bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the representation of HONO chemistry in CMAQ and examining its impact on haze over China
Authors: Zhang Shuping , Sarwar Golam , Xing Jia , Chu Biwu , Xue Chaoyang , Sarav Arunachalam , Ding Dian , Zheng Haotian , Mu Yujing , Duan Fengkui , Ma Tao , He Hong
Published: March 2021

Abstract. We compare Community Multiscale Air Quality (CMAQ) model predictions with measured nitrous acid (HONO) concentrations in Beijing, China for December 2015. The model with the existing HONO chemistry in CMAQ severely under-estimates the observed HONO concentrations with a normalized mean bias of −97 %. We revise the HONO chemistry in the model by implementing six additional heterogeneous reactions in the model: reaction of nitrogen dioxide (NO2) on ground surfaces, reaction of NO2 on aerosol surfaces, reaction of NO2 on soot surfaces, photolysis of aerosol nitrate, nitric acid displacement reaction, and hydrochloric acid displacement reaction. The model with the revised chemistry substantially increases HONO predictions and improves the comparison with observed data with a normalized mean bias of −5 %. The photolysis of HONO enhances day-time hydroxyl radical by almost a factor of two. The enhanced hydroxyl radical concentrations compare favorably with observed data and produce additional sulfate via the reaction with sulfur dioxide, aerosol nitrate via the reaction with nitrogen dioxide, and secondary organic aerosols via the reactions with volatile organic compounds. The additional sulfate stemming from revised HONO chemistry improves the comparison with observed concentration; however, it does not close the gap between model prediction and the observation during polluted days.
On the importance of atmospheric loss of organic nitrates by aqueous-phase ●OH oxidation
Authors: González-Sánchez Juan Miguel , Brun Nicolas , Wu Junteng , Morin Julien , Temime-Roussel Brice , Ravier Sylvain , Mouchel-Vallon Camille , Clément Jean-Louis , Monod Anne
Published: March 2021

Abstract. Organic nitrates are secondary species in the atmosphere.
Their fate is related to the chemical transport of pollutants from polluted
areas to more distant zones. While their gas-phase chemistry has been
studied, their reactivity in condensed phases is far from being understood.
However, these compounds represent an important fraction of organic matter
in condensed phases. In particular, their partition to the aqueous phase may
be especially important for oxidized organic nitrates for which water
solubility increases with functionalization. This work has studied for the
first time the aqueous-phase ⚫OH-oxidation kinetics of four alkyl
nitrates (isopropyl nitrate, isobutyl nitrate, 1-pentyl nitrate, and
isopentyl nitrate) and three functionalized organic nitrates (α-nitrooxyacetone, 1-nitrooxy-2-propanol, and isosorbide 5-mononitrate) by
developing a novel and accurate competition kinetic method. Low reactivity
was observed, with kOH ranging from 8×107 to 3.1×109 L mol−1 s−1 at 296±2 K. Using these
results, a previously developed aqueous-phase structure–activity
relationship (SAR) was extended, and the resulting parameters confirmed the
extreme deactivating effect of the nitrate group, up to two adjacent carbon
atoms. The achieved extended SAR was then used to determine the ⚫OH-oxidation rate constants of 49 organic nitrates, including hydroxy
nitrates, ketonitrates, aldehyde nitrates, nitrooxy carboxylic acids, and
more functionalized organic nitrates such as isoprene and terpene nitrates.
Their multiphase atmospheric lifetimes towards ⚫OH oxidation were
calculated using these rate constants, and they were compared to their
gas-phase lifetimes. Large differences were observed, especially for
polyfunctional organic nitrates: for 50 % of the proposed organic nitrates
for which the ⚫OH reaction occurs mainly in the aqueous phase (more
than 50 % of the overall removal), their ⚫OH-oxidation lifetimes
increased by 20 % to 155 % under cloud/fog conditions (liquid water content LWC = 0.35 g m−3). In particular, for 83 % of the proposed terpene nitrates, the
reactivity towards ⚫OH occurred mostly (>98 %) in
the aqueous phase, while for 60 % of these terpene nitrates, their
lifetimes increased by 25 % to 140 % compared to their gas-phase
reactivity. We demonstrate that these effects are of importance under
cloud/fog conditions but also under wet aerosol conditions, especially for
the terpene nitrates. These results suggest that considering aqueous-phase
⚫OH-oxidation reactivity of biogenic nitrates is necessary to
improve the predictions of their atmospheric fate.
Estimation of PM2.5 Concentration in China Using Linear Hybrid Machine Learning Model
Authors: Song Zhihao , Chen Bin , Huang Yue , Dong Li , Yang Tingting
Published: March 2021

Abstract. The satellite remote-sensing aerosol optical depth (AOD) and meteorological elements were employed to invert PM2.5 in order to control air pollution more effectively. This paper proposes a restricted gradient-descent linear hybrid machine learning model (RGD–LHMLM) by integrating a random forest (RF), a gradient boosting regression tree (GBRT), and a deep neural network (DNN) to estimate the concentration of PM2.5 in China in 2019. The research data included Himawari-8 AOD with high spatiotemporal resolution, ERA-5 meteorological data, and geographic information. The results showed that, in the hybrid model developed by linear fitting, the DNN accounted for the largest proportion, whereas the weight coefficient was 0.62. The R2 values of RF, GBRT, and DNN were reported 0.79, 0.81, and 0.8, respectively. Preferably, the generalization ability of the mixed model was better than that of each sub-model, and R2 reached 0.84, whereas RMSE and MAE were reported 12.92 µg/m3 and 8.01 µg/m3, respectively. For the RGD-LHMLM, R2 was above 0.7 in more than 70 % of the sites, whereas RMSE and MAE were below 20 µg/m3 and 15 µg/m3, respectively, in more than 70 % of the sites due to the correlation coefficient having seasonal difference between the meteorological factor and PM2.5. Furthermore, the hybrid model performed best in winter (mean R2 was 0.84) and worst in summer (mean R2 was 0.71). The spatiotemporal distribution characteristics of PM2.5 in China were then estimated and analyzed. According to the results, there was severe pollution in winter with an average concentration of PM2.5 being reported 62.10 µg/m3. However, there was slight pollution in summer with an average concentration of PM2.5 being reported 47.39 µg/m3. The findings also indicate that North China and East China are more polluted than other areas and that their average annual concentration of PM2.5 was reported 82.68 µg/m3. Moreover, there was relatively low pollution in Inner Mongolia, Qinghai, and Tibet, for their average PM2.5 concentrations were reported below 40 µg/m3.
Lasting impact of winds on Arctic sea ice through the ocean's memory
Authors: Wang Qiang , Danilov Sergey , Mu Longjiang , Sidorenko Dmitry , Wekerle Claudia
Published: March 2021

Abstract. In this paper we studied the impact of winds on Arctic sea ice through the ocean’s memory by using numerical simulations. We found that the changes in ocean freshwater content induced by wind perturbations can significantly affect the Arctic sea ice drift, thickness, concentration and deformation rates regionally even years after the wind perturbations. Changes in the Arctic liquid freshwater content cause changes in the sea surface height and surface geostrophic currents, which further enforce a lasting and strong impact on sea ice. Both the changes in sea surface height gradient force (due to changes in sea surface height) and ice-ocean stress (due to changes in surface geostrophic currents) are found to be important in determining the overall ocean effects. The revealed ocean effects are mainly associated with changes in sea ice dynamics, not thermodynamics. Depending on the preceding atmospheric mode driving the ocean, the ocean’s memory of the wind forcing can lead to changes in Arctic sea ice characteristics with very different spatial patterns. We identified these spatial patterns associated with Arctic Oscillation, Arctic Dipole Anomaly and Beaufort High modes through dedicated numerical simulations. The dynamical impact of the ocean has strong seasonal variations, stronger in summer and weaker in winter and spring. It implies that declining trends of Arctic sea ice will very possibly allow a stronger ocean impact on the sea ice in a warming climate.
„Formularz z Uppsali“. Późnośredniowieczna
księga formularzowa biskupstw pruskich (Fontes Towarzystwo Naukowe w Toruniu,
t. 109), komentarz i edycja Radosław Biskup, Toruń: Towarzystwo Naukowe
w Toruniu, 2016, ss. 396.
Authors: Elertas Dainius , Ščavinskas Marius
Published: March 2021

Omówienie publikacji "Formularz z Uppsali". Późnośredniowieczna księga formularzowa biskupstw pruskich (Fontes Twoarzystwo Naukowe w Toruniu, T.109), Komentarz i edycja Radosław Biskup, Toruń: Towarzystwo Naukowe w Toruniu, 2016, ss.396.
The population of the Klaipeda Region after 1945: a case of repatriates
Authors: Pocytė Silva
Published: March 2021

Celem niniejszego artykułu jest omówienie sytuacji repatriantów z okręgu kłajpedzkiego w okresie
pierwszych lat powojennych, w oparciu zarówno o publikowane wcześniej, jak i niepublikowane wspomnienia
mieszkańców oraz dokumenty archiwalne. Chronologiczne granice podjętych tu badań spinają lata 1945–1951.
Przyjrzymy się sytuacji w jakiej znalazła się ludność powracająca do okręgu kłajpedzkiego z niemieckich stref
okupacyjnych.
Sytuacja repatriantów po 1945 roku była integralną częścią procesów demograficznych zachodzących
w rejonie Kłajpedy w ciągu kilku kolejnych lat powojennych. Należy jednak zauważyć, że nadal brakuje komplet�nych badań nad ludnością tego obszaru w owym czasie, w tym przyczynami przemieszczania się, składem spo�łecznym i etnicznym nowej populacji oraz stosunkami pomiędzy nowymi osadnikami a zamieszkującymi region
nielicznymi autochtonami.
Trudy związane z dostosowaniem się do nowego systemu politycznego, nowego klimatu kulturowego i go�spodarczego, problemami z pielęgnowaniem tradycji protestanckiej w realiach promowania postaw ateistycznych,
wszystko wpłynęło na to, że część powojennych repatriantów w latach 1958–1963 „powróciło“ ostatecznie do
Niemiec. Ci co pozostali musieli dopasować się do istniejącej sytuacji politycznej i stać się częścią nowego społe�czeństwa Regionu Kłajpedy
Prevalence, Risk Factors, and Psychological Effects of Primary Nocturnal Enuresis in Chinese Young Adults
Authors: Hu Hui Jie , Zhang Zhen Wei , Liang Yu , Luo Yan Yan , Dou Qi Feng , Song Cui Ping , Zhang Hui Min , Zhao Ying , Tian Guang Run , Zhang Ke , Mao Qiu Fang , Song Jing Gui , Rittig Soren , Wen Jian Guo
Published: March 2021

Purpose: This study aimed to investigate the prevalence, risk factors, and effects of primary nocturnal enuresis (PNE) on physical and mental health in young adults in mainland China.Methods: An anonymous questionnaire was used to collect information including the sociodemographic characteristics, history of PNE, family history, daytime voiding symptoms, Pittsburgh Sleep Quality Index (PSQI) scores, Self-Esteem Scale (SES), and Self-Rating Depression Scale (SDS). A total of 22,500 university students from 23 provinces and 368 cities in mainland China were included.Results: In total, 21,082 questionnaires were collected, and 20,345 of them qualified for statistical analysis. The PNE prevalence was 1.17%, and the distribution of monosymptomatic nocturnal enuresis (MNE) and nonmonosymptomatic nocturnal enuresis (NMNE) was 66.1% and 33.9%, respectively. In total, 28% of respondents with PNE reported bedwetting daily, 31.6% between 1 and 7 times weekly, and 40.4% between 1 and 4 times monthly; 80% of PNE cases had no history of treatment. The prevalence of PNE in patients with a family history, frequency, urgency, urinary incontinence, and recurrent urinary tract infections was significantly higher than in those without these conditions (P<0.001). PNE was significantly correlated with the PSQI total score (sleep quality) (P=0.011). The SES score was lower and the SDS was higher (P<0.001) in the PNE group than in those without PNE.Conclusions: In mainland China, the PNE prevalence among young adults was found to be high, and PNE had significant effects on physical and mental health. Risk factors included a family history, daytime voiding symptoms, and lack of treatment.
数字经济时代服务贸易的创新发展研究
Authors: 刘 莉
Published: March 2021

新技术的发展与运用使我们进入到一个技术革命和产业革命蓬勃变化的新时期，数字经济的发展是这个时期的主流趋势。数字经济时代的服务贸易具有创新发展的新趋势和新要求，我国在这一领域既有新机遇和新优势，也面临新挑战。本文在总结数字经济对服务贸易创新发展的积极影响，和我国在这一领域发展面临的有利条件的基础上，着重阐述数字经济时代服务贸易的创新发展思路；并从产品创新、模式创新、营销方式创新、与制造业融合方式的创新和研发系统的创新等不同领域，总结值得借鉴的创新策略。
论我国上市公司信息披露制度
Authors: 黄 洁 , 张 芸
Published: March 2021

上市公司信息披露制度，有利于资本市场的稳定发展。尽管在信息披露方面，已有相应的法律法规，但由于我国证券发展较晚，披露制度在一些方面仍有不足，违规事件屡有发生，既损害中小股东、投资者的利益，又影响证券市场的发展。因此，有必要从我国信息披露制度中的不足之处出发，借鉴美国的有关规定，对上市公司信息披露制度作出一定的修改。
生态语言学视角下的生态友好语言研究以“What’s the Forest Doing”在大学英语教学设计中的应用为例
Authors: 蔡 绵绵
Published: March 2021

生态语言学为探索语言的生态因素以及语言与生态的关系提供了理论基础。语言体系、语言政策和语言规划必须以维护人类社会良好的生存环境为出发点和终结点。本文将生态语言学理论结合COCA语言库检索数据，应用于大学英语课堂教学实践，启发学生分析不利于生态和谐的语言表达，并思考其背后所蕴含的语言策略和意识形态之间的关系，从而寻求构建生态和谐的语法表达，树立正确的生态价值观，构建环境友好型社会。
中印纺织品产业内贸易变动趋势分析
Authors: 程 靖然
Published: March 2021

自唐朝以来，中国和印度频繁地进行贸易往来，丝绸之路成为了两国之间贸易往来的重要渠道。与此同时，两个国家的消费者也有更多的需求偏好相似，对于产业内贸易的发展有着积极的促进作用。两个国家在纺织品行业中都迎来了朝气蓬勃的发展时期，其产业内贸易的发展也十分迅速，不断拉动两国经济贸易水平的持续上升。1995年中印双边贸易额为11.63亿美元，在二十年后的2014年突破700亿美元，到2019年已达到913.6亿美元，同比增长1.6%。通过这些数据可以发现，中印之间的贸易额对比其他发达国家还相差甚远，但两国目前的经济贸易正进行飞速的发展。中国和印度在世界中都是人口大国，市场份额较为庞大，随着近几年两国不断进行政治往来，其经济交往也不断加强，产业内贸易的发展也得以持续推动，且对双边贸易起一定的积极作用。本文基于对中印纺织品产业内贸易G-L指数变动以及影响两国纺织品的各类因素进行分析，深入探究中印纺织品产业内贸易的发展趋势，发现其主要的影响因素分别为中印两国的人均GDP差值、两国间净出口贸易差额、生产规模、外商直接投资以及两国的开放程度。通过研究结果可以更好地改善两国之间的贸易环境，进一步调整产业结构，以及推动两国经济实现贸易自由化。
对中国空调产业进出口贸易模式的探索 基于产品生命周期模型
Authors: 王 紫涵
Published: March 2021

全球变暖趋势的持续，使得空调产业的进出口贸易模式呈现了一些新的发展趋势和变化。中国空调产业作为全球空调产业中重要的一部分，为促进全球经济发展扮演了关键性角色；准确定位产业生命周期阶段，有利于培育具有国际竞争力的细分产业并实现产业创新，对于企业决策和政府产业政策起到关键作用。本文基于产品生命周期理论，对中国以及美国、日本、越南等国的空调产业净出口趋势做交互对比分析，综合运用含结构变化的单位根检验方法以及生长曲线拟合法，推估出中国空调产业周期变动趋势的拟合效果。最后，为实现我国空调产业的可持续发展，提出当前存在的问题及对策建议。
U-Pb zircon and titanite ages and Sr-Nd-Hf isotope constraints on the timing and evolution of the Petrohan-Mezdreya pluton (Western Balkan Mts, Bulgaria)
Authors: Peytcheva Irena , Tacheva Elena , von Quadt Albrecht , Nedialkov Rossen
Published: March 2021

A combination of methods is applied in the present study to define the exact age of the Petrohan and Mezdreya plutons and trace their magma evolution. Field, petrological, and geochemical studies of the Petrohan pluton revealed its complex evolution and emphasized the role of magma mingling and mixing, complementary to the normal assimilation and fractional crystallization (AFC) processes. Using high-precision conventional U-Pb (CA)-ID-TIMS zircon and titanite dating in combination with CA-LA-ICP-MS zircon dating and tracing, we suggest an incremental growth of a common Petrohan-Mezdreya pluton. It was assembled over minimum 4.5 Ma from 311.14±0.48 Ma to 307.54±0.54 Ma. The younger age of the gabbro (308.12±0.33 Ma), compared with the age of granodiorites (311.14±0.48 Ma), provides numerical proofs for magma replenishment during the assembling of the Petrohan pluton. Whole-rock strontium-neodymium (initial 87Sr/86Sr ratios of 0.70521–0.70527 to 0.70462 and 143Nd/144Nd of 0.51221 to 0.51210) and Hf-zircon isotope data (ε-Hf from –5.8 to +3.6) argue for interaction of mantle derived magma with crustal melts but also mixing and mingling and transfer of zircon grains between the gabbroic and granitic melts. Possible petrogenetic scenario includes melting of subcontinental mantle lithosphere and crust and evolution trough AFC, FC and mingling/mixing processes. Considering the Petrohan-Mezdreya pluton as part of the Variscan orogeny in SE Europe, our new data support the accretion/collision of both the Balkan and Sredna Gora/Getic units with Moesia in the Early Carboniferous followed by syn- and post-collisional Carboniferous and Permian magmatism.
Palaeoecological analysis and environmental development of the Kostenets Neogene Basin, Bulgaria
Authors: Ognjanova-Rumenova Nadja , Yaneva Marlena
Published: March 2021

A comprehensive lithological and biostratigraphic investigation into diatoms and chrysophycean stomatocysts was conducted on two boreholes from the central zone of the Kostenets Neogene Basin. The diatom flora consists of 105 species, varieties, and forms. The results of these different analyses presented herein indicate three successive stages in the palaeoenvironmental development of the Kostenets Basin, at the end of the Miocene and the beginning of the Pliocene.
The Botevgrad basin main characteristics and evolution
Authors: Dotseva Zornitsa , Vangelov Dian , Gerdjikov Ianko
Published: March 2021

The Botevgrad basin is one of the numerous Late Pliocene–Quaternary basins developed over the Balkanide orogen. The basin is developed in the West Balkan tectonic zone and on the northern slopes of the Stara Planina Mountain along the Plakalnitsa fault zone, the front of the orogen. The basin was interpreted as half-graben formed on the SW block of the Dragoybalkan fault, considered as the Plakalnitsa fault zone’s extensionally reactivated roots. Our data suggest that the basin formation is more complicated and all basin boards are fault predestined. The boards are morphologically well prominent and their geometry is a result of the reactivated older faults’ segmentation, combined with the different rheology of the basement lithologies, mainly Palaeozoic low-grade metamorphites and intruded into them syn- to post-metamorphic granitoids. The distribution of the numerous depocentres, the orientation of drainage systems, watershed shape and depositional system migration indicate polyphasic basin evolution. The basin shape and other data, such as criteria for sense of shearing, and intrabasinal push-up blocks’ rotation, suggest that the Botevgrad basin should be interpreted as pull-apart basin.
Robust Output Feedback of Minimum Phase Nonlinear Systems
Authors: Elisante Emrod
Published: March 2021

A robust output feedback controller is synthesized for minimum phase multivariable nonlinear systems based on thedifferential geometry approach. Using the internal model control structure within the input-output (I/O) linearizationframework, the controller is combined with a closed-loop observer to estimate transformed states in the outer-loop. It isshown that the controller-observer combination achieves robust tracking and estimation using simple tuningparameters. The effectiveness of the proposed system is illustrated by a simulation example for control of concentrationin a chemical reactor.
Assessment of Strength Compliance with Standards for Tanzania Eucalyptus Wood Poles Treated with Copper-Chromium-Arsenic Compounds
Authors: Mrema Alex Lyatonga
Published: March 2021

Samples of copper-chromium arsenic compounds (CCA) treated Eucalyptus poles for power transmission were sampledfrom a lot following Military Standard MIL-STD 105D, Single sampling, Tightened Inspection, Acceptable Quality Level(AQL) of 4 as provided for in the South African Standard SABS 754:1994 from lots containing 151-500 poles. Sampleswere randomly selected from a lot. Maximum fiber stresses were evaluated taking into account the actual taper in eachpole. The cantilever loading test was performed on the samples following SABS 754:1994. It was found out that theaverage taper for the poles was smaller than that assumed in the standard due to the different pole growthcharacteristics and environment in Tanzania and that the average modulus of elasticity obtained for the poles was lowerthan the average assumed in SABS 754:1994. The poles also showed excessive deflections at working loads. It isrecommended to the Tanzania Bureau of Standards that although SABS 754:1994 is meant to be used for eucalyptuspoles grown in Southern Africa south of the Sahara that are treated with creosote or CCA there is a need to review it totake into account the actual characteristics of the poles grown in Tanzania where they are normally grown in highlandareas with higher rainfall and colder climates.
Accuracy Analysis for Kolmogorov Entropy Esed in Studying the Chaotic Dynamics of CFB Reactors Based on Solids Concentration Fluctuations
Authors: Manyele S.V.
Published: March 2021

Yatta Canal is situated in Yatta division, Machakos district about 100 km from Nairobi along Thika- Garissa road. It is about 60 Km long and supplies water for domestic, livestock and irrigation use. Over the years, the water supply has been unreliable especially during dry season leading to conflicts between upstream and downstream consumers. Sometimes the Government has been forced to intervene to restore order. The study aimed at assessing the use of Yatta canal, based on the principles of Integrated Water Resources Management (IWRM) which stipulates efficient use of water and involvement of all stakeholders in decision making for sustainability. Based on this concept, it was established that the current water demand outstrips supply and that there is inefficient water use especially for irrigation. Waterallocation process favours landowners, and stakeholders are not fully involved in planning, management and development. Further, women’s participation in decision-making is minimal. There is no environmental voice during water allocation and thus the reserve/ base flow in the canal has not been maintained. This means that IWRM concept has not been practiced and this has resulted to conflict among various water users. As Yatta canal gets water from Thika river, there is need to establish Thika river basin water users association where stakeholders can influence decisions on water allocation and management. This will create a forum to discuss efficient water use at all levels and promote internal policing to ensure fair allocation, thus minimizing conflicts and promoting the IWRM concept.
Quality Control in the Construction of Reinforced Concrete Buildings in Dar es salaam
Authors: Rubaratuka I.A.
Published: March 2021

Quality Control in the construction industry is very important to ensure that what is being done conforms to the applicable standards or good practice and the contract documents. In this article, results of investigations conducted at different construction sites for reinforced concrete buildings in Dar es Salaam to check if quality control measures are being implemented are discussed. It has been established that generally quality control is not properly carried out. Finally, measures to enhance quality control on sites are outlined.
Trends of Rainfall and Maize Productivity in Malawi
Authors: Kimaro T.A. , Sibande H.
Published: March 2021

Daily rainfall data between 1966 and 2005 across all Agricultural Development Areas (ADDs) in Malawi was investigated to determine changes in selected rainfall characteristics and their impact on Maize productivity. Rainfall indices analyzed included rainfall amounts (annual and seasonal), onset, cessation, dry spells and length of rainy season. Man Kendal’s trend test was applied to the time series of these indices to detect any trends in the time series. WaterRequirement Satisfaction Index (WRSI) for maize crop was used to study the spatial-temporal variation of maize productivity and thus its linkage to rainfall. Definition of onset and cessation adopted from the Department of Meteorological Service (DMS) Malawi was used in demarcating seasons to extract seasonal rainfall amount, length and other parameters. The results of the study indicate that with the exception of Karonga ADD located at the Northern tip of the country there were no significant trends in all variables related to crop productivity including onset, cessation, rainfall amount and dry spells. The spatial and temporal variability of maize production in Malawi was captured quite well by the WRSI. The relationship between long-term average WRSI and maize yield (tonnes/ha) for different stations in Malawi had a correlation coefficient of 0.82 while the relationship of countrywide average WRSI and maize yield had a correlation coefficient of 0.75. Areas with low long term average WRSI like Shire valley also showed low productivity while those with higher WRSI like Mzimba and Salima ADD had a good yield. On average Malawi has sufficient rainfall to sustain rain-fed maize crop as most of the time (67%) rain-fall is enough to give an average yield. It was also foundout that Malawi experience droughts and hence food shortages when WRSI value is close to or below 60%.
Application of Non-Destructive Testing in Evaluating Reinforced Concrete Structural Elements in Buildings
Authors: Rubaratuka I.A. , Ndumbaro P.
Published: March 2021

Of recent a large number of existing reinforced concrete buildings have required reconstruction, renovation and improvement. This tendency poses a number of problems that have to be solved, the main one being to determine the actual strength condition of the structural components/elements of the building. It includes determination of the qualityof materials used, specification of the types and description of apparent faults and damages and extent of wear of the building. To undertake this evaluation, non – destructive testing methods are used. In this paper, applications of non –destructive testing methods to determine the strength state of reinforced concrete columns with corbels and to establishtheir structural strength so as to determine the capacity of a mobile crane to be installed is outlined.
The Multivariate Statistical Analysis of Abiotic Parameters of the Lake Tanganyika Sub Catchment
Authors: Nkatagu H.H.
Published: March 2021

Results from multivariate statistical analysis of abiotic parameters conducted during the dry season at 20accessible sites on 8 rivers, 2 lakes and a dam covering the Lake Tanganyika sub catchment are discussed.Standard methods were used to determine the levels of abiotic parameters from water samples. Physicalparameters including DO, EC, Eh, turbidity, temperature, pH and secchi transparency were measured in situwhile chlorophyll a was determined in the laboratory. Nutrients such as NO3-, SiO2, PO43- and Fe2+weredetermined along with HCO3-. Factor analysis resulted in four factors including increased primaryproductivity, redox conditions, dissolution, and reduction processes. Processes including dissolution,diffusion, adsorption, absorption, nitrification, denitrification, mixing and reduction along with theanthropogenic activities, increased photosynthetic activity of algae and the geomorphology of the ecosystemscontribute to the variation of the abiotic parameters. It is recommended that quantification of river flows,sediment load and nutrient budget at various sampling points be determined seasonally for proper evaluationof the hydrologic and limnological functioning of the ecosystem.
The Systemic Nature of Action Learning Programmes
Authors: Mwaluko G.S. , Kundi B.A.T.
Published: March 2021

A lot of attention has been paid on action learning in the last four decades or so and the success of such programmes has also been widely publicized. But why have these programmes been so effective in helping organizations cope with change? Many authors state that the success of such programmes is due to the fact that they link learning to actions. Yet others claim that action learning programmes succeed because they involve employee empowerment and provide a much greater learning curve. In this paper the authors holdthat action learning programmes succeed because they are partly systemic and can be made even more effective if they are fully designed and implemented systemically. The essential features of a systemic method include the ability to help organizations deal with organic, cultural and power complexity. The conclusion that action learning programmes can succeed if they are fully designed and implemented systemically is reached by comparing the essential features of a systemic method with that of an action learning programme.The authors make use of a case study to support their conclusion.
Analytical Modeling of a Large Local Area Network - Part I: Internet Traffic Characterization
Authors: Luhanga Mathew L. , Amos Cuthbet E.B.
Published: March 2021

The goal of both IP network operators and the end users is to get the highest performance from the system for a given cost. This makes Performance a key criterion in the design, procurement, and use of computer and communication systems. In order to address problems associated with performance degradation of operational communicationssystems, over the last decade, traffic engineering techniques have emerged in an attempt to optimize communication systems’ performance and ensure more efficient use of their resources. One of these techniques is analytical modeling. Analytic performance models are an excellent tool for quickly evaluating the performance of operational or new systems. They are also well suited to comparing the performance of several alternative designs. However, analytical models can only be developed once detailed knowledge of characteristics of trafficcarried by a network is available. In Part I of this paper, traffic characterization of traffic carried by the largest Local Area Network (LAN) in Tanzania, University of Dar es Salaam Network (UDSMNET) is carried out. In Part II of this paper, an analytical model based on the Discrete Time Markov Modulated Poisson Process is proposed and validated for performance analysis of IP networks.
Potential Use of Water Guard as a Disinfectant for Domestic Water Use
Authors: Yohana L. , Mashauri D.A.
Published: March 2021

Water Guard which consists of 0.75% sodium hypochlorite (chlorine-based water disinfectant solution) has been identified as an alternative method for treatment of domestic drinking water. The aim of this study was to investigate the effectiveness of Water Guard in disinfecting drinking water from different sources drawn from Kinondoni district, Dar es Salaam as well as to establish appropriate dosage that can be used during the treatment. Results showed that, a dose of 4.0mL per 20 litrer of water guard is sufficient for disinfectionof urban water sources. The above prescribed doses provide 100% disinfection efficiency with residue chlorine of less than 0.3mg/l. Water with turbidity values of 30-35 NTU, chlorine dosage of 8mL/20 litres is recommended and this gives residue chlorine of 0.3 – 0.5 mg/L. From this study, it can be concluded that, Water guard is effective against pathogen and that there is an increase of residue chlorine as the dosage increases irrespective of from which source the water was drawn. Also the safety of water is obtained even where the residual chlorine is less that 0.1mg/l. However, there are health implications associated with theuse of Water Guard which need further research
Design and Development of a Prototype for a Web-Based Interface for Online Material for Tanzanian Youth
Authors: Chumo C. , Mjema E.A.M.
Published: March 2021

A prototype of a web-based interface for an online database was developed to be used by youth organizations in Dar-es-Salaam. A participatory approach involving secondary students in the identification of user interface requirements, in designing and testing the prototype was used. A questionnaire was designed and manned in seven secondary schools in Dar-es-Salaam to estimate the Internet usage. Interviews were conducted to countercheck the questionnaire responses. The interview and the questionnaire helped to come up with a set of user requirements for the web-based interface of an online information search. From thespecifications of the user requirements the author was able to create a youth-friendly web based prototype that can be used by youth groups in Dar-es-Salaam.
A systemic Framework for Implementation of TQM Programmers
Authors: Mwaluko G.S. , Mjema E.A.M.
Published: March 2021

The purpose of this paper is to present a systemic framework for implementation of TQM program in amanufacturing organisation that produces motor vehicle components in Port Elizabeth - South Africa. Theapproach used included conceptualisation of the systemic framework and then involvement of the stakeholdersin adding scenarios to be considered in the design and implementing the framework in the real field. Thefindings obtained during the implementation of the systemic framework established that reduction of scraprate, reduction of production costs, reduction of cycle time and employee motivation could be achieved throughthe implementation of a Systemic Framework for the TQM programme. The TQM team was satisfied that theimplementation of TQM programme using the systemic framework was relevant in their particular situation.The developed systemic framework for implementation of TQM was tested in a company that manufactures motor vehicle components. The experience gained shows that the framework has a big potential for successful implementation of TQM. The developed systemic framework has a holistic approach in implementation of TQM; in that case it can be used to guide the design and implementation of successful TQM programmes. The developed systemic framework is a holistic approach, which took on board all four basic characteristics that portray an organisation. Organisations are portrayed by four interrelated characteristics namely, organisational processes, organisational design, organisational culture and organisational politics. For a successful implementation the TQM intervention should take into consideration these four characteristics.
Improvement of Hydraulic Press for Vegetable Oil Expression in Rural Areas
Authors: Kibazoni Oscar , Damson Lonaard
Published: March 2021

Cultivation of oil producing crops especially Jatropha and croton as source of vegetable oil for biodiesel production is being encouraged in rural areas. To recover oil from seed, manual press is the feasible method in rural areas where there is no electricity. Research was conducted to improve hydraulic oil press machine for rural application. Factorsaffecting oil recovery were found to be: moisture content of seeds, operating pressure, seed oil content, and the amount of seeds pressed per batch. Percentage oil recovery was improved by reducing diameter of press cylinder, hence increasing expression pressure, and either reducing amount of seed processed per batch or placing disk within the seeds to improve oil flow. The maximum vegetable oil recovered from Jatropha seeds at a pressure of 20.8 MPa after improvement was 57.5% of the total oil in seeds. There was no significant difference in terms of oil recovery between pressing whole seeds or milled seeds. Suggested further improvement includes: higher pressure than 20.8 MPa, reduced radial distance travelled by oil and replacement of hydraulic jack with a self retracting double acting hydraulic power cylinder to reduce batch cycle.
Problems and Prospects of Hydraulic Modelling For Environmental Flows Assessment Studies in East Africa
Authors: Ndomba Preksedis M. , Nobert Joel
Published: March 2021

The objective of this paper is to document the problems and prospects of hydraulic modelling for Environmental Flows Assessment (EFA) studies based on selected case studies. Most of studies in East Africa use Holistic methodologies. An ideal data set for defining river hydraulics for most of these methods would be six data points of stage measurements over a good distribution of discharges, the stage of zero discharge and some flood-related data. Besides, in East African region EFA studies suffer from data scarcity (i.e., poorly gauged sites) and limited expertise and funding. The hydraulics studies conducted by the authors entailed desktop research, limited fieldwork for data collection, data analysis, and modelling. The hydraulic models (HEC-RAS and PHABSIM) used are governed by Manning and/or Energy equation(s) to simulate hydraulics. The optimized sensitive parameters include roughness number, expansion/contraction coefficients,roughness modifier and Beta coefficient. Data collected at medium flow, bank full discharge information at neighbouring flow gauging stations, information from previous studies, field observations on flow regimes and professional experience validated the performance of these models. The geometric characteristics for extended floodplains and/or swamps were derived from a calibrated NASA Shuttle Radar Topographic Mission (SRTM) Digital Elevation Models (DEM) of 30 arc-seconds resolution under HEC-GeoRAS GIS extension Environment. The modelling results were considered satisfactory because the relative errors for most of applications fall below 20%. The good performance achieved is attributed to the instituted quality control measures right from suitable sites selection to hydraulic modelling phases. Modelling results confidence rating of above 3 in a scale of 1 to 5 achieved depended upon the hydraulic complexity. Based on the satisfactory results in the case studies, the authors would like to note that there are some prospects of carryingout hydraulic analysis in the regions with inadequate data. However, professional input is the key to successful modelling exercises. Therefore, follow research should use more data to verify the approach adopted.
Optimising the Performance of Roundabouts in Dar Es Salaam City
Authors: Mfinanga David A.
Published: March 2021

Intersections are one of the major bottlenecks that aggravate congestion in road networks; effective control of which is an important strategy in improving traffic flow. While developing countries have found it hard to adopt sophisticated means of intersection control, they have also not optimised the performance of roundabouts. This paper reviews the  erformance of roundabouts, which have become increasingly popular in recent years, as simple and low cost forms of intersection control. The performance of three major roundabouts in Dar es Salaam has been analysed and results show that roundabouts can accommodate high traffic volumes without causing excessive delays. The results also showthat low-cost improvements on roundabouts, involving minor adjustments in geometry and improved traffic management, can significantly improve their operational performance.
Assessment of Quality Stability of Composite Flours Produced By Dar es Salaam SMEs
Authors: Rweyemamu Leonard M.P.
Published: March 2021

A study was conducted to assess quality stability of cereal flours processed by food processingSMEs in Dar es Salaam. This product is obtained by mixing various cereal grains and isconsidered as of higher nutritional values in Tanzania. The shelf-life was predicted bydetermining water activity (a w ) and moisture content (MC) levels and plotting the water sorptionisotherms (MSI). Ninety per cent of investigated samples (N=78) were found packaged in thematerials of various quality conditions. It was found that the packaging materials mostly used isplastic films (63%), paper packets/bags (26%), hard papers (3%), plastic jars (1%) andcombination of paper packets/boards inserted with plastic film (7%). Water sorption isothermswere plotted for single and multiple ingredient products. The highest levels of a w were observedfor products in paper bags with 0.63 (a w ) and 0.13 MC (kg water/kg solids). Plastic films andjars had intermediate levels at 0.52 (a w ) and 0.042 MC (kg water/kg solids), and combined paperpackets/boards with plastic films had lowest levels at 0.43 (a w ) and 0.038 MC (kg water/kgsolids) exhibiting highest stability of products packaged in these materials. Relative humidityand temperature at sampling locations ranged from 80 to 94% and 30 to 34oC, respectively.Multiple ingredient products showed the lowest a w and MC levels, whereas single ingredientflours possessed higher a w and MC values. Generally, the package system comprising paperboard (or hard paper/box) and plastic bag (plastic film) was the most stable followed by plasticfilms, and paper bag by far.
Application of Trip Generation Models for Urban Transport Planning In a Data Scarce Developing Country City: The Case of Dar es Salaam
Authors: Bwire Hanniabl
Published: March 2021

With the increase in travel demand and traffic management problems in many developingcountries cities, travel demand forecasting models are being employed increasingly tomake informed decisions about the operational improvements to the existing transportationsystem and the design and performance of future transportation systems. The mainadvantage of using travel demand forecasting models for such purposes is that they arecapable of capturing the interactive effects of different components of the system understudy. However, for some time now there have been concerns about the application oftransport planning models in developing countries. The concerns have been mainly inrelation to the variables, coefficients and models borrowed from developed countries. Thispaper first discusses the characteristics of transport problems in developing cities andprovides a review of trip generation modelling approaches. Then, the discussion extendsfurther to cover available data for urban transport planning and trip generation modelsthat have found application in Dar es Salaam, Tanzania. The paper concludes byhighlighting how available data sources and trip generation modelling approach can beimproved to cope with the dynamic conditions in Dar es Salaam.
Restoration of Historic Buildings in Zanzibar
Authors: Makunza John K.
Published: March 2021

Looking at current state of most repaired historic buildings in Stone Town of Zanzibar, it is quite clear that the repair attempts made have not been very successful. Modern materials and techniques introduced in the repair works have often proven to be incompatible with the original materials causing accelerated deterioration of buildings fabric. This shows that, there is no comprehensive study undertaken so far on identifying the appropriate materials and restoration techniques. To solve this problem, a study has been made with the main objective of developing the means of restoring historic buildings by using materials existing in Stone Town of Zanzibar. The study was conducted through visual investigation and laboratory testing of materials taken from existing historical buildings and those that are currently being used for repair. Laboratory test conducted includes chemical analysis, grading, compressive strength and water absorption. The results showed some similarities in both materials, however, the combination ratios are not the same resulting into different properties. It has therefore been established that sand of the same grading pattern as the one found in the historic building mortar must be sought and utilized in making repair mortar at a ratio of 1 part lime to 3 parts sand.
Effects of Methyl-blue Addition in Sewage Substrate on the Performance of Microbial Fuel Cell
Authors: Kidehu Joseph , Geophrey John
Published: March 2021

Experimental study was undertaken to evaluate performance of microbial fuel cell. Without addition of methyl blue, the cell generated 1.265 V, 0.403 mA and 56.12 mW/m2 after three hours of operation. With 300 µM methyl blue in sewage anolyte, 6.7% increase in voltage, 20.5% increase in current and 28.6% increase in power density was observed. By using ash- water catholyte, addition of methyl blue in anolyte led to increase of 9.0% in voltage, 38.5% in current and 50.9% for power density. Between three and twenty four hours of continuous operation of the cell with phosphate buffer catholyte, the average voltage was 1.305 V and the average current was 0.321 mA before addition of methyl blue. Methyl blue addition led to 5.1% increase in voltage and 55.2% increase in current. For the case of ash-water catholyte with methyl blue in anolyte, led to 6.2% increase in voltage and 59.1% increase in current.
Educação republicana e democrática: potencialidades e desafios para a formação inicial docente
Authors: Johann Maria Regina , Fensterseifer Paulo Evaldo
Published: March 2021

O artigo trata de aspectos da formação inicial (FI) que visam assegurar princípios republicanos e democráticos evidenciados nas leis e diretrizes da sociedade brasileira. Objetiva-se refletir acerca das noções que os professores da escola básica têm acerca da laicidade e, por consequência, intenciona-se dar visibilidade a esta perspectiva formativa como uma possibilidade de assegurar princípios republicanos e democráticos. Referencia-se em autores que tratam da Escola Republicana (ER); na Constituição nacional de 1988; na Lei de Diretrizes e Bases da Educação Nacional, Lei nº 9.394/1996; e nas Diretrizes Curriculares Nacionais para a Educação Básica; com inspiração em uma tarefa desenvolvida no interior da disciplina de Educação Brasileira. Nela, os acadêmicos entrevistam professores de escolas públicas, de diferentes áreas de conhecimento, acerca do entendimento de ER, e as possíveis implicações deste entendimento para as aulas e para o conjunto das atividades desenvolvidas nas escolas em que atuam. A partir deste diálogo, o tema adentra as aulas da referida disciplina e é tematizado à luz dos princípios da ER. Como resultado, constatam-se: o desconhecimento do tema pela grande maioria dos professores, especialmente aqueles com mais tempo de atuação no Magistério e a (quase) ausência do tema em cursos de formação continuada. De nosso horizonte de compreensão, argumentaremos a favor da presença do referido tema nos cursos de FI, a partir do entendimento de que a especificidade da educação escolar, em sociedades democráticas, necessita pautar-se pelos princípios da ER.
A metáfora, o Enem e a democracia
Authors: Velasco Diego Bruno , Rocha Ana Angelita Costa Neves da
Published: March 2021

O presente trabalho buscou problematizar os sentidos de “democracia” nas edições do Exame Nacional do Ensino Médio (Enem). O objetivo deste trabalho se insere no atual contexto educacional e político do país, em que as garantias dos direitos civis estão ameaçadas e em que consideramos necessário, na posição de docentes da Educação Básica e do Ensino Superior, discutir as disputas pela significação/validação da categoria “democracia” dentro de uma política curricular nacional avaliativa de acesso aos cursos de graduação. A fundamentação teórica se construiu no intenso debate entre a teoria do discurso e a teoria política, a partir de Ernesto Laclau e seus interlocutores. O procedimento metodológico de análise dos itens do Enem observou a estrutura e a proposta de gabarito da questão, indicando como as significações de “democracia” possibilitaram ou não produções de subjetividades ativas. Em linhas gerais, nossas reflexões foram construídas a partir dos discursos produzidos sobre a categoria “democracia” dentro das questões referentes ao tema da Ditadura Civil-Militar (1964-1985) nas edições de 2009 até 2017. A hipótese inicial deste trabalho observou que a democracia é uma potente metáfora para conjugar conteúdos voltados para formação cidadã, ainda pouco explorada pelo exame. Em termos de conclusão, destacamos que o conceito de “democracia” ficou mais restrito a uma concepção tradicional de direito ao voto, mobilizando poucos outros sentidos. Ao mesmo tempo, constatamos que o Enem reforçou a produção de discursos que tenderam a antagonizar o período da Ditadura Civil-Militar com o período da história política do país que se inicia em 1985,  apresentando poucos eixos conectivos entre tais momentos históricos.