Slow Ships Research Articles

PENERAPAN METODE SUPPLY CHAIN MANAGEMENT PADA SISTEM INFORMASI PENDISTRIBUSIAN SCRAP PT. PACIFIC MEDAN INDUSTRI BERBASIS WEBSITE

Pacific Medan Industri, a leading producer of palm oil, faces significant challenges with its scrap distribution system, which currently relies on manual processes. This manual system has been identified as having several major issues, including inaccuracies in data recording and management, delays in the shipping process, and ineffective coordination between various units within the supply chain. These issues not only lead to low operational efficiency but also risk disrupting customer satisfaction and diminishing the company's competitive edge in an increasingly competitive market. This study aims to address these problems by optimizing the scrap distribution system through the application of Supply Chain Management (SCM) principles. Using a qualitative approach that includes literature review, in-depth interviews with stakeholders, and relevant documentation analysis, this research explores the various weaknesses present in the current manual scrap distribution system. The analysis reveals significant shortcomings, such as inefficiencies in data management, lack of integration between units resulting in poor coordination, and slow shipping processes that hinder productivity and customer satisfaction. As a solution, the study proposes the development of a SCM-based information distribution system. This system is designed to address the identified weaknesses by leveraging current technology to automate distribution processes, improve data accuracy, expedite shipping times, and enhance communication and coordination between units in the supply chain. The implementation of this system is expected to enhance overall operational efficiency, improve scrap management, and ensure better coordination across the entire supply chain. It is anticipated that PT. Pacific Medan Industri will benefit from increased operational efficiency, improved customer satisfaction, and a strengthened competitive position in the market through the adoption of this SCM-based information distribution system. Keywords: Supply Chain Management, Scrap, PT. Pacific Medan Industri.

A novel sea clutter suppression method based on SVD‐FRFT at low signal‐to‐clutter ratio

AbstractThe target and sea clutter Doppler domains frequently overlap due to the frequent passage of slow ship targets through the sea clutter zone. In this letter, a novel sea clutter suppression method is suggested as a solution to this issue, whose key is a novel singular value zeroing criterion guided by the search results of two‐dimensional spectral peaks. Verified by simulations, the method proposed can improve signal‐to‐clutter ratio (SCR) from −8 to 41 dB in the frequency domain and be more effective than the conventional SVD‐FRFT (a method for joint application of singular value decomposition and fractional Fourier transformer) and improved SVD‐FRFT.

RANS investigation of the hydrodynamic interactions between two approaching ships in shallow water considering the effects of drift motion and rudder deflection

There exists a high risk of collision between two approaching ships in the lightering operation. The investigations of the hydrodynamic interactions between such two ships are of great interest to ensure navigation safety. To this end, the RANS (Reynolds-Averaged Navier-Stokes) technique based on OpenFOAM is employed to simulate the flow around two approaching Wigleys in this work. The two Wigleys are identical. Due to the slow ship speed, the water-air flow is simplified as the double-body flow in the present consideration. The computed hydrodynamic side forces and yaw moments are compared with the available experimental data, and acceptable agreements are found. The effects of lateral distance between the two ships, water depth, rudder deflection, ship scale and drift motion on the hydrodynamic forces and moments on both ships are analyzed. This study shows that the suction forces and bow-out moments generally become larger as the water depth or lateral distance decreases, while the suction forces trends to become repulsion forces when both the water depth and lateral distance are very small. It is also found that the rudder deflection of one ship has a very little hydrodynamic disturbance on the other ship, rather than the drift motion which affects much the hydrodynamic forces and moments on the other ship especially in very shallow water.

Radiation Sensitivity Analysis of Ocean Wake Information Detection System Based on Visible Light Remote Sensing

Various ships and submerged moving objects in the ocean are key targets of numerous remote sensors. Wake has developed into one of the key detection targets of ocean visible light remote sensing as the visible trail information left by moving objects on the ocean surface. In the situation of slow ship speed, deep draft, and the existence of air clouds and fog, the wake target signal is weak, and the signal-to-noise ratio is low due to the low reflectivity of the sea surface and the interference of the background waves on the sea surface. This paper analyzes the radiative sensitivity of visible light imaging systems for the most crucial wake detection indicator in order to address the aforementioned issues. The noise equivalent reflectance difference, which is widely used to describe radiative sensitivity in engineering, is derived and numerically simulated by establishing the imaging link model based on TDICCD. We calculated the noise equivalent reflectivity difference for eight bands commonly used in ocean remote sensing; results show that the index is generally on the order of 10−4, and with the increase in the central wavelength, the value of noise equivalent reflectance difference also shows a downward trend and is stable within a certain value range. This research provides theoretical guidance for the engineering design of a visible spectrum imaging system for wake detection, aids in improving the imaging system’s capacity to detect weak wake signals, and provides a basis for subsequent wake detection and enhancement processing, removal of false wakes, and retrieval of ship information.

Modeling Kelvin wake imaging mechanism of visible spectral remote sensing

Kelvin wake is an important detection target of ocean visible spectral remote sensing. In the case of slow ship speed and low atmospheric transmissivity, the wake signal is weak and the SNR (Signal-Noise Ratio) is low. Therefore, the image obtained by the visible spectral remote sensing imaging system is often “unclear”. In order to solve the problems above, this paper carries out the modeling of Kelvin wake imaging mechanism of visible spectral remote sensing. The Kelvin wake reflection distribution characteristics of rough sea surface are simulated based on the hydrodynamic model of Kelvin wake and the probability density distribution of rough sea surface, and a method to quantify the reflectance resolution for Kelvin wake imaging of rough sea surface is proposed. The changes in reflectance resolution caused by different wind speeds, ship parameters, source angle, receiver angle are also analyzed. Then the imaging link model of TDI-CCD (Time Delay and Integration Charge Coupled Devices) imaging system was established. The imaging results of a Kelvin wake reflected on the rough sea surface are simulated, and the impact of the changes of main imaging parameters (optical system F number, quantization bits, integration stages) on the imaging results of a Kelvin wake at different reflectance resolutions are analyzed. The research has clarified the mechanism of the visible spectral remote sensing system to clearly imaging the Kelvin wake, which can provide guidance on parameters design and attitude planning for the ocean visible spectral remote sensing system, and improve the ability of the imaging system to detect weak wake signals.

Scale vs Quality of Service: The Impact of Market Growth on Delivery Times

Supply chains typically benefit from economies of scale due to market growth. However, are there any tradeoffs due to rapid market growth? In particular, what is the impact on customer experience? While it is well-established that there are diminishing returns for scale in supply chains in terms of marginal costs, our empirical results suggest that there is also a tradeoff between scale and quality of service for new customers. We use data from the e-commerce platform JD that describe customer transactions and deliveries for a single product category for March 2018. We analyze 184,085 shipments and regress various metrics related to delivery speed and supply chain operational complexity while controlling for district-, SKU-, customer-, warehouse-, and order-related effects. We find that newer customers suffer from slower shipping compared to customers who have been using JD's platform longer. For example, customers who started using JD's platform within the last 6 months are about 4% less likely to get single-day shipping than customers who signed up around 4 years ago. As the historical centers of demand exhaust their growth, new customers come from progressively more distant areas with smaller warehouses, and the existing supply chain cannot keep up such geographically dispersed market growth. Hence, rapidly growing firms that are keen on acquiring and retaining their new customers may want to carefully manage this tradeoff since slow shipping can lead to a high customer churn.

Ionospheric phase decontamination based on sparse decomposition for multiple‐input multiple‐output over‐the‐horizon radar

Ionospheric phase contamination deteriorates the coherence of high-frequency echoes, reducing the detection performance of multiple-input multiple-output over-the-horizon radar (MIMO-OTHR) on slow ships. A high-precision phase decontamination method approximately extracts a single-frequency reference signal from the echo in advance, called the calibration signal, which is completed in the Doppler domain. When severe ionospheric phase contamination causes the echo Bragg peaks to overlap, this operation is difficult to achieve. To solve this problem, the authors transform calibration signal extraction into a sparse decomposition of a short-time sequence vector set and solve it by an iterative method. This process is based on the sparsity of the short-time sequence in the Doppler domain, as well as the reversibility between the original data vector, accumulated after a long coherence time, and its corresponding short-time sequence vector set, obtained by sliding window segmentation of the original data vector. Then the ionospheric phase contamination is extracted from the calibration signal to compensate for the original echo. Compared with existing methods, the proposed method can adaptively extract a calibration signal to achieve high-precision phase compensation of a MIMO-OTHR echo while adding a more robust performance against noise when considering overlapping Bragg peaks formed by serious ionospheric phase contamination.

Fast and slow ships from China: The speed of Dutch East Indiamen reconsidered

This article questions the commonly held assumption that the ships of the Dutch East India Company VOC were slower than those of other East India companies. Recently, Solar and De Zwart showed that Dutch ships were slower on outward voyages to a number of Asian destinations during the periods 1770–1775 and 1783–1792. They cited as plausible explanations differences in ship design resulting from constraints imposed by the Dutch shallow inland waterways and the slow adaptation of copper sheathing in the late eighteenth century. Research by the author of this article leads to a critical assessment of these explanations. Moreover, additional new research into homebound voyages from China undertaken by ships of four East India companies, for the periods 1730–1740, 1750–1755, 1770–1775 and 1783–1792, leads to the outcome that – concerning speed – Dutch ships could compete very well with those of the English, Swedish and Danish companies.

Multi‐mode propagation mode localisation and spread‐Doppler clutter suppression method for multiple‐input multiple‐output over‐the‐horizon radar

Multi-mode spread-Doppler clutter (SDC), caused by a stratified ionosphere, affects the detection performance of over-the-horizon radar on slow ships. To improve a multiple-input multiple-output over-the-horizon radar (MIMO-OTHR) system's performance and to mitigate the lingering effect of SDC, a novel multi-mode SDC suppression method based on full-mode spatial separation is proposed here. Furthermore, authors' method can estimate the elevation angle of direction of departure (DOD) and direction of arrival (DOA), contributing to mode localisation. By applying the bi-orthogonality of matrices, the cost function of single-mode component analysis is constructed under a least square criterion. By iteratively solving for the cost function, and by applying a systematic multistage decomposition, the elevation DOD and DOA and the slow-time Doppler information of each mode are obtained sequentially. Compared with classical SOBI and SS-SOBI methods, the proposed method improves the output signal-to-clutter-plus-noise ratio for spatial filtering. The estimated DOD and DOA do not need to be paired, reducing the angle error inherent in the SR method while performing the transmit-receive cascade refinement searching step. Simulation results demonstrate the excellent performance of the proposed method, which is beneficial to improve the ability of MIMO-OTHR to detect slow ships and determine the propagation mode.

KEMAMPUAN MEMBAYAR PENUMPANG TERHADAP TARIF KAPAL CEPAT DAN KAPAL LAMBAT JALUR PENYEBERANGAN KE KOTA SABANG

Transport aims to provide the public with a service of mobility or mobility that is affordable to purchase and creates a condition of transportation services that is safe, convenient, fast, smooth, orderly, reliable and competitive, sea transport plays an important role in every activity, indeed are in the waters. This study aims to analyze the characteristics of users of fast and slow ship transportation services, analyze the ability to pay (ATP) based on the allocation of income. From the research results obtained Ability To Pay (ATP) fast ship of Rp. 42.284, - with an ideal rate of Rp. 56,367, - and still require subsidy of Rp. 37.716, - while for aboard slow ship Ability To Pay (ATP) of Rp. 16.660, - with an ideal rate of Rp. 22,995, - and still require a subsidy Rp. 10,340,- When compared to tariffs, all respondents (100%) of ATP values are well below the official tariff rates. The value of ATP obtained is lower than the official tariff required for subsidies, for fast vessels and slow vessels it is not possible to increase tariff rates. Average value / mean level of fast ship service including good category and for slow ship enter very good service category

A machine learning approach to product review disambiguation based on function, form and behavior classification

Online product reviews have been shown to be a viable source of information for helping customers make informed purchasing decisions. In many cases, users of online shopping platforms have the ability to rate products on a numerical scale, and also provide textual feedback pertaining to a purchased product. Beyond using online product review platforms as customer decision support systems, this information rich data source could also aid designers seeking to increase the chances of their products being successful in the market through a deeper understanding of market needs. However, the increasing size and complexity of products on the market makes manual analysis of such data challenging. Information obtained from such sources, if not mined correctly, risks misrepresenting a product's true success/failure (e.g., a customer leaves a one star rating because of the slow shipping service of a product, not necessarily that he/she dislikes the product). The objective of this paper is three fold: i) to propose a machine learning approach that disambiguates online customer review feedback by classifying them into one of three direct product characteristics (i.e., form, function or behavior) and two indirect product characteristics (i.e., service and other), ii) to discover the machine learning algorithm that yields the highest and most generalizable results in achieving objective i) and iii) to quantify the correlation between product ratings and direct and indirect product characteristics. A case study involving review data for products mined from e-commerce websites is presented to demonstrate the validity of the proposed method. A multilayered (i.e., k-fold and leave one out) validation approach is presented to explore the generalizability of the proposed method. The resulting machine learning model achieved classification accuracies of 82.44% for within product classification, 80.84% for across product classification, 79.03% for across product type classification and 80.64% for across product domain classification. Furthermore, it was determined that the form of a product had the highest Pearson Correlation Coefficient relating to a product's star rating, with a value of 0.934. The scientific contributions of this work have the potential to transform the manner in which both product designers and customers incorporate product reviews into their decision making processes by quantifying the relationship between product reviews and product characteristics.

Coordinating supply chains with stochastic demand by crashing lead times

In this paper, a method to coordinate a seller-buyer supply chain (SC) system by means of controlling the lead time (LT) with the consideration of different shipping modes is proposed. To be specific, two shipping modes (one fast and one slow) are considered in the proposed model. Through spending more and using a fast shipping mode, the seller can reduce LT. The cost of LT crashing is modeled as a fixed-charge step function in which a slow shipping mode can only reduce LT to a certain level and crashing LT beyond this level needs to replace the current shipping mode with a fast shipping mode. In this model, through controlling LT as an incentive mechanism, the seller motivates the buyer to participate in the joint decision making. The conditions for both members under which they are convinced to participate in the joint decision making plan are derived. The results show that more spending and, under certain circumstances, using the fast shipping mode can provide sufficient motivation for the buyer to coordinate the order quantity and the service level (SL) decisions in the supply chain simultaneously. Numerical experiments further demonstrate that the proposed model is highly applicable, especially under the case with high demand variations.

Multi‐mode clutter suppression of multiple‐input–multiple‐output over‐the‐horizon radar based on blind source separation

Spread-Doppler clutter caused by multi-mode propagation seriously affects the over-the-horizon radar detection performance for slow ships. To solve this problem, the authors propose to suppress multi-mode clutter using spatial information in the multiple-input–multiple-output over-the-horizon radar system. Traditional processing algorithms need prior information of the target direction. However, it is often not readily available. In this study, they propose a novel multi-mode clutter suppression algorithm based on the second-order blind identification (SOBI) technique. The proposed algorithm does not need prior information of the target direction and can effectively suppress the multi-mode clutter. Considering that the SOBI algorithm affected by the similarity in sources spectra, they improve the proposed algorithm using the spatial smoothing technique. Simulation results show that, in the single target scene, the improved algorithm can effectively eliminate the spectrum burrs caused by incomplete separation, making separated signals smoother. Signal-to-clutter-noise ratio is greatly improved. The good multi-mode clutter suppression performance is obtained. In the multi-mode scenario that double targets with the same radial velocity, that is, sources spectra have similarities, the algorithm based on SOBI cannot separate all targets. Although the improved algorithm can make all targets visible and effectively suppresses the multi-mode clutter.

Analysis and simulation for broadening first‐order sea clutter spectrum in high frequency hybrid sky‐surface wave propagation mode

In high frequency (HF) hybrid sky-surface wave radar, the first-order sea clutter broadening is very severe under the influence of ionosphere and bistatic angle, which affects the detection of slow ship target. This study analyses and simulates the broadening first-order sea clutter spectrum based on a modified first-order ocean surface radar cross-section (RCS) model using wide beam. The authors first introduce the working principle, range equation and positioning principle based on the newly-developed integrated HF sky-surface experimental system; and derive an expression for the first-order Bragg frequency. Also presented is a modified RCS model of first-order sea clutter, in which the HF sea clutter spectrum distribution characteristics and broadening mechanism are fully considered. Finally, the proposed broadening first-order sea clutter spectrum model is examined by measured data. Simulation results indicate that the proposed first-order sea clutter spectrum model can well describe the characteristics of measured sea clutter.

Letter of Reference

You were my oldest-lasting friend but that’s now severed, The divorces simultaneous, your black brother, your white wife, One potato two potato three potato four. Consider this a letter, elegy if you will, For something perished, for the heavy tree Root bound, trapped, swarmed by rats. I will not save you. The debt of blackness that I owe you has been eased, Many thousands gone. Brash, black and Brooklyn-hip, The leverage tilted to you, yours the moral mandate Of the black-rap field nigger sixties that you scooped. I ransomed the guilt of my forebears The high yellow creole stock, Painful bondage, still a slave, The honors yours, the harvest combed From what I gave, many thousands gone, Gone, the insular caste dissolved in my mother’s time, The Teches, Allimonos, Trepaniers, the brilliant women, The shrewd and lethal men, always on the fringe Of black or white, Latin in style, Colored in substance, Pan-American in range, The flittings over the color lines, the tack of their journey In the slow ship of race on sullen seas Yet to be completed, this journey still in my bloodlines. I trace it, extend it like star charts, The night navigation of birds—These puzzled parts were mine, a nose here, A hand there, an ear, a toe, the whole man Not assembled, only the veiled vision, Baffled fury of my failing parents, Their dim chant and chart of guidance Like the riddles carved on an old crypt, The incoherent hum and curse of something inside Not yet dead.

Short surface waves in the Canadian Arctic in 2007 and 2008

[1] We have collected time series data of short oceanic waves as a part of the International Polar Year (IPY) 2007–2008. Using a shipboard laser wave slope (LAWAS) system operating at 900 nm, we have obtained wave slopes measurements up to 60 rad m−1 wave number. We have compared our in situ wave slopes with collocated and concurrent high-resolution upwind Normalized Radar Cross Sections (NRCS) collected by QuikSCAT. The LAWAS measured wave slope spectra were consistent with local wind speeds and QuikSCAT measured NRCS. Our measured short wave mean slopes indicate their enhancement by long waves (0–1 rad m−1) at small values of long-wave slope. Concurrent with wave slope measurements, the strength of the reflected LAWAS light beam was analyzed in terms of the light attenuation coefficient at 900 nm. We have observed a correlation between surface elevation and light attenuation. The mechanism of wave modulated beam attenuation was found to be related to the instantaneous long wave skewness.

Offshore Outsourcing, Yield Uncertainty, and Contingency Responses

In this article, we study an offshore outsourcing arrangement for a buyer of a produced good in the presence of supply yield uncertainty. We analyze the performance of contingency responses to the realized yield information at the end of production and prior to its delivery to the destination market. The contingency responses considered are: (i) Emergency Production via which an emergency order is placed with another fast and perfectly reliable offshore supplier; (ii) Emergency Production and Delivery via which an expedited shipping of (partial or total) good units is used on top of Emergency Production. Within a periodic review inventory system with uncertain demand setting, we theoretically characterize the optimal decisions on the cycle order size, the emergency order size, and the way to split the available good units between the fast and slow shipping modes. We provide comparative statics on how the choices of these quantities are affected by each other and by the demand and yield uncertainties. We use numerical examples to illustrate the values of such contingency responses and the impact of other factors on the cost of meeting demand.

A Dollar for Your Thoughts: Feedback-Conditional Rebates on eBay

We run a series of controlled field experiments on eBay where buyers are rewarded for providing feedback. Our results provide little support for the hypothesis of buyers’ rational economic behavior: the likelihood of feedback barely increases as we increase feedback rebate values; also, the speed of feedback, bid levels, and the number of bids are all insensitive to rebate values. By contrast, we find evidence consistent with reciprocal buyer behavior. Lower transaction quality leads to a higher probability of negative feedback as well as a speeding up of such negative feedback. However, when transaction quality is low (as measured by slow shipping), offering a rebate significantly decreases the likelihood of negative feedback. All in all, our results are consistent with the hypothesis that buyers reciprocate the sellers’ “good deeds” (feedback rebate, high transaction quality) with more frequent and more favorable feedback. As a result, sellers can “buy” feedback, but such feedback is likely to be biased. Data, as supplemental material, are available at http://dx.doi.org/10.1287/mnsc.2014.2074 . This paper was accepted by Teck-Hua Ho, behavioral economics.

Slow shipping hobbles Chinese science

Slow shipping hobbles Chinese science

Production and Transportation Integration for a Make-to-Order Manufacturing Company with a Commit-to-Delivery Business Mode

When a make-to-order manufacturing company adopts a commit-to-delivery business mode, it commits a delivery due date for an order and is responsible for the shipping cost. Without loss of generality, we consider that transportation is done by a third-party logistics company, such as FedEx or UPS, which provides multiple shipping modes such as overnight, one-day, two-day delivery, and more. When the transportation time has to be short, clearly, shipping cost is more expensive than it could have been. How should a company schedule production for accepted orders so that the company can leave enough transportation time for orders to take slow shipping modes to reduce the shipping cost? We study this problem of integrating the production and transportation functions for a manufacturing company producing a variety of customized products in a make-to-order environment with a commit-to-delivery mode of business. Various realistic scenarios are investigated in increasing order of complexity. When partial delivery is allowed by customers, we provide both a mixed-integer programming (MIP) model and a minimum cost flow model. We show that nonpreemptive earliest due date (NEDD) production schedules are optimal when partial delivery is allowed and shipping cost is a decreasing convex function with transportation time. When partial delivery is not allowed, we develop an MIP model and prove that the problem is NP-hard. An efficient heuristic algorithm with polynomial computation time is provided for the NP-hard problem. It gives near-optimal production schedules, as shown via thousands of numerical experiments. We also provide models and analysis for other scenarios where shipping cost accounts for customer locations and quantity discounts.