A Longitudinal Study of Anti Micro Patterns in 113 Versions of Tomcat

Background: Micro patterns represent design decisions in code. They are similar to design patterns and can be detected automatically. These micro structures can be helpful in identifying portions of code which should be improved (anti-micro patterns), or other well-designed parts which need to be preserved. The concepts expressed in these design decisions are defined at class-level; therefore the primary goal is to detect and provide information related to a specific granularity level. Aim: this paper aims to present preliminary results about a longitudinal study performed on anti-micro pattern distributions over 113 versions of Tomcat. Method: we first extracted the micro patterns from the 113 versions of Tomcat, then found the percentage of classes matching each of the six anti-micro pattern considered for this analysis, and studied correlations among the obtained time series after testing for stationarity, randomness and seasonality. Results: results show that the time series are stationary, not random (except for Function Pointer), and that additional studied are needed for studying seasonality. Regarding correlations, only the Pool and Record time series presented a correlation of 0.69, while moderate correlation has been found between Function Pointer and Function Object (0.58) and between Cobol Like and Pool (0.44)

Aeronautical Engineering: A continuing bibliography

This bibliography lists 347 reports, articles and other documents introduced into the scientific and technical information system. Documents on the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and associated compounds, equipment, and systems are included. Research and development in aerodynamics, aeronautics and ground support equipment for aeronautical vehicles are also included

Structure and properties of crystalline inclusions trapped in minerals

This thesis deals with the characterization of mineral inclusions by means of various non-destructive techniques. Two type of inclusions are analyzed: inclusions in diamonds and inclusions in metamorphic rocks, in particular the host-inclusion pair quartz in garnet. The work on inclusion in diamonds focuses on rare inclusions of magnetic minerals, such as iron oxides, and employs a multi-analytical approach: X-ray diffraction, Raman spectroscopy, magnetometry, and X-ray tomography. Magnetic properties can help in the identification of the composition of the inclusions and thus of the environment in which the host-inclusion system grew. X-ray tomography was employed to locate the inclusions in the samples, asses the presence of fractures, and support the identification of the phases. The characterization of the quartz-in-garnet pair is focused on the determination of the stress state of the inclusions and the influence of such stress on the structure and properties of the system. It is shown how to characterize the crystal structure of inclusions in-situ by means of X-ray diffraction. A thorough characterization of the polarized Raman scattering of quartz as a function of pressure and temperature was performed to guide the interpretation of the results from inclusions. The high-pressure Raman experiment verifies the validity of the approach based on the phonon-mode Grüneisen tensor to calculate the pressure in the inclusions, also for the E modes. Furthermore, it points out that strong multiphonon interactions can contribute to the stability of alpha-quartz at ambient conditions and provides new pressure calibrations. The heating experiment performed in situ by Raman spectroscopy shows that the quartz inclusion in garnet does not undergo the alpha-beta phase transition. The comparison of the free and trapped crystal data clearly shows a different response to heating and the applied models cannot reproduce the experimental data. It can be shown that the disagreement between the data and the prediction is due to the elastic anisotropy of quartz, suggesting that at a new model taking into account elastic anisotropy is needed

Biomechanics of a parasitic wasp ovipositor : Probing for answers

Insects such as mosquitoes, true bugs, and parasitic wasps, probe for resources hidden in various substrates. The resources are often, located deep within the substrate and can only be reached with long and thin (slender) probes. Such probes can, however, easily bend or break (buckle) when pushed inside the substrate, which makes probing a challenging task. Nevertheless, the mentioned insects use their probes repeatedly throughout their lifetime without apparent damage. Furthermore, the probes are also used for sensing the targets, can be steered during insertion, and can transport both fluids (e.g. blood, phloem sap) and eggs. Insect probes seem highly versatile structures that satisfy many functional requirements, including buckling avoidance, steering, sensing, and transport. Similar requirements also hold for minimally invasive medical procedures, where slender tools are used to minimize damage to the patient. Understanding the probing process in insects can bring insights in the insect ecology and evolution and it may also help in the development of novel surgical tools. In this thesis, I focus on the mechanical and motor adaptations of insect probing, while other aspects are only briefly discussed. In chapter 2, we review the literature on the probing structures and their operating principles across mosquitoes, parasitic wasps, and hemipterans. Probes are either modified mouthparts (mosquitoes, true bugs) or special tubular outgrowths of the abdomen (parasitic wasps). Despite having different developmental origins, the probes share three major morphological characteristics, which may reflect the shared functional requirements of buckling avoidance and steering: (i) the probes consist of multiple, interconnected elements that can slide along each other, (ii) the probe diameters are very small, which leaves no space for internal musculature, and (iii) the distal ends (tips) of the probe elements are asymmetric and often bear various serrations, hooks, bulges, or notches. How such slender multi-element probes avoid buckling during insertion has been hypothesized in the so-called push–pull mechanism. According to this mechanism, the probe is inserted into the substrate by reciprocal movements of the elements. The insects therefore simultaneously push on some of the probe elements, while pulling on the others. The tip serrations are directed such, that they primarily increase the friction upon pulling of the elements. This puts the pulled elements under tension and makes them effectively stiffer in bending (like when pulling a rope). The elements under tension can serve as guides along which the other elements are pushed inside the substrate without the risk of buckling. The insect alternates the pushing and pulling between the elements to incrementally insert the probe in the substrate. This mechanism has, however, never been quantified in insects and it was hitherto unknown whether the animals rely on it during probing. The probe tip asymmetry presumably facilitates steering. The asymmetric tip geometry leads to asymmetric reaction forces from the substrate on the tip during insertion, which push the probe tip sideways into a curved path. Controlling the tip geometry therefore allows for control of probing direction. Although offsetting the elements by sliding already changes the shape of the probe tip, these changes might be too small to induce the necessary change of probing direction. A number of mechanisms that enhance the tip asymmetry during the sliding of the elements have been suggested. However, few mechanisms have been observed or studied in vivo, so it is not completely clear how insects steer with their probes. Additionally, the effect of the substrate on both the steering and insertion mechanisms is unknown. To understand the biomechanics of insect probing, we investigated the probing behaviour of the braconid parasitic wasp Diachasmimorpha longicaudata. This is an ideal species for studying the buckling avoidance and steering, because it: (i) possess a slender ovipositor several millimetres in length, (ii) probes into solid material (e.g. citrus fruits), and (iii) attack fruit-fly larvae that are freely moving within the substrate (i.e. steering can be expected). The ovipositor of D. longicaudata is similar to other hymenopterans and consists of three interconnected elements (valves), one dorsal and two ventral ones. The interconnection is a tongue-and-groove mechanism, which allows for sliding of the valves, but prevents their separation. The ovipositor has an asymmetric tip—the distal end of the dorsal valve is enlarged (bulge), while the ventral valve tips have harpoon-like serrations. Additionally, just proximal to the bulge of the dorsal valve, the ovipositor is characteristically bent in an S-shape. This seems to be a feature present only in D. longicaudata and closely related species. The wasps also possess a pair of sheaths that envelop the ovipositor at rest and throughout most of the probing process, but do not penetrate into the substrate. In chapter 3, we studied the kinematics of ovipositor insertion into translucent, artificial substrates of various stiffnesses. Ovipositor insertion was filmed in a three camera setup, which allowed us to reconstruct the ovipositor insertion in 3D, while also monitoring the orientation of the insect’s body. We discovered that the wasps can explore a wide range of the substrate by probing in any direction with respect to their body orientation from a single puncture point. Probing range and speed decreased with increasing substrate stiffness. Wasps used two strategies of ovipositor insertion. In soft substrates, all ovipositor valves were pushed inside the substrate at the same time. In stiff substrates, wasps always moved the valves alternatively, presumably employing the hypothesized push–pull mechanism. We observed that ovipositors can follow curved trajectories inside the substrate. Detailed kinematic analysis revealed that the ovipositors followed a curved path during probing with protracted ventral valve(s). In contrast, probing with protracted dorsal valve resulted in straight trajectories. We linked the changes in the probing direction to the shape changes in the ovipositor tip. When the ventral valves were protracted, they curved towards the dorsal valve, resulting in an enhanced bevel which presumably caused a change in insertion direction. In chapter 4, we investigated the above described steering mechanism by quantifying the bending stiffness (three point bend test) and the geometry (high-resolution computer tomography) of the ovipositor in D. longicaudata. Additionally, we qualitatively assessed the material composition of the valves using fluorescence imaging. The thick dorsal valve bulge might be stiff and could straighten the S-shaped region of the ovipositor during the valve offset, causing bending of the tip. We discovered that the S-shaped region of the ovipositor is significantly softer than its neighbouring regions, which is mostly due to the presence of resilin in the S-shaped region of the ventral valve. Resilin is a rubber-like protein and reduces the stiffness of the otherwise heavily sclerotized valves. Additionally, we showed that the ventral valves have a higher bending stiffness than the dorsal valve along most of their length. The exception is presumably the bulge on the dorsal valve—although we could not directly measure its bending stiffness, its geometrical properties show that it is the thickest (and therefore stiffest) region in the distal end of the ovipositor. Outside the substrate, offsetting of the valves in any direction (i.e. pro- or retraction of the ventral valves) caused a straightening of the S-shaped region of the ovipositor and a curving towards the dorsal side. However, during probing in a substrate, such curving was only observed upon protraction of the ventral valves. We hypothesize this is due to the interaction of the ovipositor with the substrate. Namely, the bevelled ventral valve tips generate substrate reaction forces that promote dorsal curving, while the bevelled tip of the dorsal valve generates substrate forces that promote ventral bending. The interaction between the ventral and dorsal valves straightens the S-shaped region of the ovipositor and enhances dorsal curving. This therefore facilitates strong shape changes of the tip only upon protraction of the ventral valves, while counteracting the ventral curving of the dorsal valve. These opposing mechanisms presumably result in an approximately straight protraction of the dorsal valve. In chapters 2 and 3 we describe how the wasps use the reciprocal valve movements when probing in stiff substrates. As such substrates presumably require strong forces during insertion, the reciprocal valve movements may indeed serve to avoid buckling. However, how the valves are actuated or the forces generated during probing have never been quantified. In chapter 5, we therefore investigated the ovipositor base and the muscles driving the movements of the valves. At the base, the valves attach to plate-like structures that are interconnected with a series of linkages. The muscles attach to these plates and can move them with respect to each other. Such movements also result in the movements of the valves. To analyse the mechanics of this linked system, we performed high-resolution computer tomography scans of wasps in different stages of the probing cycle. This allowed us to compare the configurational changes of the basal plates to the valve offset, and measure the muscle cross-sections and attachment sites. We also calculated the muscle moment arms and estimated the forces and moments of the most relevant musculature actuating the ovipositor movements, by assuming a tensile muscle stress previously reported for insect muscles. For the ventral valves only, we also calculated the forces the valves can exert onto the substrate. The dorsal valve can only be moved by moving the base that is linked inside the abdomen, and therefore force estimation could not be made. The displacement magnitude of the basal plates corresponded to the valve offset, indicating that the valves are indeed moved due to the changes in the arrangement of the basal plates. We also showed that the ventral valve plates move most during the probing cycle, while the magnitude of the dorsal valve plate movements is much smaller. This suggests that the ventral valves move along the dorsal valve, while the dorsal valve moves together with the abdomen during probing. Additionally, in the situation where the animal keeps its abdomen stationary, we estimated the maximal forces actuating the ventral valves. The estimated maximal pushing forces can be higher than the estimated buckling load of the unsupported ovipositor outside the substrate. Assuming the maximal pushing forces are required during probing, antibuckling mechanisms are needed to avoid damaging the ovipositor. Buckling can be limited (prevented) by either supporting the ovipositor outside the substrate with additional sheaths, employing the push–pull mechanism, or both. Subtracting the maximal estimated pushing and pulling forces on the ventral valves, results in a net pushing force that is very close to the buckling threshold of the ovipositor, albeit still slightly higher. The sheaths, although being flexible, might provide the additional support if needed. In this thesis, I show that multi-element probes are inserted into the substrate using reciprocal movements of the individual elements. These movements appear to be necessary in stiff substrates, which presumably require high pushing forces on a single element during probing. This is in accordance with the hypothesis that reciprocal valve movements serve as an anti-buckling mechanism. Additionally, such valve movements are also important for steering of the probe during insertion. The valve offset controls the shape of the probe tip and therefore the net substrate reaction forces that result in bending of the probe. Wasps evolved special structures that enhance the shape changes of their ovipositor tips and facilitate steering. Our findings may be interesting for a broad range of audiences. Entomologists, evolutionary biologists, and ecologists may find them useful when studying the diversification of probing insects, their evolutionary success, or their ecological interactions (e.g. insect–plant, parasite–host). The anti-buckling and steering mechanisms may be helpful when developing novel, man-made probes. These mechanisms allow for minimization of the probe thickness and accurate steering control, which minimizes substrate damage during probing. Our findings may be particularly useful in the development of slender, steerable needles for minimally invasive surgery.</p

Aeronautical Engineering: A special bibliography, supplement 60

This bibliography lists 284 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1975

Empirical studies of structural phenomena using a curated corpus of Java code

Contrary to 50 years\u27 worth of advice in the instructional literature on software design, long cyclic dependencies are found to be widespread in sizeable, curated corpus of real Java software. Among their causes may be overuse of static members, underuse of dependency injection and poor tool support for avoiding them.<br /

Characterising the neck motor system of the blowfly

Flying insects use visual, mechanosensory, and proprioceptive information to control their movements, both when on the ground and when airborne. Exploiting visual information for motor control is significantly simplified if the eyes remain aligned with the external horizon. In fast flying insects, head rotations relative to the body enable gaze stabilisation during highspeed manoeuvres or externally caused attitude changes due to turbulent air. Previous behavioural studies into gaze stabilisation suffered from the dynamic properties of the supplying sensor systems and those of the neck motor system being convolved. Specifically, stabilisation of the head in Dipteran flies responding to induced thorax roll involves feed forward information from the mechanosensory halteres, as well as feedback information from the visual systems. To fully understand the functional design of the blowfly gaze stabilisation system as a whole, the neck motor system needs to be investigated independently. Through X-ray micro-computed tomography (μCT), high resolution 3D data has become available, and using staining techniques developed in collaboration with the Natural History Museum London, detailed anatomical data can be extracted. This resulted in a full 3- dimensional anatomical representation of the 21 neck muscle pairs and neighbouring cuticula structures which comprise the blowfly neck motor system. Currently, on the work presented in my PhD thesis, μCT data are being used to infer function from structure by creating a biomechanical model of the neck motor system. This effort aims to determine the specific function of each muscle individually, and is likely to inform the design of artificial gaze stabilisation systems. Any such design would incorporate both sensory and motor systems as well as the control architecture converting sensor signals into motor commands under the given physical constraints of the system as a whole.Open Acces

Dynamic Network Notation: A Graphical Modeling Language to Support the Visualization and Management of Network Effects in Service Platforms

Service platforms have moved into the center of interest in both academic research and the IT industry due to their economic and technical impact. These multitenant platforms provide own or third party software as metered, on-demand services. Corresponding service offers exhibit network effects. The present work introduces a graphical modeling language to support service platform design with focus on the exploitation of these network effects