Hydraulically interconnected suspension parameter sensitivity in half-car ride performance

In this paper, the development of a hydraulically interconnected suspension (HIS) system model and the integration of this model into a four degree-of-freedom half-car system is briefly introduced. The appropriate frequency response functions are derived in order to simulate the system response to a stochastic road profile. The sprung mass vertical and roll accelerations, the dynamic normal tyre force, and the suspension deflection are considered in the frequency domain up to 20 Hz. Four key hydraulic system parameters are identified and investigated to gauge their effects on the system's dynamic performance. The results indicate that HIS system performance can be greatly affected by these hydraulic parameters. Copyright © 2007 SAE International

Determination of Modal Parameters of a Half-Car Fitted with a Hydraulically Interconnected Suspension from Simulated Free decay Responses

This paper presents an alternative approach for determining the vibration modal parameters, in terms of natural frequencies, damping ratios and modal shapes of a roll-plane half-car fitted with a general hydraulically interconnected suspension system. The dynamic model of the system, which consists of the sprung mass and the HIS and the wheels, is formulated using the state space representation approach. The state variables describing rigid body motions of the sprung and unsprung masses are heavily coupled with those describing the dynamics of HIS fluid circuits. A numerical simulation scheme is developed to obtain the transient and free decay responses of the half car vehicle using specific initial conditions or road inputs. The obtained results are compared with those determined from the free vibration analysis of the system using the transfer matrix method. Discussions on the advantages and limitations of the presented method are also provided

Transient Characteristics of a Hydraulically Interconnected Suspension System

This paper describes vehicle dynamic models that capture the large amplitude transient characteristics of a passive Hydraulically Interconnected Suspension (HIS) system. Accurate mathematical models are developed to represent pressure-flow characteristics, fluid properties, damper valves, accumulators and nonlinear coupling between mechanical and fluid systems. The vehicle is modeled as a lumped mass system with half- and fullcar configurations. The transient performance is demonstrated by numerical integration of the second order nonlinear differential equations. The stiffness and damping characteristics corresponding to vehicle bounce, roll and pitch motions are extracted from the transient simulation. Simulation results clearly demonstrate the superiority of the HIS system during vehicle handling and stability by providing additional roll stiffness and reduced articulation stiffness

High frequency parameter sensitivity in hydraulically interconnected suspensions

In this paper, the development of a hydraulically interconnected suspension (HIS) system model and its integration into a four degree-of-freedom half-car system is briefly introduced. Frequency response functions are derived in order to simulate the system response to a stochastic road profile. The sprung mass vertical and roll accelerations are considered in the frequency domain up to 1000 Hz. Four key hydraulic system parameters which affect the system’s high frequency dynamics but not its low frequency response are identified and investigated. The results indicate that HIS system performance in the high frequency range (50-1000 Hz) can be greatly affected by these hydraulic parameters, while the favourable ride characteristics typical of HIS vehicles are retained

Some scattering and sloshing problems in linear water wave theory

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Using the method of matched asymptotic expansions the reflection and transmission coefficients are calculated for scattering of oblique water waves by a vertical barrier. Here an assumption is made that the barrier is small compared to the wavelength and the depth of water. A number of sloshing problems are considered. The eigenfrequencies are calculated when a body is placed in a rectangular tank. Here the bodies considered are a vertical surface-piercing or bottom-mounted barrier, and circular and elliptic cylinders. When the body is a vertical barrier, the eigenfunction expansion method is applied. When the body is either a circular or elliptic cylinder, and the motion is two-dimensional, the boundary element method is applied to calculate the eigenfrequencies. For comparison, two approximations, "a wide-spacing", and "a small-body" are used for a vertical barrier and circular cylinder. In the wide-spacing approximation, the assumption is made that the wavelength is small compared with the distance between the body and walls. The small-body approximation means that a typical dimension of the body is much larger than the cross-sectional length scale of the fluid motion. For an elliptic cylinder, the method of matched asymptotic expansions is used and compared with the result of the boundary- element method. Also a higher-order solution is obtained using the method of matched asymptotic expansions, and it is compared with the exact solution for a surface-piercing barrier. Again the assumption is made that the length scale of the motion is much larger than a typical body dimension. Finally, the drift force on multiple bodies is considered the ratio of horizontal drift force in the direction of wave advance on two cylinders to that on an isolated cylinder is calculated. The method of matched asymptotic expansions is used under the assumption that the wavelength is much greater than the cylinder spacing

Understanding older people’s experience with ChatGPT

ChatGPT, developed by OpenAI, has become increasingly popular across different age groups, but there is limited research on how older people use it. This study explores the experiences of older people with ChatGPT, including their knowledge, usage, ethical concerns, perceived pros and cons, learning goals, and challenges with accessibility and design. The study used a mixed-methods approach, combining semi-structured interviews with analysis of ChatGPT chat logs. Twenty participants took part, with an even number of men and women, aged 60 to 88. Chat logs were collected from 11 participants. Most participants had heard of ChatGPT through the news, courses, or from family, friends, or work. Many had a good understanding of how it works and used it for finding information, completing tasks, and getting help with everyday activities. Fewer used it for more creative or advanced tasks. Concerns about data privacy were common, though not shared by everyone. Participants mentioned efficiency, convenience, and greater independence as main benefits. On the other hand, issues like inaccuracy and misinformation were seen as major disadvantages. Opinions about how suitable ChatGPT is for older people were mixed. Some thought it was easy to use, while others believed good digital skills were necessary. Some participants wanted to learn how to write better prompts or use more advanced features, while others were happy with how they were using it. Some found the layout of the platform easy to use, while others suggested improvements. The chat logs showed that many participants could write clear prompts, but few asked follow-up questions. Those who did seemed more satisfied with the results. Overall, most older people in the study were satisfied with ChatGPT and had a positive view of it. However, they felt some improvements could make it even more useful. More research with a larger and more diverse group is needed to better understand how older people use ChatGPT over time

Rest Raw Material from Atlantic Salmon and Norwegian Chicken - Effects of Thermal Treatment and Different Drying and Storage Methods on Quality and Stability

I følge FAO (2018) har forbruket av marine produkter på jorda nådd over 120 millioner tonn de siste ti årene. Det økende forbruket har ført til økende mengde marine produkter som ikke kan bli brukt til menneskelig konsum. Disse produktene blir ofte kalt restråstoff eller bi-produkter. Dette er også et problem i kylling produksjonen ettersom kylling er en av de mest spiste kjøtt-slagene i Norge. Det har nylig vært mye interesse rundt effektiv utnyttelse av disse materialene til å produsere høy-verdi produkter, men disse materialene er svært ustabile og krever gode bevaringsmetoder. Hensikten med denne masteroppgaven har vært å studere tørking som en type konserveringsmetode, og analysere kvalitet og stabilitet av de tørkede produktene. Oppgaven er skrevet i samarbeid med Kystmiljø AS som også leverte råmaterialene brukt. Innholdet av tørrstoff, aske, protein, lipider og fettsyrer i innvoller fra atlantisk laks og norsk kylling ble undersøkt. Termisk behandling ved ulike temperaturer ble gjennomført før tørking, og effektiviteten av separering av fett, limvann og fett-redusert sediment ble undersøkt. Fett-redusert sediment ble tørket ved bruk av tre ulike tørkemetoder: vakuum frysetørking, infrarød tørking og varmluftstørking. Kvalitetsparametere som vannaktivitet, vanninnhold, farge og lipid- og proteinoksidasjon ble målt av de tørkede produktene. Et lagringsforsøk med to ulike lagringsmetoder (vakuumpakket og i plastpose) ble også gjennomført, og de samme kvalitetsparameterene ble målt. Stabiliteten til tørkede produkter ble undersøkt ved hjelp av glasstemperatur. Sesongvariasjon i fettinnholdet i innvollene ble funnet. Lakseinnvollene og kyllinginnvollene inneholdt henholdsvis 25 % og 3 % omega-3 fettsyrer. Fettsyreanalysen viste store mengder flerumettede fettsyrer i lakseinnvollene sammenlignet med kyllinginnvollene. Større mengder mettede fettsyrer og omega-6 fettsyrer ble funnet i kyllingen. Disse variasjonene i fettsyreinnhold bidro til et stort smeltepunktsområde for de ulike materialene. Termisk behandling ble studert ved 40-90°C. Mengden fett separert økte med økende temperatur, men lipid innholdet økte samtidig i det fett-reduserte sedimentet. Basert på resultatene fra de termiske behandlingene ble 50°C valgt som ekstraheringstemperatur i de videre analysene. Tørkemetodene resulterte i pulver-lignende egenskaper for lakseinnvollene. Infrarød tørking av laks resulterte i høyest vanninnhold (ca. 13 %) og vakuum frysetørking resulterte i lavest vanninnhold (ca. 2 %). Kyllinginnvollene ble seig og klebrig etter tørking i ovn, og disse prøvene hadde et vanninnhold mellom 40-50 %. Det ble konkludert at denne tørkemetoden ikke egnet seg for kyllinginnvollene. Høyt vanninnhold førte også til vekst av mugg under lagringsforsøket. Avtagende nivåer av peroksid verdi og konjugerte diener ble funnet for begge råmaterialene, og kan indikere økende produksjon av sekundære lipidoksidasjonsprodukter. Men konsentrasjonen av TBARS varierte for alle prøvene, noe som kan indikere interaksjoner med peptider og aminer. Hydrolysegraden var større for kyllinginnvollene i forhold til lakseinnvollene. To glasstemperaturer (-104°C and -67°C) ble detektert i lakseinnvollene, og disse temperaturene ble forbundet med henholdsvis lipider og proteiner. DSC analysen viste at tørking ved høy temperatur separerte fettet bedre enn ved bruk av vakuum frysetørking. Vakuum frysetørking resulterte i absorpsjon av lipider på overflaten, dermed forventes det at disse prøvene er mer utsatt for forverring. Det ble vist at optimal temperatur for termisk behandling og tørking var avhengig av type materiale og den kjemiske sammensetningen. Tørking i ovn ved 50 og 100°C var ikke tilstrekkelig for kyllinginnvollene og andre metoder bør undersøkes videre for dette råstoffet. Signifikant forskjell i pakkemetode ble funnet for kyllinginnvollene, men dette kan være forårsaket av høyt vanninnhold. De tørkede produktene kan brukes som ingredienser i dyrefôr.The consumption of marine products in the world has according to FAO (2018) reached over 120 million tonnes the last ten years. Increasing consumption will lead to increasing amount of marine products which are not consumed. These products are commonly referred to as rest raw material or by-products. Production of rest raw material is also relevant in poultry farming, as chicken is the second most consumed animal meat in Norway. There have recently been great interest in effective utilisation of these materials to produce high-value products, however, these materials are highly perishable and require appropriate preservation. The aim of this thesis was to study the effectiveness of drying as a preservation method, and analyse the quality and stability of the dried products. This Master's Thesis was conducted in collaboration with Kystmiljø AS, which provided the Atlantic salmon intestines and Norwegian chicken intestines utilised in this study. Characteristics of the materials such as the chemical composition and fatty acid composition were mapped. Thermal treatment was conducted prior to drying where different temperatures were studied for effective separation of fat, stickwater and sediment. Fat-reduced sediment were dried by either vacuum freeze drying, infrared drying or hot air drying. Quality parameters such as the water activity, water content, colour and lipid and protein oxidation were measured of the dried materials. These parameters were also measured for samples stored over thirty days using two different packaging methods (vacuum packing and in plastic bag). The stability of the dried materials were investigated using glass transition temperature. Seasonal variation of the lipid content was proved for both materials. The salmon intestines contained approximately 25 % omega-3 fatty acids compared to around 3 % in the chicken intestines. The analysis of fatty acid composition showed that the salmon contained more amounts of PUFAs, hence was more susceptible to oxidation. Saturated fatty acids and omega-6 fatty acids were more abundant in the chicken intestines. The difference in the fatty acid composition contributed to the wide range of melting points of the oils from the materials. Thermal treatment was examined at temperatures from 40-90°C. The amount of fat separated increased as the temperatures increased for both materials. However, the lipid content in the fat-reduced sediment increased as well. Based on the results from thermal treatments, 50°C was chosen and used as extraction temperature in the further analysis. Drying of the salmon intestines resulted in powder-like properties. The infrared dried salmon had the largest water content (approx. 13 %) and vacuum freeze dried salmon had the lowest (approx. 2 %). The chicken intestines obtained paste-like properties after drying in oven. The oven dried chicken samples contained between 40-50 % moisture, and it was concluded that this type of drying was not sufficient for the chicken intestines. High water content of the chicken intestines resulted in growth of mould during the storage experiment. The results from the lipid oxidation study on stored samples showed decreased levels of peroxide value and conjugated dienes for both materials. However, concentration of TBARS varied for each sample, and could be due to interactions with peptides and amines. The degree of hydrolysis was larger for the chicken intestines compared to salmon intestines. Two glass transition temperatures (-104°C and -67°C) were detected in the salmon intestines and these temperatures were associated with lipids and proteins. The DSC analysis showed that high temperature drying separated the fat better than the vacuum freeze drying method. The vacuum freeze drying resulted in absorption of lipid on the surface making these samples more perishable. It was shown that optimal temperature for thermal treatment and drying was dependent on the type of material and the chemical composition. Oven drying at 50°C and 100°C was not suitable for the chicken intestines and further analysis of other drying methods of this particular material should be conducted. Significant difference in the packaging methods was found for the chicken intestines, which could be due to the high water content. The dried products could be applicable as ingredients in pet food