Principal Parameters Research Articles

Taguchi L16 (44) orthogonal array-based study and thermodynamics analysis for electro-Fenton process treatment of textile industrial dye

Abstract Reactive orange 16 (RO16) is the most widely used azo dye in Textile industry. Complex aromatic structures and resistivity to biological decay caused the dye pollutants incompletely treated by the conventional oxidative methods. The current study presents the electro-Fenton-based advanced oxidation treatment of RO16 dye and the process optimization by Taguchi-based design of experiment (DOE). Using a 500 mL volume lab-scale experimental setup, the process was first studied for the principal operational parameters (initial dye concentration (q); [H2O2]/[Fe+2] (R); current density (ρ); and temperature (T)) effect on decolourization (D R ) and COD removal (C R ). Then, by means of the L16 (44) orthogonal array (OA) formation, standard mean and signal-to-noise (S/N) ratio, the process was optimized for the response variables. The result showed the optimized result at q = 100 mg/L, R = 100, ρ = 8 mA/cm2, and T = 32 °C; with D R and C R as 90.023 and 84.344%, respectively. It was found that the current density affects the process most, followed by [H2O2]/[Fe+2] ratio, initial dye concentration, and temperature i.e., ρ > R > q > T. Also, with the analysis of variance (ANOVA), model equations for D R and C R were developed and its accuracy was verified for experimental results. At optimized conditions, the first order removal rate constants (k a ) were found from batch results. Additionally, the thermodynamic constants (ΔH e , ΔS e , and ΔG b ) were also calculated for the nature of heat-energy involved and temperature effect study on dye degradation. The results showed that the process was thermodynamically feasible, endothermic, and non-spontaneous with a lower energy barrier (E A = 46.7 kJ mol−1).

Evaluation of Diastolic Dysfunction and the Role Thereof in Heart Failure with Preserved Ejection Fraction

Evaluation of left ventricular diastolic function is essential, especially in patients with heart failure with preserved ejection fraction. The American Society of Echocardiography/European Association of Cardiovascular Imaging guidelines were released in 2016. Four principal parameters were used to assess left ventricular diastolic function. However, there are grey areas; the situation is complex. Recently, various other indicators have been employed to explore left ventricular diastolic function.

Elucidating Λ-doublet splittings and rotational quantum number-dependent collisional broadenings in 2∏1/2 and 2∏3/2 spin-split sub-bands of NO at 5.2 µm

High-resolution ro-vibrational spectroscopic features of nitric oxide (NO) are particularly interesting because of the unpaired electron and non-zero nuclear spin of the nitrogen atom. Here, ultra-sensitive cavity ring-down spectroscopy (CRDS) coupled with an external-cavity quantum cascade laser (EC-QCL) radiation source was employed to measure the rotationally-resolved fine structure Λ-doublet splittings between the parity doublet e and f components in the (2∏1/2 - 2∏1/2) and (2∏3/2 - 2∏3/2) allowed sub-bands of the v = 1 ← 0 fundamental vibrational band of NO molecule near 5.2 µm. Subsequently, we determined several principal spectroscopic parameters such as the Λ-doubling constants, vibrational transition dipole moments and the Herman-Wallis coefficients for both e and f Λ-doublet components by probing various R-branch rotational lines (J = 0.5 to 23.5) of the studied spin-split sub-bands of NO associated with spin–orbit interaction. In addition, we performed the pressure broadening effect on the Λ-doublet splittings in collision with three vital perturbing gases at room temperature (296 K) and accurately determined the pressure broadening coefficients, γi (e,f) in cm-1atm−1 [(i = He, Ar and Zero air (mainly N2 + O2)] along with their dependence on the rotational quantum number (J). We observed the pronounced collision-induced rotational quantum effect and the result of rotationally inelastic collision in the system for each collision partner. All these measured high-resolution new spectroscopic parameters over 33 ro-vibrational transitions via an EC-QCL based CRDS method will help significantly in interpreting fundamental molecular properties of this diatomic NO molecule.

Fire resistance and design assessment of Q355 circular hollow section joints

This paper presents an experimental investigation on fire resistance of circular hollow section (CHS) T-, Y- and K-joints. A total of 15 specimens subjected to brace axial load were heated inside an electric furnace, including 5 T-joints, 5 Y-joints and 5 K-joints. The temperature inside furnace follows ISO 834 standard fire curve. The principal parameters considered in this study include the dimensionless geometric parameters of joints β and γ, as well as the load ratio n. It is found that the failure mode of the axially loaded CHS joints under fire is chord plastification. Referring to the temperature-deformation curves of these CHS joints, it is suggested to adopt 1.5% ovalisation of the chord diameter as the failure criteria of the CHS joints under fire. The fire resistance of the CHS joints is seriously reduced with an increase in the load ratio n. By comparing the temperature development and the critical temperatures of the CHS joints obtained in the tests with the ones predicted by design codes, it is found that the measured temperature development curves of the CHS joints are significantly different from the calculated ones before the joint temperature reaches 550 °C. Further investigation is essential for temperature development analysis of CHS joints, especially in the aspects of the section factor Am/V of CHS joint. The fire resistance performance of CHS T- and Y-joints is shown to be reasonably estimated with the resistance method provided in modern design codes, even though the estimation on CHS K-joints is relatively conservative.

Direct Metal Laser Sintering of the Ti6Al4V Alloy from a Powder Blend.

Additively manufactured Ti6Al4V parts have only seen major application in industries such as the aerospace and medical industries, mainly due to the high cost of production of the feedstock powder. In this article, the feasibility of in situ alloying a powder blend of elemental Ti and an Al-V master alloy to produce the Ti6Al4V alloy through direct metal laser sintering is presented and discussed. In a previous study, single track formation from this powder blend was studied and analyzed to determine the optimum principal process parameters suitable for this powder blend. These process parameters were employed in this study to produce single and double layers where the effects of varied hatch distance and the employment of a rescanning strategy on the surface morphology and alloy homogeneity were investigated. Lastly, in the current study, three-dimensional specimens were produced and analyzed to determine the alloy microstructure, homogeneity, part porosity and mechanical properties. The analyses revealed that a Ti6Al4V alloy with a density of up to 99.9% and corresponding tensile strength and ductility values of up to 942.9 MPa and 17% was produced. Furthermore, a minimum Al evaporation value of 7.2% was recorded. Therefore, in situ alloying can indeed be employed to produce high-quality Ti6Al4V parts from an elemental Ti and an Al-V master alloy powder blend.

Eutectic solvents formed by (+)-DTTA and L-menthol as novel chiral recognition and separation media for enantioselective extraction of valsartan enantiomers

The enantioseparation of valsartan enantiomers using chiral eutectic solvents (ESs) as extractants was initially studied. The hydrophobic ESs (LM-DTTA) formed by L-menthol and (+)-Di-p-toluoyl-D-tartaric acid is a suitable chiral medium for the enantioselective extraction of R- and S-valsartan. Four principal parameters affecting chiral extraction, such as phase volume ratio, initial rac-valsartan concentration, extraction temperature, and system pH, were evaluated. The results showed that LM-DTTA has better and higher enantioselectivity levels, and one-step chiral extraction achieved an ee value of S-valsartan up to 91% under the optimized conditions. In addition, this chiral medium can be recycled through simple back-extraction with sodium bicarbonate solution and reused at least five times, giving similar results. This work provides a clear example of enantioseparation of the rac-valsartan via liquid–liquid enantioselective extraction using the LM-DTTA as a novel chiral recognition and separation medium. As a result, the established enantioselective extraction method can efficiently separate the R- and S-enantiomer and promote sustainable development for the production of S-valsartan.

Application of the Principal Components Analysis to Optical Fiber Sensor for Multiparametric Detection of Strain and Torsion

In this article, a multiparameter detection method for torsion and strain based on a single optical fiber sensor (OFS) is demonstrated combined with principal components analysis (PCA). A helical intermediate-period fiber grating (HIPFG) is used to measure the strain (0–1600 μϵ) and torsion (0–±360°) simultaneously. The wavelengthshift of the HIPFG shows a linear relationship with strain with the sensitivity of −1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> nm/μϵ, but an ambiguous relationship with torsion change. Hence, PCA is coupled to the experimental data to improve the sensing performance and the first principal component (PC1) and second principal component (PC2) are obtained. Based on PC1, the strain sensitivity and torsion sensitivity are calculated to be −0.37 μϵ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> and 9050.74 (rad/mm) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> . Intriguingly, multiparameter analysis for strain and torsion is obtained with the PC1 and PC2 and the simultaneous prediction of strain and torsion is succeeded. The prediction error for strain and torsion are 7.6% and 3.5%, respectively, emphasizing the link between principal components and target parameters. The method proposed provides a new entry to multiparameter sensing and analysis.

An uncertainty hybrid model for risk assessment and prediction of blast-induced rock mass fragmentation

Blasting is an important mining operation that usually produce several damaging consequences. Adverse rock fragmentation due to bench blasting is one of them. Hence, analysis of risk level and accurate estimation of particle size distribution of fragment size are of interest. This research developed a new model to simultaneously predict and risk assessment of rock fragmentation using 64 collected data from blasting operated in the Zarshouran gold mine in Iran. In this regard, a newly rock engineering system (RES) is developed based on the reliability information of Z-number theory and causal-effect relationship of the fuzzy cognitive map (FCM). This approach is named the reliability rock engineering causality system (RRECS). To do this, 15 principal effective parameters on rock fragment size were considered in the RRECS modeling process. The uncertainty of the interaction matrix was reduced using Z-number concept. Besides, the weight of effective parameters updated based on the combination of the nonlinear Hebbian algorithm (NLH) and differential evolution algorithm (DE) in FCM. The RRECS performance was validated by statistical linear and non-linear models. The results show R2, RSME, BIAS, and Accuracy using the proposed RRECS model calculated to be 0.957, 1.956, 0.001, and 96.741 for training and 0.931, 0.996, 0.016, and 99.053 for testing parts, respectively. Therefore, RRECS has performed better than the exponential, power, logarithmic, polynomial, and linear models. Furthermore, the sensitivity analysis results revealed that the hole diameter and powder factor parameters have the highest and lowest sensitivity on fragmentation, respectively.

Multivariate Statistical Analysis of Hydrochemical and Microbiological Natural Tracers as a Tool for Understanding Karst Hydrodynamics (The Unica Springs, SW Slovenia)

AbstractVarious multivariate statistical techniques (MST) can provide valuable insights into water quality variability. Despite numerous studies in which these methods have been used, their potential has not been fully exploited. This paper presents an improved approach to better understand the hydrodynamics of karst systems. The integrated application of hierarchical cluster and principal component analysis in combination with factor analysis allowed the construction of an advanced multivariate chemograph. The analytical procedure was applied in a binary karst aquifer known for its complex hydrodynamics and mixing of water with similar hydrochemical composition. In addition, the study area provides access to an integral groundwater flow system (ponor‐cave‐spring) and offers extensive prior hydrogeological knowledge. The approach allowed reduction and discrimination of the main parameters affecting water quality characteristics. Their identification enabled recognition of three predominant recharge components: (a) stored water impact with Cl and electrical conductivity, (b) sinking stream impact with turbidity and bacteria composition and (c) karst aquifer impact with Ca/Mg ratio as principal parameters. The results supported innovative characterization of the dominant processes and isolation of temporal hydrodynamic phases of individual monitoring points within the aquifer system. On this basis, a spatio‐temporal conceptual model was developed and the hydrodynamic behavior of the main springs was revealed. The applied methodology demonstrated to be useful in ascertaining functioning of a complex karst system under flood event conditions.

Production and Analysis of Characteristics of Biodiesel Produced from Waste Cooking Oil

There is increasing interest on waste cooking oils (WCO) as a cost-effective feedstock for biodiesel production. In this study, a one-step transesterification process was adopted to produce biodiesel at a laboratory scale from waste cooking oil with a low level of free fatty acids (A.V. 1.09 mgKOH/g). The maximum biodiesel yield obtained was 85.3% when using a combination of process parameters of 25% (v/v) methanol to oil ratio, 0.8% (w/w) of KOH, a maintained reaction time of two hours, reaction temperature of 60o C, and a stirring speed of 400 rpm. In the quest to optimize the process parameters such as alcohol to oil molar ratio, and catalyst concentration, the results show that the biodiesel yield increases with the increase in methanol to oil molar ratio until the optimum ratio, then starts to decrease and it decreases if the alkali catalyst is added above an optimum concentration. The optimum values of methanol to oil molar ratio and alkali catalyst were 25% (v/v) and 0.8% (w/w), respectively. The basic physicochemical properties of the WCO biodiesel produced were found to be within the ASTM Standard D6751 specified limits for required parameters. The principal parameters were acid value, density, viscosity and flash point. The calorific value was found to be 41.05 MJ/kg.

Electrochemical Measurement of Interfacial Distribution and Diffusion Coefficients of Electroactive Species for Ion-Exchange Membranes: Application to Br2/Br- Redox Couple.

A novel method has been proposed for rapid determination of principal transmembrane transport parameters for solute electroactive co-ions/molecules, in relation to the crossover problem in power sources. It is based on direct measurements of current for the electrode, separated from solution by an ion-exchange membrane, under voltammetric and chronoamperometric regimes. An electroactive reagent is initially distributed within the membrane/solution space under equilibrium. Then, potential change induces its transformation into the product at the electrode under the diffusion-limited regime. For the chronoamperometric experiment, the electrode potential steps backward after the current stabilization, thus inducing an opposite redox transformation. Novel analytical solutions for nonstationary concentrations and current have been derived for such two-stage regime. The comparison of theoretical predictions with experimental data for the Br2/Br- redox couple (where only Br- is initially present) has provided the diffusion coefficients of the Br- and Br2 species inside the membrane, D(Br-) = (2.98 ± 0.27) 10-6 cm2/s and D(Br2) = (1.10 ± 0.07) 10-6 cm2/s, and the distribution coefficient of the Br- species at the membrane/solution boundary, K(Br-) = 0.190 ± 0.005, for various HBr additions (0.125-0.75 M) to aqueous 2 M H2SO4 solution. This possibility to determine transport characteristics of two electroactive species, the initial solute component and its redox product, within a single experiment, represents a unique feature of this study.

Experimental study of sediment washout from stormwater sumps.

Sumps are commonly used in urban stormwater systems, which can be considered as a simple pretreatment device for stormwater quality control. However, they may function as pollution sources due to sediment washout under high flow conditions. An experimental study was conducted to investigate the scour process of predeposited sediments from a sump and its influencing parameters. Under conditions with large inflows or high sediment deposit, the sediment particles could be resuspended, entrained and flushed out. The washout mass decreased exponentially with time if the sediment bed surface depth was larger than a threshold value; otherwise, the amount of washout would be much smaller. The same scour pattern was observed for all the testing cases, of which the largest scour depth always occurred below the outlet. The deposit below the inlet might increase under conditions with high flow rates and low levels of sediment bed. Dimension analysis was performed and principal non-dimensional parameters were found, including the Péclet number, the pipe Froude number, and the dimensionless particle diameter, which can be used to determine whether the washout would occur and its intensity in a stormwater sump under given conditions.

Initial clinical validation of a hybrid in silico-in vitro cardiorespiratory simulator for comprehensive testing of mechanical circulatory support systems.

Simulators are expected to assume a prominent role in the process of design—development and testing of cardiovascular medical devices. For this purpose, simulators should capture the complexity of human cardiorespiratory physiology in a realistic way. High fidelity simulations of pathophysiology do not only allow to test the medical device itself, but also to advance practically relevant monitoring and control features while the device acts under realistic conditions. We propose a physiologically controlled cardiorespiratory simulator developed in a mixed in silico-in vitro simulation environment. As inherent to this approach, most of the physiological model complexity is implemented in silico while the in vitro system acts as an interface to connect a medical device. As case scenarios, severe heart failure was modeled, at rest and at exercise and as medical device a left ventricular assist device (LVAD) was connected to the simulator. As initial validation, the simulator output was compared against clinical data from chronic heart failure patients supported by an LVAD, that underwent different levels of exercise tests with concomitant increase in LVAD speed. Simulations were conducted reproducing the same protocol as applied in patients, in terms of exercise intensity and related LVAD speed titration. Results show that the simulator allows to capture the principal parameters of the main adaptative cardiovascular and respiratory processes within the human body occurring from rest to exercise. The simulated functional interaction with the LVAD is comparable to the one clinically observed concerning ventricular unloading, cardiac output, and pump flow. Overall, the proposed simulation system offers a high fidelity in silico-in vitro representation of the human cardiorespiratory pathophysiology. It can be used as a test bench to comprehensively analyze the performance of physically connected medical devices simulating clinically realistic, critical scenarios, thus aiding in the future the development of physiologically responding, patient-adjustable medical devices. Further validation studies will be conducted to assess the performance of the simulator in other pathophysiological conditions.

Smart City IoT System Network Level Routing Analysis and Blockchain Security Based Implementation.

This paper demonstrates, network-level performance analysis and implementation of smart city Internet of Things (IoT) system with Infrastructure as a Service (IaaS) level cloud computing architecture. The smart city IoT network topology performance is analyzed at the simulation level using the NS3 simulator by extracting most of the performance-deciding parameters. The performance-enhanced smart city topology is practically implemented in IaaS level architecture. The intended smart city IoT system can monitor the principal parameters like video surveillance with a thermal camera (to identify the virus-like COVID-19 infected people), transport, water quality, solar radiation, sound pollution, air quality (O3, NO2, CO, Particles), parking zones, iconic places, E-suggestions, PRO information over low power wide area network in 61.88 km × 61.88 km range. Primarily we have addressed the IoT network-level routing and quality of service (QoS) challenges and implementation level security challenges. The simulation level network topology analysis is performed to improve the routing and QoS. Blockchain technology-based decentralization is adopted to enrich the IoT system performance in terms of security.

Sustainable Synthesis of Highly Functionalized Activated Carbon using Plasma Technology.

Surface functionalized activated carbon (SFAC) has been used for several applications, including adsorption, catalysis and energy storage materials. Existing chemical and physical activation methods for surface functionalization are mostly identified as expensive, inefficient, and non-green methods. Plasma, known as the fourth state of matter, has recently been recognized as an attractive and sustainable method for introducing a higher degree of surface functionality to activated carbon. It also improves the bulk chemical structure and the properties of SFAC. The surface functionalization process is governed by discharge gas, discharge source, discharge efficiency and discharge time. The majority of researchers have utilized oxygen plasma as the discharge gas. However, ammonia, carbon dioxide, atmospheric air, specific gases such as chlorine and hydrogen sulfide, and neutral gases such as nitrogen and argon have also been used as the discharge gas. These plasma activations were conducted under different power conditions (W to kW) and varying treatment times (seconds to hours) using different plasma sources such as dielectric barrier discharge (DBD), arc, radio frequency (RF) and microwave (MW) for the surface functionalization. Most of the researchers have experienced both positive and negative co-relationships between principal parameters and surface functional groups (SFGs), surface area, porosity and other surface features such as roughness and hydrophilicity. However, a comprehensive review on the effects of these parameters on the final material properties is lacking. Therefore, this Review focuses on the recent developments in the utilization of plasma as a surface activation technique for activated carbon. Furthermore, an in-depth analysis of the relationship between experimental parameters and the resultant surface features of activated carbon is carried out and discussed. The functionalization mechanisms related to plasma activation have also been illustrated. The aging effect, which negatively impacts surface functionalized activated carbon, is also emphasized. Finally, the recent advances in applications of SFAC, challenges and future perspectives are discussed in detail.

Characterization and spatialization of the Physico-chemical quality of the waters of a natural lake of the Middle Atlas: the case of the Ramsar site lake Aguelmam Sidi Ali

The physicochemical quality of the water represents a major stake in front of the development of the piscicultural life in the natural lakes. The present work has for objective the characterization of the waters of the two parts of the Ramsar site of the lake Aguelmam Sidi Ali as well as the definition of their future vocations, as far as they present currently a great biological, ecological, and tourist interest. A follow-up of the evolution of the physicochemical quality of the two parts of the lake (small lake and large lake), via monthly samples for analyses in the laboratory and in-situ measurements of the principal physicochemical parameters, was carried out. The samplings were spread out over the period from April to December 2019. In light of the results obtained, the waters of the two parts of the lake aguelmam Sidi Ali did not present the same degrees of mineralization and hardness, and therefore, they show a clear difference in water quality. Despite this difference, the quality of the waters of Aguelmam Sidi Ali is generally good and thus favorable to the development of the percids introduced since 1939.

Differentiation time scales of small rocky bodies

The petrologic and geochemical diversity of meteorites is a function of the bulk composition of their parent bodies, but also the result of how and when internal differentiation took place. Here we focus on this second aspect considering the two principal parameters involved: size and accretion time of the body. We discuss the interplay of the various time scales related to heating, cooling and drainage of silicate liquids. Based on two phase flow modeling in 1-D spherical geometry, we show that drainage time is proportional to two independent parameters: μm/R2, the ratio of the matrix viscosity to the square of the body radius and μf/a2, the ratio of the liquid viscosity to the square of the matrix grain size. We review the dependence of these properties on temperature, thermal history and degree of melting, demonstrating that they vary by several orders of magnitude during thermal evolution. These variations call into question the results of two phase flow modeling of small body differentiation that assume constant properties. For example, the idea that liquid migration was efficient enough to remove 26Al heat sources from the interior of bodies and dampen their melting (e.g. Moskovitz and Gaidos, 2011; Neumann et al., 2012) relies on percolation rates of silicate liquids overestimated by six to eight orders of magnitude. In bodies accreted during the first few million years of solar-system history, we conclude that drainage cannot prevent the occurrence of a global magma ocean. These conditions seem ideal to explain the generation of the parent-bodies of iron meteorites. A map of the different evolutionary scenarios of small bodies as a function of size and accretion time is proposed.

Data-driven model for feedstock blending optimization of anaerobic co-digestion by BMP maximization

Anaerobic Digestion represents an economically and environmentally friendly technology that allows the production of biogas starting from organic substrates. Single substrate digestion often unexploited the total biomass capacity, resulting in low methane yield. On the other hand, it has been proved that biogas production can be significantly improved by combining two or more substrates, performing a co-digestion, which exploits the synergy between different bacteria populations. In the last years, many experimental studies have been conducted to understand how feedstocks interact with each other when mixed, revealing how powerful the blending of substrates could improve its key properties reaching higher methane yield and increasing waste valorization. However, these tests are often time-consuming and rely on the quality of the instruments used to analyze the substrates. Some co-digestion models have been also proposed but are very specific to the co-digestion of a well-defined mix of feedstocks. Unfortunately, ready technologies and models which evaluate an optimal blending ratio, able to estimate the optimal co-digestion configurations, are not discussed so far in the literature. Consequently, this work deals with the development of a tool that can find the optimal blended feedstock composition to produce the highest methane potential. The high number of possible raw materials, and the high variability of their characteristics, reflect the complexity of the problem. So, a database has been created where data about commonly used substrates have been gathered, analyzed, and exploited to build a data-driven model that effectively evaluates the unit's optimal feedstock composition. Furthermore, the model considers supply-chain issues such as substrate availability and storage options to be more trustworthy in a wider range of industrial settings. Principal influencing parameters of the model were found to be the C/N ratio and the biodegradability of the substrates, while other ones as lipids content and total solid concentration were excluded from the optimization algorithm but still present in the database for further studies. Working temperature of the unit was fixed to 35 °C, being the most used condition applied in the literature considered. Finally, the model has been validated by comparing its results to literature experimental tests. from both batch and CSTR (continuous stirred tank) reactors, showing great reliability of the model to the cases analyzed (RMSE <20 mL/gVS for two-substrate mixture, RMSE <30 mL/gVS for three-substrate mixture). Furthermore, the optimization of an industrial case is proposed with data provided by the Thöni company, yielding satisfactory results, such as a total increment of the bio-methane potential up to 70% globally (3-to-5% BMP daily increment) after the diet optimization.

Biomechanical energetics of terrestrial locomotion in California sea lions (Zalophus californianus).

Pinnipedia, an order of semi-aquatic marine mammals, adapted a body design that allows for efficient aquatic locomotion but limited terrestrial locomotion. Otariids, like the California sea lion (Zalophus californianus), have enlarged forelimbs and can bring their hindlimbs under the body to locomote quadrupedally on land, but phocids (true seals) have reduced forelimbs and are unable to bring their hindlimbs beneath them during terrestrial locomotion. Because of these differences, phocids are expected to have greater energetic costs when moving on land compared with otariids. The mechanical costs of transport (COT) and power outputs of terrestrial locomotion were first obtained from one male and two female adult California sea lions through video recording locomotion sequences across a level runway. The center of mass, along with six other anatomical points, were digitized to obtain variables such as velocity (V), amplitude of heave (A) and the frequency (f) of oscillations during the locomotion cycle. These variables represent the principal parameters of a biomechanical model that computes the power output of individuals. The three California sea lions in this study averaged a power output of 112.04 W and a COT of 0.63 J kg-1m-1. This footage was compared against video footage previously recorded of three phocid species (harbor seal, gray seal and northern elephant seal). Power output and mechanical COT were compared for all four pinniped species by tracking the animals' center of mass. The quadrupedal gait of sea lions showed lower vertical displacements of the center of mass, and higher velocities compared with the terrestrial gait of phocids. Northern elephant seals, gray seals and harbor seals showed significantly higher COT and power outputs than the sea lions. California sea lions locomote with lower energetic costs, and thus higher efficiency compared with phocids, proving that they are a mechanically intermediate species on land between terrestrial mammals and phocids. This study provides novel information on the mechanical energy exerted by pinnipeds, particularly California sea lions, to then be used in future research to better understand the limitations of these aquatic mammals.

Measurement of the principal damping components of composite laminates

The prediction of material damping in composite laminate components may allow for the development of lighter component designs, and can be achieved via several techniques. One such example, the modal strain energy (MSE) technique requires a combination of effective strain energy modelling and accurate principal loss factor parameters. Measuring principal loss factors can be very challenging for lightly damped components due to parasitic or ‘extraneous’ damping sources introduced by the test set-up itself. To ensure high quality input data to the strain energy models an novel damping test procedure has been developed, which allows for mono-harmonic damping parameter extraction via free decay and logarithmic decrements, whilst minimising extraneous dissipation. Improvements over the established impact hammer testing technique could be shown during the validation of the approach.