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Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing technique, which allows production of highly complex solid metal parts with good mechanical properties, compared to conventionally manufactured parts. Nevertheless, the layer-by-layer fabrication process also offers several disadvantages, including a relatively high surface roughness depending on the shape of the component, its position and orientation during the fabrication process. This paper deals with investigations on the surface roughness reduction capability, and residual surface structures by laser polishing of LPBF AlSi10Mg parts under varying initial surface roughness in order to investigate the influence of the surface behavior and initial surface roughness to the achievable surface quality by laser polishing. Hereto test specimens with varying fabrication orientations regarding to the built platform are printed and further polished. Thereby the initial arithmetic roughness varies between 19.2 μm and 8.0 μm. It could be shown that the achievable surface roughness by laser polishing with continuous and pulsed laser radiation is increasing with rising initial roughness, but the relative roughness reduction is almost constant in the range of 95% - 97.5%. The analyzation of the residual roughness structures shows, that the main roughness differences is found in the middle and long structure wavelength regime, which are directly depending on the initial surface structures of 3D printing.

New fields of application, such as electromobility, place ever increasing demands on lithium-ion batteries in terms of quality and safety. In-line methods currently used for assessing the quality of the electrode foils in lithium-ion cells in the manufacturing process hardly allow any statements on quality-related microstructural features and are often limited in terms of precision and spatial resolution. This is particularly true for electrodes containing several different active materials (so-called material blends or blended cathodes). Not only their layer thickness and porosity, but also the distribution of the active materials within the electrode is crucial for the quality of the electrode. The active material distribution can be determined with several methods which differ, for example, in terms of precision, required effort, and spatial resolution. This work presents and evaluates common analytical methods – light microscopy, scanning electron microscopy, and energy dispersive X-ray analysis, as well as X-ray diffraction – for the determination of phase fractions with the aid of reference samples. Alongside the precision, criteria such as the sample preparation and measurement effort or the spatial resolution are considered.

Dashboards in modern vehicular interiors, house multiple infotainment systems that allow a continuous flow of nonessential information maintaining driver connectivity. This results in distraction of the driver's attention from the primary task of driving, leading to a higher probability of collisions. This paper presents a novel head-up display (HUD) system which utilizes gesture recognition for direct manipulation of the visual interface. The HUD is evaluated in contrast to a typical head-down display system by 20 users in a high-fidelity virtual reality (VR) driving simulator. The preliminary results from a rear collision simulation scenario indicate a reduction in collision occurrences of 45% with the use of HUD. This paper presents the overall system design challenges and user evaluation results.

Multiple infotainment sources can significantly overload the driver’s cognitive load and increase the collision probabilities. Current solutions provided have attempted to alleviate this issue with the centralization of infotainment devices to single touchscreen devices in the dashboard area. Yet this solution still requires the driver to take the eyes from the road and concentrate on operating the secondary tasks unrelated to the driving process. The paper presents a prototype Augmented Reality Head-Up Display (AR HUD) system that superimposes a selected number of infotainment data on the vehicle’s windshield only when this is safe for the driver. The selection of infotainment data and projection timing is calculated by a prototype Artificial Intelligence (AI) Co-Driver that aims to reduce the driver’s cognitive load. The proposed system was evaluated by 50 users against a typical touchscreen dashboard system. This work presents and discusses the subjective feedback related to the cognitive load that the users perceived during the trials. The paper concludes with a future plan for improving both the AI and AR HUD elements to perform in an urban environment.

Carbon fiber reinforced polymer (CFRP) offers the highest potential for lightweight applications due to its excellent weight to strength ratio in comparison to other materials. However, it is cost-intensive and therefore rarely used monolithically. This makes pretreatment and joining processes so important. Hybrid connections of CFRP and metals can be made by riveting, bolting, stir joining and by adhesive. For adhesive bonding, a pretreatment of the materials is necessary. A laser pretreatment has the advantage, that it is automatable and contactless. This paper deals with the pretreatment of CFRP with different laser wavelengths in near-infrared (NIR, 1030 and 1064 nm) and ultraviolet (UV, 355 nm) range. The influence of the processing direction relative to the fiber layer and the influence of the energy density was investigated with a short pulsed NIR infrared laser. In addition, the influence of different surface structures on the mechanical strength was investigated. The treated CFRP surfaces were examined with a light microscope and a scanning electron microscope. The tensile shear strengths were determined using CFRP and aluminum substrates, joined with a 2-part epoxy adhesive. As a comparison, UV laser treated specimens were also mechanically tested. An ultra-short pulsed NIR laser system was used to generate periodic structures on the CFRP to maximize the surface area without fiber damage and breakage. The investigations on the influence of the machining direction with NIR relative to the fiber layer showed insignificant differences in shear strengths. The variation of the energy density showed an influence on the ablation behavior of the CFRP matrix and the mechanical strength. The maximum strength with a cohesive failure in the adhesive was achieved with optimized short pulsed NIR laser parameter.

In this study the results of the post-mortem analysis of commercial 18650 lithium-ion cells with LiNi0.5Co0.2Mn0.3O2//Graphite chemistry after long-term cycling (>7000 cycles) with low C-rates (0.5C) are presented. To identify ageing mechanisms and to investigate their contribution to the overall ageing of the cell, extensive post-mortem analysis was carried out employing a broad spectrum of electrochemical and physicochemical methods including electrochemical impedance spectroscopy (EIS), electrochemical investigation of rebuilt half cells, X-ray computed tomography (CT), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). Results show that the overall capacity loss of the cell is mainly caused by the capacity loss of the positive NCM523 cathode, whereas the graphite anode basically stays intact. The degradation of the cathode, i.e. its reduced ability to store and release lithium is caused by a combination of different effects such as mechanical degradation of the electrode, including micro-cracking of NCM particles provoking electrolyte consumption and crystallographic changes of the active material.

Centrifugal pumps are rotating machines which are widely used in process operations and other applications. Efficient and failure-free operation of these pumps is important for effective plant operation and productivity. However, the complexity of pumps, combined with continuous operation, can lead to failure and expensive maintenance requirements, thus motivating interest in on-line condition monitoring. This work investigates the application of frequency-domain analysis for classification of various centrifugal pump conditions. Seven conditions are considered, namely, healthy (non-faulty); five mechanical faults: misalignment, imbalance, faulty bearing, faulty impeller and mechanical looseness; and a hydraulic fault: cavitation. A centrifugal pump test rig was built specifically for this research to simulate each fault condition and acquire the resulting vibration measurements. Signals are acquired from the pump using an accelerometer which is mounted on its bearing housing, and a data acquisition device (DAQ) is used to acquire the signals. Fast Fourier Transform (FFT) is used to identify which types of faults generate stationary or non-stationary signals. However, the accuracy of detection for the non-stationary signals is shown to require further improvement, and alternate methods are suggested accordingly.

Long distance travelling and commuting can be particularly tiring for the driver and the rear passengers. The level of driver distraction could be further increased if younger passengers onboard are idle for long time during the drive. This paper presents a novel Augmented Reality (AR) Head-Up Display (HUD) interface that aims to attract rear passengers’ attention through assortment of infotainment applications superimposed on the side car-windows. The system additionally offers a bespoke provision of educational value, which provides superimposed data and games available for the different landmarks. The simplified interface enables the use from younger passengers and seniors alike. The proposed system has undergone two main evaluations involving 50 users and 10 families aiming to identify the system usability. The evaluation took place in a full-scale Virtual Reality driving simulator, which tested the drivers/parents’ ability to avoid collisions. The evaluation outcome offered an informative appraisal of the systems efficiency and overall positive feedback from the users.

The proliferation of infotainment systems in the contemporary vehicular environment offers an abundance of information which is typically not distilled or prioritised according to the driver's requirements and driving conditions. Additionally, this requires from the driver to operate multiple interfaces, resulting in an overwhelming cognitive load and a higher probability of collision. Our work presents a new multimodal Head-Up Display interface that aims to enhance human responses during a potential collision whilst moderate the plethora of incoming information through a simplified and manageable system. The latter is fully interactive and operated with the use of an embedded gesture recognition system. The proposed system was evaluated by comparison to a traditional Head-Down Display interface system by twenty users, with the use of a high-fidelity driving simulator. The results were in favour of the proposed system which reduces the collision propensity by 90% in a motorway environment.

Ophthalmic lenses, sensors, and sunglasses, among other things, are commonly made of polymer materials. Therefore, polymer optics is a growing market mainly for medium quality but also for precision optics. Polymer optics are usually produced in an injection molding process. Due to high quality requirements on the final product, the manufacturing process of the molds has to be very accurate and precise. Thus the master tool has to be fabricated to a high quality with regard to shape accuracy and roughness. The focus of this article is on the process chain for the fabrication of molds for polymer optics and the finite element simulation of this process. The typical existing process chains contain steps like nickel plating, diamond machining and manual polishing. Some of these steps are expensive and require very experienced staff. In the new process chain, an industrial robot with special tools is used for lapping and polishing. Robot polishing replaces the former nickel plating, diamond machining, and man...

This paper presents a novel Human-Computer Interaction design approach for an automotive direct manipulation interface, aiming primarily to act as a younger passengers' interactive infotainment system in order to minimize driver distraction. The proposed design is applied in the peripheral windscreens with the use of a novel Head-Up Display system. The system evaluation by twenty users offered promising results discussed in the paper.

The purpose of the laser in laser assisted jet ECM (LAJECM) is to localise machining to specified areas so that precision and the productivity is improved. Temperature is a predominant determinant of this localisation effect and must be carefully monitored to avoid any heat affected zones or spark damage due to electrolyte boiling. This paper investigates the thermal effects in LAJECM on several alloys by temperature distribution modelling and experimental analysis. The laser influence on material micro removal has led to 25 μm deeper cavities with a reflective surface of roughness 20 nm R a , without any detectable heat affected zone.

High peak-to-average power ratio (PAPR) is a common problem in OFDM transmissions. This paper investigates the influence and effects of various μ -Law companding parameters to assist in reducing the high values of PAPR. Results for modified μ -Law companding, where the use of a further new companding profile parameter PR (peak ratio) is applied, are presented. Simulation studies of PAPR, bit-error-rate (BER) and power spectral density (PSD) are investigated as a function of μ and PR. It is shown that modified μ -Law companding significantly reduces PAPR, though marginally larger (0.5 dB) than normal μ -Law companding, and significantly improves BER to levels better than μ -Law companding. The spectral splatter due to companding is also evaluated and noted that the larger the companding profile, μ , the larger will be the sideband splatter. The results allow an optimum companding profile based on the use of both μ and PR to be chosen in relation to acceptable or desired PAPR and BER requirements. A brief evaluation of companding and selected mapping (SLM) in terms of PAPR reduction and BER is also presented.

Machinery failure diagnosis is an important component of the condition based maintenance (CBM) activities for most engineering systems. Rolling element bearings are the most common cause of rotating machinery failure. The existence of the amplitude modulation and noises in the faulty bearing vibration signal present challenges to effective fault detection method. The wavelet transform has been widely used in signal de-noising, due to its extraordinary time-frequency representation capability. In this paper, a new technique for rolling element bearing fault diagnosis based on the autocorrelation of wavelet de-noised vibration signal is applied. The wavelet base function has been derived from the bearing impulse response. To enhance the fault detection process the wavelet shape parameters (damping factor and center frequency) are optimized based on kurtosis maximization criteria. The results show the effectiveness of the proposed technique in revealing the bearing fault impulses and its periodicity for both simulated and real rolling bearing vibration signals.

A novel technique for drivetrain assembly -“mill-knurling and press-fitting (MKPF)” is proposed as an alternative to laser welding or bolting. This joining technique involves the press fitting of two mating surfaces, one with mill-knurled teeth and the other which is of a relatively softer material, enabling it to flow over the teeth making a joint. This process is applied within the rear axle differential subjected to fluctuating torque loads. Experimental analysis and simulation is used to compare the functional feasibility and the potential benefits of mill knurled joints with laser welded and bolted joints currently used in differential/bevel gear assembly.

The Exploitation of Wavelet De-Noising To Detect Bearing Faults Failure diagnosis is an important component of the Condition Based Maintenance (CBM) activities for most engineering systems. Rolling element bearings are the most common cause of rotating machinery failure. The existence of the amplitude modulation and noises in the faulty bearing vibration signal present challenges to effective fault detection method. The wavelet transform has been widely used in signal de-noising due to its extraordinary time-frequency representation capability. In this paper, we proposed new approach for bearing fault detection based on the autocorrelation of wavelet de-noised vibration signal through a wavelet base function derived from the bearing impulse response. To improve the fault detection process the wavelet parameters (damping factor and center frequency) are optimized using maximization kurtosis criteria to produce wavelet base function with high similarity with the impulses generated by bearing defects, that leads to increase the magnitude of the wavelet coefficients related to the fault impulses and enhance the fault detection process. The results show the effectiveness of the proposed technique to reveal the bearing fault impulses and its periodicity for both simulated and real rolling bearing vibration signals.

Laser assisted jet electrochemical machining (LAJECM) is a hybrid process, that combines a laser beam with an electrolyte jet thereby giving a non-contact tool electrode that removes metal by electrochemical dissolution. The laser beam effectively improves the precision of LAJECM as it is able to direct the dissolution to specifically targeted areas. This prevents the machining from unwanted areas due to stray current. This parallel application of a laser beam with the electrolyte jet enables an improvement of machining accuracy, also productivity. LAJECM has shown that machining with laser assistance can effectively facilitate material removal of 20, 25, 33, and 54% for Hasteloy, titanium alloy, stainless steel and aluminium alloy, respectively. There is also a noticeable improvement in the shape accuracy and slight decrease in surface roughness of the holes and cavities produced due to more focused machining (the order of 20%). The measured reduction in taper is of the order of 38, 40, 41, 65% for aluminium alloy, stainless steel, Hasteloy and titanium alloy, respectively.

Laser-assisted jet electrochemical machining (LAJECM) is a hybrid process that combines a relatively low-power laser beam (typically 375 mW) with an electrolyte jet to facilitate metal removal. The main purpose of the laser is to enhance the localization effect of electrochemical dissolution from the workpiece, thus giving better precision and efficiency. The laser thermally activates the material surface where it impinges, thereby increasing the electrochemical current density in that localized zone. This paper reports recent investigations of LAJECM process energy distribution and explains the influence of laser assistance on dissolution removal rates using theoretical as well as experimental analysis. It was found that laser assistance increases energy in the LAJECM process by up to 45 per cent compared with jet electrochemical machining (JECM). The process energy has also been related to volumetric removal rate, and the specific energy required for machining with given variables has been calculated. It has been proved that LAJECM is more effective then JECM as the calculated specific energy was lower by up to 30 per cent.

Laser Assisted Jet Electrochemical Machining is a hybrid process which combines a relatively low power laser (375mW) with an electrolyte jet to facilitate metal removal. The main purpose of the laser is to enhance the localisation effect of electrochemical dissolution from the workpiece, thus giving better precision and machining efficiency. The laser thermally activates the material surface where it impinges thereby increasing the electrochemical current density in that localised zone. A theoretical model is used to explain the effects of localisation of electrochemical dissolution process. Experimental analysis using aluminium alloy and stainless steel has proved that laser assistance can yield up to 54% higher volumetric rate and up to 38% better accuracy than using electrolytic jet alone.

This paper addresses the phenomenon of circular dots, which often occur on the component surface as a result of 5-axis machining. These dots occur typically at the interface of two or more patches owing to the cutter fouling adjoining surfaces whilst machining is being undertaken on a particular patch. The action described above forms a half-dot in the adjoining surface. This is made into a full dot, when, during the machining of the second surface, the first surface is fouled. This paper is concerned with an industrial case study, namely the machining of a hydraulic transmission turbine impeller blade. The work does not eradicate the dot problem; however; it reduces the occurrence. To achieve a component completely free from the dot problem it was necessary to amend the milling strategy to minimise the motion of the A and B axes.

This paper presents a methodology for the manufacture of tools embodying true three-dimensional free-form surfaces using PC-based two-and-a-half axis CADCAM systems. The numerical control machining of free-form surfaces is usually accomplished utilizing minicomputer or mainframe computer aided design and manufacturing (CADCAM) systems. The resulting NC data are suitable for either three axis or five axis machining, dependent upon machine tool type/capability and CAM package complexity. However, the cost of such packages and systems precludes their use in smaller companies with only an occasional requirement for components embodying free-form surfaces. The increasing availability of powerful yet reasonably priced personal computers (PCs) coupled with improving software provides such companies with a far cheaper alternative approach. However, a common feature of PC-based CADCAM systems is that they are limited to two-and-a-half axis machining for all but special applications such as three axis canted Z-plane milling or four axis wire electro discharge machining. All the main functions performed on mainframe systems can be performed on personal computers, such as toolpath generation for free-form surfaces, cusp height determination and change in shape and volume which may be used for component springback compensation.

A new technique for an automated detection and diagnosis of rolling bearing faults is presented. The time-domain vibration signals of rolling bearings with different fault conditions are preprocessed using Laplace-wavelet transform for features’ extraction. The extracted features for wavelet transform coefficients in time and frequency domains are applied as input vectors to artificial neural networks (ANNs) for rolling bearing fault classification. The Laplace-Wavelet shape and the ANN classifier parameters are optimized using a genetic algorithm. To reduce the computation cost, decrease the size, and enhance the reliability of the ANN, only the predominant wavelet transform scales are selected for features’ extraction. The results for both real and simulated bearing vibration data show the effectiveness of the proposed technique for bearing condition identification with very high success rates using minimum input features.

The bearing characteristic frequencies (BCF) contain very little energy, and are usually overwhelmed by noise and higher levels of macro-structural vibrations. They are difficult to find in their frequency spectra when using the common technique of fast fourier transforms (FFT). Therefore, Envelope Detection (ED) has always been used with FFT to identify faults occurring at the BCF. However, the computation of the ED is suffering to strictly define the resonance frequency band. In this paper, an alternative approach based on the Laplace-wavelet enveloped power spectrum is proposed. The Laplace-Wavelet shape parameters are optimized based on Kurtosis maximization criteria. The results for simulated as well as real bearing vibration signal show the effectiveness of the proposed method to extract the bearing fault characteristic frequencies from the resonant frequency band.

Laser Assisted Jet Electrochemical Machining (LAJECM) is a hybrid process which combines electrolyte jet and low power laser beam (375mW) to facilitate material removal. The main purpose of the laser is to enhance dissolution from the workpiece in the specific area giving faster dissolution in axial rather in lateral direction and in result higher dimension precision. Experimental analysis using stainless steel, titanium alloy and high carbon alloy has proved that laser assistance can yield up to 33% higher volumetric rate and up to 65% better dimensional accuracy. It has been also proved that laser enhances current efficiency during the machining process.

It was the development by Clark in 1956 of the membrane-covered “integral” electrode that opened the field for truly physiological in vivo - and indeed clinical - measurements of oxygen partial pressure in blood and tissue. Since then, much of our knowledge about oxygen transport to tissue has been gained by the use of polarographic oxygen (and hydrogen) electrodes — many of them of the Clark-type. It is not possible in this paper to examine all of these applications and the reader is referred to a comprehensive review by Ltibbers.

Advanced Inter-Organisational Information Systems (IOSs) are used to improve the effectiveness of the supply chain and compete in today's dynamic global market. However, this linkage increases the significance of organisational factors, which makes an impact on the business–partner relationships. The aim of this research, therefore, is to evaluate the impact of organisational factors at different levels of IOS development on partnership integration within the Supply Chain Management (SCM). An innovative model will show the critical organisational factors at three stages of IOS development. To understand the implementation and use of the IOS within the SCM and business relationships, earlier studies by researchers such as Clemons and Row and Hahn, Kim and Kim have focused on a particular type of IOS, and its impact on the organisation. Other studies, such as those by Boddy, Macbeth and Wagner, evaluated the organisational variables and their impact on the IOS implementation. This theoretical paper is unique in that it evaluates the impact of the organisational variables for different levels of the IOS development. It analyses three case studies of the companies at various stages of IOS development. As IOS development and partnership integration are becoming more critical components in the supply chains, managers must be quite aware of these factors in effectively managing the operations.

The deceleration and running down operation of any rotating system when analysed would lead to useful input function for condition monitoring. When the power supply to any rotor system is cut off, total momentum gained through the sustained operation will dissipate and the system will come to halt. The time elapsed between the power cutoff and the complete stop of the system is defined as CDT (Coast Down Time). The tribological behaviour could be effectively monitored through this parameter (CDT), which has been conducted on a horizontal rotor system with a full journal bearing at different speed and lubrication pressures. The characteristics are compared with steady state vibration in order to emphasize the potential benefit of using CDT as a useful diagnostic parameter for condition monitoring.Copyright © 2006 by ASME