Judul: Uji Performansi Alat Pengering Gabah Tipe Bak Terbuka dan Resirkulasi dengan Sumber Panas dari Sistem Heat Pump
Abstrak: Penelitian ini dilakukan untuk mengembangkan sistem heat pump sebagai pengering gabah. Pengeringan gabah sistem terbuka dan resirkulasi telah diuji pada gabah varietas Ciherang. Tujuan dari penelitian ini adalah mengetahui sebaran suhu, menentukan mutu beras hasil pengeringan dan menguji performansi pengering tipe bak terbuka dan resirkulasi. Hasil penelitian menunjukkan sebaran suhu pada 3 lapisan gabah dengan rata – rata 30.09 oC ± 4.25 oC pada sistem terbuka dan 30.73 oC ± 3.58 oC pada sistem resirkulasi. Persentasi beras kepala pada sistem terbuka dengan rata – rata 92.09% dan pada sistem resirkulasi 91.84%, tidak terdapat perbedaan yang signifikan antara persentase beras kepala sistem terbuka dan resirkulasi. Hasil pengujian performansi menunjukkan efisiensi pengeringan pada sistem terbuka 113.91 % dan resirkulasi 101.84 %, sedangkan konsumsi energi spesifik 2.23 MJ/kg uap air pada sistem terbuka dan 2.54 MJ/kg uap air pada sistem resirkulasi.
Keyword: beras kepala, efisiensi, kadar air, pengeringan

Judul: Rancangan Sistem Pemanasan dan Uji Kinerja pada Pengering Gabah Tipe Bak dengan dan Tanpa Tempering
Abstrak: Proses pengeringan gabah umumnya masih dilakukan secara tradisional dengan metode dijemur di bawah terik sinar matahari langsung yang terkendala oleh cuaca. Oleh karena itu, dibutuhkan alat pengering gabah yang mudah dalam pengoperasiannya. Tujuan penelitian ini adalah merancang sistem pemanasan pada bak pengering, melakukan uji performa, melakukan pemutuan, dan analisis biaya pengeringan yang digunakan. Pengujian dilakukan menggunakan pengeringan tempering dan tanpa tempering masing-masing sebanyak 100 kg gabah. Uji mutu beras hasil pengeringan berupa persentase beras patah, beras kepala, dan beras menir. Hasil pengeringan menunjukkan laju pengeringan tempering sebesar 6.36% basis kering/jam dalam waktu 220 menit dan pengeringan tanpa tempering 6.25% basis kering/jam dalam waktu 300 menit. Konsumsi energi spesifik proses pengeringan tempering sebesar 3.82 MJ/kg uap air dan 3.07 MJ/kg uap air untuk pengeringan tanpa tempering. Pengeringan tempering memiliki efisiensi termal sebesar 39.94% dan efisiensi termal pada pengeringan tanpa tempering adalah 86.21%. Efisiensi total pengeringan tempering lebih kecil dengan nilai 70.13% dibandingkan dengan efisiensi total pengeringan tanpa tempering yang sebesar 86.55%. Rata-rata beras patah dan menir hasil pengeringan tempering masing-masing sebesar 13.09% dan 11.25% dan hasil pengeringan tanpa tempering sebesar 19.54% dan 10.53%. Biaya pengeringan yang disarankan yaitu sebesar Rp 278.7 kg gabah, yang terdiri dari biaya listrik dan gas. Jadi, belum dapat dikatakan bahwa proses pengeringan mana yang lebih baik dan harus dilakukan pengeringan dengan kapasitas penuh agar dapat melihat hasil yang lebih akurat.
Keyword: biaya, efisiensi, gabah, pemutuan, pengeringan

Judul: Mixed effect models for high –dimensional longitudinal data with latent variables
Abstrak: A set of data that consist of repeated measurements on a large number of outcomes and covariates are known as high-dimensional longitudinal data. The high-dimensional longitudinal data may consist of several effects of interest that cannot be directly measured, known as latent factors or latent variables. During the last decade, the multivariate responses or high-dimensional in longitudinal data have been a big issue. The analysis of high-dimensional longitudinal data is complicated due to its complex correlation structures between outcomes. To understand changes over time of outcome variables, having correlations in individuals with explanatory variables is not enough. Hence, complex correlation structures between outcomes need to be considered. One approach that is commonly used to overcome high-dimensional longitudinal data is simultaneous equation modeling. A well-known simultaneous equation modeling method is the structural equation model (SEM). This approach has several appealing modeling abilities and can be used for high-dimensional longitudinal data. Under the SEM framework, the continuous time SEM is developed to avoid some issues associated with autoregressive and cross-lagged problems in SEM. Another simultaneous equation modeling method is by combining factor analysis and multivariate analysis methods to overcome high dimensional longitudinal data, namely latent factor linear mixed model (LFLMM). The factor analysis is used to reduce the high-dimensional outcomes, and the multivariate linear mixed model is used to study the longitudinal trends of several latent factors. One example of high-dimensional longitudinal data is the General Election Study. This study is carried out repeatedly to observe tendencies towards political attitudes and behavior over time in Belgium. The data contain political information, knowledge, perceptions, and preferences of a political party and the level of participation in politics. One of the most interesting things to study from the data is to analyze the change of political attitudes and behavior of respondents over time. Also, the relationship of changes in these outcomes is important to analyze. The General Election Study in Belgium was designed to include a representative sample of the target population under the Belgian electorate, so accurate estimates about the population could be made. This sampling design was created by the Institute for Social and Political Opinion (ISPO) and the Inter-university Center for Political Opinion Research (PIOP). The Belgian data set contained three subsamples, the Flemish (Dutch-speaking), the Walloon (French-speaking), and the Brussels Capital Region (Dutch and French-speaking). Several studies conducted on the Belgium data are carried out to understand the relationships between the latent variables Individualism (I), Ethnocentrism (E), and Authoritarianism (A) in Flanders. Cross-sectional or a longitudinal studies have also been carried out. In such cases, it is critical to capture the trend of the latent variables over time and, more importantly, whether there is any association or relationships between the development of nationalism (N), ethnocentrism (E), individualism (I), and authoritarianism (A) in Belgium. An empirical analysis of CT-SEM has been done to present the interdependencies among the four latent variables mentioned above on the basis of the General Election Studies for Belgium in 1991, 1995, and 1999 (Interuniversitair steunpunt politieke-opinieonderzoek, 1991, 1995, 1999). Although the four variables have been the subject of
Keyword: Belgium, CT-SEM, high-dimensional longitudinal data, LFLMM, Supplemented EM Algorithm