Preliminary design of a test rig for combining passive nonlinear isolation with active control

Resilient elements are typically used to isolate delicate equipment from a vibrating host structure. Conventionally, these isolators are designed to operate in their linear region, but more recently nonlinear isolators have been employed to increase the frequency over which vibration isolation can be achieved. Another way of improving the performance of an isolator has been to use active control in conjunction with a passive linear system. The work presented in this paper concerns the development of an experimental rig for vibration isolation and is motivated by the intention to combine the advantages of passive nonlinear isolation with active control.The structure consists of a mass suspended on four tensioned wires to form a single-degree-of-freedom system. The nonlinear stiffness of the wires is such that the system behaves like a hardening Duffing oscillator. Firstly, a static analysis is carried out, both analytically and experimentally, where the nonlinearity of the system is determined by the tension, length, cross-sectional area and Young’s modulus of the wires. For the dynamic analysis, harmonic base excitation is considered. The magnitude of the base displacement is fixed for all excitation frequencies and the level of nonlinearity is adjusted by varying the tension in the wires, a higher tension leading to a milder system nonlinearity. Finally, the motion transmissibility of the system is measured and appears to agree with the theoretical result. The rig forms a suitable platform for subsequent incorporation of an active control system for combining the benefits of passive nonlinear isolation with, for example, skyhook damping

Development of Kaya Slice (coconut jam slice): evaluation of physicochemical, sensory evaluation and macronutrients composition when cooperated with gelatin

Kaya Slice is a nutritious traditional breakfast-on-the-go that was innovated from the traditional kaya. In this study, the traditional kaya was transformed into square shape gelatin to make it a more convenient and ready-to-eat breakfast. A total of six formulations were developed by using commercial and fresh coconut milk together with different percentages of gelatin (2%, 4%, and 6%). This insight was investigated by sensory evaluation using a 9-point hedonic and scoring test in descriptive data set. The best formulation obtained from the evaluation of 35 panellists was then characterized in terms of physicochemical properties (Texture Profile Analysis (firmness), Brix, Protein, Fat, Fiber, and Calories). From the descriptive data, all formulations were accepted by the panellist. Nevertheless, ANOVA analysis indicated that C2 (commercial coconut milk + 4% of gelatin) is the best formulation. In macronutrient analysis, Kaya Slice was found to have good dietary fibre content (0.11 g/100 g), high-fat content (0.49 g/100 g), protein content (0.32 g/100 g) compare to the commercial kaya (0.00 g/100 g), (1.00 g/100 g), and (0.00 g/100 g) respectively. Low-calorie content in Kaya Slice with 45 % of °Brix value is the minimal degree of Brix and the texture was softer (hardness) (significantly different (p<0.05)) to commercially processed cheese slice as standard. Overall, Kaya Slice has a great potential in becoming new emergent of traditional nutritious breakfast on the go

Sustainability and economic evaluation of Microalgae

The enhancement of the atmospheric greenhouse effect due to the increase in the atmospheric greenhouse gases is often considered as responsible for global warming. Several analyses have been made on the key issues of scientific understanding of contemporary global climate change. Air pollution are directly related with climate changes and it has been increasing the potential of ecosystems and human health risks. The policy and scientific assessments to climate change included the consideration of the risks and expressed climatic events. Microalgae has been identified as one of the potential feedstock for various bio product production since its cultivation requires less cropland compared to conventional oil crops and the high growth rate. The potential of microalgae to produce multiple bio based products in a biorefinery framework. The integration of emerging biorefineries is potential solution to mitigate the threat of climate change, global warming and food insecurity

Queue backlog as a node metric for RPL protocol

The current de-facto routing protocol over WSN developed by IETF Working Group (6LOWPAN) named as Routing Protocol for Low Power and Lossy networks (RPL) [1], to enable IPv6 packets carrying over IEEE 802.4 and to empower the usage of IoT over WSN. Because of the potential large networks, number of nodes and the fact that multiple coexisting applications will be running in the same physical layer, RPL in the network layer faces throughput challenges. For the purpose of overcoming these problems many researchers focused on multipath solutions including a Back-Pressure routing protocol for data collection called BackIP [2], however it shows a superior throughput performance, BackIP have shortcomings of higher delay and limited applicability. In this paper, we introduce a node metric based on nodes Queue Backlogs for RPL protocol, which leads to better throughput performance while maintaining the delay and the ability to use with the different network applications. This metric depends on the Packet Queue length of the nodes with the consideration of other link and node metrics, like ETX or Energy usage, leading to better load balancing in the network. Moreover we discuss the needed design changes to enable our metric to perform in an efficient way. Keywords-IOT, RPL, WSN, Back Pressure, Queue Backlog, Objective Functio

Profil kecelaruan penutur natif Melayu dalam penulisan esei

Kajian ini cuba memaparkan profil kecelaruan penutur natif Melayu menerusi penggunaan kata ‘di’ dalam penulisan esei. Profil ini diserlahkan menerusi dapatan Analisis Kesalahan ke atas data kajian. Data kajian merupakan sejumlah kecelaruan penggunaan nahu iaitu penggunaan kata ‘di’ dalam penulisan esei 50 orang pelajar prasiswazah Kulliyyah Ilmu Wahyu dan Sains Kemanusiaan (KIRKHS) UIAM. Dapatan kajian menunjukkan bahawa subjek mengalami masalah kecelaruan pemikiran antara fungsi kata ‘di’ sebagai imbuhan atau kata sendi. Kecelaruan ini diklasifikasikan sebagai berpunca dari masalah ‘kesalahan’ dan juga ‘kesilapan’. Implikasi dapatan ini bukan sahaja penting kepada para pelajar untuk memahami dan mengatasi masalah kenahuan dalam penulisan mereka, malahan sangat penting kepada ahli akademik khususnya pendidik bahasa Melayu untuk memahami kewujudan masalah seperti ‘kesalahan’ dan ‘kesilapan’, dan seterusnya dapat menangani kekeliruan penggunaan kata ‘di’ dalam penulisan pelajar. Kajian ini turut memberi implikasi penting kepada polisi pendidikan bahasa Melayu di IPT dalam konteks mengekalkan martabat Bahasa Kebangsaan negara Malaysia iaitu bahasa Melayu

Silicon carbide schottky diodes forward and reverse current properties upon fast electron radiation

This paper investigates on the reaction of 10 and 15MGy, 3MeV electron irradiation upon off-the-shelves (commercial) Silicon Carbide Schottky diodes from Infineon Technologies (model: IDH08SG60C) and STMicroelectronics (model: STPSC806). Such irradiation reduces the forward-bias current. The reduction is mainly due to the significant increase of the series resistance (i.e. Infineon: 1.45Ω at before irradiation → 121×103 Ω at 15MGy); STMicroelectronics: 1.44Ω at before irradiation → 2.1×109 Ω at 15MGy). This increase in series resistance gives 4.6 and 8.2 orders of magnitude reduction for the forward-bias current density of Infineon and STMicroelectronics respectively. It is also observed that the ideality factor and the saturation current of the diodes increases with increasing dose (i.e. ideality factor- Infineon: 1.01 at before irradiation → 1.05 at 15MGy; STMicroelectronics: 1.02 at before irradiation → 1.3 at 15MGy | saturation current- Infineon: 1.6×10-17A at before irradiation → 2.5×10-17A at 15MGy; STMicroelectronics: 2.4×10-15A at before irradiation → 8×10-15A at 15MGy). Reverse-bias leakage current density in model by Infineon increases by one order of magnitude after 15MGy irradiation, however, in model by STMicroelectronics decreases by one order of magnitude. Overall, for these particular samples studied, Infineon devices have shown to be better in quality and more radiation resistance toward electron irradiation in forward-bias operation while STMicroelectronics exhibit better characteristics in reverse-bias operation

Synthesised Schiff Bases As A Potential Corrosion Inhibitor Of Aluminium.

The use of inhibitors for the protection against corrosion in acidic media such as nitric acid, sulfuric acid and hydrochloric acid is widely reported. Schiff bases, a group of compounds containing nitrogen atoms were found to be efficient inhibitors for corrosion in acidic media. Some research work revealed that the inhibition efficiency of Schiff bases was found to be greater than their precursor, amines and aldehydes

pH dominates variation in tropical soil archaeal diversity and community structure

Little is known of the factors influencing soil archaeal community diversity and composition in the tropics. We sampled soils across a range of forest and nonforest environments in the equatorial tropics of Malaysia, covering a wide range of pH values. DNA was PCR-amplified for the V1-V3 region of the 16S rRNA gene, and 454-pyrosequenced. Soil pH was the best predictor of diversity and community composition of Archaea, being a stronger predictor than land use. Archaeal OTU richness was highest in the most acidic soils. Overall archaeal abundance in tropical soils (determined by qPCR) also decreased at higher pH. This contrasts with the opposite trend previously found in temperate soils. Thaumarcheota group 1.1b was more abundant in alkaline soils, whereas group 1.1c was only detected in acidic soils. These results parallel those found in previous studies in cooler climates, emphasizing niche conservatism among broad archaeal groups. Among the most abundant operational taxonomic units (OTUs), there was clear evidence of niche partitioning by pH. No individual OTU occurred across the entire range of pH values. Overall, the results of this study show that pH plays a major role in structuring tropical soil archaeal communities

Technology factors influencing e-government readiness

A rapidly growing number of countries are realizing that e-government has become a powerful tool for governments, as it can assist with measures such as making public administration significantly more efficient and effective. There is an urgent need for e-government to be able to enhance government administration performance and to provide efficient services to citizens. It can contribute to shortening time and effort as well as alleviating pressures on citizens. E-government projects need government support in order to create, apply, disseminate and continue the experience by providing all necessary resources. Various means of information transmission (such as the media) are vitally important by which to educate the stakeholders and increase their awareness to ensure the success and sustainability of such projects. Moreover, governments should assess their readiness for developing e-government procedures before embarking on the implementation of such a project to avoid any possible failures. Most of the failures of previous e-government measures can be attributed to technology factors. These factors include: infrastructure; security; technological/ technical issues; hard/soft gap; digital divide; internet use; and finally, skills. The successful implementation of e-government relies on assessing the readiness of technology aspects in order to realize the benefits of e-government and reduce potential failures of e-government implementation. Existing studies on e-government readiness lack agreement on the important technology aspects; thus, there remains a need to identify the relevant factors that shape the technology aspects of e-government readiness. The aim of this paper is to identify the said technology aspects of e-government readiness

Simulation study on the effect of fuel injection and air intake boundary setup on the brake torque response by using comprehensive vehicle model for natural gas vehicle (NGV)

An analytical, dynamic and comprehensive vehicle model, replicated a high-pressure direct injection compressed natural gas (HPDI-CNG) engine in a vehicle is proposed with the objective to study the effect of fuel injection and air intake boundary condition on the brake torque response. The model simulated the output torque in transient simulations of the natural gas vehicle (NGV) in speed-sweep mode test. The vehicle model has coupled an analytical engine model developed in Simulink with a Simscape driveline model which consists of a clutch model, a simple transmission gear and a simplified vehicle model. In all problem, independent input to the model is the throttle opening ramp. The adjusted parameter in the first study is the methods to calculate the mass of fuel inlet which is based on i) fully experimental data, ii) measured air to fuel ratio (AFR) and (iii) constant injector mass flow rate. In the second problem, the pressure limit of the manifold absolute pressure (MAP) is adjusted as (i) fully experimental data (ii) 1.2 bar (iii) 1.5 bar and (iv) unlimited pressure limit. The dependent parameter in all problem is engine output torque. The results have been compared with the actual data of torque from chassis dynamometer measurement. For the effect of fuel inlet boundary set up, in the fully predictive mode, the model predicted an almost constant maximum torque at a value about 70 Nm, whereas the measured data only produced the same peak value at a very limited instant. If the model used measured AFR as the fuel input boundary, the model overpredicted the maximum peak torque of 70 Nm. In the study on the effect of MAP limit, the maximum torque for 1.2 bar, 1.5 bar and unlimited pressure set up has produced a maximum torque of 45, 62 and 70 Nm, respectively. Results of the first study showed that the use of constant injector mass flow rate has a tendency to simulate an ideal engine acceleration process. The prediction is closed to the measured data if the fuel mass is calculated based on the measured AFR. However, the use of measured AFR in our opinion have reduced the model predictability. In the second study, the increased MAP limit significantly increased the maximum brake torque response. However, the model cannot predict the abnormalities found in the experimental data. The use of MAP limit demonstrated the sensitivity of the output torque on the maximum value of the engine MAP. The results indicated that the injection fuel inlet boundary and the MAP limit have a strong significance on the model prediction and need to be improved for future use of the model