Extremum Seeking algorithm. The optimal controller parameters are then indexed into the Gain Scheduler. The proposed method does not require the modification of the standard valve controlled machine layout since it only needs for the addition of feedback sensors. The feedback signals are used by the control unit to modify the electric currents to the proportional directional valves and cancel the undesired dynamics of the machine by controlling the actuator motion. In order for the proposed method to be effective, the proportional valve bandwidth must be significantly higher than the frequency of the undesired dynamics. This condition, which is typically true for heavy machineries, is further investigated in the research. The research mostly focuses on the use of pressure feedback. In fact, although the use of position, velocity, or acceleration sensors on the vibrating bodies of the machine would provide a more straightforward measurement of the vibration, they are extremely rare on mobile hydraulic machines where mechanical and environmental stress harm their integrity. A comparison between pressure feedback and acceleration feedback alternatives of the proposed method is investigated with the aim to outline the conditions making one alternative preferable over the other one (for those applications were both alternatives are technically viable in terms of sensors and wiring reliability). A mid-sized hydraulic crane (case study 1) was instrumented at Maha Fluid Power Research Center to study the effectiveness of the proposed control method, its stability and its experimental validation. Up to 30% vibration damping and 40% energy savings were observed for a specific cycle over the standard vibration damping method for this application. The proposed control method was also applied to a wheel loader (case study 2), and up to 70% vibrations attenuation on the bucket and 30% on the driver\u27s cab were found in simulations. These results also served to demonstrate the applicability of the control method to different hydraulic machines. Improved system response and a straightforward controller parameters tuning methodology are the features which give to the proposed method the potential to become a widespread technology for fluid power machines. The proposed method also has potential for improving several current vibration damping methods in terms of energy efficiency as well as simplification of both the hydraulic system layout and tuning process

The “Projection-by-Projection” (PbP) criterion for multiaxial random fatigue loadings: Guidelines to practical implementation

This work is motivated by the increasing interest towards the application of the “Projection-by-Projection” (PbP) spectral method in finite element (FE) analysis of components under multiaxial random loadings. To help users and engineers in developing their software routines, this paper presents a set of numerical case studies to be used as a guideline to implement the PbP method. The sequence of analysis steps in the method are first summarized and explained. A first numerical example is then illustrated, in which various types of biaxial random stress are applied to three materials with different tension/torsion fatigue properties. Results of each analysis step are displayed explicitly to allow a plain understanding of how the PbP method works. The examples are chosen with the purpose to show the capability of the method to take into account the effect of correlation degree among stress components, and the relationship between material and multiaxial stress in relation to the tension/torsion fatigue properties. A case study is finally discussed, in which the method is applied to a FE structural durability analysis of a simple structure subjected to random excitations. The example describes the flowchart and the program by which to implement the method through Ansys APDL software. This final example illustrates how the PbP method is an efficient tool to analyze multiaxial random stresses in complex structures

Redesigning an Electrochemical MIP Sensor for PFOS: Practicalities and Pitfalls

There is a growing interest in the technological transfer of highly performing electrochemical sensors within portable analytical devices for the in situ monitoring of environmental contaminants, such as perfluorooctanesulfonic acid (PFOS). In the redesign of biomimetic sensors, many parameters should be taken into account from the working conditions to the electrode surface roughness. A complete characterization of the surface modifiers can help to avoid time-consuming optimizations and better interpret the sensor responses. In the present study, a molecularly imprinted polymer electrochemical sensor (MIP) for PFOS optimized on gold disk electrodes was redesigned on commercial gold screen-printed electrodes. However, its performance investigated by dierential pulse voltammetry was found to be poor. Before proceeding with further optimization, a morphological study of the bare and modified electrode surfaces was carried out by scanning electron microscopy–energy-dispersive X-ray spectrometry (SEM–EDS), atomic force microscopy (AFM) and profilometry revealing an heterogeneous distribution of the polymer strongly influenced by the electrode roughness. The high content of fluorine of the target-template molecule allowed to map the distribution of the molecularly imprinted polymer before the template removal and to define a characterization protocol. This case study shows the importance of a multi-analytical characterization approach and identify significant parameters to be considered in similar redesigning studies

Chemical analysis and computed tomography of metallic inclusions in Roman glass to unveil ancient coloring methods

This paper describes the analysis of two near-spherical metallic inclusions partially incorporated within two Roman raw glass slags in order to elucidate the process that induced their formation and to determine whether their presence was related to ancient glass colouring processes. The theory of metallic scraps or powder being used in Roman times for glass-making and colouring purposes is widely accepted by the archaeological scientific community, although the assumption has been mainly based on oral traditions and documented medieval practices of glass processing. The analysis of the two inclusions, carried out by X-ray computed tomography, electrochemical analyses, and scanning electron microscopy, revealed their material composition, corrosion and internal structure. Results indicate that the two metallic bodies originated when, during the melting phase of glass, metal scraps were added to colour the material: the colloidal metal–glass system reached then a supersaturation condition and the latter ultimately induced metal expulsion and agglomeration. According to the authors’ knowledge, these two inclusions represent the first documented and studied finds directly associated with the ancient practise of adding metallic agents to colour glass, and their analysis provides clear insights into the use of metallic waste in the glass colouring process.This paper describes the analysis of two near-spherical metallic inclusions partially incorporated within two Roman raw glass slags in order to elucidate the process that induced their formation and to determine whether their presence was related to ancient glass colouring processes. The theory of metallic scraps or powder being used in Roman times for glass-making and colouring purposes is widely accepted by the archaeological scientific community, although the assumption has been mainly based on oral traditions and documented medieval practices of glass processing. The analysis of the two inclusions, carried out by X-ray computed tomography, electrochemical analyses, and scanning electron microscopy, revealed their material composition, corrosion and internal structure. Results indicate that the two metallic bodies originated when, during the melting phase of glass, metal scraps were added to colour the material: the colloidal metal-glass system reached then a supersaturation condition and the latter ultimately induced metal expulsion and agglomeration. According to the authors' knowledge, these two inclusions represent the first documented and studied finds directly associated with the ancient practise of adding metallic agents to colour glass, and their analysis provides clear insights into the use of metallic waste in the glass colouring process

Experimental investigation of a novel formulation of a cyanoacrylate based adhesive for self-healing concrete technologies

The selection of an appropriate healing agent is critical to the success of vascular and mini-vascular networks. In self-healing concrete technology, commercially available cyanoacrylate (CA) adhesives have been shown to produce good strength recoveries; however, their rapid curing rate and short shelf-life make them unsuitable for site application. The aim of this study was to develop a modified cyanoacrylate (n-CA) with an extended shelf-life suitable for incorporation in a self-healing system. A series of n-CAs were formed from a commercial Ethyl Cyanoacrylate adhesive mixed with acrylic acid (AA) and nitro-anthraquinone (nAq) in varying ratios. When encapsulated within 3D printed mini-vascular networks (MVNs), the n-CAs remained dormant in liquid form for up to 5 days. The contact angle between the n-CAs and the cement mortar substrate, as measured via the sessile drop technique, decreased significantly with increasing AA content. The mechanical properties (bond strength) and the polymerization hardening of the n-CAs were evaluated over a curing period of 7–21 days, via a series of pull-off tests using cement mortar cubes. The 4:1:02 (CA:AA:nAq) n-CA formulation showed a significant increase in bond strength from 14 to 21 days, with a ceiling value of 2.6 MPa, while the 2:1 (CA:AA) n-CA formulation exhibited a good bond strength after 21 days (1 MPa). Nuclear Magnetic Resonance (NMR) conducted on the n-CAs suggested the formation of several new polymeric species, whilst differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) on the pre- and post-printed MVN material confirmed no significant changes in chemistry with no evidence of polymer degradation. Considered together, the experimental results show the potential for different n-CA formulations to act efficiently as a healing agent

Esophageal Eosinophilia and Eosinophilic Esophagitis in Celiac Children: A Ten Year Prospective Observational Study

The association between eosinophilic esophagitis and celiac disease is still controversial and its prevalence is highly variable. We aimed to investigate the prevalence of esophageal eosinophilia and eosinophilic esophagitis in a large group of children with celiac disease, prospectively followed over 11 years. Methods: Prospective observational study performed between 2008 and 2019. Celiac disease diagnosis was based on ESPGHAN criteria. At least four esophageal biopsies were sampled in patients who underwent endoscopy. The presence of at least 15 eosinophils/HPF on esophageal biopsies was considered suggestive of esophageal eosinophilia; at the same time, eosinophilic esophagitis was diagnosed according to the International Consensus Diagnostic Criteria for Eosinophilic Esophagitis. Results: A total of 465 children (M 42% mean age 7.1 years (range: 1–16)) were diagnosed with celiac disease. Three hundred and seventy patients underwent endoscopy, and esophageal biopsies were available in 313. The prevalence of esophageal eosinophilia in children with celiac disease was 1.6% (95% CI: 0.54–2.9). Only one child was diagnosed as eosinophilic esophagitis; we calculated a prevalence of 0.3% (95% CI: 0.2–0.5%). The odds ratio for an association between eosinophilic esophagitis and celiac disease was at least 6.5 times higher (95% CI: 0.89–47.7; p = 0.06) than in the general population. Conclusion: The finding of an increased number of eosinophils (>15/HPF) in celiac patients does not have a clinical implication or warrant intervention, and therefore we do not recommend routine esophageal biopsies unless clinically indicated

Synthesis and NLRP3-Inflammasome Inhibitory Activity of the Naturally Occurring Velutone F and of Its Non-Natural Regioisomeric Chalconoids

Plant-derived remedies rich in chalcone-based compounds have been known for centuries in the treatment of specific diseases, and nowadays, the fascinating chalcone framework is considered a useful and, above all, abundant natural chemotype. Velutone F, a new chalconoid from Millettia velutina, exhibits a potent effect as an NLRP3-inflammasome inhibitor; the search for new natural/non-natural lead compounds as NLRP3 inhibitors is a current topical subject in medicinal chemistry. The details of our work toward the synthesis of velutone F and the unknown non-natural regioisomers are herein reported. We used different synthetic strategies both for the construction of the distinctive benzofuran nucleus (BF) and for the key phenylpropenone system (PhP). Importantly, we have disclosed a facile entry to the velutone F via synthetic routes that can also be useful for preparing non-natural analogs, a prerequisite for extensive SAR studies on the new flavonoid class of NLRP3-inhibitors

Does morbid obesity influence perioperative outcomes after video-assisted thoracic surgery (VATS) lobectomy for non-small cell lung cancer? Analysis of the Italian VATS group registry

Objectives: Obesity in Europe, and worldwide, has been an increasing epidemic during the past decades. Moreover, obesity has important implications regarding technical issues and the risks associated with surgical interventions. Nevertheless, there is a lack of evidence assessing the influence of obesity on video-assisted thoracic surgery (VATS) lobectomy results. Our study aimed to assess the impact of morbid obesity on perioperative clinical and oncological outcomes after VATS lobectomy using a prospectively maintained nationwide registry. Methods: The Italian VATS lobectomy Registry was used to collect all consecutive cases from 55 Institutions. Explored outcome parameters were conversion to thoracotomy rates, complication rates, intra-operative blood loss, surgical time, hospital postoperative length of stay, chest tube duration, number of harvested lymph-node, and surgical margin positivity. Results: From 2016 to 2019, a total of 4412 patients were collected. 74 patients present morbid obesity (1.7%). Multivariable-adjusted analysis showed that morbid obesity was associated with a higher rate of complications (32.8% vs 20.3%), but it was not associated with a higher rate of conversion, and surgical margin positivity rates. Moreover, morbid obesity patients benefit from an equivalent surgical time, lymph-node retrieval, intraoperative blood loss, hospital postoperative length of stay, and chest tube duration than non-morbid obese patients. The most frequent postoperative complications in morbidly obese patients were pulmonary-related (35%). Conclusion: Our results showed that VATS lobectomy could be safely and satisfactorily conducted even in morbidly obese patients, without an increase in conversion rate, blood loss, surgical time, hospital postoperative length of stay, and chest tube duration. Moreover, short-term oncological outcomes were preserved