Corrigendum to “Modal Mass and Length of Mode Shapes in Structural Dynamics”

The literature about the mass associated with a certain mode, usually denoted as the modal mass, is sparse. Moreover, the units of the modal mass depend on the technique used to normalize the mode shapes, and its magnitude depends on the number of degrees of freedom (DOFs) used to discretize the model. This has led to a situation where the meaning of the modal mass and the length of the associated mode shape is not well understood. As a result, normally, both the modal mass and the length measure have no meaning as individual quantities, but only when they are combined in the frequency response function. In this paper, the problems of defining the modal mass and mode shape length are discussed, and solutions are found to define the quantities in such a way that they have individual physical meaning and can be estimated in an objective way.

Modal Mass and Length of Mode Shapes in Structural Dynamics

The literature about the mass associated with a certain mode, usually denoted as the modal mass, is sparse. Moreover, the units of the modal mass depend on the technique which is used to normalize the mode shapes, and its magnitude depends on the number of degrees of freedom (DOFs) which is used to discretize the model. This has led to a situation where the meaning of the modal mass and the length of the associated mode shape is not well understood. As a result, normally, both the modal mass and the length measure have no meaning as individual quantities but only when they are combined in the frequency response function. In this paper, the problems of defining the modal mass and mode shape length are discussed, and solutions are found to define the quantities in such a way that they have individual physical meaning and can be estimated in an objective way.

Biologi Ikan Kembung Rastrelliger spp, (Actinopterygii : Scombridae) : Ditinjau dari aspek Panjang Berat dan Indeks Kematangan Gonad Di Perairan Semarang

Ikan kembung (Rastrelliger spp) merupakan salah satu ikan pelagis yang hidup di perairan bersalinitas tinggi dan suka hidup bergerombol. Semakin meningkatnya permintaan akan ikan membuat semakin tinggi penangkapan ikan yang dilakukan. Penelitian ini bertujuan mengetahui tingkat kematangan gonad ikan kembung (Rastrelliger spp) dan mengetahui hubungan antara panjang dengan berat, hubungan antara berat dengan fekunditas, dan hubungan antara berat gonad dengan IKG (Indeks Kematangan Gonad) dari ikan kembung (Rastrelliger spp).Sebanyak 80 ekor Ikan Kembung yang didapatkan dari pasar kobong diukur panjang total dan ditimbang beratnya. Kemudian dilakukan pembedahan untuk diamati jenis kelamin dan tingkat kematangan gonadnya. Penelitian ini meliputi: Indeks Kematangan Gonad, Tingkat Kematangan Gonad, fekunditas dan rasio kelamin. Pengamatan tingkat kematangan gonad dilakukan untuk menentukan indeks kematangan gonad (IKG). Tingkat kematangan gonad ikan kembung (Rastrelliger spp) terdiri dari TKG I sampai TKG V. Nilai IKG yang didapatkan untuk ikan jantan berkisar 0,14-6,42% dan betina berkisar 0,64-7,25%, hal tersebut menunjukkan bahwa nilai tersebut bervariasi antara ikan jantan dan betina. Hasil penelitian dengan 80 sampel ikan kembung menunjukkan rasio kelaminnya tidak seimbang yaitu 42,5:57,5 dimana angka jantan lebih tinggi. Pertambahan ukuran panjang memberikan pengaruh yang nyata terhadap fekunditas, pertambahan ukuran panjang ikan kembung betina memberikan pengaruh yang nyata terhadap berat, pertambahan ukuran panjang ikan kembung jantan memberikan pengaruh yang nyata terhadap berat. Sedangkan berat ikan betina tidak memberikan pengaruh yang nyata terhadap IKG dan berat ikan jantan memberikan pengaruh yang nyata terhadap IKG Rastrelliger spp is one of the pelagic fish that live in high salinity and like to live in groups. The increasing demand for this fish, makes the catching activity of this fish grow higher. The aim of the research is to know the Gonad Maturation Stage (GMS) of Rastrelliger spp to know the relationship between length and weight, the relationship between weight with fecundity, and relationship between gonad weight and Gonad Maturation Index from Rastrelliger spp. 80 samples of Rastrelliger spp that were obtained from the market were measured, the measurement included were length and weight. And then a surgery was performed to examine their sex and their Gonad Maturation Stage. In the end to obtain the results of its fecundity, its gonad were taken and the weight was measured. GMI. Gonad maturation stage of Rastrelliger spp fish was I-V. the range of GMI for male fish was 0,14-6,42% and female 0,64-7,25%. That were indicated a various values of GMI male and female fishes. The result of research with 80 samples of Rastrelliger spp showed unbalanced sex ratio 42,5: 57,5 where male number was higher. The addition of length measure gave a real effect to fecundity, the increase of length of female gave a significant effect on the weight, the increase of length of male gives a real effect on the weight. While the weight of female fish did not give a real effect on GMI and the weight of male fish gives a real effect on GMI

Time as a measure: Elementary students positioning the hands of an analog clock

Elementary students have difficulty with the topic of time. The present study investigated students’ actions to position hour and minute hands on an analog clock to indicate particular times of the day. Using one-on-one interviews with students in Grades 2 and 4 (n = 48), we analyzed whether students were more accurate for one hand indicator (hour or minute) versus the other as well as their solution approaches as they positioned each hand. We first present a quantitative analysis of student performance to document whether hour and minute hands posed differential challenges for students as they positioned hands to indicate particular times. Results indicate the hour hand is significantly more challenging to position accurately than the minute hand. Students’ solutions reflected varied approaches, including consideration of the quantitative hour-minute multiplicative relationship, attention to part-whole relations, and matching numbers from the provided time to numerals on the clock. We discuss implications for theory and instruction, including the relationship of time to length measure learning trajectories and the current treatment of time in K-12 mathematics standards for the United States.

How to measure sessions of mobile phone use? Quantification, evaluation, and applications

Research on mobile phone use often starts with the question of how much time users spend using their phones. The question involves an equal-length measure that captures the duration of mobile phone use but does not tackle the other temporal characteristics of user behavior, such as frequency, timing, and sequence. In this study, we propose a variable-length measure called “session” to uncover the unmeasured temporal characteristics. We use an open source dataset to demonstrate how to quantify sessions, aggregate the sessions to higher units of analysis within and across users, evaluate the results, and apply the measure for theoretical or practical purposes.