PMN-PSMNT ceramics fabricated using the twin-crystal mixed co-firing method

(1-w)[Pb(Mg1/3Nb2/3)0.67Ti0.33O3]-w[Pb1 − 1.5xSmx(Mg1/3Nb2/3)yTi1−yO3] ((1-w)PMN-wPSMN-PT) piezoelectric ceramics were prepared using the newly proposed twin-crystal mixed co-firing method in which two pre-sintered precursor powders were mixed and co-fired with designated ratios (w = 0.3, 0.4, 0.5, 0.6). X-ray diffraction results show that all the samples presented a pure perovskite structure. The grains were closely packed and the average size was ~ 5.18 µm from the observations of scanning electron microscopy images, giving the high density of ceramics to be 97.8% of the theoretical one. The piezoelectric, dielectric, and ferroelectric properties of the ceramic samples have been investigated systematically. It was found that the performance of ceramics was significantly enhanced when compared to the ceramics fabricated using the conventional one-step approach. Outstanding piezoelectric coefficient d33 of 1103 pC/N and relative dielectric permittivity εr of 9154 could be achieved for the ceramics with w = 0.5.

Pengaruh Metode Pengolahan Terhadap Aktivitas Antioksidan Dan Karakteristik Teh Herbal Bubuk Daun Afrika (Vernonia amygdalina Delile)

This study aims to determine the effect of processing methods on antioxidant activity and characteristics of African leaf herbal tea and find out the right processing method to get the highest antioxidant activity and the best characteristics. The Completely Randomized Design was used in this study with treatment methods which consisted of 4 levels, namely Method A (steam blanching and drying), Method B (withering and pan firing) Method C (withering and Drying) and Method D (steam blanching and pan firing). This study was repeated 4 times to obtain 16 experimental units. The data obtained were analyzed by analysis of variance and if the treatment had a significant effect it was followed by Duncan’s Multiple Range Test (DMRT). The parameters tested in this study include water content, ash content, total phenols, total flavonoids, color, antioxidant activity and sensory characteristics. The results showed that the methods of processing herbal tea powder of African leaves has a highly significant effect on water content, total phenol, total flavonoids, antioxidant activity, color, and sensory tests of color, taste, flavor and have a significant effect on overall reception and have no significant effect on ash content. Herbal tea powder of African leaves processed by method steaming and drying was the best treatment with a moisture content of 6.41%, ash content of 5.27%, total phenol of 2.4169 mgGAE/g, total flavonoids 2, 6563 mgQE/g, antioxidant activity 67.28%, color (L, a, b = 4.86; -49.07; 34.71), light green color, very distinctive aroma of African tea leaves, very bitter taste, and overall reception likes.

In-Cylinder CO2 Sampling Using Skip-Firing Method

Skip-firing (or cylinder de-activation) was assessed as a method of sampling CO2 directly in the cylinder at higher speeds than previously possible. CO2 was directly sampled from one cylinder of a 1 L three-cylinder gasoline engine to determine the residual gas fraction (RGF) using a fast response CO/CO2 analyzer. Acquisition of data for similar measurements is typically limited to engine speeds of below 1300 revolutions per minute (rpm) to allow full resolution of the sample through the analyzer that has an 8 ms finite response time. In order to sample in-cylinder CO2 at higher engine speeds, a skip-firing method is developed. By shutting off ignition intermittently during engine operation, the residual CO2 from the last firing cycle can be measured at significantly higher engine speeds. Comparison of RGF CO2 at low speeds for normal and skip-fire operation shows good correlation. This suggests that skip-firing is a suitable method for directly measuring internal exhaust gas recirculation up to at least 3000 rpm. The measurements obtained may provide a useful tool for validating internal exhaust gas recirculation models and could be used to calculate combustion air–fuel ratio from the CO and CO2 content of the burned gas. These are typically complicated parameters to predict due to the slow response time and sensitivity to hydrocarbons of wide-band oxygen sensors. A differing pattern of RGF change with increasing speed was seen between normal and skip-fire operation.

In-Cylinder CO2 Sampling Using Skip-Firing Method

Skip-firing (or cylinder de-activation) was assessed as a method of sampling CO2 from directly in the cylinder at higher speeds than previously possible. CO2 was directly sampled from one cylinder of a 1-litre 3-cylinder gasoline engine to determine the residual gas fraction using a fast response CO/CO2 analyser. Acquisition of data for similar measurements is typically limited to engine speeds of below 1300 rpm to allow full resolution of the sample, through the analyser that has an 8 millisecond finite response time. In order to sample in-cylinder CO2 at higher engine speeds a skip-firing method is developed. By shutting off ignition intermittently during engine operation, the residual CO2 from the last firing cycle can be measured at significantly higher engine speeds. Comparison of residual gas fraction CO2 at low speeds for normal and skip-fire operation shows good correlation. This suggests that skip-firing is a suitable method for directly measuring internal exhaust gas recirculation up to at least 3000 rpm. The measurements obtained may provide a useful tool for validating internal exhaust gas recirculation models and could be used to calculate combustion air-fuel ratio from the CO and CO2 content of the burned gas. These are typically complicated parameters to predict due to the slow response time and sensitivity to hydrocarbons of wide-band oxygen sensors. A differing pattern of residual gas fraction change with increasing speed was seen between normal and skipfire operation.