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Various (AB)\(_{n}\) and (ABAC)\(_{n}\) segmented copolymers with hydrophilic and hydrophobic segments are processed via melt electrowriting (MEW). Two different (AB)\(_{n}\) segmented copolymers composed of bisurea segments and hydrophobic poly(dimethyl siloxane) (PDMS) or hydrophilic poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEG-PPO) segments, while the amphiphilic (ABAC)\(_{n}\) segmented copolymers consist of bisurea segments in the combination of hydrophobic PDMS segments and hydrophilic PPO-PEG-PPO segments with different ratios, are explored. All copolymer compositions are processed using the same conditions, including nozzle temperature, applied voltage, and collector distance, while changes in applied pressure and collector speed altered the fiber diameter in the range of 7 and 60 µm. All copolymers showed excellent processability with MEW, well-controlled fiber stacking, and inter-layer bonding. Notably, the surfaces of all four copolymer fibers are very smooth when visualized using scanning electron microscopy. However, the fibers show different roughness demonstrated with atomic force microscopy. The non-cytotoxic copolymers increased L929 fibroblast attachment with increasing PDMS content while the different copolymer compositions result in a spectrum of physical properties.

This paper addresses the longitudinal vehicle behavior before and during lane changes. Hereby, it is desired that the lane-changing vehicle simultaneously follows its predecessors on the lanes before and after the lane change. Specifically, the lane changing vehicle should keep a safe distance to the rearmost predecessor vehicle, while maintaining a small inter-vehicle spacing and supporting driving comfort. To this end, the paper develops an extension of cooperative adaptive cruise control (CACC). Instead of following a single vehicle as in the classical realization of CACC, it is proposed to follow a virtual vehicle that is evaluated based on distance measurements and communicated state information from the predecessor vehicles. A simulation study demonstrates the practicability of the proposed method.

The controllability prefix is known as a useful concept for the discussion and solution of synthesis problems in supervisory control of ω-languages, i.e., formal languages of infinite-length words. There, the controllability prefix is defined as the set of all finite-length prefixes that can be controlled to satisfy prescribed liveness and safety properties. In this paper, we discuss a variation of the controllability prefix to address supervisory control under partial observation for regular *-languages, i.e., formal languages of finite-length words. We derive algebraic properties that are useful for a quantitative analysis on how an upper-bound language-inclusion specification affects achievable lower-bound specifications. Our study is motivated by the synthesis of fault-tolerant supervisory controllers, where the possible occurrence of a fault may restrict the achievable pre-fault behaviour so severe, that a relaxation of the upper-bound specification becomes a practical option. As our study shows, such a relaxation can be systematically constructed in terms of the controllability prefix.

Kolumnare supramolekulare Phasen, die eine Polarisation entlang der Kolumnenachse aufweisen, haben das Potential zur Entwicklung von Datenspeichern mit ultrahoher Dichte, da jede einzelne Kolumne als Speicherelement fungieren kann. Wir zeigen anhand von Untersuchungen der Struktur und Unordnung von vier kolumnaren 1,3,5-Benzoltrisamiden mittels totaler Rontgenstreuung und DFT-Rechnungen, dass die Kolumnenorientierung und damit das kolumnare Dipolmoment empfindlich auf geometrische Frustration ist, sofern die Kolumnen in hexagonalen Stabpackungen aggregieren. Die Frustration unterdruckt die konventionelle antiferroelektrische Ordnung und erhoht die Sensitivitat fur kollektive interkolumnare Packungseffekte. Dieser Befund erlaubt es, Domanen auf der Mesoskala zu erzeugen, die eine spontane Polarisation aufweisen. Unsere Ergebnisse zeigen auf, wie das komplexe Zusammenspiel von sterischen und elektrostatischen Wechselwirkungen durch ein einfaches Design der molekularen Synthone beeinflusst wird, um spontane Polarisation zu erzeugen und die Grose der mesoskopischen Domanen einzustellen.

Owing to the high lightweight design potential polymer foams become increasingly important. For rigid polymer foams, requiring high dimensional stability under load, a high compression modulus is a key feature. Here, we demonstrate how supramolecular additives can be utilized to control the foam morphology and to significantly improve the compression behavior of extruded foams made of linear isotactic polypropylene. Three different 1,3,5-benzenetrisamides were selected as supramolecular additives. These additives are soluble in the polymer melt and form a supramolecular nanofiber network upon cooling, acting as nucleating sites for both, foam cells and polymer crystals. It is shown that the in situ formed nanofiber network is very effective in reducing the cell size of extruded foams. Depending on the molecular structure and the concentration of the supramolecular additives, the compression modulus of polypropylene-polymer foams can be significantly increased compared to a reference foam with talc. Unexpectedly, an improvement of 100% with a concentration of only 0.02 wt% of a supramolecular additive compared to the neat polypropylene foam featuring similar densities is achieved. This improvement cannot be correlated with the foam morphology and is most likely attributed to the presence of the supramolecular nanofiber network.

Reconfigurable manufacturing systems (RMS) support flexibility in the product variety and the configuration of the manufacturing system itself in order to enable quick adjustments to new products and production requirements. As a consequence, an essential feature of RMS is their ability to rapidly modify the control strategy during run-time. In this paper, the particular problem of changing the specified operation of a RMS, whose logical behaviour is modelled as a finite state automaton, is addressed. The notion of reconfigurability of specifications (RoS) is introduced and it is shown that the stated reconfiguration problem can be formulated as a controlled language convergence problem. In addition, algorithms for the verification of RoS and the construction of a reconfiguration supervisor are proposed. The supervisor is realised in a modular way which facilitates the extension by new configurations. Finally, it is shown that a supremal nonblocking and controllable strict subautomaton of the plant automaton that fulfils RoS exists in case RoS is violated for the plant automaton itself and an algorithm for the computation of this strict subautomaton is presented. The developed concepts and results are illustrated by a manufacturing cell example.

Safety-critical in-vehicle applications require an accurate global time in order to coordinate their actions. Although Controller Area Network (CAN) is the most widely used in-vehicle communication bus, it does not support synchronized clocks. Hence, the realization of clock synchronization on CAN is highly relevant. This paper develops two new ideas for the clock synchronization on CAN. The first contribution is a new software-based algorithm based on periodic reference messages. Different from existing algorithms, the proposed algorithm enables the use of timestamps that are taken close to the reference message transmission hence improves the clock accuracy. The second contribution of the paper is an original method for correcting clocks between reference messages. In particular, the proposed algorithm updates local clocks based on the bit timing on the CAN bus. Results from simulation experiments show an improvement of about 60% in the clock precision.

In this paper we propose ACCLOUD-MAN, a novel resource manager for heterogeneous cloud data centers. In heterogeneous clouds a user request can be satisfied with more than one physical resource alternative. Resource manager must decide which resource alternative will be chosen, along with the decision of the server the request will be assigned to. ACCLOUDMAN's resource management objective is to reduce the power consumption of the cloud. Manager is modeled as an Integer Linear Problem and is implemented on MATLAB, together with a simulation platform. Simulation results show that the solution times are too long for practical applications. Dividing requests into smaller groups is suggested to improve the timings. It is seen that this method improves the timings with a penalty in decision performance.

This paper presents a novel lane detection algorithm based on fusion of camera and 2D LIDAR data. On the one hand, objects on the road are detected via 2D LIDAR. On the other hand, binary bird's eye view (BEV) images are acquired from the camera data and the locations of objects detected by LIDAR are estimated on the BEV image. In order to remove the noise generated by objects on the BEV, a modified BEV image is obtained, where pixels occluded by the detected objects are turned into background pixels. Then, lane detection is performed on the modified BEV image. Computational and experimental evaluations show that the proposed method significantly increases the lane detection accuracy.

Low thermal conductivity and adequate mechanical strength are desired for extruded polystyrene foams when they are applied as insulation materials. In this study, we improved the thermal insulation behavior and mechanical properties of extruded polystyrene foams through morphology control with the foam nucleating agent 1,3,5-benzene-trisamide. Furthermore, the structure&ndash, property relationships of extruded polystyrene foams were established. Extruded polystyrene foams with selected concentrations of benzene-trisamide were used to evaluate the influence of cell size and foam density on the thermal conductivity. It was shown that the addition of benzene-trisamide reduces the thermal conductivity by up to 17%. An increase in foam density led to a higher compression modulus of the foams. With 0.2 wt % benzene-trisamide, the compression modulus increased by a factor of 4 from 11.7 &plusmn, 2.7 MPa for the neat polystyrene (PS) to 46.3 &plusmn, 4.3 MPa with 0.2 wt % benzene-trisamide. The increase in modulus was found to follow a power law relationship with respect to the foam density. Furthermore, the compression moduli were normalized by the foam density in order to evaluate the effect of benzene-trisamide alone. A 0.2 wt % benzene-trisamide increased the normalized compression modulus by about 23%, which could be attributed to the additional stress contribution of nanofibers, and might also retard the face stretching and edge bending of the foams.

In this paper we propose ACCLOUD-MAN, a novel resource manager for heterogeneous cloud data centers. In heterogeneous clouds a user request can be satisfied with more than one physical resource alternative. That is, the resource manager must decide which resource alternative will be chosen, along with the decision of the server the request will be assigned to. ACCLOUD-MAN's resource management objective is to reduce the power consumption of the cloud data center. To this end, the manager is modeled as an integer linear programming problem and is implemented in MATLAB, along with a cloud data center simulation platform. Simulation results show that the proposed ACCLOUD-MAN outperforms existing resource allocation methods such as Openstack.

Controlled wrinkling is a rather simple method of fabricating surface topographies. The production process is based on the spontaneous formation of wrinkles upon compression of a hard film attached to a soft elastic substrate. Controlled wrinkling typically features large-scale wrinkled samples with a discrete wavelength and amplitude. In this report, we employ an approach utilizing linear metal layer thickness gradients for the controlled formation of gradient wrinkle patterns. The observed wavelength modulation was experimentally achieved by preparing layer thickness gradients of gold, chromium, and indium by physical vapor deposition in combination with a poly(dimethyl siloxane) elastomer substrate. In case of chromium and indium, a thin SiOx surface layer was sufficient to ensure adhesion. However, in case of gold, an additional thin chromium adhesion layer was required. For the wrinkled gradient gold film, it was possible to tune the wavelength from 3.4 to 12.2 μm on a single substrate. The experimen...

Several manufacturing technologies beneficially involve processing from the melt, including extrusion‐based printing, electrospinning, and electrohydrodynamic jetting. In this study, (AB)\(_{n}\) segmented copolymers are tailored for melt‐processing to form physically crosslinked hydrogels after swelling. The copolymers are composed of hydrophilic poly(ethylene glycol)‐based segments and hydrophobic bisurea segments, which form physical crosslinks via hydrogen bonds. The degree of polymerization was adjusted to match the melt viscosity to the different melt‐processing techniques. Using extrusion‐based printing, a width of approximately 260 µm is printed into 3D constructs, with excellent interlayer bonding at fiber junctions, due to hydrogen bonding between the layers. For melt electrospinning, much thinner fibers in the range of about 1–15 µm are obtained and produced in a typical nonwoven morphology. With melt electrowriting, fibers are deposited in a controlled way to well‐defined 3D constructs. In this case, multiple fiber layers fuse together enabling constructs with line width in the range of 70 to 160 µm. If exposed to water the printed constructs swell and form physically crosslinked hydrogels that slowly disintegrate, which is a feature for soluble inks within biofabrication strategies. In this context, cytotoxicity tests confirm the viability of cells and thus demonstrating biocompatibility of this class of copolymers.

The influence of two 1,3,5-benzenetrisamide beta-nucleating agents in comparison to a commercial bisamide beta-nucleating agent on the morphological and mechanical properties of isotactic polypropylene (iPP) is presented. To complete the study, the neat iPP and iPP containing a 1,3,5-benzenetrisamide alpha-nucleating agent was investigated. To evaluate the effectiveness of the different supramolecular polymer additives with regard to their influence on the toughness of iPP, a difficult-to-toughen high melt flow rate (MFR) iPP grade was selected. Investigations by wide-angle X-ray scattering (WAXS) confirm that the two 1,3,5-benzenetrisamides and commercial beta-nucleating agent induce the beta crystal modification of the polymer, whereas only the alpha modification is observed for the neat polymer and the 1,3,5-benzenetrisamide alpha-nucleating agent. Scanning electron microscopy (SEM) pictures on etched samples clearly reveal a shish-kebab structure in beta-nucleated iPP with 1,3,5-benzenetrisamides. For these two samples, Charpy impact investigations show a pronounced increase in toughness, also compared to the commercial bisamide beta-nucleating agent.

Long-term stable holographic volume gratings in azobenzene-containing films have potential applications as forgery-proof security features or in holographic data storage. However, azobenzene-based polymer systems often lack sufficiently high writing speeds. Here, an approach to improve the holographic writing performance of photo-orientable azobenzene-containing polymers by blending with azobenzene molecular glasses is presented. The molecular glass enhances the photo-plastification effect and, consequently, the writing speed. This concept of improving the holographic performance of photo-orientable azobenzene polymers with azobenzene molecular glasses is demonstrated with a homopolymer and two block copolymers. In the azobenzene homopolymer, an addition of 10 wt % of the molecular glass leads to a doubling of the writing speed. Simultaneously, the long-term stability of inscribed gratings is maintained. In case of the block copolymers, the molecular glass is present in the polystyrene matrix and accumulates in the azobenzene minority phase. Adding 5–10 wt % of molecular glass improves the writing speed of the azobenzene block copolymer by a factor of 3–4. An addition of 15 wt % of molecular glass to the block copolymer containing azobenzene and nonphotoactive mesogenic side groups reduces the writing time by a factor of 15 and the long-term stability of the gratings is retained. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2110–2117

We disclose a supramolecular material that combines semiconducting and dipolar functionalities. The material consists of a discotic semiconducting carbonyl-bridged triarylamine core, which is surrounded by three dipolar amide groups. In thin films, the material self-organizes in a hexagonal columnar fashion through Jr-stacking of the molecular core and hydrogen bonding between the amide groups. Alignment by an electrical field in a simple metal/semiconductor/metal geometry induces a polar order in the interface layers near the metal contacts that can be reversibly switched, while the bulk material remains nonpolarized. On suitably chosen electrodes, the presence of an interfacial polarization field leads to a modulation of the barrier for charge injection into the semiconductor. Consequently, a reversible switching is possible between a high-resistance, injection-limited off-state and a low-resistance, space-charge-limited on-state. The resulting memory diode shows switchable rectification with on/off ratios of up to two orders of magnitude. This demonstrated multifunctionality of a single material is a promising concept toward possible application in lowcost, large-area, nonvolatile organic memories. Funding Agencies|NWO Nano program; Bavarian State Ministry of Science, Research, and the Arts for the Collaborative Research Network Solar Technologies go Hybrid; Deutsche Forschungsgemeinschaft (DFG) [SFB 953]; Vetenskapsradet [2015-03813]

The demand of new materials and processes for nanofiber fabrication to enhance the performance of air filters is steadily increasing. Typical approaches to obtain nanofibers are based on top-down processes such as melt blowing, centrifugal spinning, and electrospinning of polymer materials. However, fabrication of polymer nanofibers is limited with respect to either a sufficiently high throughput or the smallest achievable fiber diameter. This study reports comprehensively on a fast and simple bottom-up process to prepare supramolecular nanofibers in situ inside viscose/polyester microfiber nonwovens. Here, selected small molecules of the materials class of 1,3,5-benzenetrisamides are employed. The microfiber-nanofiber composites exhibit a homogeneous nanofiber distribution and morphology throughout the entire nonwoven scaffold. Small changes in molecular structure and processing solvent have a strong influence on the final nanofiber diameter and diameter distribution and, consequently, on the filtration performance. Choosing proper processing conditions, microfiber-nanofiber composites with surprisingly high filtration efficiencies of particulate matter are obtained. In addition, the microfiber-nanofiber composite integrity at elevated temperatures was determined and revealed that the morphology of supramolecular nanofibers is maintained compared to that of the utilized polymer nonwoven.

Previously, plant-wide disturbance analysis has looked into the propagation of faults through an industrial production process by investigating process measurements. However, the extent of the analysis has mostly been limited to a section of a plant. In this work, we propose a top-down approach which investigates measurements of the complete plant and identifies a section where the disturbance originates. Root cause analysis is carried out thereafter to pinpoint the faulty asset. The proposed approach has three novel elements: Using key performance indicators (KPI) as reference and starting point of the analysis, restricting measurements to a measurement type (e.g. flow) thus focusing on a section and applying the novel method of contribution plots of spectral PCA T 2 statistic to find the contribution of each measurement towards the disturbance observed in the KPI. The approach is described and carried out on a paper machine where a quality KPI showed an established oscillation.

A novel nanoimprint lithography technique based on the photofluidization effect of azobenzene materials is presented. The tunable process allows for imprinting under ambient conditions without crosslinking reactions, so that shrinkage of the resist is avoided. Patterning of surfaces in the regime from micrometers down to 100 nm is demonstrated.

The subject of this paper is the coordination of lane changes of autonomous vehicles on a two-lane road segment before reaching a given critical position. We first develop an algorithm that performs a lane change of a single vehicle in the shortest possible time. This algorithm is then applied iteratively in order to handle all lane changes required on the considered road segment while guaranteeing traffic safety. Various example scenarios illustrate the functionality of our algorithm.

Teaching students in a pleasant and successful way more and more requires the inclusion of interactive elements in the mix of didactic elements. As guessing games and quizzes always enjoy great popularity in class, we dreamt up the idea of developing a board game, based on typical gamification mechanics. Content-wise the resulting prototype game refers to Knowledge Management (KM) models, but its design is flexible so that it can be easily used for other learning contents in various settings like universities, schools or enterprise trainings. The prototype was tested and evaluated in a KM class at university. The results were promising and motivate to vary and further extent the concept.

This paper reports on the optimization of polypropylene (PP) feedstock material towards extrusion-based additive manufacturing. To achieve this, two commercially available grades of polypropylene/ethylene random copolymers (raco PP) were modified, aiming to reduce warp deformation caused by shrinkage and at the same time reduce the anisotropic property by improving the interlayer bonding quality of 3D printed parts processed by fused filament fabrication (FFF). A β-nucleating agent, several amorphous polypropylenes (aPP) and one linear low-density polyethylene (LLDPE) were selected as additive or blending component with the goal to reduce shrinkage. The polypropylene feedstock material optimization was conducted by a combination of a lab-scale filament rod processing method and utilizing printed square tubes to optimize printing performance. The achieved results demonstrate that the crystallization behavior and E-modulus of polypropylene play significant roles for warp deformation in extrusion-based 3D printed parts. The β-nucleating agent alters the crystallization behavior, even a slightly negative influence on the warp deformation was observed. The investigated polymer blend of raco PP and LLDPE shows no significant contribution to reduce warpage and impairs also the interlayer bonding. The best results were achieved by blending raco PP with selected amorphous PPs. With two aPP grades warp deformation could be drastically reduced. In addition, the interlayer bonding quality is remarkably enhanced in these blends in spite of slight decreases in stiffness and strength. In conclusion, the optimized PP feedstock material features less warp deformation, high stiffness, and most importantly, outstanding interlayer bonding qualities.

Purpose To evaluate the precision of bag-in-the-lens intraocular lens (BIL IOL) power calculation in different age groups of pediatric cataract patients. Settings Department of Ophthalmology, Justus-Liebig-University Giessen, University Hospital Giessen and Marburg GmbH, Campus Giessen, Giessen, Germany. Design Retrospective nonrandomized consecutive case series. Methods Pediatric patients diagnosed with cataract and operated with BIL IOL implantation were divided into 4 age groups: Group 1 (0 to 3 months), Group 2 (>3 months, 36 months to 17 years). BIL IOL power was calculated with the SRK/T formula. The prediction error (PE) was defined as the absolute difference between the preoperative selected target and postoperative achieved refraction. The impact of age at the time of surgery, axial length (AL), keratometry, and corneal astigmatism on PE was analyzed. Results The study comprised 87 eyes of 56 pediatric patients. The mean and median PEs for the entire group were 1.79 diopters (D) and 1.23 D, respectively. The mean PE in each age group was: 3.43 D in Group 1, 2.14 D in Group 2, 1.60 D in Group 3, and 1.33 D in Group 4. The mean PE in eyes with ALs shorter than 20 mm was 2.67 D, and 1.44 D in eyes with an AL of 20 mm or longer. The mean PE in eyes with corneal radii less than 7.3 mm was 2.45 D, and 1.66 D in eyes with corneal radii of 7.3 mm or more. In the age and AL subgroups, the PE differences were statistically significant (P Conclusions The PE was larger in the youngest study group, and it decreased gradually with age and in eyes with ALs shorter than 20 mm. The PE has to be considered during BIL IOL power calculation in children.

The response time of messages is an important parameter for the design of in-vehicle networks based on the controller area network (CAN). The message transmission on CAN is affected by several non-deterministic factors such as stuff bits that are added to CAN frames depending on the message payload or changing phases among the asynchronous CAN nodes because of clock drifts. The resulting probabilistic nature of message response times on CAN is captured by the response time distribution (RTD) that quantifies the probability of experiencing each possible response time of a CAN message. This paper proposes an original method for the exact RTD computation for each message on CAN, taking into account bit stuffing and clock drifts among CAN nodes. The proposed method features a recursive algorithm for evaluating the backlog caused by interfering messages and averages over all possible transmission scenarios. Validation experiments using different CAN message sets show a very high correlation of the computed RTDs and measured RTDs from a hardware setup in the order of 98 %. To the best of our knowledge, this is the first method for the exact RTD computation for non-preemptive communication systems such as CAN.

The response time distribution (RTD) for messages on the controller area network (CAN) represents the probability of experiencing each possible response time. The existing literature suggests to use the RTD for the design of real-time applications based on CAN. This paper shows that the RTD does not capture the response time behavior on CAN well due to gradual clock drifts among CAN nodes. Instead, the paper defines the concept of a local response time distribution (LRTD) and proposes to realize this LRTD by weak synchronization on CAN.

This paper proposes a robust and effective vision-based lane detection approach. First, two binary images are obtained from the region of interest of gray-scale images. The obtained binary images are merged by a novel neighborhood AND operator and then transformed to a bird's eye view (BEV) via inverse perspective mapping. Then, gaussian probability density functions are fit to the left and right regions of a histogram image acquired from the BEV. Finally, a polynomial lane model is estimated from the identified regions. Experimental results show that the proposed method accurately detects lanes in complex situations including worn-out and curved lanes.

Many concepts of process management are being intensively discussed in current research. The background is often that within the megatrend of digitization, workflows are automated. Furthermore, processes are fundamentally reconsidered in the digital transformation of organizations. What contribution S-BPM can make in the future of digital process management is analyzed in this paper aiming at the anniversary conference of S-BPM. As basis for the analysis serves the idea that, the suitability of BPM concepts (such as S-BPM) for certain application domains depends on essential process properties. Based on an assessment model we analyze under what conditions subject orientation can be well used (e.g., focus on collaboration). Using these results, we are evaluating the opportunities of S-BPM for the digital future. The evaluation is based on the three exemplary trends (i) digital development/products, (ii) digital production and (iii) digital business transformation. In these trend, we asses which conditions change (e.g. fast changing environments, machine-to-machine-communication, user-centered thinking) and to what degree S-BPM can still contribute in the new digital world. In a nutshell, our findings reveal that subject orientation is well suited for collaborative processes involving many different human and non-human stakeholders, but has deficiencies when dealing with autonomous and unstructured systems, both upcoming trends in the digital transformation.

In den vorangegangenen Kapiteln haben wir gezeigt, dass das Geschehen in Organisationen (Unternehmen, Verwaltungen etc.) auf Modellen aus unterschiedlichsten Disziplinen basiert. Geschaftsmodelle, Unternehmensarchitekturen mit Modellen fur Leistungen (Produkte und Services), Aufbauorganisation, Prozesse, Daten und IT-Infrastruktur beschreiben, in welchem Bereich ein Unternehmen tatig ist, wie es dies bewerkstelligt, in welchen Austauschbeziehungen mit Partnern es steht, von welcher technischen Infrastruktur es unterstutzt wird usw.

Ziel der Prozessvorbereitung im Sinne einer nachfolgenden Implementierung ist eine prazise Spezifikation von Prozessen mit der Beschreibung der Prozessstrategie und der Prozesslogik. Die Vorbereitung umfasst die Aktivitatsbundel auf der rechten Seite des offenen Zyklus, dies sind die Analyse, die Modellierung, die Validierung und die Optimierung (siehe Abb. 5.1). Das Ergebnis dieser Aktivitatsbundel ist eine Prozessbeschreibung, die prazise genug fur die Umsetzung ist.