Application of acoustic emission to seeded gear fault detection

Acoustic emission (AE) is gaining ground as a non-destructive technique for health diagnosis on rotating machinery. There are vast opportunities for development of the AE technique on various forms of rotating machinery, including gearboxes. This paper reviews some recent developments in application of AE to gear defect diagnosis. Furthermore, an experimental investigation that examines the effectiveness of AE for gear defect identification is presented. It is concluded that application of the AE technique to seeded gear defect detection is fraught with difficulties. In addition, the viability of the AE technique for gear defect detection from non-rotating components of a machine is called into question.     

Experimental study of micro- and nano-scale cutting of aluminum 7075-T6

This paper investigates micro- and nano-scale (10 nm–2 μm) machining characteristics of a non-ferrous structural alloy, aluminum 7075-T6 (87 HRB) through a series of cutting experiments. Aluminum 7075-T6 is used in the die and mold making industry for creating prototype molds. The effects of cutting conditions on the machining forces, chip geometry, surface roughness, and derived parameters such as the specific cutting energy, shear angle and mean friction coefficient in orthogonal micro- and nano-scale cutting of Al 7075-T6 are presented and compared with trends observed in conventional macro-scale cutting. Explanations for the observed trends are given.     

Effect of condensed tannins prepared from several forages on the in vitro precipitation of ribulose-1,5-bisphosphate carboxylase (Rubisco) protein and its digestion by trypsin (EC 2.4.21.4) and chymotrypsin (EC 2.4.21.1)

A series of in vitro experiments was undertaken to determine the extent to which Sephadex LH-20 treated extracts from a range of temperate forages precipitated ribulose-1,5-bisphosphate carboxylase (Rubisco) and affected the enzymatic hydrolysis of Rubisco protein by trypsin and chymotrypsin at a range of pH values. Rubisco was chosen because it represents the principal dietary protein for ruminants fed fresh forages. Condensed tannins (CT) or proanthocyanidins (PA) are routinely purified by chromatography using Sephadex LH-20 as a matrix. However, these extracts contained non-CT phenolics together with PA so the term ‘CT extract’ was preferred to ‘PA’ to describe the extracts. The in vitro precipitation of Rubisco provided a means to compare the reactivity of the CT extracts. The amount of CT extract required to precipitate all the Rubisco in 10 μg of total soluble leaf protein from white clover (Trifolium repens) when this protein was incubated with CT extracts of Lotus corniculatus, L pedunculatus and sainfoin (Onobrychis viciifolia) was similar, with between 25 and 50 μg of extract required. The CT extract of sulla (Hedysarum coronarium) also precipitated all the Rubisco, however this only occurred with 50 μg of the extract. The CT extract of dock (Rumex obtusifolius) precipitated all the Rubisco when 5 μg of extract or greater was incubated with total soluble leaf protein. However, the differences between the reactivity of all these CT extracts at a range of pH values appeared to be small. Condensed tannin extracts of L corniculatus and L pedunculatus partially inhibited the hydrolysis of Rubisco by trypsin and chymotrypsin to a similar extent, but the extent of the inhibition was affected by pH. The inhibition was greater at pH 6·0 than 7·0, whilst at pH 8·0, CT extracts had little or no affect on trypsin and chymotrypsin. It was concluded that, although the precipitation of Rubisco provided an ideal method for comparing CT extracts, reactivity alone was unlikely to account for the differences in nutritive value that occur with forages containing CT. © 1998 SCI.     

Fabrication of flexible carbon dioxide gas sensor with conductive polymer/reduced graphene oxide hybrids: Effects of substrate type and mass ratio

Flexible gas sensors made of polyaniline (PANI)-reduced graphene oxide (rGO) nanocomposite were prepared using three different substrates, namely filter paper, cotton fabric, and weighing paper, through in-situ reduction of GO and in-situ polymerization of aniline. Preliminary analysis showed that the PANI/rGO coated on filter paper possesses a superior electrical conductance than PANI/rGO coated on cotton fabric and weighing paper. Such observation was attributed to the good attachment of the PANI/rGO nanocomposites onto the high-density mesh-like structure of the filter paper with rough surfaces. In contrast, PANI/rGO coated onto weighing paper and cotton fabric of different surface structures presented lower-to-almost negligible conductance. Accordingly, PANI/rGO filter paper was selected for the subsequent evaluation of gas sensing properties. The gas-sensing performances of the PANI/rGO filter paper sensors indicated that the 5 wt% PANI/rGO (i.e., 5 wt% rGO) sample exhibited the best response of 306% for 500 ppm carbon dioxide (CO₂) gas at room temperature with a recovery rate of 41.5%. On the other hand, the optimum recovery rate of 59.5% was identified at 0.5 wt% PANI/rGO sample which exhibited a response of 155%. Owing to the synergy effect, the PANI/rGO sensor outperformed the sensor made of pure PANI or pure rGO.     

Bisphenol A (BPA) Leading to Obesity and Cardiovascular Complications: A Compilation of Current In Vivo Study

BPA is one of the most common endocrine disruptors that is widely being manufactured daily nationwide. Although scientific evidence supports claims of negative effects of BPA on humans, there is also evidence suggesting that a low level of BPA is safe. However, numerous in vivo trials contraindicate with this claim and there is a high possibility of BPA exposure could lead to obesity. It has been speculated that this does not stop with the exposed subjects only, but may also cause transgenerational effects. Direct disruption of endocrine regulation, neuroimmune and signaling pathways, as well as gut microbiata, has been identified to be interrupted by BPA exposure, leading to overweight or obesity. In these instances, cardiovascular complications are one of the primary notable clinical signs. In regard to this claim, this review paper discusses the role of BPA on obesity in the perspective of endocrine disruptions and possible cardiovascular complications that may arise due to BPA. Thus, the aim of this review is to outline the changes in gut microbiota and neuroimmune or signaling mechanisms involved in obesity in relation to BPA. To identify potentially relevant articles, a depth search was done on the databases Nature, PubMed, Wiley Online Library, and Medline & Ovid from the past 5 years. According to Boolean operator guideline, selected keywords such as (1) BPA OR environmental chemical AND fat OR LDL OR obese AND transgenerational effects or phenocopy (2) Endocrine disruptors OR chemical AND lipodystrophy AND phenocopy (3) Lipid profile OR weight changes AND cardiovascular effect (4) BPA AND neuroimmune OR gene signaling, were used as search terms. Upon screening, 11 articles were finalized to be further reviewed and data extraction tables containing information on (1) the type of animal model (2) duration and dosage of BPA exposure (3) changes in the lipid profile or weight (4) genes, signaling mechanism, or any neuroimmune signal involved, and (5) transgenerational effects were created. In toto, the study indicates there are high chances of BPA exposure affecting lipid profile and gene associated with lipolysis, leading to obesity. Therefore, this scoping review recapitulates the possible effects of BPA that may lead to obesity with the evidence of current in vivo trials. The biomarkers, safety concerns, recommended dosage, and the impact of COVID-19 on BPA are also briefly described.     

The Condensed Tannin Content of a Range of Subtropical and Temperate Forages and the Reactivity of Condensed Tannin with Ribulose- 1,5-bis-phosphate Carboxylase (Rubisco) Protein

A series of subtropical grasses and temperate grasses, herbs and legumes were analysed for the presence of extractable and bound condensed tannin (CT) using colorimetric analysis by the butanol–HCl method. Condensed tannins are routinely purified using affinity chromatography with Sephadex LH-20 as a matrix. Therefore, Sephadex LH-20 extracts were further analysed for the presence of CT by ¹³C nuclear magnetic resonance, for anthocyanidin formation after butanol–HCl treatment and for their ability to precipitate ribulose-1,5-bisphosphate carboxylase (Rubisco) protein from lucerne, at pH 7·0. Criteria for the presence or absence of CT were defined. Trace amounts of CT (0·2–2·5 g kg⁻¹ dry matter; DM) were identified and confirmed in summer grass (Digiteria sanguinalis), perennial ryegrass (Lolium perenne) and red clover (Trifolium pretense), with chicory (Chicorium intybus), lucerne (Medicago sativa) and plantain (Plantago lanceolata) identified as probably containing CT. It was concluded that the subtropical grasses kikuyu (Pennisetum clandestinum), paspalum (Paspalum diatatum), smooth witchgrass (Panicum dichotomiflorum) and crowfoot (Eleusine indica) and the temperate grass, Yorkshire fog (Holcus lanatus) probably did not contain CT. Analysis of the extractable fractions by vanillin–HCl gave higher values for CT than analysis by butanol–HCl and wrongly identified some forages as containing trace levels of CT. It was concluded that vanillin–HCl was not specific enough for the detection of trace levels of CT in forages. These results raise the possibility of plant selection programmes to increase the level of CT in grazed forages to approximately 5 g kg⁻¹ DM, the suggested minimum level required to prevent bloat in cattle and to increase wool growth in sheep. It is suggested that this be considered for perennial ryegrass, chicory, red clover and lucerne.     

Radial basis function-assisted turbo equalization

This paper presents a turbo equalization (TEQ) scheme, which employs a radial basis function (RBF)-based equalizer instead of the conventional trellis-based equalizer of Douillard et al. (1995). Structural, computational complexity, and performance comparisons of the RBF-based and trellis-based TEQs are provided. The decision feedback-assisted RBF TEQ is capable of attaining a similar performance to the logarithmic maximum a posteriori scheme in the context of both binary phase-shift keying (BPSK) and quaternary phase-shift keying (QPSK) modulation, while achieving a factor 2.5 and 3 lower computational complexity, respectively. However, there is a 2.5-dB performance loss in the context of 16 quadrature amplitude modulation (QAM), which suffers more dramatically from the phenomenon of erroneous decision-feedback effects. A novel element of our design, in order to further reduce the computational complexity of the RBF TEQ, is that symbol equalizations are invoked at current iterations only if the decoded symbol has a high error probability. This techniques provides 37% and 54% computational complexity reduction compared to the full-complexity RBF TEQ for the BPSK RBF TEQ and 16QAM RBF TEQ, respectively, with little performance degradation, when communicating over dispersive Rayleigh fading channels.     

Report on AI research in progress in New Zealand universities

There are currently six universities in New Zealand (see Fig. 1) and all have one or more departments which are active in pursuing AI research. Each year, together with the New Zealand Computer Society and the local business community, the universities organize a New Zealand Expert System Conference. In this report, we describe the facilities available and the major research work currently in progress in each of these universities. We also list the main personnel involved and whom you should contact for further information.     

Reliable and efficient communications in sensor networks

Wireless sensor networks are inherently plagued by problems of node failure, interference to communications from environmental noise and energy-limited sensor motes. These problems pose conflicting issues in the design of suitable routing protocols. Several existing reliable routing protocols exploit message broadcast redundancy and hop count as routing metrics and their performance trade-offs are revealed during simulation. In this paper, we study and analyse related design issues in proposed efficient and reliable routing protocols that attempt to achieve reliable and efficient communication performance in both single- and multi-hub sensor networks. Simulation results of four such routing protocols show that routing performance depends more on optimal (near-optimal) routing in single hub than in multi-hub networks. Our work also shows that optimal (near-optimal) routing is better achieved when historical metrics like packet distance traversed and transmission success are also considered in the routing protocol design.     

Preliminary study of a polycaprolactone membrane utilized as epidermal substrate

Solvent-cast sheets of polycaprolactone were biaxially stretched to produce 10–15 m thick films. PCL films were found to have a tensile strength of 55 MPa which is about two and a half times stronger than native skin. One of our previous studies using non-coated PCL membranes showed that only 36% of the membrane surface was covered with keratinocytes after 9 days of culture. The present study examined the effects of coating the surface of PCL membranes with fibrin on the proliferation of keratinocytes. Qualitative analysis revealed that the cells attached and proliferated better on coated PCL films. Keratinocytes exhibited healthy cobblestone morphology and proliferated as continuous monolayers over a period of 16 days. The results indicated that fibrin coated PCL films would support the attachment and proliferation of human keratinocytes and have the potential to be applied as a matrix material for tissue engineering an epidermal equivalent.