Physical Properties of Cement-Sand Brick Made by Kenaf Core: Discovering the Optimal Formulation

In this study, the effect of replacing the river sand with industrial waste and cellulosic waste was investigated. The cellulosic waste use in this study only focuses on kenaf core, while the industrial waste use in this study is quarry dust. The fine aggregate formulation is adjusted with a different percentage of kenaf core. While the quarry dust is fixed at 50% replacement level. The water-cement ratio set for the formulation is 0.75, and the cement-sand ratio fixes at 1:8. The physical properties are measured through compressive strength and density at 28 days. The result shows that 10% is the maximum replacement of sand with kenaf core to produced brick that using 50% of quarry dust. The compressive strength value of the 10% of kenaf core at 28 days is 8.16 N/mm2 while for density is 1830 kg/m3 at 28 days. All the result shows that kenaf core has the potential to be used as a lightweight fine aggregate. But kenaf core needs to combine with other materials that contribute to the strength.

Home Biogas Production using Homemade Bio-activator with Chicken Manure

The previous experiment was obtained that homemade activator is the best activator to produce biogas by using food waste consist of vegetable, fruit and rice waste. The current research is carried out by adding chicken manure as a co-activator. Chicken manure content rich in nitrogen can be significantly enhance biogas production. This study is expected to increase the biogas production. There are two processes conducted at the laboratory scale, batch and semi-continuous process. The batch process aim to activate bacteria. The ratio set at food waste/chicken manure, 2 : 1 of digester #1, 3 : 1 of digester #2, 4 : 1 of digester #3 and digester control using food waste only. Stage two aims to produce biogas by adding food waste for 6 days periodically. The ratio is set at food waste/water, 1 : 2. The highest biogas yielded is digester 2 with a cumulative volume biogas 120.77 liters consist of 71.01% CH4, 26% CO2, 2.9% O2 and 0.088% H2S. The potential of methane gas produced is 0.87 kWh and methane volume per TS and VS at around 18.72 L/kg and 34.68 L/kg, respectively.

Analisis Metode ANP pada Hubungan Kerja di PT. Pp. London Sumatera Indonesia, Tbk

Termination of Employment (PHK) for employees is a thing that is very avoided for every employee, it stops there based on their own request, but there is also a reason for regulations that no longer allow the employee to continue his work. Cases of termination of employment (layoffs) against employees in a company often occur. In PT. PP London Sumatera Indonesia, Tbk precisely in the office of the Bah Lias Research Station (BLRS) there were 76 employees laid off. And in the Bah Lias Estate (BLE) office there were 21-22 employees who were laid off. The company will make efficiency because of the excess ratio. Standardization ratio set by the company is 0.16. But the company has exceeded the existing ratio. The service period in the company is 55 years old. After 55 years the company will retire the worker according to the applicable law (Law 13 of 2000). For employees affected by the R program from the company, their rights will be paid according to applicable laws. In this efficiency, there are 4 R program criteria, namely: lose day is workers who are often absent while working or are absent, unproductive are workers who do not have work or workers who are often sick, nearing retirement. The service period in the company is 55 years old, so it is required to retire if the work period has reached 55 years. And the last criterion is undisciplined is workers who are late for work hours and are absent from work.

How to Reduce the Risk of Arteriovenous Fistula Dysfunction by Observing Prepump Arterial Pressure during Hemodialysis: A Multicenter Retrospective Study

<b><i>Objective:</i></b> Prepump arterial (Pa) pressure indicates the ease or difficulty with which the blood pump can draw blood from the vascular access (VA) during hemodialysis. Some studies have suggested that the absolute value of the Pa pressure to the extracorporeal blood pump flow (Qb) ratio set on the machine (|Pa/Qb|) can reflect the dysfunction of VA. This study was conducted to explore the impact of arteriovenous fistula (AVF) dysfunction and to explore the clinical reference value of |Pa/Qb|. <b><i>Methods:</i></b> We retrospectively identified adults who underwent hemodialysis at 3 hospitals. Data were acquired from electronic health records. We evaluated the pattern of the association between |Pa/Qb| and AVF dysfunction during 1 year using a Cox proportional hazards regression model with restricted cubic splines. Then, the patients were grouped based on the results, and hazard ratios were compared for different intervals of |Pa/Qb|. <b><i>Results:</i></b> A total of 490 patients were analyzed, with an average age of 55 (44, 66) years. There were a total of 85 cases of AVF dysfunction, of which 50 cases were stenosis and 35 cases were thrombosis. There was a U-shaped association between |Pa/Qb| and the risk of AVF dysfunction (<i>p</i> for nonlinearity &#x3c;0.001). |Pa/Qb| values &#x3c;0.30 and &#x3e;0.52 increased the risk of AVF dysfunction. Compared with the group with a |Pa/Qb| value between 0.30 and 0.52, the groups with |Pa/Qb| &#x3c;0.30 and |Pa/Qb| &#x3e;0.52 had a 4.04-fold (<i>p</i> = 0.002) and 3.41-fold (<i>p</i> &#x3c; 0.001) greater risk of AVF dysfunction, respectively. <b><i>Conclusions:</i></b> The appropriate range of |Pa/Qb| is between 0.30 and 0.52. When |Pa/Qb| is &#x3c;0.30 or &#x3e;0.52, the patient’s AVF function or Qb setting should be reevaluated to prevent subsequent failure.

Efficient Gear Ratio Selection of a Single-Speed Drivetrain for Improved Electric Vehicle Energy Consumption

The electric vehicle (EV) market has grown over the last few years and even though electric vehicles do not currently possess a high market segment, it is projected that they will do so by 2030. Currently, the electric vehicle industry is looking to resolve the issue of vehicle range, using higher battery capacities and fast charging. Energy consumption is a key issue which heavily effects charging frequency and infrastructure and, therefore, the widespread use of EVs. Although several factors that influence energy consumption of EVs have been identified, a key technology that can make electric vehicles more energy efficient is drivetrain design and development. Based on electric motors’ high torque capabilities, single-speed transmissions are preferred on many light and urban vehicles. In the context of this paper, a prototype electric vehicle is used as a test bed to evaluate energy consumption related to different gear ratio usage on single-speed transmission. For this purpose, real-time data are recorded from experimental road tests and a dynamic model of the vehicle is created and fine-tuned using dedicated software. Dynamic simulations are performed to compare and evaluate different gear ratio set-ups, providing valuable insights into their effect on energy consumption. The correlation of experimental and simulation data is used for the validation of the dynamic model and the evaluation of the results towards the selection of the optimal gear ratio. Based on the aforementioned data, we provide useful information from numerous experimental and simulation results that can be used to evaluate gear ratio effects on electric vehicles’ energy consumption and, at the same time, help to formulate evolving concepts of smart grid and EV integration.

Numerical Optimization of a Bicylindrical Resonator Impedance: Differences and Common Features Between a Saxophone Resonator and a Bicylindrical Resonator

This paper explores the analogy between a saxophone resonator and a bicylindrical resonator, sometimes called transverse saxophone or cylindrical saxophone. The dimensions of a bicylindrical resonator are optimized numerically to approximate a saxophone impedance. The target is the impedance measured on an usual saxophone. A classical gradient-based non-linear least-square fit function is used. Several cost functions corresponding to distances to the target impedance are assessed, according to their influence on the optimal geometry. Compromises appear between the frequency regions depending on the cost function. It is shown that the chosen cost functions are differentiable and locally convex. The convexity region contains the initial geometrical dimensions obtained by crude approximation of the first resonance frequency of the target. One optimal geometry is submitted to further analysis using descriptors of the impedance. Its deviations from the target saxophone are put into perspective with the discrepancies between the target saxophone and a saxophone from a different manufacture. Descriptors such as harmonicity or impedance peak ratio set the bicylindrical resonator apart from saxophone resonators, despite a good agreement of the resonance frequencies. Therefore, a reed instrument with a bicylindrical resonator could be tuned to produce the same notes as a saxophone, but due to differences in the intrinsic characteristics of the resonator, it should be considered not as a saxophone but as a distinct instrument.

DIRECTIONS SETS: A GENERALISATION OF RATIO SETS

For every integer $k\geq 2$ and every $A\subseteq \mathbb{N}$, we define the $k$-directions sets of $A$ as $D^{k}(A):=\{\boldsymbol{a}/\Vert \boldsymbol{a}\Vert :\boldsymbol{a}\in A^{k}\}$ and $D^{\text{}\underline{k}}(A):=\{\boldsymbol{a}/\Vert \boldsymbol{a}\Vert :\boldsymbol{a}\in A^{\text{}\underline{k}}\}$, where $\Vert \cdot \Vert$ is the Euclidean norm and $A^{\text{}\underline{k}}:=\{\boldsymbol{a}\in A^{k}:a_{i}\neq a_{j}\text{ for all }i\neq j\}$. Via an appropriate homeomorphism, $D^{k}(A)$ is a generalisation of the ratio set$R(A):=\{a/b:a,b\in A\}$. We study $D^{k}(A)$ and $D^{\text{}\underline{k}}(A)$ as subspaces of $S^{k-1}:=\{\boldsymbol{x}\in [0,1]^{k}:\Vert \boldsymbol{x}\Vert =1\}$. In particular, generalising a result of Bukor and Tóth, we provide a characterisation of the sets $X\subseteq S^{k-1}$ such that there exists $A\subseteq \mathbb{N}$ satisfying $D^{\text{}\underline{k}}(A)^{\prime }=X$, where $Y^{\prime }$ denotes the set of accumulation points of $Y$. Moreover, we provide a simple sufficient condition for $D^{k}(A)$ to be dense in $S^{k-1}$. We conclude with questions for further research.

Orangia Highways (A)

The decision maker is in charge of procurement auctions at the department of transportation of Orangia (a fictitious U.S. state). Students are asked to assist him in estimating the winning bids in various auctions concerning highway repair jobs using data on past auctions. The decision maker is faced with various professional, statistical, and ethical dilemmas.To analyze highway procurement auctions from the buyer-auctioneer perspective, establish basic facts regarding the project price-to-estimated cost ratio, set up and estimate a structural regression model to predict the winning bid, and compute the probability the winning price will be below estimated cost. Difficulties include heteroskedasticity, logarithmic specification, and omitted variable bias. Also to estimate a Logit regression and predict bidder collusion probability.

Study on the Effect and Mechanism of Aerodynamic Measures for the Vortex-Induced Vibration of Separate Pairs of Box Girders in Cable-Stayed Bridges

Although not always resulting in catastrophic failures, vortex-induced vibration (VIV) response can seriously impact the fatigue life and functionality of bridges, especially for separate pairs of box girders in cable-stayed bridges. This study investigates the effects of three aerodynamic measures: grating, inclined web plate, and the baffles on separated box girders in the cable-stayed bridges. The experimental result indicates that the grating of different opening ratios can control the vortex-induced vibration effectively, and the optimized grating opening ratio set in this paper is 40%. Increasing the angle of inclined web plate has a great control on mitigation of the vortex-induced vibration. However, there is an optimum angle where the amplitude of vortex-induced vibration is the smallest at low wind speed. The amplitude of vortex-induced vibration becomes larger with the increase of the web inclined angle that exceeds the optimum angle. Comparatively, the baffles installed on both sides of the inclined webs are more effective to restrain the vortex-induced resonance. The Computational Fluent Dynamics (CFD) software is utilized to investigate the mechanism of the experimental results.