live crack damage detection with local strain measurement on solid bodies subjected to hydrodynamic loading

Abstract The interaction of water free surface with solid bodies is object of interest in several mechanical, ocean, aerospace and civil engineering problems. The presence of impulsive loading and large local deformation leads to complex coupled dynamics. The possibility of live monitoring of these body could provide information about damage detection and fatigue life estimation. The definition of appropriate signal processing and modeling tools enabling the extraction of useful information from distributed sensing signals is a relevant scientific challenge. On the basis of previous works by some of the authors, this paper deals with the application of a method for real-time deformed shape reconstruction of solid bodies subjected to impulsive loadings using distributed numerically generated strain measurements signals, such as those produced by Fiber Bragg Grating (FBG) sensors. A numerical study is carried out considering a simplified model of the problem of hull structures subjected to hydrodynamic loading. The hull, analyzed in a simplified section, has been studied both in healthy condition and with the presence of crack damages. The potential for detecting, localizing and quantifying this damage using the reconstruction algorithm is investigated, by leveraging the proposed concept of control sensors, that are FBG sensors used for comparing reconstructed strains and/or displacements with measured quantities. The positioning and number of sensors and the effect of sensor layout on damage detection is investigated, with the aim of developing a real time damage detection methodology

A real time energy management strategy for plug-in hybrid electric vehicles based on optimal control theory

Abstract Plug-in hybrid electric vehicles are commonly designed to work in Charge Depleting/Charge Sustaining (CD/CS) mode, depleting the battery by driving in only-electrical mode until the SoC reaches its minimum acceptable threshold, and then sustaining the state of charge till the end of the mission, operating as a traditional hybrid vehicle. Nonetheless, a simple application of an optimal control framework suggests a blended discharge strategy, in which the powertrain is operated as to gradually deplete the SoC and reach the lower threshold only at the end of the trip. Such an algorithm has the drawback that the optimal solution can only be reached offline, depending on the a-priori knowledge of the driving event, making it unsuitable to be implemented online, as it is. The paper presents a methodology to design a heuristic controller, to be used online, based on rules extracted from the analysis of the powertrain behavior under the optimal control solution. The application is a parallel plug-in vehicle, derived from a re- engineered engine-only driven powertrain, and the optimal problem is solved with the Pontryagin's Minimum Principle. Results are also compared to the same vehicle in its standard internal combustion engine version, as well as the commonly implemented Charge Depleting/Charge Sustaining strategy

Interobserver and intraobserver reliability of a new radiological classification for femoroacetabular impingement syndrome

Purpose: Radiological evaluation of femoroacetabular impingement is based on single-plane parameters such as the alpha angle or the center edge angle, or complex software reconstruction. A new simple classification for cam and pincer morphologies, based on a two-plane radiological evaluation, is presented in this study. The determination of the intraobserver and interobserver reliability of this new classification is the purpose of this study. Methods: We retrospectively reviewed the three-view hip study in patient undergoing hip arthroscopy for FAI syndrome between October 2015 and April 2016. Any case having protrusio acetabuli, coxa profunda or which has undergone previous osteotomic surgery was excluded. Five observers used our proposed classification to identify three different stages for the cam and pincer morphologies. Inter- and intraobserver agreement of classification was determined using average pairwise Cohen’s kappa coefficient. Results: The interobserver agreement for the pincer and cam morphologies was excellent. For the pincer morphology classification, the average Kappa agreement was 0.838 (range 0.764–0.944). For the cam morphology, the average pairwise Cohen’s kappa coefficient was 0.846 (range 0.734–0.929). The intraobserver agreement was excellent as well. The average percent pairwise agreement was 0.870 and 0.845 for pincer and cam type, respectively. Conclusions: The new classification system shows excellent levels of inter- and intraobserver agreement for both deformities. This classification is demonstrated to be a useful tool in planning hip arthroscopy. Further studies are needed to correlate the classification itself with specific intraoperative findings

Performance Assessment of Electric Energy Storage (EES) Systems Based on Reversible Solid Oxide Cell

Abstract This paper focuses on the performance assessment of a novel and efficient EES (electric energy storage) system based on ReSOC (reversible solid oxide cell) technology. The ReSOC is an electrochemical energy conversion device working at high temperature (600-1000°C) that can operate reversibly either as a fuel cell (SOFC) or as an electrolyzer (SOEC). In this study, a ReSOC unit fed by mixtures of CH4, CO, H2O and H2 is proposed and analyzed. In particular, in the SOFC mode, where electricity is generated, the reactant gas, mainly formed by CH4 and H2, is converted into a mixture of H2O and CO2. The exhausts from the SOFC are used as the reactant gas for the SOEC operation. During the electrolysis process, CH4 can be also produced thanks to the methanation reaction that, under proper operating conditions, occurs at the cathode of the solid oxide cell. The ReSOC unit behavior is investigated by developing a thermo-electrochemical model, able to predict its performance (i.e. roundtrip efficiency, polarization curve, thermally self-sustaining conditions) under different operating conditions. The ReSOC model, built with a modular architecture, is performed through thermodynamic, thermochemical and electrochemical sub-models taking into account mass and energy balances, chemical reactions (reforming, shifting reactions and methanation) and electro-chemical relationships. Available literature data have been used for the model validation and a calibration procedure has been performed in order to evaluate the best fitting values for the model parameters. Furthermore, in order to estimate the thermoneutral conditions in SOEC operating mode, the ReSOC thermal behavior has been analyzed under different operating temperatures. Results pointed out that, by feeding the cell with a syngas mixture, the reforming reaction (in the SOFC mode) and the methanation reaction (in the SOEC mode) allow to simplify the cell thermal management. Moreover, the best performance in terms of stack roundtrip efficiency (about 70%), can be reached operating the ReSOC at low temperature (700°C)

Conventional and Advanced Biomass Gasification Power Plants Designed for Cogeneration Purpose

Abstract In this paper conventional and advanced biomass gasification power plants designed for small cogeneration application are defined. The CHP plants consist of a gasification unit, that employs a downdraft gasifier, and a power unit based on a microturbine in the case of conventional configuration, and on a solid oxide fuel cell module, in the case of advanced configuration. The plants are sized to supply about 100 kW of electrical power. In order to investigate and to analyze the performances of the two plant configurations, in terms of thermal and electrical efficiencies, numerical models have been developed by using thermochemical and thermodynamic codes

PEEK versus metal cages in posterior lumbar interbody fusion: a clinical and radiological comparative study

Background: Low back pain and sciatica represent a common disabling condition with a significant impact on the social, working and economic lives of patients. Transforaminal lumbar interbody fusion (TLIF) is a surgical procedure used in degenerative spine conditions. Several types of cages were used in the TLIF procedure. Purpose: To determine whether there is a difference in terms of symptomatology improvement, return to daily activities and fusion rate between metal cages and polyetheretherketone (PEEK) cages. Methods: We have retrospectively reviewed 40 patients who have undergone TLIF from October 2015 to May 2016. All patients were clinically evaluated with questionnaires and were assessed with CT scan and standing X-ray films of the full-length spine. Results: We found no significant functional differences in the two groups. At 1-year follow-up, osteolysis was present in 50% of cases of the PEEK cages and in 10% cases of the metal cages. The degree of fusion at 1 year was evaluated as complete in 40% cases of the metal cages and 15% cases of the PEEK cages. Conclusions: We have found a better fusion rate and prevalence of fusion in the group treated with metal cages, reflecting the well-known osteoinductive properties of titanium and tantalum

Micro-fragmented adipose tissue transplantation (Matt) for the treatment of acetabular delamination. a two years follow up comparison study with microfractures

Background: Delamination of acetabular articular cartilage is a common progressive abnormality in hips with femoroacetabular impingement. The aim of this study is to compare the effectiveness of two different procedures for the arthroscopic treatment of acetabular delamination: microfractures (MFx) and micro-fragmented autologous adipose tissue transplantation (MATT) technique. Methods: We carried out a controlled retrospective study of 35 patients affected by an acetabular cartilage delamination in femoroacetabular impingement (FAI). In all the selected cases the size of the defect ranged from 1 to 2 cm2, with a mean size of 1.9 cm² in MFx group and 1.6 cm² in MATT group (p=0.1). Of these, 18 patients were treated with MFx while 17 patients were treated with MATT. The two groups were similar in terms of clinical, functional and radiological aspects. All the patients were assessed before and after the procedure, for pain and function, with the modified Harris Hip Score (mHHS). The mean preoperative mHHS was 50±5 for MFx group and 53±6 for MATT group (p = 0.245). All the patients were followed-up for two years. Results: The final mHHS was 76±12 in MFx group and 97.1±3 in MATT group (p<0.001). In both groups neither a conversion to total hip arthroplasty nor a revision hip arthroscopy was observed. Conclusions: The results of this study provide proof that MATT technique improves clinical outcomes with a mHH scoring significantly higher than MFx group. (www.actabiomedica.it)

Modular tapered conical revision stem in hip revision surgery: mid- term results

Background: The aim of this paper is to evaluate the clinical and radiological outcomes of a fluted tapered modular distal-fixation stem at medium to long-term follow-up. The hypothesis of this investigation was to verify if the use of this implant design may have provided potential advantages in femoral revisions and post-traumatic instances where the restoration of the anatomy was the prime concern. Methods: We retrospectively reviewed 62 cases of femoral revision surgeries, performed in Paprosky type IIIA and IIIB bone defects between January 2001 and December 2011 with a mean follow-up of 8.5 ± 1.5 years (range 5.1–15.9 years) where a modular fluted stem was used. The clinical assessment was performed with the Harris Hip Score (HHS), and the radiographic evaluation was carried in order to assess the stability of the femoral component. Intra-operative and postoperative complications were recorded, and the rates of complications and revisions for any cause were determined. Results: Mean HHS improved 35.4 points from the preoperative assessment. Radiographic evaluation showed a stable stem anchorage in 90.3% of the cases at the last follow-up. Five (8%) implants required additional surgery. Neither breakage of the stem nor loosening of the taper junction were recorded. Kaplan-Meier survivorship was 89.4% (CI: 88.8–90%) for any complication and 92.3% (CI: 91.8–92.7%) according to revision for any causes at 81 months follow-up. Conclusions: Our findings suggest that this stem design is a reliable option in cases of complex femoral bone defects, as well as in cases with high functional deficiencies, with promising survivorship

Assessment of a Hydrogen-Fueled Heavy-Duty Yard Truck for Roll-On and Roll-Off Port Operations

The port-logistic industry has a significant impact on the urban environment nearby ports and on the surrounding coastal areas. This is due to the use of large auxiliary power systems on ships operating during port stays, as well as to the employment of a number of fossil fuel powered road vehicles required for port operations. The environmental impact related to the use of these vehicles is twofold: on one hand, they contribute directly to port emissions by fuel consumption; on the other hand, they require some of the ship auxiliary systems to operate intensively, such as the ventilation system, which must operate to remove the pollutants produced by the vehicle engines inside the ship. The pathway to achieve decarbonization and mitigation of energy use in ports involves therefore the adoption of alternative and cleaner technology solutions for the propulsion systems of such port vehicles. This paper presents the performance analysis of a hydrogen powered cargo-handling vehicle for roll-on and roll-off port operations in a real case scenario. The fuel cell/battery hybrid powertrain of the vehicle has been previously designed by the authors. On the base of real data acquired during an on-field measurement campaign, and by means of a validated numerical model of the vehicle dynamics, different mission profiles are defined, in terms of driving and duty cycles, in order to represent typical port operations. A rule-based energy management strategy is then used to estimate the energy and hydrogen consumptions required by the vehicle and to assess its suitability to accomplish the defined target port operations. Outputs from this study show the potential of the proposed solution to take the place, in a foreseeable future, of conventional Diesel-engine vehicles, today commonly used in port logistics, towards a zero-emission scenario