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Parametric study of the phase diffusion process in a gain-switched semiconductor laser for randomness assessment in quantum random number generator
No full textThe quantum phase noise in a pulsed semiconductor laser is studied thoroughly in the context of its utilization as a quantum entropy source in a quantum random number generator (QRNG) device. We performed a numerical analysis of the phase diffusion process for a semiconductor laser in the continuous-wave operation mode and gain-switched (GS) mode. The result demonstrates the amplification of randomness in the GS mode, which is gauged physically by the variance VarΔϕ. The variance value, which is mathematically related to the temporal distance between the laser pulses used in the experimental setup, also determines the stability of the setup. Furthermore, we show how the QRNG probability distribution is influenced by several experimental factors such as the quality of the interference process and the noise in the detection system
TOP2A inhibition and its cellular effects related to cell cycle checkpoint adaptation pathway
No full textIn this study, we investigate the G2 checkpoint activated by chromosome entanglements, the so-called Decatenation Checkpoint (DC), which can be activated by TOP2A catalytic inhibition. Specifically, we focus on the spontaneous ability of cells to bypass or override this checkpoint, referred to as checkpoint adaptation. Some factors involved in adapting to this checkpoint are p53 and MCPH1. Using cellular models depleted of p53 or both p53 and MCPH1 in hTERT-RPE1 cells, we analyzed cell cycle dynamics and adaptation, segregation defects, apoptosis rate, and transcriptional changes related to prolonged exposure to TOP2A inhibitors. Our findings reveal that cell cycle dynamics are altered in MCPH1-depleted cells compared to control cells. We found that MCPH1 depletion can restore the robustness of the DC in a p53-negative background. Furthermore, this research highlights the differential effects of TOP2A poisons and catalytic inhibitors on cellular outcomes and transcriptional profiles. By examining the different mechanisms of TOP2A inhibition and their impact on cellular processes, this study contributes to a deeper understanding of the regulation and physiological implications of the DC and checkpoint adaptation in non-carcinogenic cell lines
On the Benefit of FMG and EMG Sensor Fusion for Gesture Recognition Using Cross-Subject Validation
No full textHand gestures are a natural form of human communication, making gesture recognition a sensible approach for intuitive human-computer interaction. Wearable sensors on the forearm can be used to detect the muscle contractions that generate these gestures, but classification approaches relying on a single measured modality lack accuracy and robustness. In this work, we analyze sensor fusion of force myography (FMG) and electromyography (EMG) for gesture recognition. We employ piezoelectric FMG sensors based on ferroelectrets and a commercial EMG system in a user study with 13 participants to measure 66 distinct hand movements with 10ms labelling precision. Three classification tasks, namely flexion and extension, single finger, and all finger movement classification, are performed using common handcrafted features as input to machine learning classifiers. Subsequently, the evaluation covers the effectiveness of the sensor fusion using correlation analysis, classification performance based on leave-one-subject-out-cross-validation and 5x2cv-t-tests, and its effects of involuntary movements on classification. We find that sensor fusion leads to significant improvement (42% higher average recognition accuracy) on all three tasks and that both sensor modalities contain complementary information. Furthermore, we confirm this finding using reduced FMG and EMG sensor sets. This study reinforces the results of prior research about the effectiveness of sensor fusion by performing meticulous statistical analyses, thereby paving the way for multi-sensor gesture recognition in assistance systems
Smart Products, Engineering and Services. An example of modern engineering education
No full textAs digitization and Industry 4.0 progress, the need for smart products and innovative business models increases. This contribution presents the underlying novel concept of the collaborative course “Smart Products, Engineering and Services”. The objective is to enable students of mechanical engineering to develop and work with smart products, and to derive possible business models for their use. A combination of traditional lectures, flipped classroom exercises and a development project characterizes the unique character of the course. The presented topics range from the basics of sensing machine elements, intelligent mechatronic systems and the use of artificial intelligence in the latter. Further, it comprises product development methods such as agile development, V&V methods and the usage of rapid manufacturing technologies. The flipped classroom exercises serve as preparation for the project work and allow students to gain practical experience with additive manufacturing processes as well as cyber-physical systems. As part of the project work, students develop a smart product which must complete the control task of balancing a body on vertically excited surface by minimizing the bodies movement. For this purpose, the kinematics, the controller, and the usage of a force-measuring ball bearing as a sensing machine element are predetermined. Missing components must be designed and manufactured in a Makerspace using 3D printing or laser cutting and the developed controller must be implemented. The smart product is finally tested on a specially developed test rig
Optimization Approach for Long-Term Planning of Charging Infrastructure for Fixed-Route Transportation Systems
No full textAs the electrification of the transportation sector advances, fleet operators have to rethink their approach regarding fleet management against the background of limiting factors, such as a reduced range or extended recharging times. Charging infrastructure plays a critical role, and it is worthwhile to consider its planning as an integral part for the long-term operation of an electric vehicle fleet. In the category of fixed route transportation systems, the predictable character of the routes can be exploited when planning charging infrastructure. After a prior categorization of stakeholders and their respective optimization objectives in the sector coupling domain, a cost optimization framework for fixed route transportation systems is presented as the main contribution of this work. We confirm previous literature in that there is no one-fits-all optimization method for this kind of problem. The method is tested on seven scenarios for the public transport operator of Darmstadt, Germany. The core optimization is formulated as a mixed integer linear programming (MILP) problem. All scenarios are terminated by the criterion of a maximum solving time of 48 h and provide feasible solutions with a relative MIP-gap between 7 and 24%
Design of additively manufactured glass components for glass point fixings
No full textAdditive manufacturing (AM) has opened new possibilities in many disciplines. Complex geometries can now be created from a variety of materials and material compositions that were previously unimaginable. As a result, there is also the potential for customization and personalization for each user. The present paper and the related research provide insight into the possibilities to further process glass by additive manufacturing methods and thereby exploring the potential for the built environment. This research focuses on developing AM glass components to be used as point fixings for flat glass elements. The innovative laser glass deposition printing process (LGD), developed by Laser Zentrum Hannover e.V., involves locally heating fused silica glass fibres with a CO2-laser, enabling precise deposition of viscose glass on substrates of the same material. In order to implement the LGD process in glass facades an examination of the component is required. This paper introduces a series of mechanical examination techniques, such as indentation and bending tests. The results derived from the testing are the foundation for a parameter study in order to develop a button shaped point fixing for glass facades
Photoemission study of GaN passivation layers and band alignment at GaInP(100) heterointerfaces
No full textTo date, III–V semiconductor-based tandem devices with GaInP top photoabsorbers show the highest solar-to-electricity or solar-to-fuel conversion efficiencies. In photoelectrochemical (PEC) cells, however, III–V semiconductors are sensitive, in terms of photochemical stability and, therefore, require suitable functional layers for electronic and chemical passivation. GaN films are discussed as promising options for this purpose. The band alignment between such a protection layer and the III–V semiconductor should be aligned to minimize corrosion and nonradiative interfacial recombination and to promote selective charge carrier transport. Here, we investigate the band alignment between GaN passivation layers and n-type doped GaInP(100) photoabsorbers and grew n-type GaInP(100) epitaxially by metalorganic vapor phase epitaxy on oxidized GaAs(100) substrates to mimic a realistic preparation sequence. We prepared 1–20 nm GaN films on top employing atomic layer deposition and studied the band alignment at the GaN/GaInP(100) heterointerface by X-ray and ultraviolet photoelectron spectroscopy. Due to the limited emission depth of photoelectrons, we determined the band alignment by a series of measurements, in which we increased the thickness of the GaN films successively. The n-GaInP(100) surfaces, prepared with a well-known phosphorus-terminated p(2 × 2)/c(4 × 2) reconstruction, show an upward surface band bending (BB) of 0.38 eV and a Fermi level pinning due to the present surface states. Upon oxidation, the surface states are partially passivated, resulting in a reduction of the BB to 0.16 eV and a valence band offset (VBO) between the GaInP(100) and the thin oxide layer of 2.01 eV. Applying Kraut’s approach, we identified a VBO of 1.90 eV and a conduction band offset of 0.44 eV between GaInP(100) with a thin oxide layer and the GaN passivation layer. We conclude that the GaN is a well-suited passivation layer for PEC cells and facilitates selective transport of photogenerated electrons
Vegetation dynamics in a disturbed lacustrine record: The Eocene maar lake of Groß-Zimmern (Hesse, SW Germany)
No full textPalynological studies of lacustrine sediments in Eocene maar craters on the Sprendlinger Horst (Hesse, SW Germany) are complemented by 26 core samples from Groß-Zimmern. In addition, diatoms have been studied to assess palaeolimnological conditions. The palynomorph assemblage proves a middle Eocene age more or less coeval to the upper part of the nearby lacustrine succession at Messel. The core includes 33 m of massive to finely laminated bituminous shale abruptly following the underlying breccia of the diatreme filling. The lacustrine deposits are characterised by frequent mass movements and redeposition probably due to tectonic activity in combination with syn- and postsedimentary subsidence in the lake basin. Together with a diatom assemblage characteristic for shallow to moderately deep water, this indicates that the core was drilled in the area of a marginal syncline rather than in the centre of the basin. Freshwater conditions with low nutrient levels were inferred for Lake Groß-Zimmern from diatoms and coccal green algae. Despite the strong disturbance of the sedimentary record, results of cluster analysis and non-metric multidimensional scaling (NMDS) of the palynomorph assemblages can be compared to the undisturbed succession from Messel. This includes successional stages of the azonal vegetation in the crater area during an initial and early recolonisation phase as well as in the zonal vegetation, which are related to the reoccupation of the crater area by a thermophilic forest. Furthermore, slight changes of the climate can be inferred
One Does Not Simply Meme Alone: Evaluating Co-Creativity Between LLMs and Humans in the Generation of Humor
No full textCollaboration has been shown to enhance creativity, leading to more innovative and effective outcomes. While previous research has explored the abilities of Large Language Models (LLMs) to serve as co-creative partners in tasks like writing poetry or creating narratives, the collaborative potential of LLMs in humor-rich and culturally nuanced domains remains an open question. To address this gap, we conducted a user study to explore the potential of LLMs in co-creating memes---a humor-driven and culturally specific form of creative expression. We conducted a user study with three groups of 50 participants each: a human-only group creating memes without AI assistance, a human-AI collaboration group interacting with a state-of-the-art LLM model, and an AI-only group where the LLM autonomously generated memes. We assessed the quality of the generated memes through crowdsourcing, with each meme rated on creativity, humor, and shareability. Our results showed that LLM assistance increased the number of ideas generated and reduced the effort participants felt. However, it did not improve the quality of the memes when humans were collaborated with LLM. Interestingly, memes created entirely by AI performed better than both human-only and human-AI collaborative memes in all areas on average. However, when looking at the top-performing memes, human-created ones were better in humor, while human-AI collaborations stood out in creativity and shareability. These findings highlight the complexities of human-AI collaboration in creative tasks. While AI can boost productivity and create content that appeals to a broad audience, human creativity remains crucial for content that connects on a deeper level
