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Edible coating based on sodium alginate solution was applied to fresh‐cut cantaloupe melon by dipping and vacuum impregnation coating methods. One aim of this work is to produce more technical information concerning these conventional and novel coating processes. For this purpose, the effect of various coating parameters (dipping time, draining time, time length of the vacuum period, vacuum pressure, atmospheric restoration time) with several levels on physical quality parameters (percentage of weight gain, color, and texture) of noncoated and coated samples were determined in order to define adequate coating process parameters to achieve a successful coating application. Additionally, the effects of dipping and vacuum impregnation processes were compared. Both processes improved the firmness of the melon pieces. However, vacuum impregnation application had higher firmness and weight gain results, and had significant effect (P < 0.05) on color (lower luminosity, higher redness, yellowness, and chroma values). Experimental results affirm that vacuum impregnation method can be used successively to improve mechanical and structural properties of food products.
Friction surfacing offers a means of producing coatings between dissimilar materials through a solid state process; a union that would otherwise be classed as incompatible for liquid state coating processes. A method of using a rotating consumable friction rod supplemented by inductive heating was employed to produce conditions necessary for a sound bond between a stainless steel coating and an aluminium substrate. The rotational speed of and load on the coating rod influenced the bond strength significantly with low rotational speeds and high load values producing a good bond quality; however, cavitations at the coating-substrate interface showed a detrimental effect on the bond quality. Mechanical interlocking could be identified from images of longitudinal cross-sectional slices which were recorded using optical microscopy. An image recognition software tool was used to generate an interfacial roughness profile graph which described the coating-substrate interface. Additional filtering of the profile graph showed the depth of mechanical interlocking of the stainless steel coating into the aluminium substrate with the degree of this interlocking quantified by roughness values calculated from the profile graph. Large roughness values can be related to high coating push-off strengths (up to 107 MPa), and also were a result of low rotational speeds and high load values during friction surfacing. Dovetail shaped mechanical interlocks identified in the profile produced both high push-off and shear strength when compared with wedge-shaped interlocks; which, overall, provided good shear strengths up to 126 MPa.
Inductive heating effects on friction surfacing of stainless steel onto an aluminium substrate
(2015)
An experimental setup was designed to compare the principal process parametric relationships with the classical approach to friction surfacing with the addition of inductive heating. The production of the flash is described quantitatively and its influence on coating geometry and mass is presented. It was found that the coating mass and thickness decreased for an increase in the rotational speed of the consumable rod; the amount of flash produced by the consumable rod also increased. However, the effect of an increase in this rod contact pressure on the coating thickness is insignificant, whilst the coating mass decreases with rising pressure and the coating width increases coupled with an increase in flash production. Cross sections showed good bonding quality and mechanical interlocking at the bond interface. The substrate-coating interface showed a varying degree of mechanical interlocking and the presence of cavitations. Bond strength values applying shear and push-off testing of up to 106 MPa and 96 MPa, respectively, could be identified.
Friction surfaced specimens produced by the application of inductive heating and utilising a flash-reducing tool were compared with those obtained through the classical approach. It was found that the use of inductive heating resulted in an increased consumption of the coating material; however, the push-off strength could be more than doubled when compared with the classical process with high shear strength values of up to 111 MPa. The application of the flash-reducing tool reduced the flash to less than 0.05% of the material deposited as a coating and manifested itself in the form of small chips. High push-off strength values of up to 135 MPa were observed, accompanied by an increased coating thickness, coating width and bonding area. Temperature measurements with thermocouples taken during the coating process showed that the melting temperature of the aluminium substrate was reached at the substrate–coating interface. Mixed mode failure was evident at the fractured surfaces of the push-off test specimens and mechanical interlocking appears to be a main bonding mechanism. The presence of cavities were shown to have a detrimental effect on the bonding integrity, but could be reduced in size and number by the application of the flash-reducing tool.
High fogging is a power augmentation device where water is sprayed upstream of the compressor inlet with higher mass flow than that which would be needed to saturate the intake air. The main focus of this paper is on applications of high fogging on the ALSTOM gas turbine engines of the family GT24/GT26. Engine operation and performance are illustrated based on test results obtained from four different engines that have meanwhile accumulated more than 12,000 operating hours (OH) in commercial operation with ALSTOM’s ALFog® high fogging system. The effect of internal cooling (water evaporation inside the compressor) is investigated considering actual compressor boundaries matched within the complete engine. Changes in the secondary air system (SAS) and corresponding movement of the engine operating line have been taken into account. Power output gain as high as 7.1% was experimentally demonstrated for injected water mass fraction (f=mH2O∕mair) equal to 1% and considering internal cooling effects only. Higher figures can be obtained for operation at low ambient relative humidity and partial evaporation upstream of the compressor inlet.
Joining sheet metal can be problematic using traditional friction welding techniques. Friction crush welding (FCW) offers a high speed process which requires a simple edge preparation and can be applied to out-of-plane geometries. In this work, an implementation of FCW was employed using an additional wire to weld sheets of EN AW5754 H22, DC01, and Cu-DHP. The joint is formed by bringing together two sheet metal parts, introducing a wire into the weld zone and employing a rotating disk which is subject to an external force. The requirements of the welding preparation and the fundamental process variables are shown. Thermal measurements were taken which give evidence about the maximum temperature in the welding center and the temperature in the periphery of the sheet metals being joined. The high welding speed along with a relatively low heat input results in a minimal distortion of the sheet metal and marginal metallurgical changes in the parent material. In the steel specimens, this FCW implementation produces a fine grain microstructure, enhancing mechanical properties in the region of the weld. Aluminum and copper produced mean bond strengths of 77 and 69 pct to that of the parent material, respectively, whilst the steel demonstrated a strength of 98 pct. Using a wire offers the opportunity to use a higher-alloyed additional material and to precisely adjust the additional material volume appropriate for a given material alignment and thickness.
Large arrays of ordered magnetic nanostructures have been fabricated by sputter depositing Fe/Gd multilayers on an array of self-assembled nanospheres. On a planar substrate the system shows an in-plane magnetization whereas a spin reorientation transition (SRT) to out-of-plane orientation occurs on the spherules. This SRT cannot only be explained by the reduction in the shape anisotropy due to patterning of the extended film into nanometer sized islands. In fact, more important is the curved surface of the film on the nanocaps. Micromagnetic simulations of various geometries reveal that the crescent shape of the magnetic film on the spheres is ideal to get small values of the shape anisotropy for all diameters of the spheres, ranging from 1 μm down to 20 nm. The observed SRT enables a simple and cost effective bottom-up approach to produce patterned perpendicular magnetic nanostructures, having a high potential for magnetic data storage and spintronic applications.
For a further optimization of the automotive power train of diesel engines, advanced combustion processes require a highly flexible injection system, provided e.g., by the Common Rail (CR) injection technique. In the past, the feasibility to implement in the injection nozzle injection quantity sensors based on a thermo-resistive measurement principle has been demonstrated up to injection pressures of 135 MPa (1350 bar). Due to a very complex integration procedure a less-costly implementation is realized in the range of the high-pressure pipe connecting each single injector with the common pressure reservoir. The sensor output signals measured at this location of the hydraulic system are compared to those obtained from the nozzle as well as from an injection amount indicator used as standard reference method. Finally, hydraulic simulations on system level are performed showing a good correspondence in respect to the onset of fuel flow and to the period of pressure oscillations generated in the hydraulic system after termination of the drive pulse.
The aim of this study was to evaluate the influence of relative humidity (RH) on the oxygen permeability and water vapour transmission rate (WVTR) of whey protein coated Polyethylene terephthalate (PET) or whey protein monolayer films. Furthermore, the activation energies for the permeability of oxygen, carbon dioxide and nitrogen as well as the permselectivities under different set of temperatures were measured. The results showed that the permeability values through the whey protein coating and whey protein film increased with increasing RH. The water vapour permeability measured at 50% RH of (9.3 ± 0.6)−10 cm3 (STP) cm cm−2 s−1 Pa−1 increased to (16.2 ± 0.9)−10 cm3 (STP) cm cm−2 s−1 Pa−1 at 85% RH. An increase in temperature showed an expected increase of the permeability in both uncoated PET and the whey protein monolayer. The permselectivity of whey protein film was determined and the calculated ratios of the permselectivity (P(N2)/P(O2)/P(CO2):1/(4–6/(34–35)) differed from the simplified ratios given in the literature (P(N2)/P(O2)/P(CO2):1/4/16). Furthermore the calculated activation energy values for whey (51 kJ mol−1) were in agreement with other studies.
This study investigates chemical grafting with fatty acid chlorides as a method for the surface modification of hydrophilic web materials. The resulting changes in the water repellence and barrier properties were studied. For this purpose, different grades of polyvinyl alcohol (PVOH) were coated on regenerated cellulose films (“cellophane”) and paper and then grafted with fatty acid chlorides. The PVOH grades varied in their degree of hydrolysis and average molecular weight. The surface was esterified with two fatty acid chlorides, palmitoyl (C16) and stearoyl chloride (C18), by chemical grafting. The chemical grafting resulted in water-repellent surfaces and reduced water vapor transmission rates by a factor of almost 19. The impact of the surface modification was greater for a higher degree of hydrolysis of the polyvinyl alcohol and for shorter fatty acid chains. Although the water vapor barrier for palmitoyl-grafted PVOH was higher than for stearoyl-grafted PVOH, the contact angle with water was lower. Additionally, it was shown that a higher degree of hydrolysis led to higher water vapor barrier improvement factors after grafting. Furthermore, the oxygen permeability decreased after grafting significantly, due to the fact that the grafting protects the PVOH against humidity when the humidity is applied on the grafted side. It can be concluded that the carbon chain length of the fatty acid chlorides is the limiting factor for water vapor adsorption, but the grafting density is the bottleneck for water diffusing in the polymer.
Autonomous Vehicles (AVs) will soon be a reality on our roads. Up to now, their standard behaviour is predetermined since it is the result of programmed algorithms. Under risky traffic situations, however, they will face dilemmas such as, deciding between affecting the passenger or affecting others. Thus, in this experiment, we investigate how people solve a reframed version of the well-known Trolley-problem [Foot, P. 1967. “The problem of abortion and the doctrine of double effect,” Oxford Review 5: 5–15] under two conditions: when subjects actually drive a vehicle simulator, versus when they solve the same dilemma by programming a hypothetical AV. In both settings, the participants’ decisions have real monetary consequences, which affect others and themselves. Our Probit models indicate that subjects who program an AV and who are more cautious in terms of speed are less (more) likely to sacrifice a pedestrian (themselves) compared to those who actually drive and prefer a higher driving speed. Moreover, we find that the subjects’ choices are associated with risk aversion but not with moral beliefs or loss aversion. Implications of the driving vs programming discrepancies for the design of AVs algorithms are discussed.
The focus of this publication is on the development of lane-precise “Ground Truth” (GT) maps for the objective quality evaluation of automated driving functions. Therefore, attention is paid to the proper measurement of road geometry. The road geometry forms the basic layer of the HD maps.
A new map format Curved Regular Objects (CRO) is developed, which is based on the idea of OpenCRG®. For the evaluation of current Advanced Driver Assistance Systems (ADAS) an accurate High Definition (HD) maps as GT are necessary. This makes it possible to locate the high precision vehicle position and motion with centimeter accuracy. The aim is to achieve maximum accuracy of the absolute 3D positions when measuring lanes. This method for the generation of highly accurate GT maps promises an absolute accuracy of < ± 0.05 m. Various research activities benefit from the exact street reference at the Kempten University of Applied Sciences (UAS Kempten) in the Adrive Living Lab. First of all, the publication deals with the current Lane Keeping Assistant Systems (LKAS). The accuracy of the vehicle’s localization on the GT map and an objective evaluation of the LKAS is shown. In addition, the CRO data is used as a virtual sensor for the steering assistant in real time. Another application is the Visual Range Finder (VRF), which requires less computation power by using the CRO data. In addition, a current LKAS camera sensor performance is evaluated using CRO maps.
Fahrerassistenzsysteme und automatisiertes Fahren sind ein Megatrend in der Fahrzeugindustrie. Dabei stellen sich folgende Fragen: Können sich die Fahrzeughersteller auch noch in Zukunft markenspezifisch differenzieren, oder fahren alle Fahrzeuge gleich? Wie lässt sich eine Marken-DNA implementieren, und wie erzielt man den Übergang von Fahrspaß zum Spaß am Gefahrenwerden? Um Antworten zu generieren, sind klare Fahreigenschaftsziele "vor Kunde" und daraus die Anforderungen an die Fahrzeugsysteme und -komponenten abzuleiten. Aber was sind Fahreigenschaften im Kontext des assistierten und automatisierten Fahrens, und wie können diese in einer Entwicklung gezielt erreicht werden? Dieser Herausforderung hat sich Porsche gemeinsam mit der Hochschule für angewandte Wissenschaften Kempten und MdynamiX angenommen. Um die Eigenschaftsziele in allen Phasen der Entwicklung auf Gesamtfahrzeugebene validieren zu können, wurde eine modulare Simulationsumgebung, bestehend aus der Umfeldsimulation Vires VTD, Porsche-Fahrdynamikmodell und einem Reglersystemverbund inklusive Spurhalteregler aufgebaut. Die Co-Simulationsplattform AVL Model.Connect stellt dabei die Vernetzung der einzelnen Simulationen/Modelle dar und bietet entsprechende Funktionen, um diese durchgängig in den Verfahren Model in the Loop (MiL), Software in the Loop (SiL) und Hardware in the Loop (HiL) einzusetzen. Um die Spurführungsgüte, Fahrzeugreaktion und Fahrer-Fahrzeug-Interaktion realistisch abbilden zu können, ist ein gutes Lenkmodell mit Effekten im On-Center-Bereich notwendig.
Claim and Reality? Lane Keeping Assistant: the Conflict Between Expectation and Customer Experience
(2018)
In a current customer study with over 50 subjects, the customer wishes/acceptance of the Lane Keeping Assistance System were tested, evaluated and compared over 4000 km in a real road test. As a result, a considerable amount of potential can be seen for improvement in terms of customer acceptance for all three Lane Keeping Assistance Systems tested. The feeling of safety is the most important criterion, followed by the HMI and the edge guide. Furthermore, specific properties can be derived from the study, which must be fulfilled from the customer's point of view in order to fulfil the customer's wishes. There was a clear "GAP" between the degree to which the criteria were met and their importance. Only 27 % of customers would finally buy the LKAS on the basis of the product quality they have experienced. The results show that, in addition to differentiated expectations, there are primarily knowledge and experience-based deficits. Although a large part of the ADAS is known, only a few of the drivers surveyed have system expertise. Furthermore, it becomes clear from the questions according to Kano that, in addition to the pure transfer of knowledge, above all the subjective experience of the systems contributes to the enthusiasm of the users and to the increase in acceptance, provided that the first contact with the Lane Keeping Assistance represents a successful experience. Therefore, more attention should be paid to the capabilities and needs of end-users when designing vehicles. ADAS have the potential to counteract people's performance limitations, to support you where people reach their limits. However, only under the condition that they find acceptance in the target group and are used safely. The system is only used if it has the system behavior expected by the driver and he can therefore trust the system. Arndt also points out that too little confidence in ADAS means that it is not used. However, in the same context, she stresses that too much confidence can tempt the driver into relying too much on the ADAS, leading to system abuse. In addition to technical feasibility, knowledge of the requirements, needs and wishes of drivers is indispensable for their acceptance and use. Therefore, the recommendation to automotive manufacturers and suppliers is to involve various user groups in the product development process as early as possible, for example using the QFD method. In this way, ADAS are developed that meet the expectations of the customers. Especially the emotional comfort experience of the users, like lack of system trust, fear of negligence, distraction, paternalism and loss of control, will gain importance with increasing degree of automation. In order to lay the foundation for the acceptance of current developments in the field of highly automated and autonomous driving, drivers must develop a comprehensive system understanding and trust in comparison with today's ADAS of level 2 functions. Acceptance and trust in ADAS depends largely on a suitable and transparent human-machine interface. This theory has been also proven in this study. The customer wants to be informed about the current status of the system at any time during the journey via an understandable display concept and to be clear. He wants a predictable system that gives him enough time to intervene in the event of a system crash due to system limitations. In current systems, the warning comes - if at all - at the time of the drop. The driver has often already crossed the lane limit. Taking human situational awareness into account, such a short-term warning is critical. In addition, users' expectations for a Lane Keeping Assistance System do not always match the system's functionalities. According to the participants, the current system design does not offer any added value, as the driver must be ready to intervene at all times. This means that the driver not only has the task of checking himself for his primary task of driving, but must also monitor the availability of the system and prepare himself for unforeseen, in some cases also unforeseen drops off of the system. Since human hands over control to the vehicle, trust and the associated acceptance plays a central role. Ultimately the break-out of automated driving will decide on customer acceptance. "If only the engineer realizes the differences and understands the system, the customer has no benefit". The findings of the study show that in ADAS/AD development, the human being, or rather the customer should be placed much more at the center of development. Furthermore, it is necessary to focus on driving attributes and the driving experience in the sense of an attribute-based development.
Advanced Driver Assistance Systems (ADAS) warn, inform and perform monotonous tasks so that the strain on the driver's side is greatly reduced. They should lead to a further increase in customer mobility through greater comfort, efficiency and safety. As far as the theory goes - in practice, the comfort benefits addressed by the customer are not evident with all driver assistance systems. A previous study of the Lane Keeping Assistance System (LKAS) at Kempten University has shown that the physiological stress and perceived stress of the subjects using the LKAS during a test drive are significantly higher than if the same person refrains from using it. This finding clearly shows that the product "still" misses the purpose of comfort gain through relief. As a result, customer acceptance is very moderate. The motivation of this study was to identify requirements for the LKAS from the customer's point of view, to measure the degree of fulfilment in a competitive comparison and to learn from the customer assessments overall. By implementing these features, customer satisfaction with the LKAS is to be increased. The feeling of strain should lead to relief and consequently to an increase in the customer's acceptance of the product. Switching off or deactivating the system and the resulting increased safety risk should no longer occur in the future. The customer's wishes should be recognizable in the product specifications.
Validation of X-in-the-Loop Approaches for Virtual Homologation of Automated Driving Functions
(2018)
Securing and homologating automated driving functions presents a huge challenge for their market introduction due to an enormous number of scenarios and environment parameter combinations. Confronting conventional real world tests with the new challenges of automated driving is not feasible anymore and yields to a virtualization of the testing methods by means of X-in-the-Loop approaches. Since their validity is a key enabler for virtual homologation, this paper focuses on the validation of X-in-the-Loop approaches. A generic validation methodology is introduced and demonstrated for the specific use case of an automated longitudinal driving function. As a proof of concept equal scenarios are performed in real driving tests as reference and in two X-in-the-Loop approaches based on a test bed resp. a purely virtual co-simulation environment. The paper describes how a consistent implementation can be ensured to evaluate the collected data. First results show a promising correlation regarding multiple repetitions on the test bed and regarding the validation of both X-in-the-Loop approaches for a future virtual homologation of automated driving functions.
Advanced driver assistance systems (ADAS) of longitudinal control are widely used. In contrast to longitudinal controls, lateral controls are a growing market since this technique plays a major role in a successful introduction of automated driving. Customer and benchmark studies conducted by theUniversity of Applied Sciences Kempten and Consline AG have clearly shown that the vehicle behavior and customer experience such as tracking performance, driver-vehicle interaction, availability, degree of stress and the sense of security of today's lane keeping assistance systems are consistently rated as extremely unsatisfactory. As a consequence, there is a moderate level of trust and low customer acceptance. A new measuring method based on high-precision and accurate digital maps (ground truth) was developed. With this method, analysis of the entire chain of action, from sensor to tracking is possible. Position, direction and motion of the vehicle and its reference distance to road markings can be precisely measured in the digital map using a high-precision inertial measurement system (IMU) with RTK-DGPS and SAPOS correction service. The measuring method can be used in particular on public routes, since test areas are still insufficient due to the very small tracks and driving maneuver variations for lane keeping assistance systems. For a precise assessment of the sensor, planning and control performance as well as the overall driving characteristics, a very precise knowledge of the routes and the route excitation is required. For this purpose, high precision and accurate digital maps (ground truth) of real tracks were generated. A roof mounted stereo camera system combined with an RTK-DGPS IMU was used to provide offline-generated digital maps with high precision in the OpenDRIVE or OpenStreetMap format, as well as other common simulation formats like IPG CarMaker. In order to be able to carry out the dynamic driving evaluation as well as the simultaneous evaluation of the sensor, planning and control performance in the digital maps in real time, a route format with a regular grid, based on OpenCRG (Curved Regular Grid), was further developed. An IMU with RTK-DGPS and correction service (e.g. SAPOS) provides in real time the highly accurate position, direction and movement of the ego vehicle of up to two centimeters in the lateral and longitudinal direction. In addition, a special measuring steering wheel was built to objectify the driver-vehicle interaction, in particular the steering torque curve and the tracking. Particular attention was paid to the reuse of the original steering wheel with all functions, such as airbag, operation and hands-off detection. The novelty is the ability to measure the recognition, planning and control performance of environmental sensors, algorithms and controllers compared to the reference "Ground Truth". In addition, the driving characteristics of the entire vehicle can be assessed in terms of its tracking performance, driver-vehicle interaction, availability, degree of relieving and a sense of security. Another novelty is the consistent use of digital maps in driving tests as well as in the MIL / SIL / HIL simulation as a digital twin.
In a recent study with N = 50 subjects, the lane keeping assistant was tested on more than 3,500 km on public roads in the Allgäu. To test the various settings of the lane keeping assistant, different conditions were tested: 120km/h versus 160km/h as well as with versus without lane keeping assistant. The evaluation of the criteria for lane keeping assistant, such as edge management and degree of relief show a significant relationship with the experienced workload. The increased workload as well as stress when using the lane keeping assistant system could be detected and proved subjectively as well as with physiological measuring devices. The significantly higher stress experienced with the use of the lane keeping assistant system shows the immense importance that the further research on this system has.
Simulation methods supporting homologation of Electronic Stability Control in vehicle variants
(2017)
Vehicle simulation has a long tradition in the automotive industry as a powerful supplement to physical vehicle testing. In the field of Electronic Stability Control (ESC) system, the simulation process has been well established to support the ESC development and application by suppliers and Original Equipment Manufacturers (OEMs). The latest regulation of the United Nations Economic Commission for Europe UN/ECE-R 13 allows also for simulation-based homologation. This extends the usage of simulation from ESC development to homologation. This paper gives an overview of simulation methods, as well as processes and tools used for the homologation of ESC in vehicle variants. The paper first describes the generic homologation process according to the European Regulation (UN/ECE-R 13H, UN/ECE-R 13/11) and U.S. Federal Motor Vehicle Safety Standard (FMVSS 126). Subsequently the ESC system is explained as well as the generic application and release process at the supplier and OEM side. Coming up with the simulation methods, the ESC development and application process needs to be adapted for the virtual vehicles. The simulation environment, consisting of vehicle model, ESC model and simulation platform, is explained in detail with some exemplary use-cases. In the final section, examples of simulation-based ESC homologation in vehicle variants are shown for passenger cars, light trucks, heavy trucks and trailers. This paper is targeted to give a state-of-the-art account of the simulation methods supporting the homologation of ESC systems in vehicle variants. However, the described approach and the lessons learned can be used as reference in future for an extended usage of simulation-supported releases of the ESC system up to the development and release of driver assistance systems.