AN INVENTORY CONTROL POLICY WITH TRACKING INFORMATION FOR DUAL-CHANNEL SUPPLY CHAINS

Recently, many products have been sold through retail stores and direct sales via the Internet. For dual-channel supply chains, Chiang and Monahan (2010) and Chiang (2010) have proposed an inventory control policy; however, they assumed one-for-one replenishment and short replenishment lead times. For single-channel supply chains with long and uncertain replenishment lead times, Liu et al. (2009) have introduced tracking information into inventory control. However, they did not consider the cost of tracking information. Therefore, in this paper, a Markov chain model for dual-channel supply chains with long and uncertain replenishment lead times is developed, and an inventory control policy is proposed that considers tracking information and its cost. The performance of the proposed policy is evaluated and compared with two policies, one without tracking information and the other without reduplicated normal replenishment. The results show the effectiveness of the proposed policy

Mixed Sn–Ge Perovskite for Enhanced Perovskite Solar Cell Performance in Air

Lead-based perovskite solar cells have gained ground in recent years, showing efficiency as high as 20%, which is on par with that of silicon solar cells. However, the toxicity of lead makes it a nonideal candidate for use in solar cells. Alternatively, tin-based perovskites have been proposed because of their nontoxic nature and abundance. Unfortunately, these solar cells suffer from low efficiency and stability. Here, we propose a new type of perovskite material based on mixed tin and germanium. The material showed a band gap around 1.4–1.5 eV as measured from photoacoustic spectroscopy, which is ideal from the perspective of solar cells. In a solar cell device with inverted planar structure, pure tin perovskite solar cell showed a moderate efficiency of 3.31%. With 5% doping of germanium into the perovskite, the efficiency improved up to 4.48% (6.90% after 72 h) when measured in air without encapsulation

Role of device architecture and AlOX interlayer in organic Schottky diodes and their interpretation by analytical modeling

Considering the pivotal role of interfaces in controlling the performance of organic electronic devices, implications of metal/organic interfacial quality in a Schottky barrier diode (SBD) are investigated. The nature of metal/organic interfaces and the thin film quality of regioregular poly (3-hexylthiophene) based SBDs fabricated in different device architectures are investigated using experimental and theoretical modeling. The importance of oxidized aluminum nanostructures as an interlayer at the Schottky interface for the dramatic enhancement of the rectification ratio (>106 at ±5 V) has been demonstrated, which is attributed to suppressed leakage current due to the oxide layer and the formation of a charge double layer. Furthermore, electrical performances of all the SBDs were modeled in terms of an underlying particular phenomenon solely or with the combination of multiple physical phenomena. The combined modeling equation used in this work fits well for the different device architectures, which validates its generality in order to extract the device parameters

Magnesium-Doped MAPbI3 Perovskite Layers for Enhanced Photovoltaic Performance in Humid Air Atmosphere

Despite the high efficiency of MAPbI3 perovskite solar cells, the long term stability and degradation in humid atmosphere are issues that still needed to be addressed. In this work, magnesium iodide (MgI2) was first successfully used as a dopant into MAPbI3 perovskite prepared in humid air atmosphere. Mg doping decreased the valence band level, which was determined from photoelectron yield spectroscopy. Compared to the pristine MAPbI3 perovskite film, the 1.0% Mg-doped perovskite film showed increased crystal grain size and formation of pinhole-free perovskite film. Performance of the solar cell was increased from 14.2% of the doping-free solar cell to 17.8% of 1.0% Mg-doped device. Moreover, 90% of the original power conversion efficiency was still retained after storage in 30–40% relative humidity for 600 h

All‐Inorganic CsPb1−xGexI2Br Perovskite with Enhanced Phase Stability and Photovoltaic Performance

01 August Compared with organic‐inorganic perovskites, all‐inorganic cesium‐based perovskites without volatile organic compounds have gained extensive interests because of the high thermal stability. However, they have a problem on phase transition from cubic phase (active for photo‐electric conversion) to orthorhombic phase (inactive for photo‐electric conversion) at room temperature, which has hindered further progress. Herein, novel inorganic CsPb1−xGexI2Br perovskites were prepared in humid ambient atmosphere without a glovebox. The phase stability of the all‐inorganic perovskite was effectively enhanced after germanium addition. In addition, the highest power conversion efficiency of 10.8 % with high open‐circuit voltage (VOC) of 1.27 V in a planar solar cell based on CsPb0.8Ge0.2I2Br perovskite was achieved. Furthermore, the highest VOC up to 1.34 V was obtained by CsPb0.7Ge0.3I2Br perovskite, which is a remarkable record in the field of all‐inorganic perovskite solar cells. More importantly, all the photovoltaic parameters of CsPb0.8Ge0.2I2Br perovskite solar cells showed nearly no decay after 7 h measurement in 50–60 % relative humidity without encapsulation

Melamine Hydroiodide Functionalized MAPbI3 Perovskite with Enhanced Photovoltaic Performance and Stability in Ambient Atmosphere

Despite the remarkable performance of organometallic halide perovskite solar cells (PSCs), their ultimate stability is still a major issue that inhibits the commercialization of this eminent technology. Herein, melamine hydroiodide (MLAI) is added to function methyl ammonium (CH3NH3+, MA+) lead iodide perovskite for fabricating structured perovskite with enhanced photovoltaic performance and stability in the harsh ambient atmosphere (35 °C, 60–70% relative humidity). Nearly no new phase formed even incorporated 25 mol.% MLAI induces the strain in the perovskite crystal structure. The MLAI‐structured perovskite film shows a denser and smoother surface than the pristine MAPbI3 perovskite. Planar PSCs based on 2 mol.% MLAI‐functionalized perovskite show 17.2% power conversion efficiency with nearly no hysteresis which is much higher than pristine MAPbI3 PSCs. Most importantly, the solar cell devices based on 2 mol.% MLAI‐functionalized perovskite still retain over 90% of the initial performance after being kept in ambient atmosphere for more than 560 h without encapsulation

Analysis of Self-balancing Production Line with Bottleneck

自己バランスラインとは,従来のラインバランシングの手法を用いたラインと異なり,生産環境の変化に対して作業者に仕事が動的に割り当てられることによって,次第に仕事の作業が速い作業者は作業を多く受け持ち,仕事の作業が遅い作業者は作業を少なく受け持つようになり各作業者の作業速度に応じてバランスを保つことができるラインのことである.特に,各作業者の作業開始位置が1点に収束し,生産率が最大になる条件は求められてきた.しかし,ボトルネック区間の存在によってバランスをとり生産率が最大になる条件が変化することが考えられ解析の必要があるが,それを考慮した論文はほとんど見当たらない.本研究では,自己バランスラインにおけるボトルネック区間が存在する場合に対してラインを戻る時間を考慮する場合と無視する場合両方について述べ,自己バランスを達成する条件を解析する.In traditional production lines designed using the line-balancing method, each worker is usually assigned to a particular fixed work, and it is valuable to decrease the training task to master the assigned work. However, when an imbalance among workers' speeds exists, the slowest worker will delay the overall work in the production line, and the production rate of the production line will also decrease. To solve this problem, a "Self-Balancing Production Line" was introduced in which each worker is assigned to work dynamically, thus enabling balanced production to be retained. For this kind of line, convergence conditions, where the position of each worker converges to a fixed point and the production rate becomes the maximum, were derived under the same workload. However, in reality bottleneck in which a lot of works have to be processed exists, and few papers assume bottleneck. When considering bottleneck, conditions for maintaining balance that maximize production rate are changed. Therefore, it is important to analyze this effect. In this paper, self-balancing production line with bottleneck is formulated and analyzed for both cases that consider and ignore the walk-back time, and the conditions that enable balanced production are analyzed.社団法人日本経営工学会論文奨励賞受賞論

Inventory control in a two-echelon dual-channel supply chain with setup of production and delivery

This paper considers a two-echelon dual-channel supply chain model with setup of production and delivery and develops a new inventory control policy for the supply chain. Previously, a two-echelon supply chain model without setup of production and delivery is considered and a one-for-one inventory control policy is applied to the supply chain. In the inventory control policy, production is stopped when the warehouse inventory reaches the upper limit and is started again immediately after the inventory drops below the limit. Moreover, delivery to the retailer is stopped when the store inventory reaches the upper limit and is started again immediately after the inventory drops below the limit. The total cost that consists of inventory holding costs and lost sales cost is considered, and setup costs are not considered in the total cost. Once setup costs are introduced, the one-for-one inventory control policy is no longer appropriate. Then, this paper develops a new control policy for the two-echelon dual-channel supply chain with setup of production and delivery. As performance measure, the total cost that consists of inventory holding costs, lost sales cost, and production and delivery setup costs is considered, and the total cost calculated on the basis of Markov analysis demonstrates the effectiveness of the proposed control policy.Inventory control Dual-channel Supply chain Setup